What? The sun isn't always shining?!

In this episode, Princeton professor and energy modeler Jesse
Jenkins tackles the question of how we can build a decarbonized
energy system that relies on inherently variable wind and solar
power.


(PDF
transcript)


(Active
transcript)


Text transcript:


David Roberts


If you’ve spent much time discussing clean energy on the
internet, you’ve probably come across a disturbing piece of
information: the sun, it seems, is not always shining. What’s
worse, the wind is not always blowing!


It’s crazy, I know.


Unlike coal or natural gas or nuclear — “dispatchable” power
plants that we can turn on or off at will, when we need them — we
do not control solar power and wind power. They come and go with
the weather and the rotation of heavenly bodies. They are, to use
the term of art, “variable.”


Many people, bringing to bear varying levels of good faith,
conclude from this fact that we shouldn’t or can’t shift to an
electricity system that is based around wind and solar, at least
not without occasionally shivering in the cold.


Is that true? Do we know how to balance out the variability of
wind and solar enough that we can fully decarbonize the grid with
them? This is probably the number one question I hear about
renewable energy, the number one reservation people have about
it, so I decided it’s time to tackle it head on.


To help, I called on longtime Friend of Volts, Princeton
professor and energy modeler extraordinaire Jesse Jenkins. We
walked through the basic shape of the problem, the different time
scales on which variability operates, and the solutions that we
either have or anticipate having to deal with it.


This one is long and occasionally gets a bit complex, but if
you’ve ever wondered how we’re going to build an energy system
around wind and solar, this is the pod you’ve been waiting for.


All right, I am here with Princeton professor and longtime friend
of Volts, Jesse Jenkins. Jesse, welcome back to Volts. Thanks for
coming back.


Jesse Jenkins


Hey, Dave. It's always good to chat with you.


David Roberts


Jesse, the reason we're doing this is that in the course of my
research, I have come across some extremely disturbing
information which I felt like I needed to share with you and the
world as soon as possible. Apparently, the sun is not always
shining and the wind is not always blowing.


Jesse Jenkins


Wait, what?


David Roberts


I know this changes everything, so we're going to have to talk
through this.


Jesse Jenkins


Oh, man.


David Roberts


But seriously, I don't mean to make too much light of this. This
is a subject about which people say lots of dumb things, but it
is at its heart, I think, a perfectly valid question, a perfectly
valid area of concern. In fact, it is the central area of concern
about renewable energy. It is the central question to answer,
which is the term that used to be used is intermittent. Renewable
energy, wind and solar are intermittent, I think. Now the
preferred term of art is variable, but I think probably the most
accurate terminology for our purposes is non-dispatchable.


It just means we don't control it; we don't turn it on and off.
It comes and goes with the weather.


Jesse Jenkins


Yeah, I prefer just weather dependent. Right. I think it makes
more intuitive sense to people. Like you said, it's solar and
wind power, so it depends on the weather. That is not shocking,
but also defining of what the resource is.


David Roberts


Also dependent on the turning of the planets and the solar
system.


Jesse Jenkins


That's true.


David Roberts


But anyway, people know what we mean. We don't control them. A
lot of people, I think, especially people who are coming, who
haven't given a lot of thought to the clean energy transition and
are starting to grapple with it for the first time, I think
intuitively run up against this question early on in their
thinking, which is "how do we deal with this?" So, I want to take
those questions as good faith questions and talk through answers
to them to the extent we have answers, to the extent we do know
how to deal with it, to the extent we do have the tools to deal
with it, and the extent to which it remains to some extent
unsolved.


I want to start with a couple of really big picture questions
before we hone in on the details. I think the first big one to
ask is just what greenies, what climate people seem to be
recommending, and what we seem to be doing, at least in the early
stages, is shifting from an electricity system based on
dispatchable power plants that we can turn on and off at will to
a system that is fundamentally based on non-dispatchable
weather-dependent power plants that we can't turn on and off,
which, as we're going to talk through, raises a whole host of
issues and problems to solve.


So I think the first thing to address is just why do that at all?
Why take on that trouble? Why not just shift from dirty
dispatchable energy to clean dispatchable energy like nuclear,
hydro and geothermal? Why take on the burden of dealing with
variable energy at all?


Jesse Jenkins


Yeah, it's a great question, and the reality is that now the
reason is that wind and solar are really, really cheap. That
wasn't the case a decade or two ago. And we sort of set off on
this path supporting wind and solar and other clean energy
technologies in different countries, not sort of knowing exactly
where the cost declines would travel. And what we've seen is that
basically, in the west at least, the cost of building new large
scale nuclear power plants, which is our sort of most mature and
previously scaled carbon free generation technology, they've only
gone up over the last couple decades, and we can talk more about
why or that's probably a better subject for another podcast.


Just observe that that is a factual statement. In other parts of
the world, like China and South Korea and UAE, where they're used
to building large scale civil works projects, they've been able
to build nuclear plants at a reasonable expense. And it's a big
part of the mix for those countries. But what we've seen is a
tremendous decline in the cost of wind and solar power. And what
we chalk that up to is what's known as experience curves. I know
there's a great Volts cast in the archives on this topic. You can
go back to listeners.


But the idea is that as we scale up and deploy basically any
technology, but in particular wind and solar at scale, we drive a
whole set of processes kind of centered around innovation and
competition that lower the cost of the technology. And that's
done through economies of scale, either in manufacturing or
production of the technology itself. It's done through
incremental innovations and sort of improvements that just get
more efficient and better at producing and building these things
over time. It's done by learning, by doing sort of tacit
knowledge. The skilled workforce develops and the engineers of
the processes develop over time.


And all of that drives the cost of technologies down as we build
more of them. That's true for ships and flat panel TVs and
aircraft and also for wind and solar. And particularly true for
wind and solar because they are very small modular technologies
that are repeatedly built both in manufacturing and in
installation characteristics that make them well suited to not
just learning, but rapid learning or rapid experience curves. The
sum product of that is that wind and solar are the cheapest way
to get electricity, period. Not just clean electricity, but
electricity in most of the world today.


Solar is the cheapest in most of the world. And if it's not, it's
probably wind, with a few exceptions. And so that's the main
reason to rely on it. It's a cheap source of both clean and
abundant electricity.


David Roberts


Right. So this would be something that the market would be
pulling people to do anyway. These set of problems around
variability would be problems that we would be trying to solve
regardless because people want cheap energy and here's cheap
energy. And so, people are going to figure out how to maximize
their use of the cheapest energy available. In large part, this
is being driven by forces that are not directly related to
climate change. Obviously, we need to do it as fast as possible
because of climate change, but this is not, as I think many
people naively think when they first encounter it, something that
we're taking on just because of climate change.


It is because this prize is out there, this super, super cheap
electricity. And if you can run your widget on super cheap
electricity, you're going to want to figure out how you can do
that.


Jesse Jenkins


Yeah, I mean that's true. Now, I think it's important to remember
that we supported wind and solar when they were expensive
alternative energy technologies. That's what we called them back
in the mid-2000s, right? And we supported them for a variety of
reasons. Right. Because of climate change. Yes, but actually
originally because of energy security concerns that were sparked
by the Arab oil embargoes in the 1970s. And that's what drove the
early era of solar and wind development in the US, Denmark,
Japan, and other countries that wanted to get off of imported
fossil energy.


We still burned a lot of oil in power generation at that time.
And so, finding alternative sources of electricity was important
for energy security. That has come back to the fore of our
attention, of course, with the invasion of Ukraine and Russia's
unprovoked invasion there, which sparked Europe to really
dramatically reorient on a rapid pace away from imports of fossil
fuels, gas, coal, and oil from Russia, which they were very
dependent on. And it shot the cost of natural gas and gasoline
here in the US. Where we, yes, produce more fossil fuels than we
consume. So we're sort of physically energy secure, but we're
still connected to these global energy markets.


And so when a dictator on the other side of the world decides to
invade his neighbor for no reason, that drives up the cost of gas
at the pump and the cost of natural gas for our heating here in
the US, like, overnight. So there's a bunch of important reasons
to pursue these fuels. They also, of course, have no air
pollution. Right?


David Roberts


Air pollution. Yes. Let's throw air pollution in there because
the science on air pollution, as you and I know, just gets worse
and worse and worse. The evident damage of it gets worse and
worse.


Jesse Jenkins


Yeah. And not just mortalities but also it makes us dumber.
There's a lot of clear indication that particulate pollution,
actually it affects our cognition, it affects our hearts, it
affects our lungs, it impedes development of young children. I
mean, it's just nasty stuff. And so if we can produce energy
that's made from a domestic resource, like the abundant wind and
solar that we have across the United States and other countries,
that we can do so affordably and that we can do so without any
air pollution, those are all really good reasons to rely on wind
and solar and to want to tackle the associated challenge of
dealing with their variability and weather dependence.


David Roberts


One other general level question. This is something else I think
people kind of come to intuitively and there are not great
straightforward answers out there, which is and this is a variant
of the first question, but I think importantly different. A lot
of people want to say there are times when the sun will not be
shining and the wind will not be blowing, i.e., there will be
times when renewable energy output is at zero and demand will
still be there. So you'll have to have backup resources capable
of satisfying all that demand. But if you have to have 100%
backup, why not just make the backup the main thing?


Again, why go to the trouble, you know what I mean? This idea
that because they are variable, they require basically 100%
redundancy with non-variable resources strikes a lot of people as
sort of crazy. Like, why don't we just build the non-variable
resources and skip the first step? So what do you say to the 100%
backup hang up?


