Climate Changes Everything: Episode 15, Take Me To The River (Part Three)

Dams are versatile and serve multiple purposes such as flood control, power generation, recreation, and irrigation. Hydroelectric power is a greenhouse gas-free method of generating electricity. The power grid is a complex system that requires a balance between power generation and load. Hydroelectric power plays a crucial role in providing base load generation and stabilizing the power grid. However, the renewability of hydroelectric power is debatable due to the environmental impacts of dams. Climate change poses challenges for hydroelectric power, including droughts and floods. There are opportunities for innovation, entrepreneurship, and advocacy in reducing construction emissions, improving dam design, and enhancing reservoir management. Policy and regulation need to consider the trade-offs and varying impacts of different types of dams. Effective advocacy and decision-making require a comprehensive understanding of the compromises and complexities involved in hydroelectric power. Hello, and welcome back to Climate Changes Everything. This is episode 15, Take Me to the River, Part 3. In this episode, we'll finish up our deep dive into the world of dams and hydroelectric power generation. As always, eyes wide, wide, wide open. Dams, despite their often monolithic appearance, turn out to be the Swiss army knives of the infrastructural world, often serving flood control, power generation, recreation, and irrigation duty simultaneously. As you might imagine, I'm thinking of the bigger Swiss army knives here, the ones we wanted when we were kids, the ones with corkscrews and screwdrivers and toothpicks and fish scalers, and you know the ones. And hydroelectric power generation, in turn, is on its surface a greenhouse gas free way to make large amounts of electricity. But compromises and caveats and questions, oh my. These last two episodes on dams and hydroelectricity have been a roller coaster. So, three remaining areas to cover. These roles in the power grid, the impacts of climate change on hydropower, and the opportunities for innovation, entrepreneurship, and advocacy, both now and into the future. First, what roles does hydroelectric power have in the power grid? Notice that's roles plural. As dams are the Swiss army knives of infrastructure, hydroelectricity is the Swiss army knife of power generation, which is a really good thing as big pieces of infrastructure like dams hang around for a long time, almost always decades and often centuries. So, the power system, the grid. We'll take a deeper look at how the system operates soon, but for the purposes of this episode, I'll try to provide just enough background and hopefully some helpful analogies to frame it up. Simply put, the power grid is one of the great wonders of human innovation. Often called the world's biggest machine, it is a finely balanced system of power generation, feeding electricity to high voltage transmission lines, and at the end of those transmission lines, the users of that electricity hold load in electricity speak, usually via a lower voltage distribution system. Some of these loads are close to the power generators and others are far away, and everything in between. Some loads are very big, like a factory, for example, and some, like our houses, are very small, and everything in between. Some loads are pretty constant and predictable, 24-7, 365, like a hospital or a factory running around the clock, while others are quite variable, such as air condition demands that change with the weather, or office buildings, well, pre-hybrid work at least, that are occupied only during the weekday and work week, and everything in between. Finally, some loads are absolutely critical. Hospitals, police and fire stations, traffic lights, and some, like dishwashers, or even most air conditioners, can be shut off or curtailed in electricity speak, if need be. And, you guessed it, everything in between. The power grid, in turn, is designed to accommodate all of that diversity, location, size, predictability, criticality, within the pretty narrow constraints of physics and public safety. And that's where the finely balanced comes in. So, three kind of mind-boggling facts to keep in mind. One, physics dictates that electricity travels at the speed of light. Two, physics also dictates that electricity must be consumed the instant it is produced, the instant. And three, the system only works if generation and load are balanced within a very narrow tolerance. Aggregate output from generators must be very closely matched to whatever aggregate of loads is consuming electricity at any given time. At the speed of light, remember, the instant it's produced. Too much power, and the system starts to overheat and eventually burn, starting with whatever length happens to be weakest at that moment. Too little power, and the system shuts down. In this delicate dance, power system operators, for the most part, can only control the generator side of the equation. The load side, while to a large extent forecastable, is also largely out of system operator control. They are what they are when they are, and the system needs to rise or fall to meet them in that moment. So to keep the physics balanced moment to moment, the system needs a variety of types of power generators. 