sign in sign up
<<
Home , Marine Current Turbines, Tidal power, Wave farm, Wave power

28, No. 2 THE HUDSON VALLEY SUMMER 2008 r e e n i m e s G A publication of Hudson Valley Grass T Roots & Environmental Network of the By Mi c h a e l Sa n d s t r o m arnessing just 0.1% of the potential and lighthouses. plans to build power they will get and when. of the a 2.25 megawatt .1 There are, tidal are somewhat better for could produce enough electric- however, still many difficulties that make the environment than the heavy metals H 3 ity to power the whole world. Scientists less feasible than free-flow used to make solar cells. Since the studying the issue say could tidal power for large-scale energy pro- only shines on average for half a day, solar solve a major part of the complex puzzle duction, including unpredictable storm is not always as predictable due to cloud of balancing a growing population’s need waves, loss of ocean space, and the diffi- coverage. for more energy with protecting an envi- culty of transferring to shore. Although tidal and share the ronment suffering from its production Oceanic is produced same basic mechanics for generating and use. by the difference existing electricity, wind turbines can only oper- There are three different ways to tap between the surface and the water ate when there is sufficient wind and they the ocean for electricity: tidal power (free- at the bottom of the ocean, which allows a are sometimes considered aesthetically flowing or dammed hydro), wave power, engine to make electricity. However, unappealing. Moreover, water is 1,000 or oceanic thermal energy. it has a low overall efficiency (less than times denser than air, which means that Tidal power (also known as hydroki- 7%) and works well only in the tropics. the potential for generating each unit of netic) uses the rise and fall of the tides to energy per meter is much greater than produce electricity. Dammed hydro power Benefits of Free-flow Tidal Power can ever be. A tidal current (technically similar to instream hydro Free-flow tidal power is fast emerging gains over four times as much power) makes use of huge that trap as the preferred technology for tapping energy per meter squared of rotor as a 4 water as the tides go in and cause turbines ocean power. Since it is underwater, it . to spin as the water is released. However, produces power whether the ebbs this method is damaging to the shoreline or flows, generating vastly more power Current Drawbacks to Tidal Power and the animals that inhabit it. in a highly predictable manner, while Cost: The absence of production at Wave power is harnessed by machines providing economic efficiency and envi- this early stage means turbines are still that move up and down as the waves flow ronmental benefits. The turbines can be relatively expensive to build and install. by them, using pistons to turn generators. placed in the ocean or any river with a con- In order for the cost to come down, both Since these wave machines are portable, stant current over two meters per second. the governmental and corporate sectors they could provide a source of power in It has one of the lowest impacts on the must invest in them. Although the U.S. the open ocean to generate electricity for environment of any means of energy pro- government has recently approved a $7.5 ships, , power plants, duction, according to a 168-page report million grant for the research of marine released in 2006 by the technologies, this sum pales in com- Research parison to the $38 million grant Ireland is Institute (an independent, directing toward tidal research.5 nonprofit center for en- Another reason for the sluggish inter- ergy and environmental est by U.S. companies is that a large-scale, research). Tidal power $4.5 million, tidal project recently failed.6 is also one of the most A tidal company, Verdant Power, installed reliable renewable energy six turbines in the in New . Scientists know York—the first grid-connected, free-flow the movement of the tides tidal project in the U.S. However, faulty de- sign and an underestimate of the strength for the next 1000 years, of the current caused the turbines to be which means that power damaged and removed. The failure, how- companies can accurately ever, demonstrates how much potential predict exactly how much Open Hydro Turbine for generating free-flow tidal power Continued on page 2 POWER OF TIDES…page 2 power there is in the flow of water and Future Large-Scale Generation the lessons learned will help improve the next generation of turbine models. In Feasibility in the Northeast April, Verdant Power received a $2.2 mil- lion grant from the Ontario government to install a 15-megawatt turbine array in the St. Lawrence River.7

Availability/Reliability: There is a short period during high and low tides when the incoming flow is balanced by the outgoing flow and little or no power is generated. This short window, however, compares favorably to the amount of down time associated with solar or wind.

