Top Ten Enterprise Customers

9. Google

The search giant Google has found in recent years that success also comes with a higher power bill. Data centers consume 1.5 percent of the power in the U.S. and 2.5 percent in Northern California. And a big portion of that falls on the owners of large server farms like Google.

As a result, the company has joined several standards bodies with the aim of increasing the efficiency of power supplies and data in air conditioning systems. Google buys a lot of servers and components itself, of course, and its acts rebound deeply in the market because the component demands that it puts on its suppliers can lead to more energy efficient parts for all. Earlier this year, it revealed that it puts a 12-volt battery inside each server rather than rely on traditional uninterrupted power supplies. Why? Batteries can be close to 99.9 percent efficient while UPSes wallow around the 95 percent mark. It saves money. This kind of information does not go unnoticed by other buyers.

Google also has pull in Washington because it can act as an educated third party. One solar exec told us last year that Google was instrumental in lobbying for the investment tax credits because D.C. politicians saw the company as a large beta tester, not just another company seeking a tax break.

Honorable mention: IBM. As a consultant, it's helping everyone develop green supply chains (see IBM to Focus Supply Chain Heft on Green).