Energy Bar: The High Stakes of Hydropower

Alain Kilajian has traveled far and wide in his efforts to ensure hydropower is as sustainable as possible. Even to the sky-high mountains at the far end of Tajikistan.

After an 18-hour car ride from the capital of Dushanbe, partly through Afghanistan, “you go up the river to the Shakhdara River Valley,” he says. “And you’re looking at these mountains, which are wild because there’s no greenery. It’s just rocks and formations, and then you come to this hydropower plant. Sometimes I almost feel like I’m in a Mad Max movie.”

Kilajian is co-founder and executive director of the Hydropower Sustainability Alliance (HSA), an international NGO based in Lisbon, Portugal, that certifies hydropower facilities as sustainable. HSA uses 12 criteria, everything from strict environmental and biological thresholds to communication and treatment of Indigenous peoples. The reason Kilajian and HSA go to such lengths is that hydropower as renewable energy is, well, complicated.

Damn Dams

In his 1971 classic Encounters With the Archdruid, about David Brower and the environmental movement, legendary author John McPhee noted the symbolic impact of a dam to conservationists: “There is something special about dams, something — as conservation problems go — that is disproportionately and metaphysically sinister.” In McPhee’s telling, the circles of environmentalists’ hell get smaller and smaller until “the absolute epicenter of hell on earth, where stands a dam.”

Nearly 60 years later, in our time of global climate change, microplastics, and crumbling biodiversity, the idea of a dam being the center of ecological Hades seems almost quaint (maybe a coal mine? A data center? An H&M store?). But, as McPhee recounts, epic battles in Western states over dams, both defeated and built, helped create the modern environmental movement.

You can see why, since massive dams in places like Hetch Hetchy in California and Glen Canyon in Arizona and Utah drowned magnificent landscapes that rival those of any national park (the Hetch Hetchy dam was built in Yosemite National Park). Dams prevent fish from spawning and destroy critical riparian habitat. If they fail, they can kill hundreds or thousands — and have. 

Millions of people, particularly native people, have been displaced globally so that dams could be built, and millions of acres of forest and other habitats have been drowned. On the flip side, hydropower is the largest source of renewable energy on the planet — and it’s not even close. In the U.S., hydropower is a close third behind wind and solar, providing 5.4% of our juice.

Making Hydropower Better

The Boston-based Low Impact Hydropower Institute (LIHI), a sister organization to HSA, handles hydropower certification in the United States. Shannon Ames, LIHI’s executive director, explains that hydropower differs from other renewable energy sources. “Hydropower is a very unique renewable,” she says. “It sits on rivers, which are a public resource, which makes it fundamentally different than wind or solar, which can be put on private land. And therefore, we think it needs to be done differently.” 

Pushback against the environmental and human-rights abuses of large hydroelectric projects globally and in the U.S. helped set the stage for HSA and LIHI. But both organizations know that hydropower is essential to providing clean power. 

“If you look at any country that’s close to [zero carbon emissions],” Kilajian says, “most of them will have a strong component that’s hydropower. So, the reality of how the systems work without fossil fuel, at this stage, kind of requires hydropower.” 

For example, both Kilajian and Ames note that hydro, unlike wind and solar, is available 24/7 for what is known as baseload power, or the minimum amount of electricity that a power grid needs to meet basic demand. “To be really honest, you’re gonna need hydro,” Kilajian says.

And both organizations maintain high standards. Kilajian says only about 40% of the projects HSA has assessed have been certified. The rest either work to improve their operations and facilities and reapply, or have shortcomings too substantial to overcome. Ames estimates that LIHI certifies 80% of U.S. facilities that apply, though the organization will advise some facilities to wait until they make changes. Fish passage, she notes, is a major sticking point with many dams, but there are technologies and innovative designs that can help.

Ames notes that many states, companies, and organizations use LIHI’s certification to ensure that the energy they purchase is truly renewable; in this context, if a hydroelectric facility isn’t certified, it’s not “green” energy.

