Fuel cells developed by Plug Power Inc. are powering 35 warehousing trucks at a FedEx Freight service center in Springfield, Missouri.

The express transportation company (NYSE: FDX) said Tuesday that it has installed 35 of Plug’s (Nasdaq: PLUG) hydrogen-powered fuel cells in its forklift trucks. The energy-efficient units replace lead-acid batteries.

The 35 fuel cells were partially paid for with $1.3 million federal stimulus money.

In April 2009, the U.S. Department of Energy awarded $6 million in stimulus funds to install 304 of Plug’s motive GenDrive fuel cell systems in the warehousing fleets of several large corporations, including Sysco (NYSE:SYY), Wegmans Food Markets and Whole Foods.

Plug, based in Latham, New York, supplies 90 percent of the fuel cells used for materials handling and has deployed 1,000 units thus far, CEO Andy Marsh said.

The average cost of one of the company’s motive-power units, called GenDrive, is $20,000. Plug expects to ship 1,100 of the units in 2010, adding up to sales of $22 million, Marsh said.

Plug expects to double production in each of the next three years.