Long viewed as a potential “next big thing” for power generation—often drawing unwarranted hyperbole in the process—and more recently as niche distributed generation, fuel cells are finally beginning to make some noise at grid scale.

Hydrogen- and natural gas–powered fuel cells have been deployed over the past decade in behind-the-meter and microgrid applications for on-site generation, where their simplicity, reliability, and very low emissions offered advantages over diesel generators and similar solutions. The waste heat generated by the fuel cell process also allows them to step into on-site combined heat and power applications. Their ability to use renewable fuel such as biogas even enables them to fill renewable energy mandates in some areas. Such systems have typically been sub-megawatt scale or, at most, a few megawatts in capacity.

One good example is the fuel cell system at the Gills Onions processing plant in Oxnard, Calif. The two-cell, 600-kW system, supplied by Danbury, Conn.–based FuelCell Energy (FCE) and installed in 2009, runs off biogas generated from onion waste in an anaerobic digester. The $10.8 million system saves Gills more than $1 million a year in avoided energy and waste handling costs, meaning it will have paid for itself in less than a decade.

Sunnyvale, Calif.–based Bloom Energy has installed about 100 MW of these types of systems around the world. A 6-MW Bloom system powers online auction giant eBay’s massive data center in Salt Lake City.

A number of other applications have seen uses for fuel cell generation. Wastewater treatment plants and landfills are a growing niche because of their ability to cleanly and efficiently generate power from waste gases that would otherwise need to be flared. The U.S. military has looked at employing fuel cells as replacements for tactical diesel generators, and Sandia National Laboratories is researching ways to cut emissions at ports on the U.S. West Coast by supplying shore power from barge-mounted fuel cells.