Carbon Emissions From Hydropower

One surprising issue that hydropower has to tackle is that dams can have surprisingly high carbon emissions, even larger than those from a coal plant under certain conditions. These emissions are largely from methane, an extremely potent greenhouse gas. When dams are built, reservoirs (“impoundments” in hydro parlance) form behind them. These manmade lakes and ponds create anaerobic conditions where the organic material in the inundated plants and soils decay and create methane. 

The conditions that can lead to methane emissions vary greatly from project to project, but hydro operators and designers can minimize these emissions with smart siting, design, and operations. For example, water at the bottom of the impoundment is likely to have more methane in it, so a water intake for hydropower at a shallower level will have fewer emissions.

Kilajian says HSA’s low-carbon standard is 100 grams of CO2 equivalent (CO2e) per kilowatt-hour (kWh), measured and independently verified. “If a project is above that, it essentially doesn’t get certified,” he says.

But calculating the emissions from hydro facilities can be tricky, LIHI's Ames says. “Like so much with hydro, it’s going to depend on the reservoir. We also know that the science for measuring emissions at reservoirs is lacking. It is inconsistent. … As soon as there is a consistent way to measure, a better way to measure, that we can apply, then we will be able to develop a criterion around it.”

One example of the difficulty of measuring CO2e emissions is the four dams on Washington’s lower Snake River. A report by the cleverly named river advocacy group Tell The Dam Truth put their combined emissions at 1.8 million tons of CO2e annually, or about 225g of CO2e/kWh. The Army Corps of Engineers, which runs the dams, disputes these numbers. The estimate is over the HSA standard, but it’s less than the 410 g/kWh the U.S. Energy Information Agency estimates for natural gas plants, or the 1,000 g/kWh for coal. (See sidebar.)

Oversupply of Dams

Only 3% of the 90,000-plus dams in the U.S. provide hydroelectric power, and dams around the country have been torn down in recent years. Some advocates even suggest emptying Lake Powell (in Arizona and Utah, behind Glen Canyon Dam) to refill Lake Mead (in Arizona and Nevada, behind Hoover Dam), since both are critically low due to ongoing drought and climate change.

Ames is enthusiastic about expanding hydropower, noting that it can be retrofitted into existing dams and water supply facilities. At the same time, she says, “we fully support taking down dams. Absolutely, 100%. And in fact, one of our eligibility criterion is if a hydro facility is on a dam that has been formally recommended for removal, we can’t, we won’t, move forward with that application. For us, dam removal is a really, really important thing, both for climate adaptation and fish recovery.”

Pointing out that the U.S. has too many dams, she notes, “They just proliferated so crazily, and we don’t need them. And it’s usually the easiest, fastest, most effective way to improve fish habitat.” While she points to improvements in fish passages around dams, the best dam for fish is no dam.

Kilajian agrees that the U.S., at least, can do without new dams. “There’s a lot of dams [in the U.S.] that could have a hydropower component,” he says. “But in places like Mozambique or Angola, they’re way behind in their development ambition, or their development capacity, and they have a growing population, growing industry. So these places are definitely going to have increases in hydro power.”

Getting It Right

Kilajian actually started his career fighting hydropower. “In Thailand, I worked, funny enough, building barricades or blockades to block construction trucks going into [dam] sites.” But as he did more research, he saw how hydro could be done well and was inspired enough to help found HSA to make sure it was. 

“When I see a dam, it’s not like I get excited. But then if you zoom out and you think about how systems work and fossil fuels, you need this. So you’re gonna have to do it well. And this is where we come in.”

He mentions again the Sebzor project in remote Tajikistan. “It changed my brain a little bit,” he says, of seeing the benefits that the hydro project brought to an impoverished rural community. 

