What's going on with hydropower?

In this episode, Jennifer Garson of the Department of Energy’s Water Power Technologies Office discusses the state of hydropower in the US and where the industry is headed.

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Text transcript:

David Roberts

For decades, hydropower has been most common source of renewable electricity in the world. (In the US, it was passed by wind a few years ago.) Pumped hydro — large hydropower facilities in which water is pumped up and run down hill to store energy — remains the most common form of energy storage, both in the US and in the world.

Even as the vast majority of media attention in the clean-energy world goes to wind and solar power, hydropower continues churning away in the background, generating and storing vast amounts of renewable energy.

Hydro has a long and storied past, but does it have a future? What's going on with hydropower these days? Is there any prospect of building new dams or of finding more power in existing dams? What's going on with small hydropower, on rivers, streams, and reservoirs? And is ocean energy ever going to be a real thing?

I've taken hydropower for granted for a long time, so I decided it was finally time to dig into these questions. To do so, I contacted Jennifer Garson, head of the Department of Energy’s Water Power Technologies Office (WPTO). The WPTO oversees a sprawling network of prizes and grants meant to encourage hydro and marine energy projects. I talked with Garson about the future of large dams in the US, the promise of small-scale hydro for local communities, and the uncertain future of marine energy.

Alright, with no further ado, Jennifer Garson, welcome to Volts. Thank you so much for coming.

Jennifer Garson

Thank you so much for having me.

David Roberts

Alright, so we normally normally here on Volts, we do the sort of deep dive into one thing. But this here we're going to attempt something slightly different, which is a broad overview of a fairly large category, larger than I think I appreciated before I started digging around and just try to get a sort of global sense of where it's at. Because I know that from my experience in clean energy, I've sort of, like, had hydro in the back of my head as kind of this steady presence, a little bit like nuclear, like a steady presence in the background, but not something where anything kind of dynamic or new is happening. And I think you probably disagree with that.

So let's get into it. So just to start with, what are the technologies encompassed by the terms "hydro" and "marine energy" that your office covers? What is the remit?

Jennifer Garson

Yeah, so glad you asked that. And it is, sort of, just by nature of our office as we're structured that, we have two very interesting, but two very different types of water power technologies. So the first that you mentioned is hydropower. Hydropower really has been delivering power for the last 100 plus years. It's both the conventional hydropower, so very large behind the reservoir, big dams that people usually envision when they're thinking about hydro. We also have smaller non-powered dams that we power with hydropower. We also have run-of-river systems that actually have diversions in addition to dams, where you actually have water flowing to the side of the river. And then we also are thinking about hydropower. Even in conduits and canals, how do you use existing water infrastructure to provide power, whether it's for water treatment or irrigation, a whole number of different ways that you could use existing infrastructure for water power.

Jennifer Garson

On the other side of the portfolio, we have marine renewable energy. So while hydropower is probably the oldest form of renewable power — although potentially, arguably wind is too — marine renewable energy is the most nascent form of renewable energy. And that's really looking out to the power of the ocean. Everything from how do we kinetically capture power, how do we use gradients to capture power. So everything from tidal power, wave power, ocean thermal energy conversion, even salinity gradients and even pressure gradients, really looking at a multitude of ways of when you look out at the ocean and see all the power that's contained in it, how do we use different power capture systems to harness multitude of ways that the ocean generates power?

David Roberts

Got it. So water on land and water at sea ...

Jennifer Garson

Water everywhere.

David Roberts

Water everywhere. So let's start then with big dams, because I think this is when you say hydropower, this is what springs to people's minds as sort of the conventional form. I think conventional wisdom is that we've got a lot of big dams in the US creating a lot of power and it's steady and it's good, but that's more or less it. And so this is my first question. It's just do you think we're going to build any more large dams in the US or large, dam-wise, are we basically tapped out?

Jennifer Garson

So that's a really excellent question. I think there's a general agreement that we are not going to be building. Any large dams on existing waterways. I think in terms of large conventional hydropower, we are most likely tapped out. Particularly here, I should say, in the United States. That isn't necessarily true elsewhere across the world.

David Roberts

Right.

Jennifer Garson

We do think about building other big structures like pump storage, but those have been now leaning more towards what we call closed-loop systems, which are two bodies of water connected, but they're usually constructed and fabricated bodies of water. They're not connected to an existing large river. So I think for the United States, we're not going to see any large behind the reservoir, conventional hydropower, big dams built on any of our riverways anytime soon.

David Roberts

Also on the subject, I've heard conflicting things about the carbon emissions of big dams. I feel like there's been some new research lately that shows that those emissions are higher than we thought. Because you're disrupting a bunch of soil, you're creating a pool where things rot and produce methane. So what's our latest state of thinking on the large dams that exist? Are there large dams that exist that we think are less of a carbon asset than we thought, that we think need to be closed down for environmental reasons?

Jennifer Garson

So I think those are actually two separate questions, one is what is the science behind say, methane or reservoir emissions, particularly given vegetation? We are conducting studies right now at the Department of Energy really trying to understand what types of sensors and measurements are needed to either validate or invalidate that as a theory. I think that there's still unsettled research on the magnitude of the impact, also the timing of the impact. So the other thing that we talk about when thinking about reservoir emissions is, if you're talking about vegetation rot at the bottom of a reservoir for a dam or a facility that's been around for a long time, does it still hold that you have emissions or methane challenges? And I think we still need to do more research on both the kind of temporal nature and the magnitude of the problem. It's not to say that we think there's no problem at all or there's a major problem.

I really think it's a cri