Jesse Jenkins


Yeah, so the reality is you don't need 100% backup. You do need a
sufficient amount of what I call firm capacity available. It's
capacity that you can use whenever you need it for as long as you
need it. Which makes it a really important complement to
weather-dependent resources like wind and solar, as well as to
we'll get to their role later, but to energy limited or
time-limited resources like batteries or demand flexibility,
which are key parts of the puzzle as well. And so you need a
certain amount of firm capacity. It's a pretty significant
amount.


But the reality is it's not 100% backup. You don't need one for
one, because there actually are really no times when there is no
wind or solar across a large area, unless you're talking about
maybe an island grid that really has no geographic diversity. But
yes, there's nighttime and there's winter, but generally there's
some wind somewhere, right, at all times. And so you don't need
100% backup. So that's the first thing. And the second is that,
again, for all the reasons I just went through, we want to rely
as much as we can, again, not all the time, but as much as we can
on wind and solar.


Because the fuel is free, the cost of installing them is
incredibly cheap. And when you have wind and solar, you displace
other dirtier fuel-consuming resources like natural gas or coal,
and that saves money and it saves lives and it improves energy
security. So all of that is the sort of main value add of wind
and solar. I call them fuel-saving variable renewables, because
when you've got them, you don't need to consume other fuels. And
it turns out that if that's the kind of grid you're building,
then there are pretty cheap sources of standby capacity that
don't cost very much upfront and are perfectly fine to pair with
also very cheap wind and solar to play that backup role. I mean,
the one example is combustion turbines.


David Roberts


We should say that it's also unlikely that a trough in renewable
supply is going to overlap with a peak in energy demand. Those
peaks in energy demand tend to be during the daytime.


Jesse Jenkins


That's true today, although I would worry more about that in the
future as we electrify heating when the demand is likely to peak
in the winter overnight. And so it may be more likely that we do
line up one of those periods, what the Germans call Dunkelflaute
— You have no solar output or very little solar output even
during the daytime because it's winter, it's very cloudy, and
then you have a prolonged period of a big, high blocking high
that sits across a wide region, a weather front that limits the
wind output that can occur both in the winter and the summer.


And so, it is a challenge and it's something we have to plan our
renewables-based grids to be resilient to. But again, that's why
we don't depend entirely on wind and solar. We need a portfolio
or a team. The way I describe it is there's a couple of
metaphors. One is you need a balanced diet in your day-to-day
life. And the fact that starches or wheat is cheap, right, as a
cheap way to get calories, means that the bulk of your food
pyramid or whatever is going to be from those sort of cheap
sources of calories, rice, starch, all the sort of staple crops.


But of course, you also can't subsist entirely on those staple
crops. You need a balanced diet of different things, playing
different roles and combining with each other in a way that gives
you a balanced diet. So the same thing's going on in the grid. We
have imperfect substitutes here for each other. They all produce
electricity just like all foods produce calories, but they have
other characteristics as well. And just like starches and staple
crops are the staple of our diet but not the exclusive makeup of
our diet, wind and solar can be the staple of our energy diet as
well, but have to be complemented by other things.


And so we just need to be clear about that. No one's saying only
use wind and solar power all the time for everything. We're
saying these are cheap, clean, energy secure ways to produce
electricity that are scalable across most of the world. And so
they're going to play a really central role, a star role in our
overall energy mix.


David Roberts


People might be aware there is some controversy about — there are
people out there who want 100% renewable systems versus people
who want some nuclear or natural gas with CCS involved. But the
argument there is not whether you need balancing resources to
balance renewables, right? Even the people who want 100%
renewables acknowledge you need storage and hydro and et cetera,
et cetera, et cetera. They acknowledge you need resources to
balance variable renewables. It's just an argument over which
resources. Right? And we'll get to that later.


Jesse Jenkins


That's right. And I should just say before we dive into solving
the renewables challenges, it is worth noting that it's a big
diverse world out there and we have countries that are situated
in vastly different ways in terms of their geography, their
population density, their available renewable resource potential.
And so there are going to be parts of the world that can't rely
on wind and solar as the dominant source of their energy mix.
Places like North Korea or Japan or the UK.


David Roberts


I was just in Iceland, which gets 100% carbon-free electricity
with zero wind and solar. It's hydro and geothermal.


Jesse Jenkins


Yeah. So we should acknowledge that up front. And I'm not saying
like this is the solution for the world, it just is for a big
chunk of the world. And even in places like Japan or the UK,
which are pretty dense and limited land area, they can rely on
renewables for a good chunk of their energy needs. And they're
trying to do so because of the energy security, affordability and
climate clean air benefits that they offer. So it's a piece of
the mix. Whether it's the dominant majority or not, it depends on
the local circumstances. Some parts of the world are probably
going to need nuclear power or geothermal or other more
energy-dense resources to complement or even fully supplant wind
and solar because of local resource constraints.


But that is going to probably be the exception, not the rule.


David Roberts


Okay, so I want to hone in a little bit on the timescales here.
I'm going to run through and we'll sort of proceed in the
discussion from the first of these to the last. So I'm going to
run through real quickly the different timescales of variability
because renewables are variable, but they're variable on several
different timescales which pose distinct problems. So let me just
run through this real quick. So at the shortest level, you have
variable in terms of seconds or minutes. So you can think of
something like clouds drifting in front of the sun that causes a
slight dip.


There are those constant slight dips in the wind and the sun. And
so you need something that is balancing in terms of near
instantaneous short-term balancing. Then second, you have what
you call minutes to hours. So you think of like ramping. So for
instance, the sun goes down at the end of the day. You go from
100% solar resource to 0% solar resource relatively quickly over
the course of an hour or two. That's a different kind of
intermittency. And then you go up to hours and days. Here you get
to what are called diurnal cycles. Overnight, for instance, the
sun goes down at night and occasionally the sun and the wind will
flag for a couple of days and then come back.


So there's the hours to days cycle. Then you get up to weeks. You
can have weeks of unusually high demand or unusually low
renewables. And then beyond that, you have what's called seasonal
variability. So there can be entire seasons or years where solar
insulation is unusually low or wind is unusually low. So at each
of those timescales, you have a distinct problem to be solved in
the electricity grid. And we have I think it's fair to — I mean,
tell me whether you think this is fair or too crude.


I think that is roughly also the order of easiest to solve to
most difficult basically. But we can get into that. But let's
start at the normal second to second, cycle to cycle variability
of wind and sun. What's our solution there?


Jesse Jenkins


Well, here's where it's important to remind folks that the
electricity system is a pretty unique supply chain, in that
supply and demand have to be balanced every millisecond
instantaneously, basically, in this market. So if you're
consuming electricity somewhere out there, someone has to be
producing it at the exact moment that you're consuming it. That's
true for every location across the entire grid all the time,
which is different than, say, like Amazon's supply chain, where
there's a package in a warehouse somewhere, it may or may not go
out to get to you when you ask for it. It'll take anywhere from a
day to five days right, to get to you.


David Roberts


It's the ultimate just in time delivery.


Jesse Jenkins


It's like Amazon Prime on steroids. So, yeah, it has to be
balanced everywhere. Supply has to equal the demand in real time.
And there's actually really significant physical implications if
that doesn't happen, because you have a whole bunch of generators
and induction motors that are actually synchronized with the
alternating current frequency of the grid. That means that in the
US, every 60th of a second, the grid's frequency is reversing
back and forth. And the motors that are spinning to generate that
electricity and the motors that are induced to spin by that
electricity to do useful things like run industrial processes and
other things are all synchronized with that frequency.


So they're spinning at 60 Hz as well.


David Roberts


What a wild thing it is that it works.


Jesse Jenkins


Oh, yeah. I start my classes like this just to remind ourselves
that this is like the craziest continent scale Rube Goldberg
machine that we've built with incredible physical tolerances. And
it just works. Yeah. So that's important to remind ourselves
because it's not like there isn't variability in that system
already, right? Demand goes up and down. You can flip on a light
switch or plug in your EV, or flip on an electric kettle,
whenever you want. Right. You don't have to ask the grid in
advance. You just do it. And that's true across millions of
consumers all over the continent.


And power plants, transmission lines, they fail sometimes.
Substations go down, transmission lines fail, generators break.
And so not only do you have small changes in demand from your
light switch, but you can have big changes in that supply and
demand balance that happen pretty much instantaneously.


David Roberts


And this is a good distinction to mark here, which is the
distinction between predictable variability and unpredictable
variability, which are very different.


Jesse Jenkins


Exactly. So there's a certain amount of this variability and
uncertainty that already happens in the grid. There's sort of
demand changes that are both predicted and also errors in those
predictions. So we have demand forecast errors every day that are
off by several percent right, from what we thought the demand was
going to be. And we have what grid operators call contingencies
sort of the unplanned forced failures of certain grid equipment
that we have to be ready for at all times. Because if you lose a
1000-megawatt substation with a big factory on it, like an
aluminum smelter, or you lose a generator, a big coal plant or a
gas plant complex, or a nuclear power station, instantaneously,
you have to rebalance that because if supply and demand get out
of balance, the inertia of the grid physically responds.


So it's a little bit like if you remember playing on a
merry-go-round at a playground where you could sort of have a
couple of friends on it and you're spinning it around and then
somebody jumps off and all of a sudden the rotational inertia is
the same, but the weight is different. And the merry-go-round
speeds up really fast, right, because there's less mass to move
around or somebody jumps on and it slows down, right? And that's
the same thing that's happening on the grid in aggregate is if
you add load, is what the electricity system calls demand because
it acts like a physical load on the force that the generators
have to induce to create the electricity. It slows those
generators down just a little bit and they have to work a little
bit harder or you have to add more supply.


