Hydropower, a renewable energy source harnessed from the movement of water, has been utilized for centuries, evolving from simple watermills to sophisticated pumped-storage systems. These systems not only generate electricity during peak demand by transferring water between reservoirs at different elevations but also play a crucial role in energy storage and grid stability. This article delves into the history, development, and modern applications of hydropower and pumped-storage, highlighting their significance in today's energy landscape.
Hydropower, derived from the Greek word "ὕδωρ" for water, has been a cornerstone of human civilization, powering various mechanical devices since antiquity. Ancient cultures across the globe, from Greece to China, harnessed the power of water for irrigation, milling, and other mechanical operations. The trompe, a device that generates compressed air from falling water, exemplifies the ingenuity of early hydropower applications.
The advent of electricity in the late 19th century marked a new era for hydropower. Cragside in Northumberland became the first house powered by hydroelectricity in 1878, and the first commercial hydroelectric power plant was established at Niagara Falls in 1879. By 1881, the city of Niagara Falls had its street lamps illuminated by hydropower.
During the Industrial Revolution, water power was essential for powering new inventions, such as Richard Arkwright's water frame. Although steam power eventually became dominant in larger mills, water power persisted in smaller operations. The United States saw hydropower's potential in canal transportation, with systems like Lowell, Massachusetts, exemplifying industrialization built upon water power.
Technological advancements led to the transition from open water wheels to enclosed turbines, with significant efficiency improvements. James B. Francis's turbine design in 1848 boasted 90% efficiency, setting the stage for future developments. The Pelton wheel, invented by Lester Allan Pelton in the 1870s, optimized hydropower for high head streams, a design still widely used today.
Hydropower stands out among renewable energy sources for its longevity and cleanliness. Many hydroelectric plants have surpassed a century of operation with minimal emissions. However, the construction of dams for hydropower can sometimes lead to social and environmental challenges.
Most hydroelectric power is generated by dammed water driving turbines and generators. The power output depends on the water volume and the height difference, known as the head. Run-of-the-river hydroelectric stations, with minimal reservoir capacity, rely on upstream water flow and can provide a significant portion of electricity needs. For instance, in the United States, run-of-the-river hydropower has the potential to supply approximately 60,000 megawatts, which was about 13.7% of the total electricity use in 2011.
Pumped-storage systems are pivotal for meeting high peak electricity demands. During low demand, excess generation capacity pumps water to a higher reservoir. When demand spikes, the water is released to a lower reservoir, passing through turbines to generate electricity. This method is the most common form of large-scale grid energy storage, with pumped-storage hydroelectricity (PSH) accounting for over 99% of bulk storage capacity globally, totaling around 127,000 MW.
Pumped-storage systems typically achieve a round-trip energy efficiency between 70% and 80%, with some systems claiming up to 87%. However, the need for specific geographic features, such as height differences and water availability, limits site selection. These systems often require large bodies of water or significant height variations to store substantial energy amounts.
Pumped-storage systems not only manage energy loads but also help maintain electrical network frequency and provide reserve generation. They can respond to load changes within seconds, unlike thermal power plants, which are less flexible. The Ffestiniog Pumped Storage Scheme in North Wales, for example, can generate 360 MW of electricity within 60 seconds when needed.
The first pumped-storage systems emerged in the 1890s in Italy and Switzerland, with the United States following suit in 1930. Modern advancements include reversible hydroelectric turbines and variable speed machines for enhanced efficiency.
Pumped-storage plays a critical role in balancing the output of intermittent energy sources like wind and solar. It provides a load during periods of high electricity output and low demand, facilitating additional peak capacity. With the growth of photovoltaic generation, pumped-storage's importance is set to increase.
Hydropower and pumped-storage have come a long way from their humble beginnings. They now serve as vital components of our energy infrastructure, offering clean, renewable energy and enhancing grid reliability. As we continue to shift towards sustainable energy sources, the role of hydropower and pumped-storage will undoubtedly become even more significant.
For further reading on hydropower and its sustainability, visit the International Hydropower Association and explore the Water Encyclopedia for more information on hydroelectric power.
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Project HARP
The HARP project, abbreviated from the High Altitude Project, was considered a joint project of the United States Department of Defense and Canada's Department of Defense, originally designed to study low-cost re-entry vehicles. Generally, such projects used rocket launchers to launch missiles, costly and often inefficient. The HARP project used a non-rocket space launch method based on a very large weapon capable of sending objects at high altitudes using very high speeds.
