While climate change has no scientific connection to earthquakes, one of the contenders to provide renewable energy may. Two geothermal projects – one in Basel, Switzerland and the other in Northern California – have recently been shut down amid concerns about increased earthquake activity believed to be related to the tapping of thermal energy in the earth’s inner layers. While the move seems precautionary, the seismic activity has raised concerns. Since shifts in the earth’s tectonic plates cause tremors, there appears to be a causal relationship between the drilling and earthquakes, as the activity occurred at both locations.

Two main types of geothermal energy have emerged as possible contenders for a renewable energy future. The type mentioned in a recent New York Times article refers to deep well drilling – several thousands of feet below the Earth’s surface – for electricity production by heating water which turns a turbine. Despite the concerns over seismic activity, this type of geothermal energy provides a possible source of base load power, something that wind turbines and photovoltaic systems cannot offer. However, as the California and Swiss projects have shown, the increased earthquake activity presents a monumental concern.

While the aforementioned deep well geothermal source generates electricity by using a turbine to spine generators just like wind, coal, and natural gas fired power plants, a local version of the energy source can be used for cooling and heating buildings. Instead of the deep well drilling, geothermal pumps can be dug closer to the earth’s surface. These wells, or fields as they are sometimes called, tap into the constant temperature found 2.5m (8 feet) below the earth’s surface. The temperature will depend on the location of the system. During warm summer months, air is pumped through the system – which is cooler than the ambient environment – and mixed with warmer air to produce the desired temperature as prescribed by a standard thermostat. During cooler months, the air from the geothermal system is warmer than ambient outside air, thus requiring less energy from a boiler or heating system to bring the air to the desired temperature.

The four minute video below provides an excellent explanation of how ground source geothermal works:

Geothermal energy very well may represent one of the options to bring the country and the globe into a renewable energy future. Regardless of what happens to the deep well drilling, geothermal presents other opportunities, such as the open and closed loop systems mentioned in the video. Much like Iceland has tapped the heat from thermal pools and vents on the island, other possibilities exist – like country’s use of steam produced from the tectonic activity, which does not require drilling – for geothermal in a clean energy future.

- Eric Wilson

[Image source: KCET.org]