The firm said the cost of fuel cells needs to decline, however, to set the growth curve in motion and that the energy tax credit could act as a catalyst. 

It sees the total market for fuel cell backup power at about 160,000 units a year, a figure it says represents roughly $2.5 billion in potential sales. Citigroup believes Plug Power (PLUG) , up 2.2% to $6.42, and Hydrogenics (HYGS) , rising 3.2% to $3.55 as the largest beneficiaries of this trend. Other alternative fuel technology companies in rally mode were Capstone Turbine (CPST) , surging 25% to $3.89, Beacon Energy (BCON) , advancing 11.4% to $5.26, Millennium Cell (MCEL) , adding 16.3% to $2.22, and Mechanical Technology (MKTY) gaining 8% to $3.05.