Apple Inc. (Nasdaq: AAPL), targeted by Greenpeace International over its energy consumption, says its 500,000- square-foot data center in Maiden, N.C., will be powered entirely by renewable sources by the end of the year.

North Carolina Utilities Commission, meanwhile, approved Apple’s request to build a solar farm at the facility on Thursday. (Read the ruling here.)

The move, announced today on Apple’s website, follows a week of protests at the company’s headquarters in Cupertino, California.

Greenpeace demonstrators criticized the world’s largest technology company for using too much coal to power the data facility.

“By the end of 2012, we’ll meet the energy needs of our Maiden, North Carolina, data center using entirely renewable sources,” Apple declared on its website.

“To achieve this, we’re building our own facilities that will provide over 60 percent of the clean power we need. It’s another example of Apple’s commitment to designing for energy efficiency — from the ground up.”

Apple reiterated its plan to generate 60 percent of the Maiden facility’s power itself, through a large deployment of fuel cells and a 100-acre solar farm located next to the data center.

The company provided additional detail today, saying it has another 100-acre site nearby. Once these projects are completed, Apple will generate 124 million kilowatt hours of power per year, enough to power 10,874 homes.

“Apple’s data center in Maiden, North Carolina, will draw about 20 megawatts of power at full capacity,” the company said W

“We’ll be producing an unprecedented 60 percent of this power onsite. To do that, we’re building what will be the nation’s largest private solar arrays and the largest non-utility fuel cell installation operating anywhere in the country. That’s a scale of onsite renewable energy production that no other company has matched. Onsite energy generation minimizes our dependence on the grid and reduces our environmental impact. And when our solar arrays and fuel cells are operating, Apple’s Maiden data center will be the most environmentally sound data center ever built.”

Fuel cells turn biogases, which can be taken from wastewater, into electricity.

Greenpeace: “Great Sign”

In a statement, Greenpeace praised Apple’s announcement but also said it would monitor Apple’s efforts.

“Apple’s announcement today is a great sign that Apple is taking seriously the hundreds of thousands of its customers who have asked for an iCloud powered by clean energy, not dirty coal,” said Greenpeace Senior IT Analyst Gary Cook.

“Apple’s doubling of its solar capacity and investment in local renewable energy are key steps to creating a cleaner iCloud. Greenpeace and Apple’s customers look forward to hearing more detail about how Apple plans to fulfill its commitment to renewable energy for its North Carolina and Oregon data centers. Apple is still one of Duke Energy’s largest customers, and will have to demand Duke provide the clean energy it needs to legitimately claim the iCloud is 100 percent powered by renewable energy.

“Greenpeace will continue its campaign to push Apple – and other IT giants like Microsoft and Amazon – to clean the cloud until Apple has policies to ensure that as Apple’s North Carolina data center and others continue to grow they will grow using exclusively clean energy. To guarantee that, Apple must adopt a firm siting policy to prioritize renewable energy when it chooses locations for new data centers. Only then will customers have confidence that the iCloud will continue to get cleaner as it grows. “

Read the Apple announcement here.

(Bloomberg news contributed to this story.)