Hydroelectric power isn't the only green energy driving Microsoft's new datacenters in eastern Washington.

The trucks ferrying cement to and from the massive building site and equipment used inside the first building are all powered with biodiesel made from Washington-grown canola oil, said the head of a company selling the biodiesel to Microsoft.

The construction company working on the new data centers approached Steve Verhey, the chief executive of Central Washington Biodiesel, with a problem earlier this year, he said. The company had built the shell, including walls and ceiling, of the 500,000-square-foot (46,451-square-meter), 11-acre building and found that laying the cement floor and finishing the rest of the interior presented a health and safety issue. That's because cement trucks and other machinery that run on diesel and propane emit harmful exhaust into the enclosed space.

They wanted to know if biodiesel might solve the problem, Verhey said. The exhaust from biodiesel contains half the carbon monoxide of regular diesel, he said. In addition, one gallon (3.78 liters) of biodiesel lets off just 1.5 pounds (0.68 kilograms) of carbon dioxide, compared to 22 pounds per gallon for regular petrodiesel, he said, so biodiesel has a much smaller impact on the environment.

During their first meeting, the construction company decided to switch fully over to biodiesel for the project, he said. Seven cement trucks were working 12-hour days, six days a week for a while, running on biodiesel, until the floor of the massive building was complete, he said.

Microsoft spokesman Lou Gellos confirmed that the construction company is using biodiesel at the Quincy, Wash., site. "It smells like you're in a fast-food restaurant in there," he said. Biodiesel, which in this case is made from the same type of oil that is often used in restaurant fryers, can let off a scent similar to fried food when it's burned in engines. The first building there is now finished, he said.

The site also includes two 33,000-gallon tanks of petrodiesel to power generators for backup power, Verhey said. While those tanks were already full by the time he met the construction crew, Verhey would have been cautious about filling them with biodiesel because it has a shorter shelf life compared to petrodiesel, he said.

Microsoft and other big Internet companies are building massive data centers in eastern Washington and Oregon. Those regions offer cheap electricity powered by hydroelectric plants. According to the Washington State Department of Community Trade and Economic Development, the state is the leading hydroelectric power producer in the country.

Microsoft said the data center at Quincy will be its largest yet and that it was designed to have minimal or no carbon footprint. Yahoo is also building a datacenter in Quincy, and Google is building one in Oregon.