One of your friends has to come run up and help you push the
merry-go-round as more people get on. And the same thing, the
opposite happens. If supply exceeds demand, it gets easier to
push, just like when somebody jumps off the merry-go-round. And
so the generators all speed up and so do all the motors that are
connected to the grid. And what's challenging here, again, is
that the tolerances there are incredibly narrow. So just a 1%
deviation in that speed of the grid is enough to trigger devices
to disconnect to avoid damaging themselves because they spin up.


If you have a generator that's designed to go a certain speed and
it starts to go faster than that, it can start to throw turbine
blades out at very high velocities and self-destruct a whole
building, right? A whole very expensive generator that you don't
want to blow up. And same thing with industrial equipment, right?
If they start moving too fast or even too slow, they can cause
damage. So we have these protection devices that will trip
offline devices as the frequency gets out of this very narrow
range. And that can also cause a cascading failure because if you
lose one generator because the frequency is too high or too low,
then you'll start to lose the next generator and then the
frequency will drop even more and then you'll lose the next
generator and it'll go even lower.


And so you get these cascading failures. And the grid operator's
job, really the number one job is to avoid that outcome at all
costs, right? To make sure that this crazy Rube Goldberg machine
is resilient to those kinds of scary unplanned contingencies. So
we always have enough backup generation, enough flexibility what
we call operating reserves or contingency reserves or spinning
reserves — lots of different names for these products — of
basically backup generators that are there able to increase their
output if they're already producing or decrease it very rapidly
or that are offline but can start up quickly to step into the gap
when something occurs.


And that's how we keep this crazy system running right now. So
there's sort of a physical response of inertia as you turn on or
off devices and then we have all of these sort of cascading
markets of different paces of response time that we have backup
capacity waiting for from seconds to minutes to half hour, hour
long kind of startup times. And that system of redundancies is
how we keep the grid running today. And it will be the same set
of solutions and some new ones that will come in to help augment
what we do today.


That'll help us deal with the variability that we now are adding
from wind and solar to a system that is already variable and has
dealt with variability since its very beginning.


David Roberts


Right. It's fair to say, though, that we have a lot more.


Jesse Jenkins


Yes, we will have more.


David Roberts


The second to second variability, for instance, is going to be a
lot more from a wind and solar based system.


Jesse Jenkins


Yeah, it adds a new source of forecast error. Right. Because your
wind and solar is now also variable with the weather and we get
better at forecasting that the closer to real time we get. But
there are still errors in those forecasts. And certain power
plants, coal plants, nuclear plants, others are slow to react to
changes. And so we actually commit them to operate a day ahead of
time. Usually we give a day ahead schedule for the next 24 hours
and that predicts the sort of average demand over the course of
each hour that we're trying to meet.


And so generators get turned on and are ready to meet that demand
based on the forecast. And if the forecast is wrong a day ahead,
then we need to deploy those flexibility resources at different
timescales to cover the surpluses or deficits that we have in the
system. And again, that's already how it works. We're just going
to do more of that. And in some ways, we're going to be reducing
the conventional sources of that flexibility. Because right now
we get most of that flexibility from hydro and fossil power
plants that are committed and operating on the grid but are held
back from operating at their maximum or minimum levels to have
some flexibility to ramp up or down quickly.


So the less of that we have because we're shutting down those
plants to make room for wind and solar when they're producing,
the more alternatives we need or we end up actually having to
curtail wind and solar output in order to keep a minimum amount
of those fossil generators online to maintain reliability. So
that's the first option is you just curtail the renewables. But
of course that's wasting free energy. And so we'd like to have
other ways to take advantage of the wind and solar and still
manage that short term variability. And that's where things like
batteries and synchronous condensers and capacitor banks and
other devices that we can add to the grid to augment their
flexibility on those short timescales come in.


David Roberts


Is it safe to say that with those options, especially batteries,
do you worry as we get closer to net zero, closer to a 100%
carbon-free system, do you worry about this second to second
variability or do you think basically with batteries, we
basically have that problem solved and can handle that?


Jesse Jenkins


It's very low on my worry list. And that's not because it's not
something that somebody has to worry about. It's just that I
think there are very good control engineers and power engineers
and grid operators out there solving these problems already. And
we've known about these problems for decades. And so there are a
lot of solutions already out there. And so pretty much everything
is figured out in this space, I would say, with the exception
perhaps of the physical inertia that really immediate
microsecond, microsecond response that we get from the physical
spinning mass of all of these interconnected generators.


Beyond that, the next line of defense is what we call frequency
regulation or frequency reserves. Those are the ones that sort of
move up and down on a second by second time scale to track a
control signal. They say go up a little bit, go down a little bit
to sort of keep things balanced out. And a few years back, maybe
about a decade now, some of the grid operators in the US opened
those markets up to batteries and particularly lithium-ion
batteries —


David Roberts


Grid services.


Jesse Jenkins


Yep. And it turns out that lithium-ion batteries are incredibly
good at this job because you don't need very much battery
capacity, right?


You don't need a bunch of energy in the tank to be able to do
this because it's generally about neutral, right? You're sort of
going up and down and up and down and up and down around a middle
point. And so you can maybe only have 15 or 30 minutes of full
power discharge capability. And that's still enough to provide
frequency regulation because you're really only charging
discharging on few second to minute long timescales and they're
incredibly fast. So the power electronics responds really quickly
to the control signal and it can flip from full on to full charge
very quickly, much faster than a physical generator could do,
even a hydro generator, which traditionally were the fastest
response.


And so when PJM and other grid operators opened up these markets
in around maybe 2009, I think, to storage, we saw the first
commercial scale deployment of grid connected batteries and they
basically ate the entire market because they're just the best way
to do this.


David Roberts


Yeah, there's not much left of that market in places where it
opens up. It's pretty easy to cover those needs.


Jesse Jenkins


Yeah, you only need probably a few thousand megawatts of
frequency regulation nationally. So that's like a few nuclear
power plants worth of capacity nationally. And we have built that
and a few hundred megawatts usually per grid region. And so the
batteries just came in and you built a few grid batteries and
they have taken on that role very capably. And the market is sort
of full.


David Roberts


Is that what they call synthetic inertia?


Jesse Jenkins


No. So that's the next challenge. So yeah, this is frequency
regulation, which is on the sort of second by second timescale.
That initial response of the physical inertia is like
milliseconds that just happens instantaneously because again, all
of the devices are interconnected and physically synchronized.
And so when the demand goes up a little bit, all the generators
kind of lean into it a little bit and produce a little bit more
and vice versa when the demand drops. And so that is where we
currently depend on the physical inertia of generators who are
connected to the grid and producing power.


And we get that for free. It's not something we pay those
generators for, it's something that they just physically have
provided for free. And it's been ample and well in excess of the
amount that we generally need with rare exceptions like islands
or micro grids where it's much more challenging to keep enough
inertia. And so we haven't been paying generators for that. It's
just sort of a bonus that we get from having these synchronized
generators online and grid connected inverter based resources,
which includes wind, solar and batteries and fuel cells and any
other kind of direct current device like that electric chemical
device.


They're not synchronized spinning masses of copper and steel like
generators are and so they don't provide that physical inertia.
And so synthetic inertia is basically a computerized control
strategy to make those inverter based resources act like a
physical inertia device would and to sort of automatically
compensate based on local measured characteristics. This is too
fast to send a control signal out even from a centralized
dispatch. It has to be locally metering what's going on, and
directly responding to the local conditions without knowing
what's going on in the rest of the grid. And so you are basically
designing control strategies to use the power electronics in an
inverter to change the reactive power production or consumption
of the battery or the solar panel or the wind farm, which can, if
you do it right, can tune it well, can simulate and replace the
physical inertia that you get from the system.


This is something that, again, people have been working on for
decades in the lab. We've done lots of experiments. It's one of
those ones that grid operators are very reluctant to deploy at
scale and rely on in a field experiment because if it goes wrong,
the grid goes down potentially. And so it's one of those ones
like, it probably would work if we were willing to just jump off
the cliff and try it. But for obvious reasons, this is an
incredibly conservative industry. And so there's been various
small scale deployments to try to see how it works.


But nowhere in the world that I'm aware of is relying
substantially on synthetic inertia today. Again, with the
exception, maybe, of small micro grids. I should say that there's
a dumber, simpler and slightly more costly solution that we can
fall back on, even if that doesn't work, which are called
synchronized condensers, which is basically a generator without
the turbine, without the spinning prime mover that are just
spinning hunks of copper wires in magnets that are on the grid
and are synchronized. They consume a little bit of electricity to
spin around and stay synchronized. So they do use up some
variable, some of the energy production, and they do cost money
because they're basically half of a generator, the magnet part
without the turbine.


But these have been around for a long time, and they're used in
certain locations to buffer short term variability from, say,
starting up a steel mill, electrical steel mill or aluminum
smelter. That is this big new demand that comes on very quickly.
They've been used in that context and to support the voltage at
certain little pockets in the grid where it's been hard to do so.
And I recently read a thesis a dissertation from University of
Melbourne PhD student who modeled this as an option without any
synthetic inertia in the grid, but a minimum physical inertia
requirement and found that it would add to a fully decarbonized
system about 1% or 2% to the cost of that system, if we only
relied on synchronized condensers to do the job.


So, again, these are mature technologies we know how to build. At
worst, they add a couple of percent to the system. At best,
they're free, because all of these inverter connected devices
that we're adding can perform the same role as physical inertia
via synthetic controls. And again, that's more perspective at
this point, but I think it's an imminently solvable challenge.


