July 5, 2016
The leaders of the United States, Mexico, and Canada pledged to generate half of their electricity from clean power by 2025 at a trilateral summit last week in Ottawa. Increasing North American clean energy generation from its current level of 37% is an ambitious, but important goal, and achieving it will require improvements on multiple different pathways.
For the United States, one of the major challenges will be how to quickly displace coal-fired power plants without leaning heavily on natural gas, a cleaner, but by no means clean source of energy. Though renewable energy sources such as wind and solar are expected to be among the fastest growing forms of electricity generation over the next 25 years, they simply won’t be able displace enough coal use on their own. Wind and solar have been highly competitive in states like Hawaii, California, and Texas, but in the areas of the country where coal is used most heavily, renewables have not been competitive enough to make a major impact.
One clean, renewable energy source that has the potential to be cost-competitive against coal in states like Ohio and Kentucky is hydroelectric power. Hydroelectricity is already a powerful source of electricity in the United States, generating half of all renewable electricity in the U.S. and 7% of total electricity. Every state in the U.S. uses hydropower, with eleven states generating more than 10% of their electricity from it, and states like Washington generating 70% of their electricity from hydropower according to the U.S. Energy Information Administration.
Hydroelectricity offers unique advantages over other forms of electricity, including the ability come online immediately and without an external power source, making it great for filling gaps in energy supply and jump-starting grids following a power outage. Pumped storage, a form of hydropower, can also complement intermittent renewables like wind and solar by acting as a battery - using surplus power from extremely sunny or windy periods to pump water up to a higher elevation, thus storing it in potential energy, and dispersing it as needed.
Most hydropower comes from large dams, but only 3% of the 80,000 dams operating in the United States currently generate electricity. Most dams were built for irrigation, flood control, or navigation, though nearly all have the potential to generate hydroelectricity, as well. In a 2012 study, the U.S. Department of Energy estimated that retrofitting non-electricity producing dams has the potential to generate 12 gigawatts (GW) of power - a 15% increase in conventional hydropower generation in the U.S.As seen in the map below, most of this potential is concentrated along the Mississippi, Ohio, Alabama, and Arkansas Rivers, much of it running through what has traditionally been coal country. An interactive version of the map can be found here. Even just retrofitting the top ten non-power producing dams along these rivers would generate 3 GW of electricity - more than the Hoover Dam and enough electricity to power 1.2 million homes.
Hydroelectricity is not completely without risks or tradeoffs. Eric Holthaus has a good piece at Slate detailing the many challenges facing hydropower and why the global dam-building spree is cause for concern. One particular worry is the effect of climate change on river flows, which is decreasing hydroelectric capacity, particularly during droughts. Many electricity-generating dams like the Hoover Dam will need to be retrofitted just to continue producing current levels of hydropower as a result of declining river flows.
Furthermore, some dams just aren’t worth the economic, social, and environmental costs, even with the potential for electricity generation. Dams can be a highly destructive force due to the areas they flood to create reservoirs, and if poorly designed or managed, can cause irreparable damage to the land downstream or to other important natural resources such as fisheries. Many dams built in the U.S. over the past century are now being torn down as the environmental and economic costs have been realized.
The potential for hydroelectricity generation won’t and shouldn’t save these most destructive dams, but for the many dams across the country that continue to provide important, sustainable benefits, we shouldn’t pass up the opportunity to also generate clean hydroelectric power.
The climate and energy challenges facing the United States and countries around the world can’t afford to wait for major improvements in solar panel prices, electricity storage, or grid management reforms before progress is made on emissions reductions. The situation is too urgent and the timeline is too tight to let the status quo abide without immediate action. Hydropower won’t be the answer by itself - no power source will be - but it provides a powerful potential source of electricity that can immediately compete with and displace dirtier sources like coal.Building new dams is fraught with environmental, social, and economic risks, and there are legitimate questions about whether hydroelectric output can keep up in the face of growing water challenges, but at the very least, retrofitting existing, non-electricity producing dams can help us tackle the problem now and buy us more time until other renewable energy options are more viable.