…Hydropower is Still Very Relevant…
Hydropower is the largest source of renewable energy and produces 16% of the world’s renewable electricity with over 1,600 GW of installed capacity.
Chart from International Hydropower Association
China has the largest installed hydropower capacity, followed by the United States. China and Brazil also have some of the longest and highest voltage DC transmission lines to move the power from their hydropower sites to where it can be used.
In terms of new capacity, however, the United States ranked 11 in 2017.
Hydropower requires large land areas in mountainous terrain, and for this reason has fallen out of favor among environmental groups. There have, in fact, been efforts to remove dams in the US.
Glen Canyon Dam is an example, with its 1,320 MW generating capacity that would disappear if the dam were to be removed. The U.S. Department of Interior also recommended the removal of four Klamath River dams to save salmon.
China’s Three Gorges Dam is an example of where there were huge benefits, but where the negative consequences, such as the forced resettlement of 1.3 million people and the flooding of archeological sites, received wide media condemnation.
One of its largest benefits, however, has been flood control where thousands of people were formerly displaced and killed by flooding of the Yangtze River. The 1931 Yangtze flood reportedly killed over 400,000 people.
The total installed generating capacity of the Three Gorges Dam is 22.5 GW.
Three Gorges Dam. Photo by D. Dears
Hydropower provides baseload power and can also follow load which makes it a valuable resource.
Accidents are fairly rare at hydropower plants, though the worst was probably the 2009 accident at the Sayano-Shushenskaya plant in Siberia when a pressure surge, i.e., water hammer, lifted one of the ten, 900 ton turbine-generators off its bearings. The roof of the turbine room collapsed and there was considerable damage to a few other turbines. Water flooded the powerhouse and caused electrical shorts and transformer failures. At least 69 people were killed.
Recently, hydropower has regained the interest of environmentalists as it can be used for pumped storage.
The first pumped storage plant in the United States was built in 1928 on the Housatonic River near Milford Connecticut. It was rated 30 MW and used to meet peak loads. Water was pumped from the Housatonic River to a lake above the river, where the water from the lake could be released and flow downhill though turbines to generate extra electricity when it was needed.
Only a few years ago pumped storage enlisted the wrath of environmentalists. In 1962, ConEdison proposed building a pumped storage plant at Storm King Mountain on the Hudson River. It took 17 years, but environmentalists finally were able to block construction of the plant.
Today, hydropower could provide some of the storage needed to provide electricity when the wind doesn’t blow and the sun doesn’t shine. Quoting the National Hydropower Association, “More than 97% of all installed capacity of energy storage is provided by pumped storage.”
There have been proposals to build storage at ground level to avoid using large land areas for reservoirs. One such proposal would create two parallel vertical, cylindrical holes in the ground that would create two chambers for water storage. The deeper chamber would store water while the upper chamber would have a pump for pumping water from the lower chamber, i.e., reservoir, into the upper chamber that would act as an artificial lake. The artificial lake is higher than the water storage chamber so gravity can be used to allow the water to flow through a generator back to the lower chamber when there was a need for electricity.
While some of these might work, there would need to be too many for the idea to be practical.
Hydropower still has great potential for generating electricity around the world, and for using pumped storage to a limited degree.
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