Does geothermal energy cause pollution?

Is geothermal pollution a problem for the electricity generated from geothermal sources, or for geothermal heating and cooling? Also, how about pollution from solar and wind energy?

Answer from Green Energy Efficient Homes

Geothermal energy can be used in two main applications. The first is on a large scale – generating electricity by injecting water into a geothermal heat source and using the resulting steam to drive turbines. The second is on a building or household scale: using a loop of tubing that goes into the ground, to extract heat from the house and pump that heat into the ground (during hot weather, for air conditioning) or to extract heat from the ground and pump that heat into the house (during cold weather, for heating).

Geothermal electricity generation does involve a small amount of geothermal pollution in that the steam coming up from below ground carries some toxic gases, but in most plants these gases, as well as the steam, are condensed and reinjected into the ground so the effect on the environment is negligible. There are no CO2 emissions from geothermal energy so it is a much better source of electricity than coal or natural gas or nuclear (or even large-scale hydro generation which requires the flooding of large areas of land).

Geothermal heating and cooling only causes pollution to the extent that the electricity source required to run a geothermal heat pump may come from a polluting source such as coal. However, the amount of electricity used for geothermal heating and cooling is typically about a quarter the electricity that would be required to heat or cool the same space with electrical heaters and conventional air conditioning. And if you install a home geothermal heat pump and buy your electricity from a green electricity supplier, then you don’t have to worry about either geothermal pollution from the heat pump system, or pollution from the electricity used to run it.

Solar and wind energy do not cause any pollution in their operation because they simply convert photons or the kinetic energy of moving air into electricity. Again, no CO2 is released in the conversion of solar or wind energy into electricity, or in the conversion of solar energy into home heating – or even air conditioning, as you can actually use the heat from solar energy to run an air conditioner!

Green Energy Efficient Homes articles cited

2 replies
  1. Rose Adams
    Rose Adams says:

    I am an engineering studen and i am working on a eco friendly house made totally out of recycled materials for a competition. I was considering useing geothermal energy to heat and cool the house and to provide electricity. So far i am finding the idea to be a contender my only concern was the expanses and possible pollution. If you have any advice feel free to let me know. Thanks

    • Robin
      Robin says:

      The expense is considerable given that you either need a really big trench (for horizontal installation) or a very deep hole (for a vertical installation) along with all the piping, the heat exchanger, pump, etc plus a way to distribute the heat in the house.

      If you focus on making a very well insulated house with passive solar, a simpler heating system may work – a heat pump for instance if your climate doesn’t get too cold, or heat pump with woodstove for backup.


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