David Roberts


Okay, so this is the super short-term variability. Let's call it
a solved problem, at least as these things go. So let's move up a
little bit. Then you get big ramps, ramps in the morning when the
sun comes up and goes down. Occasionally wind will die down
quickly. What do you do about these sort of minutes to hours
midday variability?


Jesse Jenkins


So I'll say what we do now and then what we could do, which would
be better. Right now, again, we rely on fast-acting thermal or
fossil power plants to play that role.


David Roberts


Mostly natural gas, right?


Jesse Jenkins


Mostly natural gas. Sometimes diesel, internal combustion engine
reciprocating engine generators. So what we do is we commit a
bunch of generators that are ready to act when the sun is about
to set, and they are operating at their minimum stable output
level, which is not zero. So generally, they don't get to just
sort of sit there and park at zero. They have to be on at
somewhere between 40 and 60% of their output, usually, or 30 and
60% of their maximum output is as low as they can go. So during
the middle of the day, when the solar is at its maximum, many of
these are shut off, but then they start to get recommitted in the
afternoon hours, right before this evening ramp and run at sort
of crouch there at their minimum output level and then ramp up
really quickly as the sun sets to compensate.


And so gas turbines are really good at this. They're really fast
to respond. I mean, they're, what, run jet engines, right? I
mean, jet engines are basically gas turbines. And we derived our
gas turbine generators from jet engines. So the fastest ones are
as fast as a jet fighter. They're literally the same engine. We
have one here at Princeton in our central plan as an aero
derivative gas turbine. It's the same. It's used in like an F-16
fighter. So they're really fast to respond because they can
handle a dog fight. But then you also have bigger what are known
as frame combustion turbines and combined cycle power plants that
usually also use these frame turbines connected to a second steam
generator, so they use the hot gas from the combustion turbine as
the steam generation source for a steam turbine as well.


David Roberts


That's combined cycle.


Jesse Jenkins


That's why we call them combined cycle, because they combine a
Brayton and a Rankin cycle, a gas and steam turbine.


David Roberts


So we don't want to do this. We can't do that in a fully
decarbonized grid. I mean, you can, I think, keep some fossil
plants online and use them very, very rarely. But I don't think
you could do that on a day-to-day in a decarbonized system.


Jesse Jenkins


Yeah, I mean, theoretically you could do this with a hydrogen
turbine or something like that, but you would probably consume
way more hydrogen than you want because hydrogen is a very
expensive fuel to produce. And so, yeah, you don't want to keep
doing this on a day to day basis. But I want to add that, again,
we do this now. And this is how we keep the grid running even
when California gets nearly 100% of its electricity during the
middle of the day from solar and wind. The downside is that
because you have to have those generators running at their
minimum level before they can ramp up, because it takes between
30 minutes and several hours to turn on once you call on them.


And like a combined cycle power plant takes the longest of the
gas generators. The air derivative turbines can maybe turn on in
30 minutes, but generally they have to be sort of on and parked
and ready for that ramp. And you need some of them just sitting
there, even for the unforecasted variability. Right. We know that
the afternoon ramp is happening, but —


David Roberts


They're displacing wind and solar while they're sitting there —


Jesse Jenkins


Exactly. And so that limits the ability of wind and solar to
displace their fuel consumption because they're on, not because
they're the cheapest generator to meet demand at that hour, but
because we know we need their flexibility for the ramping periods
or the contingencies that we're waiting for. So it would be great
if we had a really fast way to flexibly produce or consume energy
to match the variability of wind and solar. And fortunately,
there are lots of good ways to do that too, batteries being the
first and most significant new source of that kind of hourly
flexibility. But also the demand side can be called upon much
more as well.


David Roberts


We should note that batteries in this capacity are way faster
than the turbines.


Jesse Jenkins


Yeah, once again, they can do that frequency regulation on a
second by second basis. So they surely can deal with the sunset.
And yeah, they don't need to be committed. They can sit there,
they're on the grid all the time. They can go from fully
discharging to fully charging or back. So they actually have
twice the ramping capability. Right. Because if you have 100
megawatts of battery, it can switch from being 100-megawatt
consumer to 100-megawatt producer, giving you 200 megawatts of
ramping in that battery and they do it in a second, right. From
one to the other. And so they're really good at this.


And we're already seeing them deployed at gigawatt scale in a lot
of markets in the world, particularly those with high solar
penetrations, because this daily cycle is so predictable. You get
really cheap power during the middle of the day and really
expensive power in the evening ramp and so they can make money
arbitraging that spread, buy low and sell high.


David Roberts


Yes. And you also mentioned demand shifting, which is just trying
to move large sources of load under that curve when solar is
producing all this energy away from the times of sharp ramps.


Jesse Jenkins


Exactly. You mentioned at the beginning that we're shifting from
a system of dispatchable generation to one of variable or
nondispatchable generation. Well, we're also hopefully shifting
from a system of nondispatchable demand, constant demand that
doesn't know what the price of electricity is and just keeps
consuming no matter what to dispatchable or flexible demand.
Because power electronics are cheap, computing power is cheap,
controls technologies are very sophisticated and it would not be
very hard to wire up a whole bunch of HVAC controls and hot water
heaters and EV chargers to be much more flexible on both minutes
to hours to even daily timescales.


There's a lot of flexibility in an EV, right? I mean, I have a
300 miles range EV. That's enough for five to seven days of
driving in my typical driving pattern. So not only can I shift
which hours during the night or daytime, if it's plugged in at
home during the day, that I consume energy, but I can even choose
which days to consume, right? I can shift from Monday to
Wednesday or Wednesday to Saturday, right? And that's probably
the most flexible of these loads. But think about a hot water
heater. That's just a big thermal battery.


It's a big insulated tank of water and when you charge it and
heat it up or not, it is quite flexible. You can do it right as
you're drawing down the hot water, or you can preheat it and get
it above the desired temperature. And there are even more
sophisticated ways to do that. Parts of the world that
traditionally relied heavily on hydro or nuclear power, where you
had the problem of too much generation overnight: What those
parts of the world did way back in the 50s through to today is
they have ceramic brick heaters that heat up a big ceramic brick
when the power is cheap, and then let that brick reradiate heat
into your house during the daytime right when —


David Roberts


Thermal storage!


Jesse Jenkins


It's cheap —


David Roberts


We love thermal storage.


Jesse Jenkins


And again, this is not Sci-fi. This is like they do it in Quebec
and the UK and they've done it since the 60s. So we could be
building big thermal batteries in everyone's home whenever we put
in a new HVAC system, right? It could just be part of the HVAC
design, is that you have a big hot water tank or a big hot brick
tank.


David Roberts


We also get to what I think is one of the most fascinating
questions and I think unexplored as yet questions in this whole
area, which is when you are talking about big industrial loads,
how much of that load is shiftable, how much of big industrial
load could be shifted? I don't think there's been a ton of
exploration of that to date. And I think we're going to be
finding out soon what the answer to that question is.


Jesse Jenkins


Yeah, and actually, I have a paper that we just resubmitted this
week. After revisions on this, we can provide a link to the
working paper in the show notes on what we call demand sinks. So
these are consumers that are extremely flexible in when they
decide to consume and will basically match their consumption to
the availability of low-cost power. And since wind and solar are
the cheapest way to make low-cost power, that will mean they can
sync up their output to wind and solar. And so we actually offer
four different categories of demand in that paper to try to help
kind of talk through the options here.


So if we're thinking about the demand side, there's firm demand.
That's the normal stuff that we're used to having where it wants
to have three or four nines of reliability, we usually say, which
is like 99.99 or 99.999% reliability basically all the time. And
that's most of our current demands. Residential, commercial,
lighting and cooking and refrigeration, industrial, most
industrial loads, hospitals and other critical loads, and most
heating demand today. And that's the demand we expect to serve.
And if you don't, it's a big problem, right, that's when you're
having rolling blackouts. Then we have interruptible demand or
curtailable demands.


This is the sort of category of demand response that we have. So
these aren't necessarily shifting their production, they're just
stopping consumption when the price of electricity is really high
or when they're being paid a lot of money to do so. And that's
where things like aluminum smelters or industrial demand response
contracts that they have with a whole bunch of industrial
refrigeration warehouses or consumers with backup generators who
can turn on and get off the grid when the price of power is
higher than the cost of running their generator. That's a lot of
the demand response we have today.


That's also where hydrogen boilers, other things could
potentially play a role. So there's some new ones coming in that
category too. Those ones, you don't want to call on those very
often, but they can help you avoid building a bunch of generation
that just sits there for that like half a percent of the hours of
the year when you really need some backup because they can
consume less during those periods for a few hours at a time. Then
you have what we call shiftable demands. These are the ones we
were just talking about where you can move around when you
consume within a kind of hourly or even daily scale.


Flexible EVs, heating demand, data centers potentially can do
this — something Google has explored, moving around in both space
and time where they do the compute loads.


David Roberts


Yeah, Google is doing a ton of work trying to figure out how much
of their compute load is shiftable.


Jesse Jenkins


Yep. Yeah, one of my former MIT classmates who I happened to see
last weekend at a wedding was working on this with Google. Yeah,
fun stuff to optimize, right? Great control problem to play with.
Then things like agricultural pumping is another one that's often
done already. Like California irrigation districts will shift
when they pump their water into the canals and the reservoirs and
things like that. So that's another tried and true demand. And so
those demands, they meet their needs, right? It's just a question
of when they do it. So it's different than curtailable or
interruptible demands. And then this last category of demand
sinks are the really price sensitive consumers who really can
choose when to consume.


