Electricity is important to power our homes, towns, and cities. It is produced in many ways, however, some of the most common ways often have a large environmental impact. Fossil fuels amount to 60% of US power and produced 1,542 metric tons of CO2 in 2022. There have been many efforts to find an alternative to energy production that is renewable, lessening the impact on the environment. These efforts include solar, wind, geothermal, and hydropower. Hydropower makes up 6.2% of the total power produced in the US. They produce no emissions to operate and are infinitely renewable as long as there is water. But how do they work?
Hydropower plants harness the power of the natural never-ending water cycle. They do this by converting the kinetic energy of flowing water into electricity. Water is first run through a penstock (a pipe) that feeds into a turbine. This spins the turbine, which in turn spins a generator and produces electricity which can be brought to a nearby power station. These plants are usually located near a water source with a large head (change in elevation). This is because the greater the flow and the higher the head, the more electricity can be produced.
Hydropower plants come in three main types, impoundment, diversion, and pumped storage with the most common of these being impoundment. These plants are typically found in large dams located in reservoirs. In an impoundment system, water from the reservoir is passed through the turbine generator to produce electricity before it is released downstream into a river. These plants can produce a substantial amount of power and can be used for multiple purposes. They can be regulated to meet changing electricity demand, flood control, recreation, fish passage, and more.
Diversion plants, or “run-of-river facilities”, are smaller and potentially require fewer resources. This is because these plants may not require a dam, diverting water through a separate channel adjacent to the river. From this channel, water can be run down the penstock into the powerhouse, using the natural change of the river bed elevation to move the water.
Finally, pumped storage plants take a different approach. These plants are located between two bodies of water with different elevations. While energy is in high demand, these plants flow water downhill, through the plant, to the lower body of water producing electricity. However, when energy is in low demand, the generators can be reversed using energy from a different source. This transforms the generator and turbine into a pump, pushing water back uphill into the higher body of water. Because these plants can produce power at any time of day, they can be used in conjunction with other alternative energy sources like solar.
Hydropower plants can range dramatically in size. Large hydropower plants are defined by the Department of Energy as having a capacity of 30 megawatts or more and are often used to power cities with large populations. Small plants (100 kilowatts to 10 megawatts) and micro plants (up to 100 kilowatts) are often operated privately and may be used for one’s own energy needs, or to sell power to utility companies.
While hydropower may not suffice as a main source of energy production, its potential should not be ignored. Water is everywhere so power potential is abundant, especially when used in conjunction with other modes of production. All of this leads to a cleaner and renewable future for energy.
By Jack Boardman