Acciona Energy, a subsidiary of Acciona based in Madrid, is a Spanish company developing renewable energy projects, including small hydro, biomass, solar energy and thermal energy, and the marketing of biofuels. It also has assets in the field of co-generation and wind turbine manufacture. As of 2007 [update], it is carrying out research projects to produce hydrogen from wind power and to manufacture more efficient photovoltaic cells. 
As of 2007 [update], Acciona Energy has 164 wind farms in nine countries representing over 4,500 megawatts (MW) of wind power installed or under construction.  Acciona Energy is also the developer, owner and operator of Nevada Solar One,   the world's first solar thermal plant built in more than 16 years,  and the third largest facility of its kind.
On September 18, 2009, the 100.5 MW EcoGrove Wind Farm in Lena, Illinois, U.S. became operational. The wind farm comprises 67 Acciona Windpower 1.5 MW turbines, and will produce enough to power 25,000 homes and offset 176,000 tons of carbon annually. The EcoGrove facility is spread across 7,000 acres (2,800 ha). Acciona Windpower's main product is the AW1500, a 1.545 MW output machine. There is a prototype AW3000, a 3 MW model, operational in Pamplona, Spain.
In June 2014, Kohlberg Kravis Roberts announced it was taking a one-third stake in the international energy business of the company, at a cost of €417 million ($567 million). The renewable energy generation business operates renewable assets, largely wind farms, across 14 countries including the United States, Italy and South Africa. 
- Acciona Energy
- Wald, Matthew (2008-03-06). "Turning Glare Into Watts". The New York Times. Archived from the original on April 1, 2009. Retrieved 2008-03-06.
- In the Desert, Harnessing the Power of the Sun by Capturing Heat Instead of Light
- Acciona Dedicates 400 Acre 64MW Nevada Solar One Plant
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- "Equity investor KKR picks stakes in Acciona Energia unit for 417mn euros". Spain News.Net. Retrieved 24 June 2014.