Hydropower Is Cheap, Clean, Already Big, and in a Bit of Peril
We’ve heard an awful lot of awful news when it comes to the climate crisis. But there are also very smart people working on clever ways for us to dig ourselves out of the hole we’re in. UNAPOCALYPSE is a series from Esquire that highlights ways humans can mitigate and adapt to the damage caused by a changing climate.
You can find last week's edition here.
Right now, in 2022, 6.3% of all American electricity comes from a single renewable energy source. That’s more than all other renewables combined. Water power is both ancient and crucial to the future of human civilization, but unlike geothermal energy, hydroelectricity is already all over the place. Washington State gets 66 percent of its power from water, part of a hundred-year American legacy of damming rivers and allowing falling water to turn turbines to produce the juice. That’s the conventional model: The Hoover Dam (and Lake Mead, which it created) is one of 90,000 dam setups in the United States. Most of those were built for the more basic purpose of controlling water—flooding and irrigation—but quite a few are cranking out the megawatts.
Going forward, hydro will continue to play a big part in decarbonizing the energy grid. That will involve retrofitting some dams and boosting the productivity of those already rigged for electricity generation. But as Dr. Melissa Lott, Director of Research at Columbia University’s Center on Global Energy Policy, told me, there are also whole new ways of harnessing water energy: so-called “run-of-river” facilities that disrupt the flow (and surrounding ecosystem) far less than traditional dams, and “pumped storage,” which can serve as a kind of battery to store energy. The latter could work in tandem with more intermittent energy sources, like wind and solar, to build a more robust and resilient grid of the future. There are even hydro opportunities in your own backyard.
Which isn’t to say it’s all perfect. Hydro is awash in permitting issues and bureaucracy, often tied to the many aging dams across the country, and the longer investment window in hydro plants can be less attractive to investors than wind and solar. Plus, hydro is in a perplexing place as the planet heats up and dries out due to climate change: its ability to contribute to combating the climate crisis is imperiled, to some degree, by the climate crisis. Just look at Lake Mead. Still, it’s unlikely we can make it all happen without the water power. In a conversation edited for length and clarity, Dr. Lott helped explain why.
What are the basic mechanics of hydroelectric power as we know it?
The big technologies we use today are mostly what you think of with hydro, which is big dams. We block a river or block some form of water and trap it into what becomes a big lake, effectively. We call them reservoirs. So that's one type of technology. We run water through turbines that spin and produce electricity.
The other way that we do it is a little less intensive when it comes to construction. It's something called run-of-river. That means we actually put the mechanical things that generate electricity in a river, without blocking it. We let the water flow over these pieces of equipment to generate electricity that way.
Most people think of the Hoover Dam, or they've been out to Lake Powell or something like that, or they've seen pictures of Three Gorges Dam in China. That's one way we do it, but we also do it in a way that's not [quite] invisible to the eye, but it's a lot less intense and doesn't involve those huge concrete structures.
What are the drawbacks and benefits of dams versus run-of-river facilities?
Dams do disrupt the local ecosystem more. Effectively, you're blocking off some water that was flowing. You're making a huge lake that wasn't there before. We generally don't do this in a small way. We generally build big dams. We disrupt the local ecosystem quite significantly. With a big dam, what you're creating is kind of a water battery. You're storing water in a place, you know you have it. There are some trade-offs: You've got to think about evaporation when you concentrate all that water together. Evaporation off the top of these facilities is quite significant. Or if you don't get a lot of rain, or there's not a lot of snow melt, these types of things, you can have water go down quite far. But the water is there, you know it's there, and you can use it to generate electricity whenever you want. It becomes a big battery.
When you're looking at run-of-river, you depend on the river. I'm from Texas. Any of us who spend time near the border, we know that rivers don't always flow. Sometimes you have really dry weather and they're not flowing. Then your run-of-river isn't useful. If the water stops flowing, you have no electricity.
But you want both technologies. It just depends on what resources you have available to you. Some rivers just don't make any sense to put a dam on.
Yeah, you look at Lake Mead and see the water level dropping. Is this a way for us to fight climate change—by changing our energy system—that is also a bit imperiled by climate change?
