Portland Jetport Uses VALE Grant for Geothermal System

A new geothermal heating and cooling system is one of the crown jewels of a recent $75 million terminal expansion at Portland International Jetport in Maine. The project was a creative first in the industry, because the airport used an FAA Voluntary Airport Low Emissions (VALE) grant to fund $2.5 million of the $3 million project. Typically, FAA has awarded VALE grants for the purchase of hybrid carts or the electrification of ground equipment.

The geothermal project was a compatible fit for Portland Jetport, because the airport takes an environmentally conscious approach to serving an area that emphasizes its outdoor beauty and recreation options. (The entire state of Maine markets itself as "Vacationland.")

As a city-owned building, all of the airport's renovations and new construction were required to meet Leadership in Energy and Environmental Design (LEED) Silver standards, per a green building ordinance enacted by Portland in 2009. Airport officials, however, decided to pursue an even higher standard for the most highly visible city-owned building.

 "We started out aiming for the LEED Silver certification," explains airport director Paul Bradbury. "Now we're going for the Gold (under LEED v2.2.)"

Making it Happen

Bradbury is the person credited for reconciling the airport's geothermal project with established VALE criteria. "The city council has always been progressive in terms of sustainable design, and I've long looked toward a geothermal system as a way to go," says Bradbury. "So when the VALE opportunity arose, we seized it."

However, he cautions other airports that VALE funds are not simply granted on the basis of a good idea. "It's not enough to just file for a grant," Bradbury explains. "We had to spend considerable money to do all of the research and advance testing to demonstrate the project would work as promised."

In other words, there was risk involved. If its VALE application had been denied, the airport would have been out $300,000 to $500,000 in preliminary expenses.

Designs for a conventional heating and cooling system were also made, but the airport held off purchasing traditional equipment until it heard back about funding for a geothermal system. "Had the VALE applications been denied, we would have had to go with our original plan," Bradbury recalls. He credits the design and construction teams for helping the airport secure a VALE grant.

Inside the System

Lead architect Jim Stanislaski, AIA, LEED AP, says the airport's geothermal system is like a giant battery buried deep beneath the ground that helps maintain a constant temperature within the terminal. "The building will inject heat into the ground during the summer and take heat out of the ground in the winter," explains the Gensler associate. "This results in significant energy savings."

The geothermal system built at Portland Jetport is Maine's largest, with nearly 23 miles of high-density polyethylene piping and 120 ground wells that reach up to 500 feet deep. The system moves up to 475 gallons of water per minute with a 125-horsepower pump. Under normal operation, it takes approximately 30 minutes for water to complete a round trip to the farthest well.

The energy efficiencies provided by the geothermal system outside the terminal are complemented by the use of low-energy radiant-heated flooring inside.

Projected Returns

Like many buildings in New England, the airport burns No. 2 fuel oil for almost all of its heating. The new geothermal system is designed to reduce the facility's oil consumption by more than 50,000 gallons per year, reports Bradbury. Based on conservative estimates of this year's heating oil prices, the airport expects to save more than $160,000 per year. Although VALE criteria only address energy savings related to heating, the energy required for air conditioning the terminal will be reduced as well.

According to Stanislaski, the system will prevent the emission of 1,000 tons of carbon dioxide and .9 tons of nitrogen oxide per year. Although the overall system's expected lifespan is 40 years, the well field should be productive much longer, he predicts.

For information on the glycol recycling system used at Portland Jetport, see page 30 of our September 2011 issue.