And this is where it's an interesting question which categories
will emerge here? What we found in our paper is that in order to
do this, you kind of need a weird combination of things. You need
something that's highly automated because you can't have a lot of
labor sitting around idle when you stop consuming. Right. Because
that's usually too much of a cost. It needs to be very energy
intensive, meaning a big chunk, if not the most of your cost of
production is the cost of energy inputs. And it needs to produce
something of value that isn't so valuable that you never want to
turn off.


This is the current problem with crypto mining with bitcoin, is
that the bitcoin prices are so high — or they have been, I don't
know, they're all over the place now, so maybe they're lower now
— that you want to consume even if the electricity is several
hundred dollars per megawatt hour, $100 per megawatt hour, it
means you basically consume 98, 99% of the time anyway. So that
makes you more like an interruptible demand, not a flexible
consumer. But if the price of the product is lower, where your
willingness to pay is only ten or 20 or $30 a megawatt hour, then
you want to concentrate to when the load is — or the power is
cheap.


And then finally it has to be not very capital intensive because
if you're going to idle your production and shift your
consumption around to low price hours, you're going to have a low
utilization rate for that capital, all that equipment. And so it
can't be too expensive or you'll need to run it all the time. And
that's where kind of direct air capture fails the test right now
because it meets the other requirements, highly automated,
totally energy intensive, but it's too capital intensive to run
at anything less than maybe 95% of the time. So there are a few
here that I think may work.


And one is, I think we share is one of our favorite technologies
out there, which is resistance heating with thermal storage.
Right. So Rondo or Antora, who you've interviewed on here I'm on
the advisory board of Rondo Energy, I should disclose and big fan
of what they're up to. But here you basically take in renewable
electricity whenever it's available and you use a big thermal
battery like the hot water tank or the ceramic bricks that we're
talking about in the home to decouple —


David Roberts


Box of rocks.


Jesse Jenkins


Yeah, or a box of rocks or even just rocks in the ground covered
up with dirt to decouple the constant heat demand of an
industrial process from the variable input of the wind and solar.
And that's a great option. Another option is to just install
resistance heaters alongside gas boilers. So don't replace the
gas boiler fully or at all, but run it in a hybrid mode, where
when energy prices are cheap electricity prices are cheap, you
switch off of gas to electricity, and when electricity prices are
higher than the gas cost, you go back to gas.


And that makes it look like a very flexible demand sink. That was
a technology we put in the model for the Net Zero America study
and we saw like terawatts of that load in the final Net Zero
system. Right.


David Roberts


So the system wants —


Jesse Jenkins


Wants that cheap renewable electricity if it can use it. Right.
So if you can find a way to meet your constant energy demand for
industrial heat while tapping into this cheapest source of
energy, period, whenever it's available, that's a really valuable
thing to do.


David Roberts


Yeah, I think that one's going to be huge in like a decade.


Jesse Jenkins


Yeah, I think so. I think the industrial heating is the biggest
one that people largely are sleeping on. Although not you and I
of course. And then the other one that's getting most of the
attention right now I should say is hydrogen production from
electrolysis.


David Roberts


Right? Yeah.


Jesse Jenkins


Where again today electrolyzers are pretty expensive so you
probably want to run them at least 70% of the time. But that's
still very flexible. I mean 30% of the hours is a lot of hours
you can shut down. And as the cost of electrolyzers fall, which
we expect they will just like solar and batteries did, probably
by 50% over the next six years or so, then you can afford to run
them at 30 or 50% utilization rate and then they're a really good
flexible consumer. Now I want to add that both of these, any of
these demand sinks, what we found in our paper, they don't really
help the broader grid operate.


What they do is allow you to just tap into that weather-dependent
but very low-cost clean electricity and make greater economic use
of it and displace fossil energy consumption elsewhere in the
energy system. But it's sort of additive to all the demands that
we already are going to have in the grid and the flexibility that
we need to handle those demands. So we added a whole bunch of
demand sinks in our modeling and we found is that it didn't
really reduce the amount of firm generating capacity or battery
capacity that you wanted on the system, but it also didn't
increase it much. It just sits there and soaks up that good cheap
renewable energy when it's there —


David Roberts


But allows you to use more wind and solar.


Jesse Jenkins


Much more. Yeah, much more.


David Roberts


Okay, so we've covered seconds and we've covered minutes and
hours and it sounds like on the minutes to hours thing, combining
batteries and then all these demand, as you say, these various
sources of shiftable demand. Do you think that the sort of
ramping problem is solvable to solved? Let's say it's also low on
your list of worries.


Jesse Jenkins


I think we have solved that problem in the sense that we know the
technologies; they are not Sci-Fi, they can be deployed at scale
now. They are not deployed at scale yet at the scale we would
need. So in the next ten years or five years we are still going
to have to rely on those gas turbines and things like that to do
a good chunk of this. But over time, as we build more batteries,
as we wire up more flexible loads and give them the incentive to
participate in this demand shifting, as we get more interruptible
consumers signed up, we'll be able to do more of this without
relying on so much gas backup capacity.


And that's a good thing from a decarbonization perspective.


David Roberts


So then we get up to hours to days variability in terms of
diurnal cycles, the sun going down every night in the sort of
daily storage needs. What are our options there?


Jesse Jenkins


Yeah. So here we probably again, we rely right now on fossil
generators, right. Ramping up and down. We can rely to some
degree on lithium-ion batteries. They are most economic to
operate for just the highest price periods for that sort of peak
in the evening ramp, or maybe twice if there's a double peaking
system in the morning too. And it's not a function of like
physically you could slow the discharge rate and run a
lithium-ion battery for 24 hours of discharge. You just have to
discharge at a much slower overall rate than you could. And so,
economically, batteries and given their cost today, are really
best suited to somewhere between like two and six hours of
duration.


David Roberts


Yeah, although that number has been edging upward, I feel like,
for as long as I've been paying attention.


Jesse Jenkins


Right. Because the reason I'm emphasizing that technically they
can do longer is that what limits that is not the technology per
se, it's the economics of the battery.


David Roberts


I mean, you could theoretically just stack batteries to the
heavens and solve all of this if you had infinite money.


Jesse Jenkins


If you've got ten four hour batteries, you've got a 40 hours
battery. Or if you have one four hour battery that you discharge
at one 10th of its rated capacity, you have a 40 hours battery.
Right. So that's not rocket science. The problem is you need to
make enough money every time you charge and discharge to cover
your overall fixed cost of a battery. Right. So batteries make
money off of kind of capacity contracts and flexibility services.
So they're sort of paying for their standby ability, but also
from buying low and selling high. Right. This sort of buy sell
spread.


David Roberts


Right.


Jesse Jenkins


And the problem with any arbitrage play is that the more you buy
low, the higher the low price gets. And the more you sell high,
the lower the high price gets. And you're not the only one
playing this game.


David Roberts


Everybody else is arbitraging too.


Jesse Jenkins


Exactly. And so we've seen this happen is that basically the
price spreads start to collapse as you build more of these
flexible demands and more of these batteries all kind of playing
on the same price signals. And so that creates a race between the
declining cost of these technologies and their declining value as
you do more and more with them. And as long as the costs keep
falling, or we develop cheaper lower cost per kilowatt hour of
storage capacity batteries or storage technologies, then
batteries can stretch to play a longer and longer duration role.
And so, just to put some numbers on that, right now lithium-ion
battery systems are probably $250 to $350 per kilowatt hour of
capacity installed. If they fell to 100 ish dollars —


David Roberts


Isn't that DOE's stretch goal?


Jesse Jenkins


Yeah. So the pack costs are already falling below $100. So the
actual battery pack itself, but you have to install it and give
it cooling and power control electronics and wire it up to the
grid and everything. And so the labor and the balance of system
costs, just like for solar modules, which are only like a third
of the cost of a solar system now at scale, the pack cost is a
piece of it. And so we would need to get the pack cost down a lot
more. If you want to hit the $100 per kilowatt hour total system
cost level, you'd still need to probably a stretch for
lithium-ion to hit that target.


But maybe lithium-ion phosphate batteries are looking like a
better option to do that. Sodium sulfur batteries or sodium-ion
batteries, sorry, are being introduced now as a cheap, low-range
option for EVs. Well, EV batteries need to charge and discharge
very quickly and they need to have a high enough energy density
to give you a lot of range in a small package for not very much
weight. None of those apply to a grid battery.


David Roberts


Yeah, right.


Jesse Jenkins


A grid battery can charge and discharge over hours, not minutes.
And the energy density doesn't matter. The gravimetric density,
the weight part, doesn't matter at all. The volumetric density
only really has a small impact on the amount of space you need to
put them, which can impact the installation costs and cost of the
land.


David Roberts


So here you get into this weird because we're going to discuss
later long-duration energy storage, where we're talking about
days and weeks. So here you're getting into this weird sort of
liminal space between —


Jesse Jenkins


Yeah, diurnal storage.


David Roberts


lithium-ion batteries, which gets you up to whatever, six, maybe
eight hours.


Jesse Jenkins


Yeah, maybe 16. Right. This sort of diurnal scale is what it
seems like is necessary to manage most of the day-to-day
variability of demand and solar and wind, which they have pretty
pronounced daily cycles because the sun goes up and down every
day.


David Roberts


So that's where you get into flow batteries and things like this,
which are sort of like longer than short term, but shorter than
long term.


Jesse Jenkins


Yeah. So, iron flow —


David Roberts


I don't know how much of that space is going to be left. My sort
of instinct is that that space is going to get eaten from below
by lithium-ion and eaten from above by long duration and there's
not going to be much of it left. But, what do you think?