24-7 base load generators, plus more flexible load following generators to adjust to changing system loads, plus peaking units to match spikes in demand when every other generator is already running flat out, say during a heat storm, or when generators or other generators are offline, either for planned or unplanned maintenance. Plus, increasing amounts of intermittent renewables like solar and wind. Intermittent because Mother Nature controls the fuel, the wind, the cloud cover between the sun and the planet, and thus the output at any given moment, not the human operator. Which brings us to hydroelectric power, reservoir hydro in particular, the Swiss army knife of the system. Hydroelectric can play that base load part, the steady generation underlying the stability of the system. In that connection, we have one more important complication. That stability is not just a function of generator load matching, but also of frequency. So what is frequency? Frequency is the pulse of the power system. 60 beats per minute in many parts of the world, including the U.S., and 50 beats per minute in others, Europe, for example. That pulse represents the alternating current in the system. The rotation of turbines, and thus the coils of magnets in the generators, creates and enforces that heartbeat. In very simple terms, that allows minor changes in the generation load balance to exist without interrupting the system. The mass basically powers through the discrepancy. So think back on coal plants, the natural gas plants, the oil-fired plants that we've talked about so far in the podcast, rotating mass that pushes through the minor disturbances to keep the system safe and stable, regulating the frequency, the heartbeat of the system. Hydroelectric is no different, and in many cases, those turbines are really, really, really big, lots and lots of mass, and can play a big role in system stability. That frequency regulation function has become especially important as intermittent renewable energy like solar has come onto the grid in greater and greater quantities. Remember, that's generation whose output the system operators really can't control. Unlike fossil and hydroelectric, it's Mother Nature's speed on the accelerator and brake pedals, not human speed. Reservoir hydro tends to be very quick on the accelerator and brake. The operators just open and close water valves. So there's an important renewable energy integration function here too, filling in the gaps as both loads and intermittent renewables interact with the system in real time. It's important to note here that most hydroelectric plants were built well before the words environment or climate entered the lexicon, and renewable energy joined the power system in any quantity at all. Hoover Dam, for example, was completed in the 1930s, almost 100 years ago, but today is an important renewable energy integrator in the Western US grid. Sometimes that old Swiss army knife turns out to have a tool that functions in a way you never needed or even conceived of before. So, is hydroelectric power itself renewable? That's a thorny and very political question. The water cycle is renewable, of course, and hydroelectric power production, as we've seen, is GHG-free and in fact capable of displacing a lot of fossil generation. But, always the but, the dams themselves, as we've seen, may be as harmful to the global climate as they are to the local environment. We also know that many of them have been around for decades or more. So, counting existing big hydro as renewable is not going to decarbonize the system any more than it already is today. It's not additional, quote-unquote. And you can put mental quotation marks, too, around the word decarbonize, given the compromises, caveats, and questions we've already talked about. You can read the word additional in all sorts of ways. Additional renewable energy generated, of course, but also additional jobs added, additional taxes paid, additional political points scored, and so on. So, legislative and regulatory schemes about hydro's renewableness are very mixed. In the U.S., most states do not currently count any but very small hydro as renewable. That said, California, with the second biggest hydroelectric fleet in the U.S., has realized that its zero GHG future has to include hydro. And thus, the regulations don't count it against today's renewable energy goals, but it almost certainly will count against greenhouse gas goals closer to 2045, when California aspires to have a greenhouse gas-free power system. It's a very important distinction there between tools like renewable energy and goals like greenhouse gas reduction. And so it goes around the world. Compromise, caveats, and questions. Second, how does climate change everything when it comes to dams in general and hydroelectric power in particular? I see two big questions for hydroelectric power and our changing climate. Droughts and floods. In other words, too little water on one hand and way too much on the other. Droughts are the obvious threat to the hydroelectric power in a changing climate. Less water from the water cycle means decreased energy generation. At the