The carrot and the stick
Microsoft said what really sets it apart is its carbon fee. The fee, implemented last July, is a charge-back model to business divisions that use energy that produces carbon emissions.
Microsoft's business groups were told they must build into their budgets the price of carbon emissions for the energy they use.
The business divisions pay a carbon fee for each metric ton of carbon emissions associated with the operation of data centers, software development labs, office buildings and employee air travel. The carbon fee goes into a central fund used to purchase renewable energy and carbon offsets to achieve net carbon neutrality.
The charge-back model makes the company's business divisions responsible for the cost of offsetting the carbon emissions, Henretig said.
It also forces business units to include carbon in their long-term cost plans and figure out how to not only reduce the amount of energy they require, but how to make investments that will lead to the transition to cleaner sources of energy.
"We are trying to push accountability out within the company to the point of use," said Henretig, who would not disclose the fee Microsoft charges divisions or carbon emissions.
Unlike Microsoft, Google reduces its carbon emissions through the use of carbon credit offsets -- investing in an activity that reduces carbon emissions elsewhere when renewable energy isn't available.
The carbon credit is verified by a third party, and it signifies that greenhouse gas emissions are lower than they would have been had no one invested in the offset. One credit equals one metric ton of carbon dioxide prevented from entering the atmosphere, according to Google.
For example, if a Google data center is located in a region without renewable energy, Google would invest in renewable energy in another region that may not even effect its facilities directly.
"The deals we enter into, you can be assured we've done internal analytics to ensure it meets our cost thresholds," Demasi said.
Solar array field at White Sands Missile Range in Nevada (Source: U.S. Army)
The U.S. military's efforts
Along with large corporations, the U.S. military is turning out to be one of the largest deployers of renewable energy.
Last month, the U.S. Army installed its largest solar power farm to date at the White Sands Missile Range in New Mexico.
The solar array, which cost $16.8 million, is a 4.46 megawatt ground-mounted system comprised of Solaria solar modules that were deployed by Siemens. The White Sands Missile Range solar energy system will take up two acres of land and will generate approximately 10 million kilowatt-hours of clean electricity annually. That's enough to save an estimated $930,000 a year.
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