At Veridian @ County Farm we're exploring installing geothermal heating and cooling throughout the neighborhood to help minimize energy consumption.
Today, many communities across the country in virtually every climate zone have successfully installed geothermal.
Geothermal is more accurately called geothermal exchange. It's simple, proven technology that has been around for over 40 years. It is nothing more than a large heat exchanger similar to the coils you see in the back of your refrigerator. The coils are placed inside bore holes deep in the ground or laid horizontally where space allows.
Since the ground temperature stays about 52 degrees year round it makes for a an easy and virtually free transfer of heat. In the winter when the air temperatures are below freezing, the geothermal furnace does a heat exchange with the warmer ground, rather than using energy to force feed heat. In the summer, the pump reverses and dumps excess heat from the house into the cool ground. As a bonus, some of this excess heat can help heat water for virtually free.
A geothermal furnace is generally no more expensive than a conventional furnace. However, drilling the bore holes does add to the up front capital cost. This additional cost is paid back quickly through the 60-80% energy savings.
By supplying the geothermal bore holes for the ground loops at scale in a new development, geothermal becomes exceptionally more affordable on a first cost basis. Many of the incentive, financial, permitting and logistical hurdles are removed when designed at the neighborhood scale. When amortized as part of development costs, geothermal becomes an attractive option with a diversity of financing possibilities.
Here's some of the many examples of communities using geothermal energy to help get neighborhoods to zero emissions necessary to avoid catastrophic impacts of climate change.
1. Grow Community - Bainbridge Island, WA
2. Whisper Valley - Austin, TX
3. The Bridges - Lincoln, NE
4. Cypress Pointe North - Cayman Islands
5. Badger Mountain South - Richland, WA
Orca Energy from Seattle is partnering with Bosch to offer a variety of options for developing neighborhood geothermal. Check some out here: http://www.orcaenergies.com/
In 2011, the University of Michigan funded a study to retrofit an entire Ann Arbor neighborhood with geothermal. Since 2011 geo systems have become even more affordable. The study found that neighborhood scale systems would be an excellent pathway for the City to meet is carbon reduction targets and eliminate natural gas combustion heating systems.
In Michigan, the most common type of geothermal heating and cooling is a heat exchange system that utilizes the constant temperature of the earth below the frost line. This system transfers the constant temperature to the internal heat exchange unit and reduces the amount of energy necessary to maintain desired temperatures. This efficiency also saves money. Residents who switch to geothermal usually see energy costs reduced by half. Those who have switched also say that the heat is better quality than conventional systems. On the neighborhood scale, the homes can all connect to a large loop system or have individual, unconnected systems in their own yards. Large loop systems are more suitable for new developments of dense residential communities, since they can be installed without disturbing any established streets, sidewalks, and underground infrastructure. Additionally, the developer can bundle the cost into the selling price of the new units. Individual systems are more suitable for existing neighborhoods because their installation does not necessarily require disturbing streets or infrastructure: the owner can install the system on their property without crossing into the right-of-way. This installation as a result can be much less expensive, however, requires the owner to incur the fees of the system. The underground pipes of individual geothermal systems are positioned either vertically or horizontally. Vertical systems have bores (wells) that range from 150’ to 450’ deep. These systems typically require 100 square feet of surface area. Horizontal systems require trenches dug 6’ deep and extend horizontally, requiring at least 300’ of open surface area. The costs increase with depth of drilling, so vertical systems can be more expensive to install, but they may be necessary if property space is limited.