Yeah. It's certainly a trade-off we need to be aware of. As the climate changes, how does that affect how much hydro power we have? How does that affect how much water we have in a given year? We've got these huge climate models that scientists have looked at for decades. Then we've got these big energy models that we use for planning, for building out power plants, all of that. The cool thing that's happening now is we're actually marrying those two things up.
The climate changes take a couple different forms. One, it could be hotter, so we have more days in the summer where we need electricity. So the question isn't, ‘do you have hydropower over the course of a year or a decade?’ but ‘do you have it on that day in summer, when you need it, when people are turning on their electricity?’ Then, what are the risks over time, if rainfall patterns change? Maybe it's still raining in your area, but is it raining where you need it to actually charge up that water battery or to fill that river? Those types of questions are really important. We have some of the answers, but we don't have all of them yet.
Is hydro considered baseload power, or firm power, in the way that geothermal is?
It's considered firm power, but there's a slight difference between baseload and firm. ‘Firm’ means it's available 24-7-365. If I need it, I can use it. ‘Baseload’ means that it's generating electricity really constantly. A lot of hydropower facilities currently do run as baseload. They just supply a steady amount of electricity over time. Then we use other technologies, like natural gas, to fill in the gaps, as we use more and less electricity throughout the day.
In the future, there's a question of, do we want to actually have our electricity market support using hydro differently? If you have a ton of wind and a ton of solar, and when the sun is shining and the wind is blowing, that electricity is super cheap, incredibly cheap, do you then actually say, "Hey, hydro power, we're going to pay you to wait a little bit. You can let out some water later and generate electricity when the wind and sun go away"?
This isn't how hydro power has operated, for the most part, in the past. But if you think of it for dams, at least, as a really big water battery, then there's an opportunity to use it that way and to use it to complement the other things in our electricity mix.
I’m fascinated by storage issues with wind and solar. How do the pumped storage facilities fit into that?
If I describe dams as being kind of a water battery, pumped storage is a water battery. We take excess electricity—electricity that we don't need in any given moment—and we use it to move water up a hill or up some elevation change. There are actually some really cool technologies where instead of moving water up a hill, they actually will move water to above and below an underground cavern. You just need an elevation change. If you have that, you can use it as a pumped hydro facility.
You take really cheap electricity—it could be from wind or solar. The wind is blowing, but we don't need [the energy immediately] in our homes. Instead of throwing that electricity away, you use it to move water up a hill. Then later, when the wind and sun aren't around, you just let that water flow down that hill. It does the same thing that you see in dams or in run-of-river hydro. It spins a turbine, generates electricity and puts it back in the system.
You do lose a little bit of electricity along the way. It takes energy to move something up a hill. The laws of thermodynamics mean that you don't get it all back when it flows down. But if you would've otherwise wasted that electricity, it becomes a really cheap way to have a massive battery on your system.
In terms of where this is deployed now, what states are big on this? I know China is really big, but who else is doing this right?
In terms of the United States, we can look at Washington state, where last year, they got about two-thirds of their electricity from hydropower. Internationally, I would highlight two countries that I find really fascinating, Iceland and New Zealand. You can learn a lot from them.
New Zealand gets about 70% of its electricity from hydro power. They're dealing with all the things we were talking about: What happens when it doesn't rain for three or four or five years? What happens when you have dry years? How do you manage that in your system? They actually have this one hydroelectric dam on the South Island that produces 12% of the country's electricity over the course of a year.
Iceland is awash with water. They have so much water. Iceland is hydro and geothermal. They use geothermal power to heat their homes. They use hydropower to power their industries.
These countries have really figured out how to not just use hydro, but use it for a huge percentage of their electricity generation, which means that they've dealt with all the challenges. Say hydro is 1% of the electricity you get over the course of a year—if it goes away, you care, but it doesn't take down the grid. But these countries have so much hydro in their systems, they've had to actively manage all the different trade-offs that hydro has, compared to other types of electricity generation.
Where is there a lot of potential?
