Americans are slowly but surely starting to realize their need for renewable energy. More and more renewable energy farms are being erected as we try to steer away from our dependency on fossil fuels. We are working hard developing technologies with wind and with solar energies, but sometimes it’s not windy and sometimes it’s not sunny. However, the Earth’s core is always extremely hot, and this is where geothermal energy can play its part. Geothermal’s popularity has been increasing in recent years (especially in California) and there is definitely a reason why. Geothermal’s goal is to harness the heat generated from the Earth and to put it to work; literally. Geothermal is an enormous resource, low maintenance, efficient, and could be an important part of the solution to our present energy crisis.
Geothermal energy sounds great, but what is actually going on in the cycle? The concept of geothermal is basically a system of fluids exchanging heat energy to produce work. Hot brine is brought up from the Earth’s crust using heat pumps and is passed through a heat exchanger. A heat exchanger is exactly what it sounds like; mainly via conduction heat is transferred from the brine to the turbine fluid. Many geothermal plants use iso-butane because it has a lower evaporation temperature than steam and reaches a higher pressure at the turbine, which makes the turbine more efficient. Thus, the power plant is using the high temperature and pressure of the turbine fluid to push and rotate the turbine, which is what actually generates the electricity. In addition to its high efficiency, geothermal energy is also very environmentally friendly because its two main byproducts are water and air vapor. The byproducts are clean, geothermal runs 24 hours a day, and the plants are easy to maintain. The benefits are wide and undeniable.
The only part that may hurt the environment is the drilling itself; however, rules and regulations set by several commissions and associations keep the drilling in check. Drilling is extremely expensive and can account for as much as 50% of the total investment cost. Drilling can cost anywhere from $5-$10 per foot putting the total cost of drilling in the millions. Also a great deal of research and testing goes into choosing a geothermal power plant location to avoid having to drill more than once. A profitable geothermal power plant would require a premium location with a low elevation (which is closer to the Earth’s core) because less drilling is required. Thus geothermal power plants are usually located along the borders of tectonic plates.
Rongere, F. (2012). Geothermal. Unpublished raw data, Mechanical Engineering, San Jose State University, San Jose, CA.
Money is always a pressing issue and is unfortunately the main downfall of geothermal energy. Geothermal is a really big step towards sustainability, which is the ultimate goal of moving to a new energy source. It is our duty to make wiser decisions that keep our planet and our future generations in mind. Our nation often talks about goals that we have for future years, but those future goals can only be accomplished if we take action now.