Slide Show: The World's 10 Largest Renewable Energy Projects
From wind and wave to sun and trash, a look at how existing power plants are providing electricity generated from renewable sources on a massive scale
Bonus: World's Largest Landfill Gas Recuperation Plant
Puente Hills in Whittier, Calif.
Producing power from the gas that seeps out of landfills is a better alternative than simply flaring it. (Though it's debatable whether or not landfill gas constitutes a renewable resource, because yields of combustible gas from landfills decline between 2 and 15 percent per year after a landfill is capped and no more garbage is being added, according to Jeff Pierce, vice president of power plant development company SCS energy). Landfill gas is about half methane and half carbon dioxide and also contains water vapor, which makes it more difficult to handle than conventional natural gas.
The world's largest landfill gas plant sits atop the Puente Hills landfill—the largest in the U.S.—which accepts trash from Los Angeles County. Pierce says that because this active landfill is still growing, production at the 20 year old Puente Hills landfill gas plant has not yet peaked, and averages about 50 megawatts.
Another 50-megawatt landfill gas plant sits atop another gigantic dump in Incheon, South Korea. Currently there are no plans for units larger than either the Puente Hills or Incheon facilities. Jeff Pierce, SCS Energy
10. World's Largest Hydroelectric Dam
China's Three Gorges Dam
On December 18, 2007, the electricity production capacity of China's Three Gorges Dam reached 14.1 gigawatts, surpassing for the first time the 14-gigawatt generating capacity of the Itaipu Dam on the border of Brazil and Paraguay, making it the largest and most productive dam in the world. By 2011, it will produce 18 gigawatts of electricity, or as much as 18 large nuclear power plants. Just one of the dam's main generators can produce 700 megawatts of electricity. It s construction cost $26 billion.
A still-larger dam, the Grand Inga Dam, has been proposed for completion between 2020 and 2025 in the Democratic Republic of Congo on the Congo River: Its output could reach 39 gigawatts of power. Andrew Hitchcock
9. World's Largest Wave Power Plant:
Aguçadoura Wave Farm near Póvoa de Varzim, Portugal
The world's first and only commercial wave power plant resembles a 500-foot- (150 meter-) long, 11 foot- (3.5 meter-) wide snake that floats, half-submerged, on the sea surface. Each unit is anchored perpendicular to the beach, and has four segments connected in a line by hinges that house independent hydraulic power plants. As each segment surges up or down with the crest of an oncoming wave, its hydraulic power plant pumps a biodegradable hydraulic fluid through a turbine which produces up to 0.75 megawatt of electricity per unit. Three of these, constructed at a cost of $13 million are currently producing a total of 2.25 megawatts at peak off the coast of Portugal, and there are plans to eventually expand the wave farm to 21 megawatts.
8. World's Largest Dry Biomass-Fired Power Plant
Oy Alholmens Kraft in Pietarsaari, Finland
Like most biomass-fired power plants, the Oy Alholmens Kraft power plant relies on locally sourced bark, branches and peat to fuel its enormous boiler—the largest of its kind in the world at 550 megawatts of heat. Burning all that generates a peak output of 240 megawatts of electricity. (The plant also generates 160 megawatts of steam, which is used directly by nearby industry and for district heating.) Both the peat and the wood by-products burned by this plant are harvested sustainably. In the case of the wood, trees equal in amount to those felled are planted every year and are later harvested at maturity. Peat is also continuously generated by decaying plants in wetlands, and although it is produced slowly, it can be harvested sustainably as long as it's carefully managed.
"We need more than 120 trucks [of biomass] per day," says Stig Nickul, managing director of the plant. "One truck is enough for six to seven minutes."
By 2010, Wales will be able to claim a 350-megawatt biomass-fired power plant, but its waste wood feedstock will have to be imported from Canada, making it of questionable renewable value. Alholmens Kraft Oy Ab Advertisement
7. World's Most Productive Geothermal Field
The Geysers in Sonoma and Lake Counties, Calif.
Despite having declined from a peak production of 2,000 megawatts in the mid-1980's to the present value of about 1,000 megawatts, The Geysers remains the most productive geothermal field in the world, providing nearly 60 percent of the electricity used in California's North Coast region, which stretches from the Golden Gate Bridge to the Oregon border. (The decline is due to depletion of the aquifer from which the plants draw their steam; newer plant designs re-inject the water in order to eliminate this problem.)
The first commercial geothermal power plant in the U.S. was built at The Geysers in 1960; it produced 11 megawatts of power. Individual plants at this location now average about 50 megawatts, but are dwarfed by the largest geothermal power plant currently proposed, which would be built in Sarulla, North Sumatra, Indonesia, by geothermal technology company Ormat and its partners, producing 330 megawatts of electricity at peak. Calpine
6. World's Largest Photovoltaic Power Plant
Olmedilla Photovoltaic Park in Olmedilla de Alarcón, Spain
The Olmedilla Photovoltaic (PV) Park uses 162,000 flat solar photovoltaic panels to deliver 60 megawatts of electricity on a sunny day. The entire plant was completed in 15 months at a cost of about $530 million at current exchange rates. Olmedilla was built with conventional solar panels, which are made with silicon and tend to be heavy and expensive. So-called "thin-film" solar panels, although less efficient per square meter, tend to be much cheaper to produce, and they are the technology being tapped to realize the world's largest proposed PV plant, the Rancho Cielo Solar Farm in Belen, N. Mex., which is expected to cost $840 million, cover an area of 700 acres (285 hectares), and produce 600 megawatts of power. Nobesol
5. World's Largest Solar Thermal Plant
Solar Energy Generating Systems in Southern California
Solar Energy Generating Systems (SEGS) has been the world record holder for largest solar thermal project since its completion in 1990. SEGS consists of nine separate solar thermal power plants spread across the Mojave Desert, which collectively can produce 354 megawatts of power. They were designed, built and operated by Luz International, which subsequently went bankrupt when the tax breaks that made the plant profitable evaporated. The chairman of Luz is back, however, heading up Brightsource, a new solar thermal energy company that has just signed the two largest contracts for solar thermal electricity in the world. These contracts will be serviced by 14 solar thermal plants with a total output of 2,600 megawatts, to be built between now and 2017. These facilities differ substantially from SEGS, which uses long troughs to collect the sun's heat; they will consist of thousands of mirrors that will reflect the sun's energy onto a central heating tower.