Jesse Jenkins


Yeah, I mean, it depends. It's sort of a race to market, I think,
and which technologies kind of get to scale and get on that cost
curve first because there's a lot of path dependency here, right.
If you can get to market and scale up and start driving down your
costs before another startup can, you may be able to edge them
out of the market. And this is something that any of these
startup battery companies need to keep in mind. Because
lithium-ion and sodium-ion and all of the automotive battery
technologies are coming like a freight train for your market,
too, if you're in this diurnal space because there's going to be
huge price pressures and competitive pressures from the auto
sector to get a better, cheaper, lighter weight battery.


David Roberts


Yeah, this is such a key point. I want to underline this. You
have lithium-ion batteries competing in this daily space with
other flow batteries and things like that. But flow batteries are
getting all their money in development and drive from this space.
But lithium-ion batteries have the much, much, much larger EV
market behind them.


Jesse Jenkins


Yes, it's probably two orders of magnitude bigger.


David Roberts


Yeah, so it's an unfair advantage.


Jesse Jenkins


It is. And I think it's really important to realize that if
you're an investor and entrepreneur in this space, you should
expect lithium-ion to just keep getting better, or sodium-ion or
other substitutes from the automotive sector and that will help
stretch them from four hours to six to ten and being economic in
that space. And so, yeah, I do think you're going to see a
shrinking market unless you're like a factor of two or more
better than lithium-ion is today and you're going to get to
market soon because lithium-ion will be half the cost eventually,
you are going to be in trouble. And so there are plenty of
solutions here.


David Roberts


There are lots of chemistries in the lab, you read the MIT press
releases or whatever. There are lots of interesting chemistries
competing for this space, but as you say, they're so far behind
that they would have to be such an order of magnitude higher
performance to get a foothold.


Jesse Jenkins


Some of them say they can and I think probably can. And so we'll
probably get a half dozen of new diurnal ten to 24 hours kind of
duration batteries, which are sometimes called long duration.
Which is why I think it's useful to separate this diurnal
timescale from the sort of multi-day or seasonal role, which is a
whole different one, which requires an even cheaper battery or
cheaper storage medium. But yeah, again, there are solutions
coming here. Some of those flexible demands can even shift around
on the order of days. Think about EV demand again. If we had
ubiquitous charging at work or on the streets that you could
drive and plug into a small low-level charger pretty much
anywhere, then in solar-dominated markets, which is probably
going to be most of the world soon.


It makes the most sense to charge your car during the daytime and
not at night. Right now, because most people charge at home, the
easiest thing to do is to just avoid that peak afternoon evening
consumption and charge in the middle of the night, which is
generally cheaper. But you could also charge during the daytime
if you can plug in during the day. And if we shifted all of our
EV consumption around, it could very well provide this sort of
diurnal capability also because, again, you have multiple days
worth of charge usually in your battery, and you can shift large
fleets of EVs fractionally to produce a lot of storage capacity
in aggregate.


And so I do think there's a lot coming in this space.


David Roberts


Right? You think diurnal is again solvable with technologies that
are either here or on the near horizon.


Jesse Jenkins


Yeah, exactly. And maybe a little bit behind some of the shorter
timescales that we're talking about, because we are talking about
technologies today that are in Series B or C venture capital
rounds and still need to get to market and produce at scale. But
most of those are coming in the next two to three years, right.
They're going to be producing at commercial scale soon, and we'll
see what costs they hit and whether they can scale to gigawatt
hours per year. But there's a lot of innovation, a lot of
investment, and a lot of potential on both the battery or storage
and demand side to fill that role.


And again, in the meantime, we've got gas turbines. And so it's
important to remember in all of this, there's no reason to wait
for these technologies to come forward. We're just going to keep
building more wind and solar, maintaining our gas as we add these
additional resources to augment them. And if all else fails,
right, and we don't get there with these diurnal technologies,
what it does is it just provides an economic limit on the amount
of wind and solar that we can add, because we'll start curtailing
wind and solar more than we would ideally. And that just reduces
the amount of energy that those wind and solar farms can sell out
of value.


And that also creates a race between declining wind and solar
costs and curtailment or declining value of wind and solar. It's
something I've talked about a lot in the past. Again, if wind and
solar just keep getting cheaper, they can keep winning that race.
But if they stall out of the way wind has appeared to over the
last couple of years, and we'll see if it gets back on track,
then the limitation in diurnal flexibility options will present
an economic limit on the amount of wind and solar we can add. If
solar just keeps getting cheaper, like, say, solar drops —


David Roberts


Which will then provide an enormous financial incentive for
people to come forward with these solutions —


Jesse Jenkins


To do this, exactly. Yeah. So, think about if solar just got half
the cost it is today, which is still achievable, right? That
solar PV could decline by another 40 or 50% over the next five to
ten years. If that happens, then you can afford to waste half of
your solar production that you would otherwise need to sell
today. Right. Because you just knocked the cost in half. Probably
more than that, because prices are not evenly distributed. And
then yeah, now you've created this huge amount of free energy
during the middle of the day that somebody can come and arbitrage
with a daily storage or demand flexibility option.


So, I think we're on a pretty inexorable path to solving that
problem as well. Even though it's not technically solved today.


David Roberts


This seems like a good place to bring in transmission, which is
another in the basket of solutions to variability, I think, on
virtually all these timescales, really. I mean, transmission
helps in all these ways, but I think in the diurnal timescale it
is going to be the most sort of notable contribution, which is
just the broader of a geography you connect up, the more smooth
your overall profile is.


Jesse Jenkins


That's right, yeah. We haven't talked about the geographic nature
of this, but again, what this is all driven by is the weather.
That's what drives demand wind solar variability. And over longer
timescales you tend to have to go over broader geographies to
decorrelate the output. Right. So if you're just talking about
those seconds to minutes, the clouds and the variability of an
individual wind farm, you can go not very far away and get a
solar farm or a wind farm that is not in the same cloud or not
dealing with the same wind gust as it goes across the plains.


And you can balance those short term variabilities out over
relatively small geographic areas. When it comes to hours to days
timescales, you kind of need continent scale, not the entire US
continent, but at least big chunks of it scale interconnection.
And we do have grids that span continents, so that's not an
impossible thing. In particular, if you go east to west, you see
the timing of that peak demand shift as the sun sets right across
the country. And so you can spread the solar and demand out in
the evening hours. You can't get rid of the nighttime entirely
unless you have a grid that spans the whole world.


But across the expanse of the United States or Europe or China,
other big east to west countries, you can do a lot there. And
wind fronts tend to be driven by these big synoptic scale weather
patterns that span big areas. You'll see them talked about on the
news. And we've got a high pressure front off of the Atlantic
that's affecting the Northeast today. And those affect big
regions, but not the whole country. So if you can connect from
Pennsylvania to Oklahoma, right, it maybe has very different
weather patterns going on. And you can deal with some of these
even multi day kind of fronts potentially as well.


David Roberts


Okay, so we've got second to second, more or less covered. We've
got minutes to hours covered, coverable, easily forecasted to be
coverable. Then we've got hours to days, which is, as you say,
the site of enormous activity right now. A lot of people working
on those things and solutions either in hand or anticipatable
relatively soon in the next decade. Then we get up to weeks and
seasons. And I guess the first thing I'd ask is, is there a
meaningful difference here technologically in terms of what we
need between weeks and seasons? Are those going to be distinct
categories?


Jesse Jenkins


Well, yeah, I don't know that there's a huge difference between
weeks and seasons. I think once you're cheap enough to do weeks —
so what we tend to see is that it's not that you're doing
seasonal discharge. Like you're not discharging for months at a
time. But what you might do is charge very slowly for weeks at a
time in the spring or the fall and the sort of shoulder seasons,
and then step in for five or seven or 20 days in the peak demand,
low wind and solar period in the winter or the summer and during
those Dunkelflaute or whatever.


David Roberts


Right. Once we're beyond days, we're just talking basically about
long-term solutions. And here, as I understand it, this is the
most difficult, least answered, least settled form of variability
that we're dealing with here, which is just what is that resource
that's not wind and solar, that when wind and solar are unusually
low for weeks or seasons at a time, can step in for weeks and
seasons at a time without generating carbon. So that's a head
scratcher of a category.


Jesse Jenkins


It is. And this is what I call the — we published a paper, Nestor
Sepulveda and I, back in 2018 on firm, low carbon resources,
looking at this need. We followed that up with a later paper in
2020 on long duration energy storage. How cheap does batteries or
other technologies need to be to actually fill that role? With a
storage technology the answer is really cheap, like two orders of
magnitude cheaper than a lithium-ion battery.


David Roberts


Right. So, lithium-ion batteries are not —


Jesse Jenkins


They're not going to do this.


David Roberts


— cheap enough to do this.


Jesse Jenkins


No.


David Roberts


But what can?


Jesse Jenkins


Yeah. So the options on the generation side and we can come back
to the storage front in a minute, are, again, the default in all
of these conversations is we just keep using fossil fuels for
less and less and less and less of this job. Right. So if, again,
we can't develop any other technology, all we can do is have some
combustion turbines and diesel generators sitting around for that
week.


David Roberts


Yeah, right.


Jesse Jenkins


That is not the end of the world from a CO2 perspective. Right.
It would be challenging to maintain the gas and fuel delivery
infrastructure for that. And it'll get more and more expensive to
do than today. Right. So it won't be as cheap as today's gas
turbines, but we run our models and they're pretty damn price
insensitive to that cost, especially on the variable side,
because you're not going to burn a lot of fuel in those power
plants. Right. They're going to sit there, they're going to
provide a lot of power when you need them. But because you only
run them for a week or five days or 20 days, they don't burn very
much fuel over the course of a year.


