Renewable energy is energy that’s derived from natural sources that we are unlikely to run out of. These replenishable power sources include wind, moving water, heat from the earth, sunlight, ocean waves, and even organic waste. While renewable energy is often misconstrued as a new technology, humans have been harnessing nature’s power for heating, lighting, transportation, etc. for a very long time.
The United States uses and produces a mix of different energy sources. In 2017, renewable energy accounted for 12.7% of the primary energy production, including geothermal energy. Geothermal energy has been used for thousands of years for cooking and heating purposes, and modern technology has allowed us to harness it more effectively. This key renewable energy source covers a significant share of electricity demand in countries like Iceland, New Zealand, El Salvador, and Kenya. However, the United States has the highest worldwide installed geothermal capacity at 3.8 GW.
At this point, you may be wondering how does this type of energy works. Well, have you ever seen pictures of a volcano or a geyser, or better yet, seen them in person? Have you ever relaxed in a hot spring? If so, then you’ve seen geothermal energy in action. Geothermal energy is heat within the earth; the word geothermal comes from the Green works “geo” (earth) and “therm” (heat). Geothermal resources are reservoirs of hot water below the earth’s surface which can be tapped into for a variety of applications including electricity generation, direct use, and heating and cooling. We acquire geothermal power through the use of steam created by pumping water deep underground (where the earth is naturally heated). The steam then rises and turns a turbine that generates energy, similar to as a wind turbine does.
Given its significant potential and increasing popularity in regions throughout the world (including the U.S.), we wanted to take a look at some of the advantages and disadvantages of geothermal energy.
Pros of Geothermal Energy
- For as long as the earth exists, there will always be geothermal energy to harness. Through sustainable reservoir management, the rate at which energy is extracted will be balanced with its natural recharge rate
Abundant, Consistent, & Predictable Energy Supply
- Salts and dissolved minerals contained in geothermal fluids are usually reinjected with excess water back into the reservoir at a depth well below groundwater aquifers. This recycles the geothermal water and replenishes the reservoir
- Because we don’t have to worry about weather fluctuations, geothermal plants produce electricity around the clock with minimal interruption
- As wind, overcast days, or total cast days are not of concern, so geothermal energy output is highly predictable
Massive Potential (as talked about above)
- The USGS has identified the potential for geothermal energy production in 13 Western states of up to 16,457 MW from known geothermal systems; up to 73,286 MW from resources yet to be discovered; and up to 727,900 MW from the use of EGS (Enhanced Geothermal Systems).
- U.S. geothermal resources can be harnessed for power production without importing fuel, not only boosting our domestic economy, but also reducing transportation emissions
- Because different workers are needed for each phase of its development, with continued growth, employment opportunities in a wide variety of occupations with varying education and training requirements (from doctoral scientists to roustabouts) will increase
Small Environmental Impact
- Because there is no mining or transportation associated with the production and generation of geothermal energy, no fuels are required in the process. As such, levels of air pollutants they emit are low. In fact, geothermal power plants emit about 99% less carbon dioxide than fossil fuel power plants of similar size
- Since they’re so compact geothermal plants have a small footprint; using less land per GWh (404 m2) than coal (3642 m2) wind (1335 m2) or solar PV with a center station (3237 m2)
Innovation in Technology
- Geothermal power is often considered one of the most important sources of renewable energy (behind solar, wind, and hydro) but it now accounts for just a small portion of the world’s power capacity; the exploration of geothermal technology is becoming increasingly popular
Cons of Geothermal Energy
More expensive than other forms of energy, although it pays off in the long run
- There is a high cost of electricity, ending up somewhere between $2-$7 million for a 1 MW geothermal plant
- This type of energy is very location specific – we don’t have the power to choose where we construct the geothermal plant and there are only certain zones where it is an option
- Hot water pumped from underground reservoirs usually contains high levels of sulfur, salt, and other minerals. However, geothermal plants have closed-loop water systems, in which extracted water is pumped directly back into the geothermal reservoir after it has been used. The water is contained within steel well casings cemented to the surrounding rock to avoid water contamination
Reservoirs Can be Depleted
- This can occur if water is removed faster than it’s replaced. However, the sustainability of geothermal installations can be achieved through proper management
Requires Significant Amounts of Water
- Depending on the cooling technology used, geothermal plants can require between 1,700 and 4,000 gallons of water per megawatt-hour. The good news is that most geothermal plants use either geothermal fluid (as opposed to freshwater) in order to reduce its overall water impact
Limitations in Existing Technology
- In order for the geothermal process to work on an industrial scale, the water in the ground must be extremely hot. Although lower temperatures can still provide heating and cooling solutions, they aren’t useful for electricity generation. This means the full potential of geothermal energy can’t be obtained until technologies are able to catch up with the industry
By now, it’s hopefully clear that a long-term solution for meeting Earth’s energy demands isn’t going be dependent on just one type of energy, but rather a combination of different energy sources that we can use for generations to come. After reading through the list of pros and cons, we hope that you recognize that geothermal energy is undoubtedly a source that must be considered.
Creating a sustainable future starts with the energy you use in your home. Kiwi Energy offers environmentally-focused energy plans that help contribute a more sustainable future.
Photo Credit: http://geo-energy.org/Basics.aspx