"The overarching theme of why we moved from trough to tower is that it's much more efficient," says Keely Wachs, director of communications at BrightSource, who notes that the cost of the tower design is also significantly lower, making it cost-competitive with other sources of energy. Gregory Kolb, Sandia National Laboratories
4. World's Largest Tidal Power Turbine
SeaGen Turbine in Strangford Lough, Ireland
Like wind turbines, but powered by the flow of water instead of the flow of air, tidal power turbines transform tides or deep ocean currents into electricity. The 1.2-megawatt SeaGen tidal power turbine, which consists of a matched pair of turbines, each up to 66 feet (20 meters) in diameter, is currently the only commercial-scale tidal power turbine in the world. This system costs about $5 million per installed megawatt of capacity, or about 30 percent more than offshore wind power, according to the manufacturer. The blades have the ability to turn 180 degrees in order to spin in either incoming or outgoing tidal currents. The turbines can be raised for ease of maintenance, as depicted in this photo. The inset illustration shows the turbines under normal use.
By 2015, the SeaGen turbine will be surpassed by a massive tidal power turbine project in the Wando Hoenggan Waterway off the coast of South Korea, to be built jointly by Lunar Energy and Korean Midland Power Company for $820 million. Generating 300 megawatts of capacity, the 300 one-megawatt, 60-foot- (18-meter-) high turbines will be anchored to the seabed by their own weight. Sea Generation Advertisement
3. World's Largest Tidal Power Barrage
Rance Tidal Barrage in Bretagne, France
Many of the world's largest renewable projects have been around for quite some time: Completed in 1967 at a cost of approximately $134 million, the Rance tidal barrage (dam) is the world's first, and remains the world's largest, power plant that produces electricity from tides. The Rance barrage works by blocking the entrance to the estuary of the Rance River, where average difference between low and high tides is 26 feet (eight meters). The 24 10-megawatt bulb turbines that sit in the barrage beneath the surface can be turned by the water as it flows both into and out of the estuary, allowing the dam to produce electricity almost continuously.
In the future, the U.K. has proposed a tidal power barrage across the Severn Estuary that separates England and Wales. Whereas a number of different barrages have been proposed, the largest would be a 7.4-mile- (12-kilometer-) long dam that could produce 8.6 gigawatts of energy, or 5 percent of the electricity currently used in the U.K.
2. World's Biggest Offshore Wind Farm
Lynn and Inner Dowsing Wind Farm Near Skegness, Lincolnshire, England
Visible from the beach of Skegness, England, the 54 3.6-megawatt turbines of the Lynn and Inner Dowsing offshore wind farm collectively can produce up to 194 megawatts of electricity at peak. Each turbine is 353 feet (107 meters) in diameter and turns on a hub that is 265 feet (80 meters) above sea level. Every turbine sits on a pylon that was driven into the shallow seabed by the Resolution, a vessel purposely built for the installation of offshore wind farms. (It extends six legs into the seabed to stabilize itself before installation of the pylon on which each turbine sits.) The total cost of the project was nearly $500 million.
By the end of 2009, Lynn and Inner Dowsing will have been superseded by the 209-megawatt Horns Rev 2 wind farm sited in the North Sea between 19 and 25 miles (30 and 40 kilometers) west of the westernmost tip of Denmark, which will cost about $670 million. And the 1,000-megawatt London Array in the outer Thames Estuary is projected to be completed in 2012. Centrica Energy
1. World's Biggest On-Shore Wind Farm
Horse Hollow Wind Energy Center in Taylor and Nolan Counties, Tex.
About 100 miles (160 kilometers) west of Dallas, 47,000 acres (19,000 hectares) of Texas cedar and scrub oak have been given over to the 421 wind turbines that comprise the Horse Hollow Wind Energy Center. The 291 1.5-megawatt turbines built by GE and the 130 2.3-megawatt wind turbines built by Siemens together deliver 735 megawatts of peak power. The farm was completed in 2006 and is operated by NextEra Energy, a subsidiary of Florida Power & Light, which operates wind facilities that deliver over four gigawatts of power across the U.S.
Horse Hollow won't retain the crown for long, however: By the middle of 2009, E.ON Climate and Renewables will complete the fourth phase of the Roscoe Wind Farm in Texas, which will deliver 781.5 megawatts from 627 turbines.
Other giant wind farms that have been announced include the Shepherd's Flat Wind Farm in Oregon (800 megawatts, 303 wind turbines) and a wind farm in Markbygden, Sweden, (four gigawatts, 1,101 wind turbines). NextEra Energy Resources Advertisement