25x’25 Vision: By 2025, America’s farms, forests and ranches will provide 25 percent of the total energy consumed in the United States, while continuing to produce safe, abundant, and affordable food, feed and fiber.

Why Renewables: Hydroelectric and Tidal Power

What is hydroelectric power?

Hydroelectric power uses energy from the movement of water to generate electricity. Water flows over a turbine and spins blades connected to a generator.  Electricity is then fed to the electric grid, an individual consumer or a storage device. The most common type of hydroelectric generating facility is a dam where water is stored until it is needed to produce electricity. Hydroelectric power is considered renewable, though some people have raised concerns over large hydroelectric dams due to their impacts on ecosystems, water quality, and natural river flow.

What is tidal power?

Tidal power is similar to hydroelectric power as it makes use of moving water to spin a turbine to produce electricity. As tides rise and fall due to the gravitational pull of the sun and moon, water flows through the mouths of bays and other narrow points. Tidal power facilities place turbines in these currents or trap water at high tide to release through turbines later. As the tides are generated by the ongoing movements of the planet, tidal power is considered renewable.

What are the benefits of hydroelectric and tidal power?

  • Low Lifetime Cost: Generating energy from flowing water is very simple and cheap. While constructing dams and turbines require high initial investments, ongoing costs are very low as the water is typically free.
  • Reliable and Predictable: Hydroelectric and tidal power facilities produce power on a predictable, and in the case of hydroelectric dams that store their energy source until it is needed, controllable schedule. They are immune to international energy market fluctuations, and they can rapidly adjust their output to meet demand, often faster than fossil fuel based power plants.
  • Cleaner Air: Hydroelectric and tidal power do not produce the air pollution from electricity generation facilities powered by coal, natural gas and other non-renewable fuels. Avoiding carbon monoxide, particulate, and toxic pollution emissions can prevent many tens of thousands of premature deaths in the United States each year from respiratory and heart diseases. When a hydroelectric or tidal power replaces electricity from a coal-fired power plant it also eliminates a potential source of sulfur emissions – a major component of acid rain.
  • Climate Mitigation: Hydroelectric and tidal power facilities produce zero emissions of CO2 or other greenhouse gases.
  • Flood Protection: Dams can protect downstream communities and businesses from damaging flooding.
  • Energy Storage: Dams and tidal barriers can also be used to store energy generated elsewhere by employing pumps to move water against gravity so it may be used later. For instance, electricity generated from a wind farm when there is low electricity demand could pump water from a lower reservoir to a higher reservoir. The energy used to move this water can then be converted back to electricity by releasing that water through the dam’s hydroelectric turbines at times of high demand for electricity, in essence timing wind power production to demand.

What is the potential for increasing hydroelectric and tidal power output in the future?

Over the past century, most high quality hydroelectric dam sites have been developed or are protected from development for specific reasons. Today, hydroelectric provides roughly 6.5% of domestic electricity generation. However, there is a growing market for small-scale hydroelectric turbines that can provide limited distributed energy production. In suitable locations, these smaller generators can compete on cost with other distributed generation technologies.

Promising sites for large scale tidal power installation are rare and pose recreational and environmental problems due to the barriers necessary to capture the tides for generation. However, technologies such as turbines that do not rely on tidal barriers are being developed that produce energy from the ongoing currents and tidal flows. These could be more flexible and appropriate to the many variable coastal conditions, but it remains to be seen if and how they fit into the energy market.

Are dams and tidal power installations threats to fish and wildlife?

Diverting water from its natural course does affect an ecosystem, often far upstream and downstream from the dam or tidal power site. However, progress continues to be made to overcome these impacts and ensure that the river systems and tidal basins remain healthy and supportive of the flora and fauna that depend on them. These power systems can not be considered renewable unless they provide for the continued health of their host ecosystems and take action to prevent their long-term problems such as siltation and changes to groundwater supplies.

Hydroelectricity, Tidal Power and the 25x’25 Alliance

25x’25 is a unique Alliance of interests, established initially in the agricultural and forestry sectors and now includes partners from the national security, business, labor, environmental, and religious communities. Hydroelectric and tidal power can provide secure, reliable electricity from either centralized or distributed generation facilities in concert with the irrigation needs of the nation’s working lands.