I'd say the biggest potential in the United States is mostly run-of-river. That's because we have a bunch of dams in the country now, and we can improve the technologies in those dams so that they produce more electricity than they can with the current equipment that they have. But overall, it would be a hard ask to double the number of dams. The potential is really, where do we have rivers that are flowing and can we put these run-of-river technologies in?
Some of the potential we haven't tapped into at all is the water that is offshore. Let's think about tidal power. Let's think about the oceans. There's a lot of energy in there, and we can tap into that. Especially if we're going to build out things like offshore wind—well, why wouldn't you also think about building different hydro technologies that actually take advantage of the energy that's flowing underneath that turbine?
I’ve read that states that lean on hydro tend to have lower energy bills.
The EIA [Energy Information Administration] has their price per kilowatt hour per state, but in general, hydro is really cheap. If you've got that resource, it's cheap electricity. It's also not as volatile as other things. I say that because the fuel is free. It's like wind and solar: Once you build it, it just generates electricity and you know how much it's going to cost, generally. We know a lot about maintenance and operations and how that works for hydro facilities, so we can see cost coming. Digital technologies are helping us be better about that. We can do preventative maintenance more easily. The result is a steady stream (no pun intended) of low cost electricity.
It seems like it's more of an upfront cost associated with it, but it also seems like, because of the window on a lot of these hydro projects, they tend to be 50 years, versus 20 years for solar. And I’ve seen some issues with the permitting processes, too. Is that holding back investment a bit?
What I'd call non-technical barriers are the biggest part of the problem when it comes to the major hydro facilities. When you build a big dam, you're affecting an ecosystem, you're affecting a community. There's only a few places where we can do that.
Even run-of-river, we want to understand how this is going to affect the aquatic populations that we have in our rivers. We don't want to disrupt all of that. You have to ask local communities, “Do you want this? Is this something that you're willing to put in your electricity mix? Is this something you're willing to do to your local river? Are you willing to have this dam? Are you willing to put this thing in the waterway?”
A lot of our 90,000 dams were just built for controlling water. How many of them are actually producing hydro or a good amount of hydro? Could they be retrofitted?
We have a bunch of different opportunities when it comes to existing dams and existing infrastructure. One, we can improve the turbines in the ones that do currently generate electricity. Two, we can take existing dams that don't actually produce electricity, and we can retrofit them. That wouldn't require us to block new waterways or really disrupt new ecosystems. We already built the facilities. How do we maximize the amount of electricity we can get out of them?
Most dams were built for flood control and to support things like irrigation, so the electricity is not the primary benefit of those facilities. That's just a dynamic that other power plants don't really have. You build a field of solar panels, and they're there to generate electricity. Maybe provide a little bit of shade, but that's about it. Hydro's a little more complicated.
One benefit of geothermal is that you could deploy it in your backyard. Is there any future for that with hydro?
Oh, run-of-river is definitely a thing that you can do. This is a huge part of New Zealand’s hydro, actually, these run-of-river facilities that people build on their property. “I've got a flowing river. I'll just put this little generator in it. I'll have local electricity that is there. Even if the grid goes out, I have this local electricity.” So it's great and a backup in the middle of the storm.
I have been to a number of farms in New York state that have running rivers behind them. People put microturbines into them, just these little tiny pieces of tech that can sit in the river and spin and generate electricity that you can use locally. People will either use it to charge a battery that they use as backup power, or they can feed that electricity back into the grid. That's technology we have today.
What does hydro look like in your idealized future?
In the decades to come, we have an important question to ask ourselves, which is, do we keep all those existing hydro facilities running? If we decide that we want to keep them as a part of our electricity mix, then the technology's going to look pretty similar, but it's going to have new, more efficient turbines, more efficient ways to harness the power that's in that water.
We won't see hydropower doubling or tripling. We're not going to see a massive build out of dams in this country. But if we go to net-zero electricity, we will probably see all the existing dams staying operational and just using more efficient technology in the future, to harness more of the electricity. Our existing hydro is this incredible source of clean electricity and also energy storage. So as we try to get all the way to net zero, it's just a vital technology. If we take it out, we've got challenges as to what we replace it with.
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