The telecommunications company will be Bloom Energy's largest non-utility customer. Mon, Oct 15 2012 at 8:00 AM EST AT&T Bloom Energy Box in San Ramon, California Photo: AT&T; AT&T is expanding its green energy portfolio with the planned addition of 9.6 megawatts of fuel cell power. Bloom Energy’s Bloom Boxes will generate the clean energy, which will bring AT&T’s total Bloom Energy portfolio to 17.1MW of clean power generation.