Impacts on aquatic : While it is still uncertain what effect a large scale free-flow tidal power would have on aquatic over time, the tests conducted so far indicate that and marine animals can avoid the slow mov- ing turbines.8 Dammed , on the other hand, uses rapidly spinning Scorecard of Power Generation in the Northeast (Courtesy of Elizabeth Murphy of Natural Currents) turbines which create strong suction at the intake valves, causing serious injuries to aquatic animals trapped in the . currently four sites in the Northeast that ing Tidal Currents for Large-Scale Power Generation. Noise generation has been posed as have been approved (with a fifth pending) March 16, 2007. www.iom3.org/events/pdf/ a possible threat, yet hydro-acoustic by the Federal Energy Regulatory Com- Peter%20Fraenkel%20MCT.pdf 5 testing shows that the carries just mittee (FERC) on which tidal plants could Cleantech. Marine power getting $7.5M in funding from U.S. May 6, 2008. http://media.cleantech. far enough to warn large fish and be built now. If turbines were placed at com/2803/marine-power-getting-7-5m-in- 9 not to come too close to the turbines. these sites, the energy yield would be 889 funding-from-u-s Other possible environmental concerns mega of power, 1.25% more than is 6 Roland Piquepaille’s Technology Trends. Tidal 13 include motor oil leakage from the mov- produced at an average plant. This Flow to Power New York City. August 4, 2004. ing parts of the turbine and disturbance would mean more than 850,000 tons of http://radio.weblogs.com/0105910/2004/08/14. of the -floor bottom (especially during carbon dioxide would be prevented from html installation). However, studies show that entering into the atmosphere each year. 7 Cleantech. Ontario backs Verdant Power tidal the base of a turbine can actually serve as Tidal power is still in its infancy; it project. April 11, 2008. http://media.cleantech. an artificial reef, attracting both sea-floor needs more research and development com/2691/ontario-backs-verdant-power-tidal- project dwellers and fish.10 to make it efficient and more workable. 8 Verdant Power. Environmental Monitoring. 2007. Tidal power alone cannot provide enough http://verdantpower.com/what-environmonitor Tidal Power Progress energy to supply all of the United States, 9 Electric Power Research Institute, Inc. Instream Hammerfest, Norway is currently the only especially in the middle of the country. Tidal Power in . Environmental and place on earth that has a working free- However, used in conjunction with other permitting issues. June 2006. flow tidal-powered turbine connected alternative energy sources, it can help 10 Electric Power Research Institute, Inc. Instream to the grid. Installed in 2003, it has ten- eliminate the need for and Tidal Power in North America. Environmental and meter long blades and produces 300kW nuclear-based power plants, thus reduc- permitting issues. June 2006. of electricity, enough to heat and light ing the level of green house gases and 11 Freeman, Kris. Tidal Turbines: Wave of the Future? 35 Norwegian homes.11 Because of the preventing the accumulation of radioac- Environmental Health Perspectives. Vol. 112, tive waste. # 1. January 1, 2004. www.ehponline.org/ success of this single turbine, there are docs/2004/112-1/toc.html plans underway to install another 19 1 RenewableEnergyWorld.com. Portugal to 12 Environmental News Network. World’s Largest Tidal nearby next year. In , the Host World’s First Wave Farm. May 19, 2005. Turbine Successfully Installed. April 8, 2008. www. world’s largest tidal turbine was recently www.renewableenergytoday.net/rea/news/ enn.com/energy/article/34319. installed. Capable of producing 1.2 mega- story?id=30275 13 Union of Concerned Scientists. Environmental watts of power, it will begin operating 2 Edison Electric Institute. Transmission Infra- impacts of coal power: wastes generated. August later this year, providing power to over structure Costs Associated with Wind Power. 18, 2005. www.ucsusa.org/clean_energy/ June 25, 2007. www.eei.org/industry_issues/ 12 coalvswind/c02d.html one thousand Irish families. electricity_policy/federal_legislation/RPS_wind_ If the United States would install an ar- transmission_costs.pdf Michael Sandstrom, a student at Vassar ray of turbines along the Northeast coast, 3 Choi, Charles Q. Study: Making solar cells cleaner College, worked for Clearwater on an not only would it be the first of its kind than burning. MSNBC. Feb. 27, 2008. www. internship during spring 2008, researching in this country, but it could spark huge msnbc.msn.com/id/23376364/ and analyzing data on the methods and investment interest globally. There are 4 Fraenkal, Peter. : Exploit- effects of harnessing tidal power.