Geothermal energy gives us two ways to harness the heat that the Earth naturally produces every day. We can produce electricity through the use of a geothermal power plant and we can also use this energy to support HVAC systems. It is an environmentally friendly source of energy, considered to be renewable, and it does not produce the same amount of pollution as the continuous combustion of fossil fuels.
Geothermal energy can also be difficult to access. Some of the best locations for tapping into this energy are in very remote areas, making it very costly to transport resources to the location and to send power to local grids to be consumed. Here are some of the additional geothermal energy pros and cons that are worth considering.
What Are the Pros of Geothermal Energy?
1. Geothermal energy is a sustainable power resource.
Geothermal energy is able to sustain its own consumption rate. Because it is naturally produced by our planet, it is not a finite resource like fossil fuels happen to be. Current estimates place the sustainability of this type of energy in the range of several billion years. In comparison, current coal reservoirs that have already been mined are estimated to last 400 years in the United States.
2. It is also a stable source of energy.
We are able to predict the output that geothermal energy is able to produce. This gives it an advantage when compared to other forms of renewable energy, such as wind or solar. The heat that the planet is able to provide is virtually constant. This allows a power plant to have a high capacity factor that is very close to its total capacity, making it a very efficient energy resource as well.
3. Geothermal energy can be installed at the local level.
Although there is an estimated 2 TW power capacity for geothermal energy in terms of electrical production, it is also a resource that can be installed at the local level. The heat beneath the ground is resistant to the seasonal heating and cooling that occurs in the air around us. In many instances, a heat sink that is drilled a few meters into the ground is enough for a homeowner to utilize geothermal energy for their HVAC systems.
4. It is an incredibly efficient form of energy for heating and cooling.
For homeowners, the best furnaces that are powered by either electricity or natural gas are about 90% efficient. Many that are being used today are in the 75%-90% range. When geothermal energy is installed for a home’s heating and cooling, the heat pump being used averages an efficiency of 400%. Most geothermal heat pumps which supply up to 4.5 units of heat for every unit of energy that is supplied to it.
5. Geothermal systems require very little maintenance.
In the United States, some geothermal systems have been used for more than 60 years. Over this period of time, they have required very little in the way of maintenance. Annual filter changes and equipment checks are typically all that is required. The fans, compressors, and pumps for these systems are all housed indoors, so they are protected from the environmental changes that can disrupt other forms of power generation or heating and cooling. They do require electricity in order to operate, but that is their only real environmental impact once installed.
6. It can be installed on a small land footprint for both residential and industrial use.
Some geothermal systems can be installed with just a few square feet of space using vertical installation technologies. When installed on an industrial scale, geothermal power has the smallest footprint per megawatt of any other form of energy, including non-renewables. The land usage for a geothermal planet is generally less than 400 acres, including exploration, drilling, and construction activities.
7. Any water can be used for injection.
Although clean water from a natural reservoir is the preferred method of use for geothermal energy, wastewater products can also be heated and reused to generate power as well. Local utilities can inject treated wastewater back into a reservoir so that it can be recycled for use in geothermal reservoirs that may be struggling to sustain themselves.
8. Geothermal requires no combustible fuel.
Geothermal energy is produced without the need for ongoing mining efforts. After access to the reservoir is obtained, no other digging is required to sustain the energy production. Transportation of the energy resource is not required either, as the electricity can be hooked up directly to the local grid and sent to homes and businesses. This further reduces the environmental impact that geothermal energy has when compared to other energy production methods.
What Are the Cons of Geothermal Energy?
1. There can be localized environmental issues with geothermal energy.
Geothermal energy that is close to the surface is often associated with volcanic activity in some form. This means there are usually localized emissions that include silica or sulfur dioxide. The water vapor clouds that can sometimes form around these areas will smell like rotten eggs, which can be very bothersome. Toxic metals, including boron and arsenic, can also be found in geothermal energy reservoirs.
2. Using geothermal energy is known to create localized earthquakes.
The installation of geothermal power plants in New Zealand and Germany have created localized land instability. This has created earthquakes in those areas that were not generally prone to experiencing them. It occurs because hydraulic fracturing is used to develop the geothermal systems that power plants in this industry use. Most of these earthquakes are considered to be minor, often under 4.0 on the Richter scale, but the State of Oklahoma experienced a 5.6 quake that was associated with wastewater disposal from fracking efforts.
3. The costs of developing geothermal energy are very high.
Between the exploration and drilling costs that come with accessing a new geothermal reservoir, along with the actual construction costs, geothermal energy is one of the most expensive resources we currently have. The total cost can be as high as $7 million per megawatt generated, so a 10 megawatt power plant would have a potential cost of $70 million. This is 2.5 times higher than the maximum potential cost of a wind turbine that can generate the same amount of energy.
4. Geothermal energy is location specific.
Not everyone has access to geothermal energy. This means it is a location-specific resource that can be very costly to transport for consumption. Some countries, such as Iceland, are able to generate over 30% of their total electricity demands from this industry. In the United States, geothermal energy provides less than 1% of the total electricity that is used and is just 8% of the non-hydroelectric electricity that is generated.
5. Not every geothermal energy reservoir is fully sustainable.
Geothermal energy as a total energy is completely sustainable. The planet changes and evolves over time, however, so some reservoirs can be depleted over time once they have been tapped. This is because weather pattern changes can alter how much rainfall occurs in a region, which affects the amount of fluid that is found in that reservoir. Some fluids can be injected back into the reservoir to sustain them for a longer period of time, but even that is still just a temporary solution.
6. Home-based geothermal systems are also quite expensive.
Despite the high efficiency rates of a geothermal heat pump, the cost that homeowners must pay to utilize this technology is quite high. It is not unusually for a geothermal pump system to cost as much as $30,000. There can also be high levels of water usage, which means exterior water from the property may be required and that will add to the cost as well.
7. It requires high water temperatures in order to operate.
In order for most geothermal processes to work on an industrial scale, the water in the ground must be heated to a minimum of 350F degrees. Lower temperatures can still provide heating and cooling solutions, but are not useful for electricity generation. This means the full potential of geothermal energy cannot be obtained until technologies are able to catch up with the industry.
8. Connection costs to a new geothermal site can be in the billions of dollars.
Because the prime sites for geothermal energy are location-specific and away from urban areas, it can be very costly to connect the power generated by a geothermal power plant to the local grid. For a very rural location, the cost could be several billion dollars. There will also be losses experienced during the transmission of electricity over these long distances that will impact the efficiency of that specific system.
These geothermal energy pros and cons show us that we can harness the power of the Earth. Current technologies may limit our ability to maximize the energy potential that is underneath our feet and there may be location issues to consider, but it is one of the most environmentally friendly systems that can be implemented today.