Energy efficiency and environmental protection are two of the biggest issues facing the world today. Recent efforts have focused on shifting energy production away from environmentally unfriendly fossil fuels such as coal and oil, toward cleaner, renewable energy sources like solar, wind and hydropower.
Hydropower is currently the largest source of renewable energy in the United States. Hydroelectric plants supply about 6 to 8 percent of all the electricity produced in this country [source: Nelson]. Typically, hydroelectric power is harnessed by building a dam on a river and storing the water in a large reservoir. As the water flows through gates in the dam, it turns turbines, which are connected to the generators that produce energy.
Hydroelectric power plants are effective energy generators, yet they tend to be large and expensive to build. One company says it has created a smaller, more portable, and even more environmentally friendly way to produce clean and efficient hydropower. Bourne Energy, based in Malibu, Calif., has designed a power system that harnesses energy not from dams, but directly from flowing rivers.
Bourne Energy's RiverStar harvests energy all along a river, rather than at one site, so it is smaller and easier to install [source: Bourne Energy]. RiverStar modules are placed in arrays of 20 units across the width or length of a river. They are held in place by high-tension steel cables that are attached to either side of the river. Each floating module is made up of a turbine that looks like an upside-down windmill, as well as a stabilizer, energy absorber, mooring system and energy conversion system. Flowing water passes through the turbines, and as they spin, they collect energy, which drives a generator module.
Read on to learn just how much energy RiverStar might be able to produce.
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.
Advantages of RiverStar
RiverStar is a portable system that doesn't require any construction to be done on the river bottom. Each module collapses so that it can be shipped to the river site. According to Bourne Energy, it can be installed in as little as a month. And when it is no longer wanted or needed, it can be removed from the river just as easily [source: Bourne Energy].
Thanks to its portability, RiverStar can be used in areas of the world that have up to now been too remote to receive power. In addition to providing electricity to these locations, RiverStar can provide drinkable water and treat wastes [source: Bourne Energy].
RiverStar units may also be gentler on the environment than current hydropower plants. Although hydroelectric plants are far cleaner than coal and gas plants, they can still produce greenhouse gases such as methane when debris and vegetation fall into the reservoir and decay (this is particularly true in warm, humid climates) [sources: New Scientist, Nelson]. According to Bourne Energy, RiverStar produces zero carbon emissions.
But what about environmental concerns? Because the RiverStar turbines spin at a low RPM, they shouldn't harm the fish and other wildlife that pass by. They also shouldn't disturb the river sediment or affect the water temperature, as dams can do.
Bourne Energy says that RiverStar is designed to coexist with populations living along the rivers where it is built. Residents can lease out their land and get paid for the energy that is produced from it. The arrays are constructed so that they do not interrupt local marine traffic. And RiverStar can be camouflaged with plants and other vegetation so that it looks like small islands, rather than energy-producing equipment.
Limitations of RiverStar
RiverStar sounds like an ideal solution to the world's continually growing energy demands. The question is -- can it deliver? Bourne Energy is still a startup company. It doesn't yet have the funding or capacity to produce the number of RiverStar systems it envisions, and it has yet to install one of these systems, so it's impossible to know at this time whether RiverStar might have any serious limitations.
One of the problems in getting a new hydropower system implemented is securing governmental licensing approval, according to Chris Catlin. The company has to get permission to place its system in rivers where people live and work. RiverStar would also have to be tested to make sure it is leaving little or no environmental footprint. In the United States, the Federal Energy Regulatory Commission issues licenses for companies to build and operate hydroelectric power projects. License applications usually take about two years to approve, and so far, Bourne Energy has not filed an application with the FERC to implement its RiverStar system in the United States.
Although Bourne Energy has not yet installed a RiverStar system, Catlin says that there has been some interest in the system internationally. The company has already signed a letter of intent with the Chinese government. Other countries have also indicated their interest.
RiverStar is not the only hydropower system of its kind. Other companies are also in the process of developing similar projects. Verdant Power, based in New York and Canada, is planning to test a kinetic hydropower system on the St. Lawrence River in Ontario, Canada. This system also uses underwater turbines, which the company says could generate up to 15 megawatts of energy for the local area [source: Verdant Power].
For now, the question of whether a hydropower system like RiverStar will become a major new source of energy in the future remains unanswered.
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Related HowStuffWorks Articles
- Bourne Energy. "Fast Track to Global Energy Independence."
- Bourne Energy. RiverStar. http://www.bourneenergy.com/future.html
- Catlin, Chris. CEO of Bourne Energy. Personal interview conducted April 29, 2009.
- Clifford, Damon. "Bourne Energy Puts Renewable Energy on a Fast Track." Alternative Energy Foundation. March 3, 2008. http://www.alternativeenergyfoundation.org/blog/2008/bourne-energy-puts-renewable-energy-on-a-fast-track/
- Energy Business Journal. "Water Company in a Box - Bourne Energy Develops Sustainable Water Making System." June 2, 2008, pg. 162.
- Gizmag.com. "Bourne Energy's RiverStar: A Fresh Approach to Hydropower." March 5, 2008. http://www.gizmag.com/bourne-energys-riverstar-current-electricity-generators-the-new-face-o/8922/
- Graham-Rowe, Duncan. "Hydroelectric Power's Dirty Secret Revealed." New Scientist. Feb. 24, 2005. http://www.newscientist.com/article/dn7046
- Nelson, Kristen. Spokesperson for the National Hydropower Association. Personal interview conducted May 5, 2009.
- Renewable Energy World. "New Developments in Hydropower Can Supercharge Obama's Green Jobs Plan." Jan. 16, 2009. http://www.renewableenergyworld.com/rea/partner/bourne-energy-5699/news/article/2009/01/new-developments-in-hydropower-can-supercharge-obamas-green-jobs-plan-54526
- Softpedia. "New Ways of Harnessing Hydropower." April 4, 2007. http://news.softpedia.com/news/New-Ways-of-Harnessing-Hydropower-51208.shtml
- Verdant Power. Free Flow System. http://www.verdantpower.com/what-systemsint