Aside from listing general sustainability measures it is taking at the site of its newest data center in Maiden, North Carolina, information coming out of Apple on the construction project has been scarce. The latest bit of detail to come out was about the project’s co-generation plant.

In a document Apple filed with local officials on 28 March, the company revealed a number of details about the fuel-cell installation it had not shared publicly before.

Apple plans to sell electricity the plant generates to the local utility. Details on how and whether it is going to buy that electricity back to power its data center were filed but sealed.

The fuel-cell facility’s total power capacity will be 4.8MW. It will hold 24 200kW fuel-cell systems that will use directed biogas to produce alternating-current (AC) electricity, Apple wrote in the documents field. Each AC system consist of six direct-current (DC) systems and one module for fuel intake and electricity output that converts DC to AC.

Apple will buy fuel for the cells from the local utility called Piedmont Natural Gas. The company plans to bring the full system online by the end of November.

Other sustainability measures at the site include the use of free cooling, higher-voltage power distribution and a 20MW solar array, among others. Value of the massive solar array near the data center was recently questioned by an Amazon technologist.