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.

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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