I am going to use the word Geothermal to mean more than the narrow definition of just producing electricity which many people think of when they hear the word. Geothermal to me means ‘ground heat’ or heat from the Earth broadening its application.
Background and History
The word Geothermal has its root in Greek words for Earth and Heat. Geo or gaia means Earth and thermo or therm for heat or warmth. Heat from the Earth has been known for a long, long time with many ancient people making use of thermal springs that naturally rose to surface. Some of them were enclosed to hold in the heat and create a hot pool in which to bath while in other areas the water would have been hauled a short distance for use. Ancient people used this form of Geothermal heat for bathing as far back as ten-thousand years.
It was not until more recent years that we have seen the use of the Earth’s heat to produce electricity. July 4th 1904 the first power plant using dry steam from a geothermal source went online to produce electricity in Larderello Italy. In 1911 the plant was upgraded to industrial levels for higher electrical production. It was the only power plant in the world producing electricity in this way until 1958. The site has seen more than 30% drop in steam pressure from its peak in the 1050’s.
In 1958 the Wairakei plant in New Zealand made use of flash steam technology. Pacific Gas and Electric began to operate a Geothermal plant in 1960 in California. A binary cycle plant was put into use in Russia in 1967 and in the 1970’s in the United States after the energy crisis. The binary cycle plant makes use of much lower steam pressure. Now there are some 60 plants world wide producing electricity.
Many of the newer power plants make use of wells drilled to pump water underground before it resurfaces as steam unlike older plants which made use of areas where steam naturally rose from the ground.
Some Pro’s and Con’s
- compared to fossil fuels it is environmentally friendly and less polluting
- it is a safe form of energy
- for the most part it is renewable for as long as the Earth’s core remains intact producing heat
- it can produce electricity at a fair price and is not subject to price fluctuations as fossil fuels are
- it costs little to operate a Geothermal power plant
- it reduces our dependence on fossil fuels and can be a transition energy source to include other renewable energy sources
- more energy can be extracted by using the remaining heat in conjunction with Stirling engines to produce more electricity or for heating in nearby homes or businesses thereby getting a bigger return
- it is costly to setup a Geothermal plant
- the heat source does not last and begins to decline soon after a power plant goes online
- is not available everywhere, very localized
- it could release poisonous gases like hydrogen sulfide which is hard to deal with or dispose of
- pipes can become clogged with mineral deposits shutting a plant down
- Earthquakes and after shocks can occur do to the drilling and pumping of water underground
- it has limited applications, heat and electricity production only
There is only one Con I can see that is never adequately discussed – is there any potential damage it could cause to the Earth’s core by extracting ‘too’ much heat at one time like if there were too many Geothermal plants built around the world to meet future energy needs. All the water pumped underground to extract the Earth’s heat could cause a cooling effect as has been seen with existing power plants where steam pressure is lost overtime as the heat in the area is lost. Until this majorly important question is answered without a brush-off with words like, ‘there’s plenty of heat, it can’t happen’ I can not in all honesty support it as a ‘major’ energy contributor and only see it on the sidelines.
Now onto a way I am fully supportive of. In Europe new home designs with a heat pump work in two ways have been used successfully for a number of years now and should in my opinion be used in the U.S. too. I will admit I have not absorbed all the information as I am not an engineer or scientist to fully understand the inner workings but I do know enough to relay the information for you here.
First, the home is super insulated to make best use of the heating and cooling without wasting energy as typical McMansions or other low insulation construction methods do. The home will have several solar panels to collect the Sun’s heat throughout the day storing excess heat in one or more tanks in the basement. Once the tanks are fully charged the excess heat is not wasted but stored in the ground beneath the house using the heat pump. When heat is needed it is extracted from the tank and then from underground. In this way you maximize the amount of heat stored without wasting it. In summer months the heat pump can act as a means of cooling a home by storing the heat underground for cooler months. In new homes radiant heat can be installed in both the floors and walls but in older homes the old fashioned radiators or baseboard radiators can be installed.
By combining Solar Heat collection and heat pumps that make use of the ground beneath a home as storage and extracting the heat the whole system becomes more energy efficient with very little need for additional or backup heating or cooling. The ground essentially becomes a heat battery that is recharged part of the year and drawn from when needed. Makes sense to me.