We need qa mix of green power sources. Here’s why geothermal, often overlooked, is most important.
Lots of us quit counting renewable energy sources after naming wind and solar and while those are two good ones, they’re far from alone. Hydropower, using dams to drive generators has been with us so long that we often overlook its contribution to the overall energy mix. A record 4,185 terawatt hours (TWh) in electricity was generated from hydropower in 2017, according to the 2018 Hydropower Status Report, from the International Hydropower Association.
Renewables made up 17.1 percent of all US power generation in 2017 but without hydropower that percentage drops to 9.6 percent. So, hydropower is a big deal. Can it go bigger? Probably not. Consider that most of the available rivers have been dammed already and then consider that the political climate is not in favor of more dams and then add to that the reality that climate change is responsible for a significant decline in the amount of water behind existing dams and you have a recipe for not adding significantly to the hydro power profile.
Geothermal power generation is another form of renewable energy generation and it might be the 21stcentury equivalent of hydropower. The two have in common a source that’s really close to nature, they don’t require conversion like coal-to-steam-to-electricity, and almost no negative climate impacts. Many conservation-minded people however, point out that dams come with a cost to the ecosystems of rivers.
Geothermal works by capturing heat from the earth’s crust and conducting it as very hot water (300 degrees C or more) from deep underground to a conventional steam turbine that drives a generator. When the super-hot water meets the normal atmosphere it turns to steam instantly expanding and that drives the turbine. But electricity generation isn’t the only use of geothermal energy, another is zone heating in which the hot water is piped to buildings for heating.
The Romans used this approach in Britain when the built public baths in a place still called Bath, UK. Other civilizations have also tapped heat from the earth. Below are some more recent examples of uses for geothermal energy from world-wide sources. There are zone…