SOUTH PORTLAND — Driven to control costs and carbon emissions, city officials are reconsidering a natural gas heating system for the planned municipal services building on Highland Avenue.

In August, city councilors indicated a preference for a wood-burning biomass heating system that would cost more to install but less to operate than either natural gas or heating oil, according to initial projections. At the time, councilors asked for more information on the environmental impacts of a wood-chip burning system before making a decision.

Now, city officials are weighing biomass against natural gas after Unitil representatives expressed an interest in extending the company’s gas main 600 feet down Highland Avenue to serve the municipal services building.

“We will be revisiting that with the City Council,” said City Manager Jim Gailey.

The council’s decision could benefit residents who live near the city’s transfer station at 929 Highland Ave., where construction of the energy-efficient municipal services building is expected to start in March.

“This is a very typical way that natural gas infrastructure expansion works,” said Unitil spokesman Alec O’Meara, noting that when a larger user acquires service, it opens access to other potential customers in the area.

The planned municipal services building is part of a $15.7 million project that got underway in August, when construction started on a new solid-waste transfer station at the Highland Avenue site. Scheduled to be completed in June 2017, the building will house the city’s public works, transportation, parks and recreation divisions, and will provide space for maintaining vehicles from all municipal departments, including police, fire and rescue.

City staffers and consultants are designing the building to be environmentally friendly, in keeping with the city’s 40-page Municipal Climate Action Plan. It will have solar hot water, a truck-washing bay that recycles water and an energy-efficient heating system geared toward minimizing the city’s contribution to global warming.

In comparing the costs of natural gas to wood-burning systems, city staffers will tally the carbon emissions and other environmental impacts resulting from the production, delivery and burning of either fuel.

The initial proposal to the council found that an oil or natural gas system would be much cheaper to install, costing $100,000 or $200,000, respectively, compared with $1.4 million to $1.6 million for a biomass system.

However, the estimated annual cost of heating the municipal services building with wood chips would be about $40,000, compared with $86,000 using oil and $112,000 using natural gas, according to the initial proposal.

Factored over 30 years, the total cost of installing, maintaining and fueling a biomass system would be just over $3 million, compared with nearly $3.8 million for natural gas and nearly $4.2 million for heating oil.

Moreover, the initial proposal found that greenhouse gases produced by a biomass system would be tiny – 8 tons per year – compared with heating oil and natural gas – 458 tons and 328 tons per year, respectively.

Gailey said it’s unclear when the council will decide on a heating system, but it should happen soon so the city can seek competitive bids from contractors.

Kelley Bouchard can be contacted at 791-6328 or at:

kbouchard@pressherald.com

Twitter: KelleyBouchard

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