Pros and cons of geothermal energy: Digging deep

Deep beneath your feet lies a renewable energy source that's been powering communities for over a century. Geothermal energy taps into the Earth's core heat to generate electricity and warm homes, offering a unique alternative to solar panels and wind turbines. But does this underground champion live up to its promise, or do hidden challenges limit its potential?

What is geothermal energy?

Geothermal energy harnesses heat from the Earth's core to generate electricity and provide heating and cooling solutions. This renewable energy source has powered communities since 1913, when the first commercial geothermal power plant opened in Larderello, Italy. Prior to this, in 1904, Prince Piero Ginori Conti tested the first experimental geothermal generator at the same location, which produced enough power to light five light bulbs.

The process works by drilling deep into the earth to access hot water and steam trapped in underground reservoirs. This natural heat source maintains consistent temperatures year-round, typically ranging from 50-60°F just below the surface to over 700°F in deeper geothermal reservoirs.

Types of geothermal systems

The geothermal industry currently provides about 0.4% of total U.S. electricity generation, with most facilities concentrated in western states. California and Nevada together account for 95% of the nation's geothermal power generation, with California representing approximately 70-75% of total US capacity.

Advantages of geothermal energy

24/7 baseload power generation

Geothermal power plants operate 24 hours a day, 365 days a year, regardless of weather conditions. Most geothermal facilities achieve capacity factors between 70-90%, with modern plants reaching up to 95%, meaning they generate electricity at nearly full capacity most of the time. Compare this to solar energy's typical capacity factor of 25% and wind energy's 35%.

This reliable power generation makes geothermal energy an excellent baseload energy source that can complement intermittent renewables without requiring expensive battery storage systems.

Superior capacity factor and reliability

Geothermal plants maintain the highest capacity factors among renewable energy sources, operating at 70-90% of maximum output. Here's how major energy sources compare:

Small land footprint

Geothermal power plants require significantly less land area than other renewable energy sources. A typical geothermal facility uses about 1-8 acres per MW of installed capacity, compared to solar farms at 5-10 acres per MW and wind farms at 30-141 acres per MW.

Long-term cost effectiveness

While geothermal systems require substantial upfront investment, their operating costs remain extremely low over their 30-50+ year lifespans.

Once operational, geothermal facilities have no fuel costs and require minimal staffing. Operating expenses typically range from 1-3 cents per kWh, significantly lower than fossil fuel alternatives.

Multiple applications beyond electricity

Geothermal energy offers versatility beyond electricity generation:

Disadvantages of geothermal energy

Location-dependent limitations

Geothermal resources concentrate in specific geological zones rather than being widely distributed. High-temperature reservoirs suitable for electricity generation concentrate primarily along tectonic plate boundaries and volcanic regions. Currently, viable geothermal resources for power generation exist mainly in California, Nevada, Utah, Hawaii, Idaho, Oregon, and Alaska.

This geographic constraint severely limits where new geothermal power plants can be built, unlike solar panels which work effectively across most of the United States.

High upfront investment costs

Geothermal projects require substantial initial capital investments, with drilling operations accounting for roughly half the total cost. Construction costs typically range from $4,000-6,000 per kW of installed capacity.

These high initial costs create significant financing challenges, especially for smaller developers and communities.

Potential environmental concerns

While generally environmentally friendly, geothermal development can create localized environmental issues:

Geothermal vs. Solar energy

Availability and accessibility

Solar energy wins for accessibility. Homeowners across the country can install solar panels on their rooftops, while geothermal heat pumps require suitable ground conditions and significant excavation. For electricity generation, solar farms can be built virtually anywhere with adequate sunlight, while geothermal power plants need specific geological conditions.

Performance and reliability

Unlike intermittent renewables, geothermal systems deliver electricity around the clock. Solar energy produces power only during daylight hours, achieving capacity factors of 15-25% in most locations.

For most homeowners, solar panels offer better accessibility and lower upfront costs. However, in suitable locations, geothermal systems provide superior long-term value through higher capacity factors, longer operating life, and exceptional heating and cooling efficiency.

Sergey Fedorov

Co-founder & CTO

Sergey has been running A1 SolarStore since 2017 with the main idea in mind – making going solar easier for everyone. Based on a thorough market research and his personal experience, he shares his ideas on both solar industry and management related topics

More articles from this author

Illustrator: Dasha Vasina