Nuvera Fuel Cells, specializing in hydrogen-energy technology, is expected to decide before the end of the month whether to move its world headquarters into a vacant commercial building at 129 Concord Road.

The company is reportedly eyeing another site in the Merrimack Valley as an alternative.

"We are down to the final stages. They're definitely in the process of ramping up production and they're looking at bringing 100 people and employing 200 to 300 more over the coming years," Billerica Assessor Richard Scanlon said. "This is the wave of the future and we see this as being a real growth company."

Cabot Corp., already located on Concord Road, also plans to expand its Billerica campus by building a new 32,000-square-foot laboratory space that would add 50 new jobs and pump $10 million to $12 million into the facility.

Both projects lend credence to claims from town officials that the business economy is starting to rebound. The growth of Billerica's commercial-tax base is viewed as a key by selectmen and others to easing the tax burden on homeowners.

Proposals are also on the table to rennovate the Billerica Mall with the addition of Home Depot and dramatically upgrade the former KMart distribution warehouse on Salem Road.

"It shows that Billerica is centrally located and businesses are interested in moving here," Selectmen Chairman Michael Rosa said. "This is one of the best ways we can offset residential taxes."

Nuvera Fuel Cells would occupy Building One at 129 Concord Road, a 100,000 square-foot facility owned by the New Boston Fund that has sat vacant since 2000. The company plans to invest $15 million into the property with rennovations and additional manufacturing equipment.

To lure Nuvera to Billerica, Scanlon is working to put together a tax-incentive package that would exempt Nuvera from paying the full tax assessment on any new growth to the building.

A similar deal is being negotiated with Cabot, and the town will need approval from Town Meeting in May.

"The base value of the properties will remain the same, but we share in any new growth," Scanlon explained. "The town doesn't lose anything by doing this. And without it we wouldn't even be in the ballgame."

Town Meeting in the past has been very supportive of tax-incentive programs to lure business back to Billerica since the technology bubble burst about five years ago.

"We're not giving up a lot and if it helps bring them to Billerica I think it's well worth it," Rosa said.

Company officials from both Nuvera and Cabot could not be reached for comment.

Nuvera manufactures hydrogen fuel cells used today to power a variety of industrial vehicles and equipment. The technology, however, could one day become a clean, cost-efficient and reliable energy source for automobiles, the company's Web site says.