That means that even if the fuel is really expensive, like it's
all synthetic methane or hydrogen that you produce from
renewables in another period of the year, or you produce from
biomass gasification or whatever, those could cost several times
as much as current natural gas. And that still would be fine from
a total economics perspective because you don't use very much of
it.


David Roberts


So we could learn to live at peace with some marginal natural gas
plants sitting around waiting on these periods.


Jesse Jenkins


Yeah. Again, the things that we don't like about fossil fuels,
whether it's gas or coal or oil, are all related to how much of
it we burn, not how much capacity we have sitting around to burn
it. Right.


David Roberts


That's a crucial point.


Jesse Jenkins


So all the pollution, all the fracking, all the fuel production,
all the transportation, all the methane emissions from the fuel
cycle, all that scales with how much volume we use, not the peak
power output. And so it isn't the end of the world. If we don't
get to a 100% carbon-free grid, we get to a 98% carbon-free grid
and we run some gas turbines.


The thing that we're actually researching right now and I think
is important to consider in that context, they call that the
fallback plan. Right. We don't get any new innovation and we have
to do this plan, which is unlikely. Then the thing I'm exploring
with my group now is how much fuel storage or firm pipeline
capacity or whatever do you need to make sure that you actually
have the fuel around when you really need it? Because if you
don't, then all that standby capacity is worthless.


David Roberts


That's a lot of infrastructure to maintain for a few power
plants.


Jesse Jenkins


For backup use. As I said, it's very insensitive to variable cost
of the fuel, but it may be much more sensitive to the capital
cost of the fuel, of the equipment you need to secure the fuel
supply. And because you're not using it very often, so you don't
get to amortize that cost over a lot of hours. And so it may be
that that becomes more expensive than we think if we start to
account for all those additional things like the need to have
onsite fuel storage or something.


David Roberts


Yeah, like maintaining the natural gas distribution system. Is
this weird sort of like yes or no, on or off question. And if
it's on then that's a shitload of money. And if it's off, you're
saving a bunch. It's not really something you can half do.


Jesse Jenkins


Yeah, right now power plants, gas plants basically are non-firm
consumers. So they just use the gas capacity on the pipelines
when it's there and when it's not, they don't, generally, but if
you're going to be the last resort firm resource, you better make
sure your fuel supply is secured. Otherwise, you're useless and
people will freeze to death. And that's not okay. So that's one
option is we just figure out how to secure gas turbines running
on either methane or synthetic methane or biogas or hydrogen or
something, or —


David Roberts


Capturing and burying their CO2 or let's mention the Allam cycle
real quick.


Jesse Jenkins


Yeah, well, so I would say that's not a great option for this
very intermittent capacity role because that capital equipment to
capture CO2, and to store it, is not going to be used at such a
low utilization rate. So then we go into the next category beyond
these sort of backup combustion turbines or fuel cells or
something. And that's where you have gas with carbon capture or
maybe coal, but probably not. And advanced nuclear and advanced
geothermal. Even a gas plant with carbon capture is sort of in
the middle. It's got fuel costs, so it's non-zero variable costs
and has some capital costs.


So you want to run it maybe 40% to 70% of the hours of the year.
And so it will do more than just fill in the standby capacity if
you build that. It'll also supply some of our carbon-free
generation and we'll need less wind and solar because of that.
But that is an option. And then the final one. Geothermal and
nuclear, both fission and potentially fusion are majorly capital
intensive upfront cost, but very low if any fuel cost. And so if
they are in the mix, we want to run them most of the time, not
all the time.


They don't need to run base load. The term is there is no base
load that we need to meet anymore. In a system with lots of
variable renewables, what we need is something that can
complement the variable renewables. So even geothermal or
nuclear, it would make sense to couple with a storage option. So
we've looked at coupling nuclear fission with thermal storage the
way some of the new designs are going to do. We've looked at
geothermal plants that both closed loop and enhanced geothermal
can shift their production on daily or even weekly or seasonal
timescales. So they just concentrate all their output in the best
periods and store it up in the other periods.


So they will operate flexibly. I call them flexible base
technologies, but they're going to be operating at 70% to 90%
utilization rates, not standby. Again, those are with the
exception of fusion, which still has some very serious
engineering questions to work out. We know we can build nuclear
power plants, we know we can build geothermal, we know we can
frack wells. And we're starting to do the first hydrofracking for
geothermal with enhanced geothermal technologies being built.
Like right now. These are technologies that are right over the
horizon and are well capitalized now by startups and by public
sector support and are going to be built in first commercial
scale projects over the next two to five years.


And so we'll see which of those start to look really viable. And
by the end of the decade, I think we'll have this part of the
toolkit worked out as well. And we'll really have an
understanding of which ones of these are ready to scale and which
ones aren't.


David Roberts


So the idea here is if you hit the Dunkelflaute, if you hit the
period of low wind and solar, you just ramp up your nuclear and
your geothermal and your carbon captured natural gas plants to
compensate.


Jesse Jenkins


Yes. Or you have very, very low-cost energy storage, like what
Form Energy is working on with very cheap iron air battery. Or
you could do very large compressed air in big salt caverns that
if they're big enough, get really cheap. Or you could store
hydrogen underground.


David Roberts


These are long duration energy storage.


Jesse Jenkins


All of these are potentially sort of $1 to $10 per kilowatt hour
type range of cost of storage capacity, marginal storage
capacity. And if that's the case, then we found that they could
displace much, if not all of that firm generation role and act as
basically a firm storage option for those.


David Roberts


Interesting. So if we successfully develop and commercialize a
few of these long duration technologies, we are reducing our need
for clean, firm, reducing our need for nuclear and geothermal.


Jesse Jenkins


What we found is it's pretty difficult to fully eliminate it, but
you could do a lot more with long duration storage and renewables
and less — need, less firm.


David Roberts


Interesting. Give us a sense of — I think a lot of people are
curious about this is, like, where are we on those long duration
energy storage technologies? I mean, technologically they don't
seem that mysterious, but none of them, as far as I know, are
commercially used yet, except for pumped hydro.


Jesse Jenkins


Yeah, and pumped hydro is way too expensive for this role. It's a
diurnal technology, too, that is really sized for and has the
cost for daily or multi-hour kind of applications.


David Roberts


So we don't have long duration energy storage at a commercial
scale —


Jesse Jenkins


No —


David Roberts


yet really?


Jesse Jenkins


Partly because we haven't had to. We have chemical fuel, we don't
need it. We have diesel and coal and natural gas and that's our
storage. Right? So what we're trying to figure out is a way to
get by without those fuels. One option is really cheap
electrochemical storage or alternative chemical storage, like
hydrogen or synthetic natural gas stored in salt caverns or the
way we store gas seasonally today. Those are all doable. But
yeah, I basically say they're in the same place as all of the
clean firm generation options, which is that there are multiple
startup companies that have clear line of sight and are
capitalized and are scaling and are trying to work it out.


And we'll know in the next three to five years which of those are
real and which of those can't get off the ground. And so again,
when I published our paper, when Esther and I published our
paper, initially, it was very speculative, right? Which of these
could take off? Most of the nuclear designs existed on paper. The
Allam cycle existed on paper. We were just talking notionally
about hydrogen with no policy support whatsoever. Right? And now
you have strong public policy support in well capitalized
companies in all of these categories moving forward. And so I
think we're again in a good position to solve this problem.


It's not an unsolvable challenge.


David Roberts


Let's quickly just spell out what we mean by Allam cycle, natural
gas, in case for the non-super nerds out there who are not
following this. I wrote a piece in Vox about it three or four
years ago, but I haven't heard a lot about it lately. But spell
out what that is.


Jesse Jenkins


So, this is a technology that is commercialized by a company
called Net Power, recently went public via SPAC. And I should
disclose that I served as a consultant to the SPAC company as
they were exploring that acquisition. And so it's now a publicly
traded company that is building their first commercial project in
the Permian Basin, West Texas. They're building another one. I
got a couple of others planned and they have operated a pilot
scale facility outside of Laporte, Texas to try to prove out the
design. But what it does is it basically burns natural gas in a
pure oxygen environment.


So it uses an air separating unit to get oxygen out of the
atmosphere. And then when you burn gas with only oxygen instead
of the air, you don't get any air pollutants. So you don't get —
it already burns with very little no particulates. But all of the
nitrous oxides, the NOx emissions that we get from gas power
plants, the nitrogen comes from the air. It comes from partial
combustion and high temperature combustion that dissociate
nitrogen out of the air and combine it with oxygen and produce
NOx. And so if you burn it in a pure oxygen environment, there's
no nitrogen available to become NOx.


And so it produces power with no air pollution. And it produces a
pure CO2 stream from that combustion that can be easily captured
at 99.9% capture rate and then sequestered or stored. And so it
has the potential to be a very low air pollution, basically no
air pollution and nearly 100% capture gas power plant.


David Roberts


Really cool, really cool machine.


Jesse Jenkins


Yeah, I should say it doesn't eliminate the upstream impacts of
gas supply chains, but everything from the power plant it can
clean up. And so that's a huge difference from our current gas
plants. It's also different from a post-combustion capture
system, which bolts on to a conventional gas plant. Those have a
harder time capturing 100% of the emissions. It takes a lot more
energy to do that and they all add a lot of cost and reduce the
efficiency of the process. The Allam cycle itself, it has some
other complicated systems to it. It uses supercritical CO2 to run
the turbines instead of water and it keeps it at a constant
phase.


Long and short of it is it's much more efficient and compact than
a combined cycle plant too. And so if this can be made to work —
and again you have to show that it can work, work on a sustained
basis at commercial scale — then it's a potentially much more
affordable option and can capture much higher emissions levels
with zero air pollution relative to a gas plant with conventional
gas combined cycle plant with carbon capture.


