CARIBOU, Maine — Cary Medical Center held a valve-turning ceremony this month to herald the use of compressed natural gas as the facility’s primary fuel source.

The preparation to use CNG set the hospital back approximately $600,000, but the conversion is expected to save about $250,000 in annual energy costs.

“We anticipate that the payback on this project will be in about two and a half years,” explained Shawn Anderson, chief operating officer. “After that, we anticipate an annual savings of some $250,000.”

Cary has negotiated a five-year contract for the gas, Anderson said during a brief tour on Dec. 20 of the boiler room and outside stations where the gas will be delivered, stored and processed.

“[We] are confident that the price of natural gas will be much less volatile than fuel oil,” Anderson said. “This project will lead to substantial savings for us and represents our ongoing effort at Cary to reduce our energy costs.”

Cary Facilities Manager Jim Cavagnaro said the hospital’s four primary boilers were converted to dual-use units, meaning they will be able to burn both natural gas and No. 2 fuel oil.

“The ability to burn both types of fuel is very important in the event of any dramatic changes in the energy picture,” he said. “But we are very confident that natural gas will be our major energy source of the future.”

During the tour, Cavagnaro said Cary has contracted with Xpress Natural Gas of Baileyville as the fuel supplier. The gas will be delivered north on trailer trucks, each containing four cylinders.

Mechanical Services Inc. was the local primary contractor for the conversion project. Preparation also included the construction of a concrete pad and decompression building behind the hospital, along with underground piping to connect the gas cylinders to the hospital’s boiler room.

Though feasible on the business side, natural gas is not yet available on a residential scale because of high costs associated with conversion, added Cavagnaro. Another local hospital, The Aroostook Medical Center of Presque Isle, converted to natural gas last year, and uses the same supplier.

Just prior to the valve turning, Clyde Coleman, project engineer at XNG, explained the gas storage particulars and the decompression process. “We use a simple, basic process of taking high-pressure gas, heating it a little, and decompressing it,” he said.

Though many people are leery of CNG, Coleman said the danger of explosion or fire is minimal. To burn, the fuel would have to have a certain mix of oxygen with the methane, but the gas stored in the containers is 100 percent methane.