How much potential does geothermal energy have globally and in the US?

Geoscientists estimate vast energy reserves in the Earth's crust, enough to last for hundreds of millions of years. The US Department of Energy sees potential to increase geothermal electricity generation to over 60 GW by 2050, providing 8.5% of US electricity, with even greater potential for direct heating.

Why is geothermal energy not expanding more rapidly despite its potential?

Geothermal energy is limited by the rarity of ideal locations, requiring deep drilling which is expensive, especially when projects encounter unexpected geological conditions. The best sites have already been exploited, leading to diminishing returns and rising costs compared to solar and wind.

What are the main challenges and costs associated with geothermal drilling?

Drilling for geothermal energy is expensive due to the depth required (often deeper than oil wells) and the time-consuming nature when unforeseen issues arise. Drilling accounts for over 50% of costs, with costs escalating significantly for deeper wells. Unexpected problems like equipment failure on-site can incur tens of thousands of dollars per day.

What new technologies are being developed to improve geothermal drilling?

Several new technologies aim to reduce costs and increase efficiency, including microwave drilling, percussive drilling (hammer drills), high-pressure water jets, thermal shock methods, plasma torches, and laser-assisted rotary drilling.

What are the risks associated with geothermal energy extraction?

Risks include potential for induced seismicity (small earthquakes) similar to fracking, especially with Enhanced Geothermal Systems. Accidental well blowouts, high-pressure gas bursts causing fatalities, and cooling of rocks in supercritical reservoirs can also lead to seismic activity.

Do geothermal plants emit greenhouse gases?

Yes, geothermal plants can emit greenhouse gases like carbon dioxide and methane carried by the circulating fluid. The amount emitted varies greatly by location; some plants in Turkey and Italy emit more CO2 than natural gas power plants.

What is supercritical water in geothermal contexts?

Supercritical water exists at temperatures above 374 degrees Celsius and pressures around 200 times atmospheric pressure. It is neither liquid nor gas but a combination of both, capable of carrying significantly more energy and improving the efficiency of electricity conversion.

Key Moments

Geothermal Energy: How Big is the Potential?

Sabine Hossenfelder

Science & Technology3 min read22 min video

Feb 18, 2023|481,196 views|22,965|2,295

geothermal energy renewable energy geothermal geothermal energy how it works geothermal energy potential how much geothermal energy is there geothermal drilling geothermal risk geothermal energy risk climate change hossenfelder science without the gobbledygook

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Key Moments

TL;DR

Geothermal energy has vast potential but faces high costs, technological challenges, and risks of seismic activity.

Key Insights

Geothermal energy taps into the Earth's internal heat, a massive and long-lasting resource.

While theoretical potential is huge, practical exploitation is limited by location, depth, and drilling costs.

Technological advancements are improving drilling efficiency and exploring new methods like enhanced geothermal systems.

Risks include induced seismicity, equipment damage from corrosive chemicals, and potential greenhouse gas emissions.

Current geothermal energy production is a small fraction of global energy supply, despite comparable costs to renewables.

Geothermal energy is not a "panacea" for climate change but can be a valuable part of the energy mix with further development.

THE VAST POTENTIAL OF EARTH'S INTERNAL HEAT

Geothermal energy harnesses the immense heat within the Earth, a relic from its formation as a hot plasma ball. This internal heat, estimated to be around five to seven thousand degrees Celsius at the core, can be accessed by digging only a few kilometers deep. Geoscientists estimate that the upper 10 kilometers of Earth's crust contain approximately 10^27 Joules of energy, enough to power global consumption for hundreds of millions of years. This suggests a colossal, long-term energy reserve beneath our feet, with the potential to far outlast current energy sources.

REALISTIC EXPLOITATION AND CURRENT ROLE

Despite its vast potential, geothermal energy currently plays a minor role in global energy production. In 2020, its total global power capacity was around 15 Gigawatts, a fraction of solar or wind capacity. The US Department of Energy estimates that US geothermal generation could rise to over 60 gigawatts by 2050, providing 8.5% of electricity. Countries like Iceland lead in per capita usage, with geothermal supplying 66% of their primary energy. However, widespread adoption is hindered by geographical limitations and the difficulty of accessing suitable energy sources.

