In the past few decades, solar panels and wind turbines have often snagged more hype when it comes to renewable energy. We sometimes assume that because these technologies feel newer, the path to greener power generation lies with them.
Yet sources like solar and wind would have a long way to go before meeting our global and domestic energy needs for a 100 percent renewable future. The power that both provide depends more directly on weather conditions and time of day. In order to be consistent energy sources, they would need to be paired with major storage capacity — and that battery technology isn’t there yet.
In the meantime, as climate change worsens fast, there’s a proven clean energy source we shouldn’t forget, and it’s a powerful one: hydropower. Globally, hydro is by far the largest share of total renewable generation capacity, producing over twice as much energy as wind, and over four times as much as solar. In the U.S., it provided nearly 32 percent of renewable electricity generation last year. “We don’t get the headlines that some of the other technologies do,” Malcolm Woolf, president and CEO of the National Hydropower Association, has told CNBC. “But I think folks are increasingly realizing that you can’t have a reliable grid without hydropower.”
Humans have used the energy provided by the movement of water for mills, factories, and other types of production for centuries. The model for today’s hydropower plants remains simple to understand: water flows from an upper reservoir to a lower one, spinning an electricity-generating turbine along the way.
Now, in the age of climate change, there’s a new appreciation rising for the vital fact that energy generated this way is carbon-free. Plus, hydropower can be had locally, so we don’t have to rely on another country or region for it. In the Pacific Northwest alone, it provides about 46 of the region’s annual electricity generation, and 54 percent of its flexible capacity (which is important for peak demand periods). If you live in Washington, for example, — the nation’s largest hydroelectric power producer — there’s a good chance your electricity comes from hydropower. Sixty-six percent of the state’s electricity net generation came from hydroelectric power (from both utility-scale and small-scale facilities) in 2020. Or, if you live in Oregon, you might be a customer of one of the 34 consumer-owned utilities that depends on hydroelectric power provided by the Bonneville Power Administration.
Hydro can even support other renewables, filling the gaps for wind and solar. That makes it a big player on the path to fully renewable energy. Technologies like pumped storage hydropower store energy that can be used with wind and solar at times of high demand. Pumped storage facilities let water flow from higher to lower reservoirs like usual — but they can also recharge, using power from the grid to pump water from below up to the higher reservoir, storing potential energy that can be released when needed. New pumped-storage models like closed-loop facilities (which aren’t connected to an outside water source) or smaller tank-based facilities (which involve tanks rather than reservoirs) use technologies that are minimally disruptive to the environment.
In the past few years, important concerns have been raised about issues like environmental impact and future water availability. Rivers and fisheries can be affected by the dams that hydropower often requires. Another question has been how droughts could affect reliability for an energy source dependent on water. Yet many of the misconceptions about hydropower come from older technologies and dated assumptions. The National Hydropower Association has called for starting with the “3R’s:” retrofitting dams to increase renewable power generation; rehabilitating dams to address any safety concerns; and removing dams that no longer serve a purpose. “Our efforts are already bearing fruit,” Woolf has said.
For instance, by 2030, $127 billion will be spent on modernizing old plants globally, accounting for some 90 percent of hydropower investment in Europe and North America. There are around 90,000 dams in the United States. Only about 2,300 of them currently generate hydroelectric power, but their impact is outsized — they account for 7 percent of the nation’s energy production, and 37 percent of its renewable energy supply. It’s why some are advocating for retrofitting some dams and removing others. “There are a lot of dams that are on the landscape that aren’t serving a purpose and wouldn’t be economic generators were you to add hydropower to them,” hydropower reform program director at American Rivers Kelly Catlett has told the Washington Post. “But where you have a dam that is serving another purpose and it’s going to be around for a while, why not put hydropower generation on it?”
Much innovation has been done around reducing impact as well. Many companies have made major investments in creating pathways for fish. Fish ladders, trap-and-haul operations, and fish elevators have all been added to allow fish to pass, and their designs are continually being tweaked to make them even more inviting and effective for more species. Newer technologies are emerging as well, like special turbines that are safer for fish to pass through. One company designed compact “restoration turbines” with blades that are thicker and more steeply slanted than standard. The blunt edges of the blades deflect fish, and their slope reduces the chances of a direct impact, allowing 99% of fish to pass through its turbines safely, they claim.
One concern for hydropower is the incidence of droughts with climate change. While that may be true for other areas of the country, climate experts predict the Pacific Northwest will continue to see about the same amount of annual rainfall, even under climate change scenarios. There are also opportunities to adopt new technologies to increase hydropower efficiency, even under low water conditions.
This kind of modernizing investment will help us ensure that plants can operate for decades to come, providing energy even in challenging conditions. That will allow hydropower to help the world make the transition we need to a 100 percent renewable future.