same time, the associated hotter temperatures tend to increase electricity demand, especially for air conditioning, while also driving up demand for both drinking water and agricultural irrigation. Remember that many dams, especially the big reservoir dams, were designed and built well before climate change was a thing. And thus, generally speaking, the designers assumed a lot more water than the age of climate change may reliably provide. On the opposite end of the spectrum, floods. Too much dam water, or more specifically, too much water behind the dam. Climate scientists predict that many parts of the world, including here in California, will see less frequent but more severe rain events. Dam capacities are finite. They can only impound so much water before some water has to be released or the dam might fail. California's recent experience with the Oroville Dam is a great example of this, as is the Three Gorges in 2010, as we talked about last episode. Three Gorges had to let a lot of water through the dam during central China's 2010 floods, while parts of Oroville failed spectacularly, terrifyingly, in each case sending deadly and destructive amounts of water down the river. So third and finally, where are the opportunities for innovation, entrepreneurship, and advocacy? Let's talk to the innovators and entrepreneurs first. Where are the opportunities to do good and do well in hydroelectric power? Well, reduced construction emissions would be a big help, given the amount of carbon-intensive materials like concrete that go into building a dam. That means both quantity and quality. Lower quantities of carbon-intensive material through design optimization. In other words, can a modern dam, designed and engineered with 21st century knowledge and tools, use less material than one designed and engineered with 19th century or 20th century knowledge and tools? At the same time, finding higher quality materials, higher quality from a carbon efficiency perspective, with which to build the dam. Choosing recycled materials instead of new, where possible. Choosing low-carbon materials instead of high-carbon materials, wherever possible. Low-carbon cement is a great example of opportunity. Around the world, low-carbon and even zero-carbon cement is a rising area of focus for research universities, startups, and research and development labs. It will take a while for engineers, constructors, and regulators to get comfortable with these new products, especially in high-consequence applications like dams, but it's coming. Similarly, the more local the supply chain and the cleaner the power at the site, the lower the GHG footprint and better for the economy, both economically and in terms of environmental justice. More broadly, combining our eyes wide open with a cost-benefit lens that looks both at the entire project and the full project lifecycle, as we've been doing in these episodes. More specifically, opportunities like replacing decades-old turbines and other power generation components with more modern, high-efficiency equipment, so that more electricity is produced from the same amount of water and dam and reservoir and environmental and other impacts. Plus, better reservoir management relative to GHGs and more effective fish passage and other aquatic habitat enhancements, such as nutrient flux and dissolved oxygen management. Switching gears slightly, how about the advocates out there? Where are the opportunities to engage on policy, legislation, and regulation to make the best compromises around hydroelectric power for both existing and new projects? It starts, no surprise, with our eyes wide, wide, wide open. In other words, recognizing that just like every other form of energy, hydroelectricity is a compromise. Dams last a long, long time and uses change. That Swiss army knife analogy again. Climate compromises, environmental compromises, socioeconomic compromises, land-use compromises, political compromises. From a policy perspective, too, maybe it's time to move beyond embedded assumptions of uniformity. For hydro, for example, you've seen that different types of dams in different places can, in fact, create very different climate, environmental, socioeconomic, and other outcomes. A little more granularity beyond hydro is hydro, so to speak, can create a much more accurate picture, better information leading to better decisions. And that speaks to decisions around dam presence or removal, too. Climate change, nutrient flux, and dissolved oxygen, both in the reservoir and downstream. The buildup of toxic materials behind a dam impacts on fish populations and public safety considerations like seismic risks. It won't surprise you that effective advocacy and innovation and entrepreneurship, for that matter, snubs the seduction of simplicity and leans into these compromises. As always, eyes wide, wide, wide open. Next time, we'll look at another ostensibly GHG-free power generation technology with, you guessed it, big positives, big negatives, and big compromises, caveats, and questions. Nuclear or nuclear, if you happen to favor the pronunciation of America's 43rd president. No matter which way you say it, I'll see you soon for the next episode of Climate Changes Everything. Thanks for listening.