Geothermal Energy is Actually Renewable But...
We've seen the consequences of strip mining in the coal industry. The demand for coal as fossil fuel to heat homes and power locomotives in years past led mining companies to look for new ways to quickly mine softer coal that lies close to the surface of the ground.
The hard anthracite coal is only found in vein deeply embedded in rock but softer coal (lignite and bituminous) and tar sands are often located just below a layer of rock near the ground's surface.
Geothermal energy is renewable as the source of the energy is never removed from the Earth. When mining fossil fuels, oil and coal are permanently removed from the Earth. These fossil fuels were formed over millions of years and are not renewable. When a coal field is mined out, it is closed. When an oil field has been drained, the company drills for oil elsewhere.
Geothermal Energy Can Regulate Temperatures
Geothermal energy is renewable because the energy is in the form of heat. The central core of the Earth is iron and the second part of the Earth's core is a layer of molten rock surrounding that iron center.
The heat produced comes mainly from decay of radioactive particles. The Earth's core is slowly cooling and that will continue to happen. This cooling will most likely occur over millions or even billions of years.
The heat flowing from the Earth's core warms layers of rock and reservoirs of water trapped beneath the surface of the Earth. This heat is constant. You can see the effect when you visit one of the famous caves that are tourist attractions.
You can go from a very hot day in the sunshine into a deep cave where you may begin to be chilled within a few minutes. The cave maintains a constant temperature and that temperature will vary by only a couple of degrees from hot summer months to frigid winters occurring on the land above the cave. In most caves, the temperature is a solid 56 degree Fahrenheit.
You might think this is a cooling effect but it is temperature regulation. The heat from the Earth warms the rock surrounding cave to a certain temperature and that remains the same no matter how surface temperatures fluctuate. It is this constant temperature that leads some people to build underground homes or Earth bermed homes.
These homes are highly energy efficient as they retain the lower Earth temperatures found just ten feet below ground. However, homes buried in the Earth carry their own set of problems of design and lighting. The most challenging aspect of building such a home is keeping out the moisture that is also part of the Earth around the house.
Renewable and Sustainable
With a new focus on protecting the environment, people are looking for energy sources that produce the electrical power they demand without causing great damage to the Earth or depleting the natural resources that seem abundant. There was a time when we believed there was no end to the oil and coal resources but we know now that is not the case.
Oil fields run dry. Coal mining is dangerous work and often open pit mining and strip mining have left ugly scars on the land. Drilling for oil carries the risk of pollution of our oceans and land with oil spills that can be difficult to contain and almost impossible to clean up after the fact.
Wood for building homes and furniture is often require to be from renewable forests. The company cutting down trees must also plant trees to replace those they destroy. Bamboo has gained in popularity for everything from flooring to kitchen cabinets because it is a renewable resource with a plant that grows very quickly to maturity.
Some hardwood species are now protected or restricted as it can take a hundred years for the tree to be replaces with a similar specimen. In the 1960's black walnut became a popular wood for home décor. The style was a new modern look and black walnut was readily available.
The sales increased dramatically and rising demand led to people selling black walnut trees right out of their lawns. It was not uncommon for a few years for someone to offer hundreds of dollars to a homeowner for the right to cut and use black walnut trees on his property. The tree quickly became scarce in the natural landscape and the specimens have never recovered in areas of the Midwest where they were so widely harvested.
Summary
Geothermal energy is the best source of energy because it is sustainable. As long as a generating plant does not remove more heated water and steam from an underground geothermal reservoir than the Earth can reheat, the energy source will not stop producing until the center of the Earth cools.
In a few areas where multiple deep wells are used to generate geothermal energy, the production of electricity had to slow down for a time to allow the geothermal energy fields to recover their temperature. However, the sustainable nature of this power source is so reliable the fields do quickly heat once again to their maximum temperature and production can resume.
