Besides, she said, much of the front yard has other landscaping that was untouched. The couple prefer to take this long-term perspective: They are making a $22,000 investment in their home now. They will start to realize utility bills cut by about half. They'll recoup that upfront outlay, depending on their thermostat settings and utility rates, in 10 years at the outside, but most likely sooner.
"Everything else after that is gravy," she said.
Part of that gravy could flow from the state. Come July 1, the Maryland Energy Administration maximum grant to a homeowner for installing a geothermal system will rise from $1,000 to $3,000, and jump to $10,000 for a commercial use. Officials expect the number of applications for the $591,000 cash pool that is to be shared with grants for solar-energy systems to continue to climb.
"It will go quickly," said David Cronin, MEA assistant director for renewable resources.
The centuries-old basics of the technology rely on exchanging heat and cold. Water in the pipes naturally transfers heat more efficiently than air does, said Toni Boyd, assistant director of the Geo Heat Center at the Oregon Institute of Technology in Klamath Falls, Ore.
In a closed-loop system, the type used in Maryland, hundreds of feet of pipes circulate a blend of water and often alcohol (sometimes refrigerant), extracting warmth from the ground in the winter. The pipes connect to the heating and cooling system in the house.
A heat pump inside uses the network for a forced-air system that warms the home's air. That's reversed for summer air conditioning, when the home's heat literally gets returned to the ground in an environmentally important exchange, Boyd said.
Based on home size and other factors, heating businesses determine the size of the systems needed inside and outside. Well-drillers site the narrow shafts for the vertical pipe loops and the trenches bringing them into the house, based on geological maps, other utilities, well requirements, and state and local government codes.
Short of extensive property that allows burying Slinky-like pipes close to the surface, vertical is the way to go, whether through mud, sand, rock or water, experts say. Each vertical pipe is a long and narrow U-shape.
That has allowed geothermal systems on rowhouse lots, said Brad Rogers, an owner of Baltimore Green Construction and related companies, who expects to install one in the renovation of a Charles Village rowhouse this summer.
