Bloom Energy has just completed its largest installation to date of its fuel cells, placing 12 of its powerful Bloom Boxes at Adobe’s San Jose campus.

The company makes fuel cells that generate energy onsite. Each of its parking-space sized Bloom Boxes contains thousands of ceramic squares that can convert air and natural gas into electricity while producing little to no emissions.

The fuel cells will power Adobe’s three office towers (four boxes assigned to each tower) and are expected to generate one-third of the location’s electricity. Adobe will purchase methane as feedstock through a five-year contract with a Pennsylvania landfill and expects to save 121.5 million pounds of carbon over the next decade.

Each box packs a wallop – it can generate 100 kilowatts of energy, enough to power 100 average American homes. The so-called “power plant in a box” was unveiled earlier this year to great fanfare and bold assertions – the boxes, company representatives said, could one day replace electricity from the grid itself.

One selling point that fuel cells have above other renewable energies are that they aren’t dependent on weather conditions, the way solar and wind are. In fact, that’s how Adobe came to settle on the fuel-cell solution after the company installed 20 wind turbines at its campus last year and was looking for ways to deepen its green practices.

“While the wind is fairly constant, they’re not a large producer of energy at this point. Fuel cells look like they offered the best alternative,” said Randy Knox, senior director of workplace solutions for Adobe.

The company hired a professor to look at three possibilities, who deemed Bloom Energy “the future of fuel cells.” Adobe hasn’t ruled out solar for other locations – it just doesn’t work for an urban environment.

Urban areas and clusters of office towers don’t have the large rooftop space needed to install solar panels. So while solar may work for, say, Wal-Mart stores, it doesn’t make as much sense for an office building.

“At this point and based on everything I’ve seen, I would say fuel cells are by far the best solution in an urban environment,” Knox said.

Adobe’s installation is a big one, but it isn’t the first big name to jump on board Bloom’s fuel cell train. Wal-Mart, Google, FedEx and eBay have all installed the boxes. Big installations can cost up to $800,000 per box, but the company has indicated plans to produce smaller versions for residential use at around $3,000 per unit.