For commercial producer Matthew Grocoff, living green with a geothermal system has meant sustained comfort at a fraction of the original cost. And, with a global drive toward sustainability, Grocoff believes geothermal energy may no longer be taking a backseat in the discussion of energy alternatives.

Grocoff said he and his wife, Kelly, moved to Ann Arbor from Santa Monica, Calif. bringing with them a Californian consciousness about water and energy efficiency. Still in the ongoing process of renovating their home in the Old West Side of Ann Arbor, the Grocoffs have retrofitted a 110-year-old Victorian-style house with the latest eco-friendly technology.

After insulating the house, buying energy-saving light motion sensors and installing Energy Star appliances, the couple set its sights on a geothermal unit to heat and cool their new home.

Referring to the Envision — a geothermal system created by WaterFurnace — as “green bling,” Grocoff was eager to share the details of his return on the investment. To first cover the upfront cost of the system, the Grocoffs took out a rehabilitation loan to be paid back over the 30-year life of the geothermal system, adding $40 to their monthly mortgage payment.

“The payback was immediate,” he said. “As soon as the geothermal started running in March (of 2006), it cut our utility bill by 200 bucks.”

What may be more remarkable, however, is that the Grocoffs paid $350 for heating, cooling and hot water for the month of January prior to installing the system. After the geothermal system became operational, the Grocoffs spent around $550 in total for 2007 — a monthly average of about $45.

With the savings in mind, Grocoff said everyone looking to purchase a new furnace in the next five years should instead invest in a geothermal system. Grocoff cited the 30 percent tax credit incentive guaranteed for implementing a geothermal system as outlined in the energy rebate section of the recent stimulus plan as one major reason to install one.

In its simplest sense, geothermal energy relies on extracting heat from the Earth’s interior to generate power. Current geothermal systems come in two types.

In one form, deep boreholes are drilled into the ground and fluids are run through a system for direct exchange of heat. Generators that use this form often rely upon hydrothermal resources like hot springs to produce electricity.

The second type of geothermal systems, like the one in Grocoff’s home, take advantage of the Earth’s static temperatures at shallow depths of 20 feet or more where seasonal variation is not felt. At about 50 degrees Fahrenheit year-round, the ground is an effective heat sink in the summer and a heat source in the winter.

Considering his original motivations to pursue green renovations, Grocoff echoed the sentiments of environmental pundits, saying that current levels of energy consumption are unsustainable.

“It has become obvious with automobiles, and it’s soon becoming obvious with our homes,” he said.

Henry Pollack, professor emeritus of geological sciences, said the new appeal for geothermal systems has come from the rising price of carbon-based fuels. The initial installation cost of the system is paid back over a number of years, and the savings have always been relative to the cost of natural gas.

“When carbon-based fuels were cheaper, the payout [for geothermal] was eight, 10 or even 12 years,” he said. “Now, with the payoff in seven or fewer years, geothermal has become an attractive alternative.”

Pollack has spent most of his research career measuring sub-surface temperatures across the globe in an effort to map heat loss from its interior.

He said the expense of drilling boreholes and the scarcity of locations with “hot rocks” puts deep mining for heat far behind wind power as an established source of energy.