TECHNOLOGICAL CHALLENGES AND DRILLING COSTS

The primary hurdles for geothermal energy are the high costs and technical difficulties associated with drilling. Drilling costs are heavily front-loaded, with wells often needing to be twice as deep as oil wells. Drilling just 4 kilometers can cost millions, and 10 kilometers can cost tens of millions. These expenses are exacerbated by the time spent waiting for operations to proceed when unexpected issues arise, such as equipment failure or geological surprises. The oil and gas industry benefits from a century of accumulated expertise, which geothermal projects are still developing.

ADVANCES IN DRILLING AND ENHANCED GEOTHERMAL SYSTEMS

Several innovations aim to reduce drilling costs and improve efficiency. These include better site assessment, improved management training (incorporating physics principles), and new drilling techniques. Percussive drilling, water jets, thermal shock methods, plasma torches, and combined laser and rotary drilling are being developed to penetrate rock faster and at a lower cost. Enhanced Geothermal Systems (EGS) are exploring ways to create artificial geothermal reservoirs by fracturing rock and circulating water, making more locations viable for geothermal energy extraction.

RISKS AND ENVIRONMENTAL CONSIDERATIONS

Geothermal energy extraction is not without risks. Incidents like the one in Staufen, Germany, where drilling caused ground expansion and building damage due to geological reactions, highlight unforeseen geological consequences. More generally, creating fractures in rocks for EGS is similar to fracking, increasing the risk of induced seismicity (small earthquakes). Well blowouts and gas releases have also occurred. Furthermore, while often comparable to solar in lifecycle emissions, some geothermal plants can emit significant amounts of CO2 and methane, especially from supercritical reservoirs, and some even exceed natural gas plants.

THE FUTURE OUTLOOK FOR GEOTHERMAL ENERGY

Geothermal energy holds significant promise, but it currently remains underexplored and underfunded. While advancements in technology and research are promising, drilling operations are likely to remain risky and expensive for the foreseeable future. It is unlikely to be a singular solution for climate change, but with continued investment in research, technological development, and mitigation of risks, geothermal energy can become a more substantial and reliable component of the renewable energy mix, offering a stable, 24/7 power source.

Mentioned in This Episode

●Software & Apps

●Companies

●Organizations

●Concepts

●People Referenced

Drilling Cost Estimates

Data extracted from this episode

Depth	Estimated Cost (USD)
4 kilometers	$5 million
10 kilometers	$20 million

CO2 Emissions Comparison (g/kWh)

Data extracted from this episode

Energy Source	Lifecycle Emissions
Natural Gas Power Plant	~500
Solar	~40

Common Questions

In Staufen, drilling for geothermal heat led to water under pressure leaking into a Keuper layer rich in clay and shale. This water reacted with calcium sulphate to form gypsum, which expanded and caused buildings to crack and rise unevenly.

Topics

Technology & Innovation Science & Mathematics Renewable Energy Energy Production Energy Infrastructure Climate Change Mitigation Environment & Climate Geothermal Energy Drilling Technology Earth Science

Mentioned in this video

Locations

Staufen

A small German town where a geothermal drilling project led to structural damage in buildings.

Iceland

The world leader in geothermal energy production per capita, utilizing it for primary energy needs.

Turkey

A country where the expansion of geothermal energy has picked up in recent years.

Australia

A country where accidents at geothermal projects have occurred.

Sumatra

A location in Indonesia where a high-pressure gas burst at a geothermal project resulted in fatalities and injuries.

Indonesia

A country where the expansion of geothermal energy has picked up, and also experienced a well blowout.

Kola Superdeep Borehole

The deepest artificial point humans have drilled into the Earth's crust, located in Russia.

Newberry, Oregon

The location of a test site for AltaRock Energy's Enhanced Geothermal Systems.

Organizations

Kenya

A country where the expansion of geothermal energy has picked up.

Spain

A country from which researchers reported that cooling of rocks in supercritical reservoirs can induce earthquakes.

University of California

The university where Brian Keating is an experimental physics professor.

MIT

Researchers from MIT are developing a method combining rotary drilling with a laser to drill deeper and faster.

Chile

A country where accidents at geothermal projects have occurred.

National Renewable Energy Laboratory

Researchers from this laboratory claim that every house in the US could be heated by geothermal sources for millennia.

IPCC

The Intergovernmental Panel on Climate Change, which is cited for comparing geothermal emissions to solar power.

People

Jill Tarter