While offshore wind installations are very costly to build and maintain, second only to solar thermal, all wind power is expensive.

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Google said its "Renewable Energy Cheaper Than Coal" initiative will focus initially on solar thermal power, wind power technologies, geothermal systems and other technologies.

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Google (nasdaq: GOOG - news - people ) said its "Renewable Energy Cheaper Than Coal" initiative will focus initially on solar thermal power, wind power technologies, geothermal systems and other technologies.

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The most promising initiatives near term, he thinks, include solar thermal, high-altitude wind power and deep drilling to tap geothermal power.

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The wind gains strength from the thermal energy of the ocean, eventually condensing vapors and circulating air fast enough to form high-speed wind and heavy rain.

CNN: graphic

The company owns and operates wind, hydroelectric and thermal power generation facilities.

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Of that total, hydropower and wind provided the majority, while photovoltaics and solar thermal contributed approximately 5%.

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It builds biomass power plants, huge wind turbines for offshore wind farms and, as of today, concentrated solar thermal power plants.

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As I noted in my February 24 column, the U.S. Energy Information Administration (EIA) estimates that for new power-generating facilities entering service in 2016, onshore wind power will be 49% more expensive than conventional coal over the lifetime of the respective facilities, offshore wind will be 90% more expensive than coal, solar thermal will be 155% more expensive than coal, and solar photovoltaic will be 295% more expensive than coal.

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The EIA estimates onshore wind power will be 80% more expensive than conventional natural gas power, offshore wind power will be 142% more expensive than natural gas, solar thermal power will be 208% more expensive than natural gas, and solar photovoltaic will be 377% more expensive than natural gas.

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