Hydroelectric Power is a renewable energy source that is produced by capturing the kinetic energy of flowing or falling water. Although this technique has been practiced since ancient times, it is a technology that still has a great deal of potential for growth.
Hydropower: A Leader in Renewables
Hydropower is the largest source of renewable energy in the world. Globally, this technology represents around 16% of total electricity consumed and dominates 85% of renewable electricity. In the United states, Hydroelectric energy accounts for around 10% of the total electricity generated, allowing the nation to avoid 200 million metric tons of carbon emissions each year.
According to the US Department of Energy, hydropower could grow by 50,000 megawatts by 2050. This would lead to a reduction of 5.6 billion metric tons of greenhouse gas emissions and a savings of $209 billion dollars by avoiding the damages of heat-trapping emissions. With new technology hydropower can become even more efficient, and have greater production capacities.
The term “hydropower” covers multiple technologies ranging from large to small and old to new: https://www.youtube.com/watch?v=tpigNNTQix8
Reservoir Hydropower Plant: This type of impoundment facility is most common, representing the majority of U.S. hydropower generation. Impoundment facilities, typically larger in size, require a river dam to store water in a reservoir behind a generating facility. The water released from the reservoir then flows through a turbine, which spins blades producing mechanical energy that is then sent through transmission lines. This technique provides flexibility to generate electricity on demand and as needed, reducing dependence the the variability of inflows.
Pumped Storage Plant: Electricity demand is not “flat” and constant, it fluctuates based on peak hours and usage. PSP’s act like a battery, storing power in the form of water when demands are low and producing maximum power during daily and seasonal peak periods. When electricity supply exceeds demand or can be generated at low cost, these plants take energy from the grid to power generators that pump water from a lower reservoir to a higher reservoir, where the water is then stored. During periods of high electrical demand water is released from the upper reservoir back down to the lower reservoir, thus spinning the turbines and generating electricity. PCP is a net consumer of electricity, but provides for effective electricity storage.
Diversion hydropower plant: Diversion plants, also called run-of-river plants, harness energy from the available flow of the river. They do this by channeling portions of a river through a canal or penstock, and may not require the use of a dam. These plants include short-term storage or “pondage” allowing for some hourly or daily flexibility, but this generation profile is mainly driven by natural river flow conditions or releases from any upstream reservoir. In the absence of an upstream hydropower plant, generation depends on precipitation and runoff in addition to having seasonal variations.
- Clean Energy: Hydropower is renewable and clean. The generation process does not produce toxic by-products or pollutants, and water can be used later for irrigation and consumption.
- Safety: Unlike nuclear energy and fossil fuels, hydropower does not pose a potential health risk to the public. There are no oil spills, or nuclear leaks.
- Flexibility: The water flow and energy output can be adjusted based on consumption and storage capacity. Many facilities can go from zero to maximum output, making them ideal for meeting sudden changes in electricity demand.
- Cost-Effective: According to a recent analysis by Navigant Consulting, Inc. hydropower was the most affordable at $.02/kWh. States that get the majority of their electricity from hydropower (Idaho, Washington, Oregon) have energy bills that are lower than the rest of the country.
- Durability: Dams can be operational for decades with few investments once required once constructed.
- Multi-Functional: In addition to electricity production, dams can be used for irrigation, shipping and navigation, flood control, or to create reservoirs for recreation.
- Environmental impact: The construction of a dam damages ecosystems, changes water levels, and floods large areas. Some fish, such as salmon shad and sturgeon, may be prevented from swimming upstream to spawn. Technologies such as fish ladders have been developed to help salmon go up over dams, but the presence of these dams still changes migration patterns and harms fish populations. Hydropower plants can also result in low dissolved oxygen levels, which harms river habitats.
- Displaced people: The construction of a large dam often requires that entire towns move out of the area. In the construction of the Three Gorges Dam in China, it is estimated than 1.2 million people were displaced.
- Expensive: building a dam requires a large initial investment
- Accidents: in the past, dams have breached leading to flooding and casualties
Modernizing: New technology must be employed at existing sites by installing more efficient turbines, enhancing performance, and minimizing environmental externalities so that existing infrastructure can generate more power sustainably
Converting Non-Powered Dams: Out of 80,000 dams across the U.S. only 3% have electricity generating equipment. Converting these facilities will increase America’s renewable energy by 12 GW
Conduit Technology: Retrofitting existing tunnels, canals, pipelines, aqueducts, and other manmade structures that move water with electricity-generating equipment will utilize already available infrastructure into an energy-generating asset.
Micro-Hydroelectric Systems: The next phase of hydropower will focus on smaller units that are less environmentally disruptive and costly, but still useful in supplying electricity to remote areas. According to Idaho Falls-based research lab, about 170,000 megawatts of hydropower remains untapped and unrestricted from development by the federal government. Small or micro-hydroelectric power systems can produce enough electricity for a home, farm, or ranch and should not be overlooked. At least 100 countries are developing small hydro plants. These smaller so called run-of-the-river facilities does not require the construction of dams which requires high initial investments, blocks water and kills aquatic life.
Marine and Hydrokinetic Technologies: In recent years, a profusion of new technologies have emerged in the market including tapping into the kinetic potential of Ocean waves, tides and river flows. About 71 percent of the Earth’s surface is water-covered, and the oceans hold about 96.5 percent of all Earth’s water. Thousands of megawatts of untapped potential are available from such projects. The predictability of tidal power is attractive for grid management. Unlike many other sources of renewable energy, water is continuously moving and consistent, removing the need for back-up plants powered by fossil fuels.
- Tidal turbines installed on the seabed at sites with high current velocities are a great starting point. To be successful in these installations, engineers and designers can look marine biology as a means to gain insight into how these turbines can gracefully move underwater.
- Despite being nearly 80,000 pounds, Humpback whales can swim in tight circles and dive hundreds of feet. In 2004 Scientists at Duke University, West Chester University, and the U.S. Naval Academy discovered that the bumps on their fins, called tubercles, aid in their surprising dexterity. According to asknature.org, “Wind tunnel tests of model humpback flippers with and without leading-edge tubercles have demonstrated the fluid dynamic improvements tubercles make, such as a staggering 32% reduction in drag, 8% improvement in lift, and a 40% increase in angle of attack over smooth flippers.” This biomimetic approach to design could aid in developing underwater turbines that will limit friction and drag, thus harvesting more energy.