Solar, wind and hydropower are all sources of renewable energy. Yet moving water may be the most efficient of the three sources. It is denser than air, and, because river water is constantly flowing, it can provide power at all times of the day and in any weather conditions. By contrast, solar and wind power are only available about 25 percent of the time [source: Renewable Energy World]. (But read more on how this could be remedied in "How Solar Thermal Power Works" and "Is there a way to get solar energy at night?" (please link to new articles).) An estimated 2,800 gigawatts of power is available in the world's 200,000 miles (321,869 kilometers) of major rivers, just waiting to be harnessed [source: Bourne Energy].
According to Bourne Energy, each RiverStar unit can generate up to 50 kilowatts of energy in a 4-knot current. One array can produce about 1 megawatt of electricity, enough to power about 1,000 homes [source: Bourne Energy].
Bourne Energy is also producing a backpack unit that weighs less than 30 pounds (14 kilograms) and can generate 500 kilowatts of energy. It is designed to be carried into remote areas and placed in small streams. This lightweight version of RiverStar not only can bring energy to areas that are currently without power, but it can also provide freshwater to these areas as well, says Chris Catlin, CEO of Bourne Energy.
The company is also testing two other energy-generating products: TidalStar and OceanStar, which are designed to harness the energy from tides and waves.