“A river’s a live system,” he says. “It’s a cultural symbol. Communities rely on it. And when you come in, especially in these remote areas, some of them beg you to build a hydropower project there. I’ve seen the infrastructure that comes, the roads, the health centers, etc.”

He explains, “We think of London or D.C. or Lisbon, and there’s, like, 17 supermarkets selling you avocados. That’s one reality on this planet, and this is another reality. And at least for this reality, the hydropower project has brought along a lot of benefits to them. We push for those types of hydropower projects.”

Five Takeaways

• Hydropower is the largest source of renewable energy in the world and ranks third in the U.S. behind wind and solar.
• However, hydropower has a long list of environmental and social negatives, from habitat destruction, displacement of people, and inundation of scenic landscapes.
• Hydropower can also have surprisingly high carbon emissions, largely from methane generated by the reservoirs behind dams. These emissions are difficult to measure and estimate.
• Groups like the Hydropower Sustainability Alliance (internationally) and the Low Impact Hydropower Institute (in the U.S.) use rigorous criteria to certify hydro projects as using the best sustainability practices.
• To meet zero-carbon goals, growth in hydropower will likely be necessary. In the U.S., this can be accomplished by adding or improving hydropower at existing dams, but globally, new dam projects will probably be needed.

What You Can Do

The best way to reduce carbon emissions is to use less energy of all types and to use renewable energy when possible. You can support groups like the Hydropower Sustainability Alliance and the Low Impact Hydropower Institute that work to make hydro better. You can also support groups that work to improve river health, like American Rivers.

Telling the Dam Truth

Gary Wockner founded the river advocacy group Tell The Dam Truth specifically to highlight the relatively unknown issue of greenhouse gas emissions from dams.

“I wouldn’t say we’re anti-hydropower, but we support the protection and restoration of free flowing rivers,” he says. “We don’t exist to be against hydropower. We exist to protect and restore rivers, and of course, dams are one of those big threats. And hydropower, specifically, has been built and is still continuing to be built under the myth that it is clean energy. And it’s not.”

While hydro is generally cleaner than other forms of energy, it does have emissions, and Tell The Dam Truth wants those emissions measured accurately and accounted for. They’ve created a model, called All-Res, that attempts to capture the emissions from dams from cradle to grave. 

“What we’ve tried to do with All-Res,” Wockner explains, “is pull together the very best science and the most recent science, and keep it incorporated in our modeling tool.”

Tell The Dam Truth has also petitioned both the U.S. EPA and the State of California to include greenhouse gas emissions from dams in their official tallies of greenhouse gas emissions. It produced reports on the ongoing emissions from the four dams on the Snake River, and also on the avoided emissions resulting from the removal of four dams on the Klamath River in Oregon and California.

“Those dams [on the Klamath] had been there for a long time,” he says. “All the reservoirs were what we call eutrophic, meaning they were algae-filled and warm and stagnant. And those are the kinds of conditions under which reservoirs will create more methane. Removing all four of those reservoirs and making the river free again stopped a consequential amount of emissions from being generated each year.”

The All-Res model estimates that removing the Klamath dams avoids 275,000 metric tons of CO2e annually, about as much as taking 64,000 cars off the road for a year. The savings comes not just from avoiding emissions, but from regrowing vegetation. 

“Basically, all of the former inundated area under the reservoir was replanted, and now it is growing vegetation and trees,” Wockner notes. “And that vegetation and trees actually sequesters, or traps and holds, carbon. So you have a situation where it used to be a carbon emitter … and now they are carbon sinks, so they are sequestering carbon.”

Wockner takes pride in his group’s connection to environmental history. “The American environmental movement basically started with the fight of the dam in the Hetch Hetchy Valley in California, of course. It was a signature moment there, with John Muir fighting against the dam. And then one of the biggest dam fights in history was with Sierra Club president David Brower in the Grand Canyon. And so protecting rivers and fighting dams has a very long and very deep history there in the American environmental movement.”