What’s the renewable energy with the most potential? It’s probably wind or solar, whose technologies are falling precipitously and making those investments economical. However, don’t discount hydropower, which now accounts for about 10% of the electricity and which could also grow in the coming decades.
“Hydropower provides many benefits in the fight to address climate change and for cleaner air,” says the National Hydropower Association. “Let’s not lose sight of what we know for certain about hydropower — it has greatly contributed to a healthier environment and economic prosperity and can sustainability grow to do more.”
The advocacy group points to a US Department of Energy report that says the energy form could grow by 50,000 megawatts by 2050. That, in turn, would cut greenhouse gas emissions by 5.6 billion metric tons and save $209 billion in avoided damages from heat-trapping emissions, it says.
In the United States, hydropower has grown from 56,000 MW in 1970 to more than 100,000 MW today, according to the U.S. Department of Energy. Scientists at the Idaho National Engineering and Environmental Laboratory, meantime, say that the United States could more than double its supply of hydropower by accessing smaller streams in addition to dams that are traditionally used for such purposes. The next phase of hydropower, however, will focus on smaller hydro units that are less disruptive environmentally but still useful in supplying electricity to remote areas.
The Idaho Falls-based research lab says that about 170,000 megawatts of the clean and sustainable energy form remain untapped and are not restricted from development by the federal government. Meanwhile, at least 100 countries are developing small hydro plants, with the most potential in the former Soviet Union, South Asia and South America.
The conventional way to produce hydroelectricity is through dams. But the amount of power is contingent upon the speed of the water that turns the turbines. Dams can increase the velocity by raising the water level. But they leave big footprints and can cause local populations to disperse. While dams are used to irrigate farms and supply water to cities, they are also responsible for displacing people and costing livelihoods as reservoirs occupy once-useful land.
More recently, hydro has been criticized for increasing heat-trapping emissions. Critics say that hydroelectric dams produce significant levels of carbon dioxide and methane; artificial greenhouse gas emissions could be from rotting vegetation in dams, for example. The latest to have reached this conclusion is Washington State University.
“If methane emissions are an issue, it is one for freshwater systems in general, not centered on hydropower generation itself,” the hydropower association responds.
Perhaps the most fruitful activity will come from those smaller so-called run-of-the-river facilities. They generate power by redirecting the river’s flow using distributed hydropower units that include underwater watermills. While such technology is dependent on stream flow and access to power lines, it does not require the construction of dams that block water and kill off aquatic life.
Indeed, several hundred permits are now pending with the Federal Energy Regulatory Commission, with many of those being granted preliminary approval. Most of those would be run-of-the-river units. The Obama administration has been focused on improving both run-of-the-river technologies as well as the reservoirs that may use pumped storage that releases the water to create electricity when it is most needed. That increases reliability.
“Now almost every hydropower project can be compatible with the environment,”says Michael Sale, executive director of the Low Impact Hydropower Institute, in a story for the Christian Science Monitor. “They may have to give up some energy when doing that, but hydropower delivers a lot of benefits when it’s done right.”
Hydropower is now the leading source of renewable energy, although wind and solar are fast on its heels. Still, hydro could expand its market as well — if it can limit its environmental footprint.