A day after being criticized by Greenpeace for its energy practices, Apple said Greenpeace's estimates for power use at the company's latest data center are much too high.
Apple said that its data center now under construction in North Carolina will use about 20 megawatts at full capacity. Greenpeace put the estimate at 100 megawatts.
Greenpeace gave Apple, Amazon, and other companies low marks for locating their data centers in areas that rely heavily on coal and "dangerous nuclear." Those companies also scored lower than competitors, including Google and Yahoo, because they disclose less information on energy use.
Before publishing its report yesterday, Greenpeace shared its estimate for the power Apple's North Carolina power plant would use based on the size of the investment and size of the facility. Apple (and Amazon) told Greenpeace the number was incorrect but didn't offer a more accurate number.
Today, Apple issued a statement, run at Data Center Knowledge, which for the first time disclosed the expected power usage. It also notes that the facility in Maiden, N.C., will have a solar array and run fuel cells powered by biogas, or methane captured from landfills or other organic sources.
"We believe this industry-leading project will make Maiden the greenest data center ever built, and it will be joined next year by our new facility in Oregon running on 100% renewable energy," Apple said.
In response, Greenpeace's lead IT industry advocate Gary Cook questioned how Apple's 500,000-square-foot data center would only consume 20 megawatts, but welcomed more transparency from Apple.
The back and forth between the companies illustrates the sometimes strained relationship between the environmental advocacy group and tech companies.
Greenpeace pressures these companies to purchase more renewable energy and to lobby for policies to promote efficiency and cleaner energy, part of a campaign to raise awareness about the environmental footprint from data centers.
The large tech companies themselves, meanwhile, have taken a number of steps over the years to lower energy use at their data centers, with Facebook even open-sourcing its efficient hardware designs and Google investing in wind farms near its data centers.
Apple's Maiden, N.C., plant will have 4.8 megawatts' worth of power from fuel cells, which is expected to be the largest in the country. The solar installation is estimated to be 20 megawatts, which is also very large for a corporate array.
Apple estimates that 60 percent of its power will be supplied by those on-site renewable-energy power sources.