David Roberts


As has come up several times already in our discussion, there are
several contexts in which it would be very handy to have a couple
of sort of low utilization natural gas plants hanging around. So,
if you could build those in such a way that they are air
pollutant-free and easily capturable CO2, it's a big help.


Jesse Jenkins


Yeah. And if you can site them in ways that where you can source
from gas fields that have very low methane leakage and don't have
to transport across big pipelines and don't use the distribution
hour — there's a lot of upstream impacts to consider. But yeah,
you could do it in a not zero impact, but much, much more benign
system than our current gas plants.


David Roberts


And do you think of e-fuels? So for listeners, you can strip
hydrogen out of the air with electrolysis and then combine
hydrogen with hydrocarbons that you've captured elsewhere to
create basically carbon-neutral fuels. This is how we're going to
solve aviation fuels, probably how we're going to solve shipping,
some form of methanol. There's a variety of these e fuels
available and possible. Do you think of those conceptually as
long term energy storage?


Jesse Jenkins


Yeah, I mean, you can think of them either as long duration
storage or as firm generation. I mean, I think they're kind of a
mix of the two because you're probably going to get some of their
initial energy inputs from electricity, but maybe not all of
them. So you can think of it in the extreme manner: We don't use
any electrolysis. We get all of these from biomass and from
methane reforming with carbon capture, other non-electrolytic
sources. And then it just looks to the electricity sector like a
fuel because it doesn't consume electricity to produce. It just
gives you electricity.


David Roberts


Right.


Jesse Jenkins


On the other extreme: It's a full round trip electrochemical
process. You use electricity to produce the fuel, you store the
fuel, you burn it back into electricity. What's interesting is
that they sit in between and that they're part of a much larger
fuel system that is predominantly used outside of the electricity
sector and has input options besides electricity. And I think
that's also a big advantage because just like lithium-ion
batteries are going to kind of coast on the much larger EV market
for batteries, it means there's more things you can do with these
long duration storage options.


You can power ships and you can power industrial processes and
you can use them as chemical feedstocks as opposed to an
electrochemical battery that can only do electrical storage. And
so I think those are pretty viable options to kind of eventually
play the role of a long duration firm generation/storage option.
And the long duration electrochemical battery makers need to keep
an eye on that market too because it could be coming for the
other side of your market. They do know this. I mean, I've talked
to several of them that they're keeping an eye on hydrogen and e
fuels and other things.


But that's the other route is that we just burn these fuels
occasionally. But again, that comes back to that fuel supply
assurance question that I raised before, which is the piece we're
researching now.


David Roberts


Yeah. How do you set up an entire infrastructure to create fuels
that are only used marginally or used?


Jesse Jenkins


Well, see, this is where I think those ones have an advantage in
the sense that you would use them in other sectors, right? You
would use these fuels to produce jet fuel or to produce shipping
fuel or as a feedstock for petrochemicals or others. And so you
could sort of tap into that larger, more established and more
constantly used fuel system the way that power plants today tap
into the natural gas system. It would be smaller probably than
today's gas distribution system, but it could be similar in that
it's sort of a multi-use fuel network and reaches economies of
scope and scale because of that.


So it is an option, one that we see in our kind of multisector
modeling that we do. And I think whether you see that as a
generation option or as a storage option or some hybrid in
between, it certainly fits the role of a firm resource and can be
our potential backup kind of source.


David Roberts


Stepping back here, we've walked through the time cycles of
intermittency from seconds all the way up to seasons. And
basically what you're saying is that in all those cases there are
options either available or in development. It's probably safer
to say that the seconds side of things is more solved, there are
more options. We're more ready for that. And when you get up to
the seasons level of intermittency we're a little bit more out in
the future. We're a little bit more theoretical. There's a lot of
stuff in the lab. There's a lot of competition that needs to be
had, but there are options there as well.


So one thing you could take from this is just, "oh, variability
is nothing to worry about." And yet people see California having
problems. People see high renewable energy penetration systems
starting to run into these problems. So how do we square those
two stories in our head, this idea that we know how to do it, yet
even at relatively low penetration, we're starting to run into
tensions and problems.


Jesse Jenkins


Okay, Dave, do you ever encounter challenges in your day-to-day
life? Do you have writer's blocks?


David Roberts


I'm a podcaster. It's all easy.


Jesse Jenkins


You need to figure out what to make for dinner for your kids. Do
you just throw up your hands and cover your head and go back to
bed? Of course not, right? You wouldn't get through your life if
you did that. Also, some of those challenges, you don't solve
them the first time you sit down to do it, right? But these are
challenges, not barriers or impenetrable walls that we can't
pass, right? These are not rules of nature or fundamental limits.
They are challenges. They have costs to overcome them. Those
costs change as we apply innovation and ingenuity to solve them
in new creative ways and as technologies improve and they take
time to solve because this is a big system and we're trying to
rebuild it as we use it.


David Roberts


And some experimentation and failure along the way.


Jesse Jenkins


So I think we just have to keep in mind you can take these
challenges very seriously, and we should, and the industry does.
And you can see them as solvable, and we should because they are
and not despair because we can overcome them. So I think you have
to hold all those things in mind and that's not an unusual or
unique thing. Like that's how we get through our lives. We
encounter challenges, we find solutions, we implement them, we
iterate, we try again. And we don't generally give up right away.
At least you don't get very far if you do.


David Roberts


Or give up before we even really are trying, before we've even
tried at all.


Jesse Jenkins


"Ah, can't possibly do it." And so that's where we are, right? We
have a bunch of solutions. We've talked about them here. They are
not all at scale, ready to use predominantly today. We cannot
stop using natural gas power plants tomorrow. In fact, I would
counsel we don't shut really any down over the next decade or
longer because we probably need them as we rapidly replace coal.


David Roberts


You can idle them, not shut them down. Right? There's a
distinction there.


Jesse Jenkins


What we care about is how much fuel they burn, not how much power
capacity they have. And so we need to keep that front and center.
So I think it's interesting is that over the last few years, I
think a really clear roadmap has emerged for decarbonization of
the power sector. And that roadmap looks like this: It says
deploy wind and solar and batteries and demand flexibility as
quickly as we can. Right? We know these things can work, they're
effective. They need to scale up and play a bigger and bigger
role in our energy system as fuel saving and balancing resources.


The second thing we have to do is use those resources to just
shut down our coal-fired power plants as quickly as is practical.
Yes, they're the highest source of air pollution and carbon
emissions and the cheapest thing to replace in the grid. So best
bang for the buck is shut those plants down as quickly as we can.
In any net zero pathway we run, they're offline by 2030,
basically, all the coal plants in the US. Third, while we do
that, we have to keep our existing natural gas and nuclear power
plants running because they provide firm generation today.


And we don't have enough of that multi-day diurnal firm
generation ready at scale right now. And so you want to keep
existing nuclear as a foundation to make more rapid progress on
and you need to keep the gas power capacity even as we use less
and less gas burned in the generators and in some places in the
country where we're really rapidly retiring coal, we may even
need to add more gas capacity. But we should do so recognizing
the role that those gas plants are going to play in the longer
term as this sort of backup kind of resource.


And then the final thing, of course, is we have to build a lot
bigger grid, right? The fourth thing, we can't tap renewables. We
can't meet growing demand for electricity from EVs and heat pumps
and hydrogen production without a bigger grid. And so we have to
do that at the same time. And all those things together, those
four things we've seen in study after study can get us an 80% to
90% reduction in greenhouse gas emissions from the power sector
even as we expand electricity supply and keep costs pretty much
comparable to what they are today.


Even lower after you account for subsidies from the Inflation
Reduction Act.


David Roberts


And of course, all this innovation going on in all these areas is
going to produce all kinds of things we can't anticipate.


Jesse Jenkins


And that lets us go the rest of the way. So the next decade is
doing those four things and cutting emissions 80% to 90% and then
simultaneously because yes, we can walk and chew gum. We're smart
big people with lots of big boys and girls with the ability to do
two things at once. We are going to be deploying and innovating
and scaling the rest of the toolkit that we need. The synthetic
inertia, the firm low carbon generation, the multi-use fuels, the
demand sync technologies, the long duration low-cost energy
storage, all of that will be commercially ready — not every
technology out there, but something in each of those categories
will be commercially viable in the early 2030s.


And then we put the pedal to the metal, deploying those things to
go the rest of the way to close the distance to 100% or 99%
carbon-free grid. That's how we get the job done.


David Roberts


Beautiful. A substantial social and political challenge, just —


Jesse Jenkins


For sure.


David Roberts


to put it mildly. But technologically, the road ahead is more or
less clear.


Jesse Jenkins


Yes, and it didn't say like, "we have all the technologies we
need." I've been hearing that for 25 years. We have all the
technologies we need to make rapid progress, and that should be
all we need to start making rapid progress. And if we walk and
chew gum at the same time, if we're clear-eyed about the
challenges ahead of us, we don't see them as impenetrable
barriers, but rather as innovation challenges to overcome. And we
invest the resources and scale the technologies to do so
proactively, which is what we are doing now as a private and
public sector, then we're going to get there, we're going to
solve these problems.


David Roberts


Beautiful, beautiful, Jesse. All right, variability: check done.
Marking that off my list. Moving on to the next thing. I assume
once this podcast circulates, I will no longer be running into
people on the Internet who are informing me that the sun goes
down at night.


Jesse Jenkins


I look forward to that day on Twitter.


David Roberts


All right, thanks so much, Jesse.


Jesse Jenkins


Thanks. Take care.


David Roberts


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