what is geothermal energy?

Why is the Earth hot?

The Earth was estimated to have formed 4.5 Billion years ago alongside its celestial partners that comprise the solar system. The Earth formed through the accretionary process (https://encyclopedia.pub/entry/34136) of dust, ice, and gases colliding with each other, forming larger bodies. These larger bodies eventually coalesced into the Sun, the planets and their moons that we see now. That accretionary process produces vast amounts of heat that the geological community believe is still trapped below the earth’s surface.

The current estimates are that 20% of the heat that is contained within the Earth is this primordial heat left over from the Earth’s formation. The vast majority of the trapped heat, therefore, comes from another source. The most probable source of this heat is generated by the natural radiation of four main element isotopes: Thorium 232, Uranium 238, Potassium 40 and Uranium 235.

How are these isotopes still heating the Earth after 4.5 Billion years?

Each of these isotopes has a half-life measured in the billions of years. The term half-life is the expected time it takes for half the quantity of a given isotope to undergo radioactive decay. Thorium 232 has a half-life of 14,000,000,000 years, which is more than three times longer than the estimated age of the earth. This would mean that more than 80% of the Thorium 232 has yet to decay, which explains why the Earth can still be heated internally.

The future of geothermal energy is, therefore, a very long-term proposition as it will not have reached the first complete half-life depletion before the Sun expires. The Sun is roughly halfway through its fuel supply, and at the end of its life, it is expected to expand to form a Red Giant as it consumes heavier and heavier elements before eventually shrinking to become a White Dwarf. When the Sun expands to form a Red Giant, its size could increase so that it engulfs the Earth.

How much heat escapes from the earth?

The heat from the Earth flows into space as heat moves from hot to cold. The calculated heat flow to the surface and into space from the Earth’s interior is in the order of 47 TW (Terrawatts) or 0.087 Wm². To put this into perspective, the Sun’s influence is much larger at 339 W/m², reaching the Earth’s surface at sea level. This means that the Sun’s heat has a much greater impact on the Earth’s atmosphere and the planet’s surface than the heat from within the Earth. The heat absorbed by the Earth’s surface maintains the top 10-15m to a similar temperature as the average atmospheric temperature directly above that point on the Earth’s surface.

It is below that top layer that the heat from the Earth’s interior begins to be the dominant reason for the temperature increase with depth

How much heat do human use in a year?

How does the heat emanating from the Earth’s interior compare to the current level of the energy used by the human race for space and water heating? According to the IEA (International Energy Agency), humans use 29 EJ (Exa Joules 1×10¹⁸) of energy annually for heating. This equates to approximately an average of 0.025 W/m² across the earth, which is 2% of the thermal heat that escapes from the interior.

This demonstrates the huge untapped capacity of the earth that could be used for heating that is readily available and carbon-emissions free.

Would geothermal drilling deplete the heat coming from the Earth?

The scale of the planet and, therefore, our effect on the heat escaping from the centre of the Earth would make an insignificant difference. The deepest hole ever drilled is located in Northern Russia, 100km West of Murmansk, close to the Norwegian Border.

The Kola Superdeep Borehole SG-3 was drilled down to a depth of 12,262m in 1989. The aim was to study the continental crust, which is approximately 35km thick on the Baltic Shield at this point. To put that extraordinary achievement on a cut-away diagram of the Earth, it would be 1/3 of the crust (the outer black line on the diagram below) or 0.1% of the distance to the centre of our planet.

How can we use Geothermal Energy

Numerous applications exist for the use of geothermal energy across a wide variety of industries, ranging from electricity generation to direct heating solutions.

In the power sector, geothermal plants harness steam or hot water from the Earth’s crust to produce electricity, offering a reliable and sustainable energy source that reduces dependency on fossil fuels. Additionally, geothermal energy is utilised in agricultural practices, where it aids in greenhouse heating, enhancing crop growth and extending growing seasons.

Furthermore, this renewable energy source plays a crucial role in district heating systems, providing efficient heating for residential and commercial buildings. As technology advances, the potential for geothermal energy continues to expand, promising significant environmental and economic benefits across multiple sectors.

Geothermal energy is particularly well-suited for the agriculture industry due to its ability to provide consistent, reliable heat for various farming practices.

By utilising geothermal resources, farmers can maintain optimal temperatures in greenhouses, promoting year-round crop growth and improving yields.

This sustainable heating method reduces reliance on fossil fuels, lowering operational costs and minimising environmental impact. Additionally, geothermal energy can be used for soil heating, enhancing germination rates and accelerating plant development. The stable temperatures help control pests and diseases, further improving crop quality.

Overall, the integration of geothermal energy into agriculture not only boosts productivity but also supports sustainable farming practices, making it an invaluable resource for the industry.

Geothermal energy is ideal for drying applications, particularly in industries such as agriculture, food processing, and timber production.

By providing a consistent and controlled heat source, geothermal systems can efficiently dry crops, fruits, and vegetables, preserving their quality and extending shelf life. This method reduces the need for fossil fuels, lowering energy costs and minimising carbon footprints.

In the timber industry, geothermal drying helps to prevent warping and cracking, ensuring that wood maintains its structural integrity. Moreover, the stable temperatures provided by geothermal systems can enhance drying efficiency, significantly speeding up the process while maintaining the desired moisture levels.

Overall, the use of geothermal energy for drying not only optimises production but also aligns with sustainable practices, making it a smart choice for various sectors.

Geothermal systems used for cooling typically involve geothermal heat pumps (GHPs), which leverage the stable temperatures found underground to provide efficient climate control. In cooling mode, these systems work by circulating a fluid—usually water or a refrigerant—through underground pipes, known as ground loops.

Here’s how it works:

Heat Absorption: When cooling is needed, the heat pump draws heat from the indoor air and transfers it to the fluid circulating through the ground loops. This process cools the indoor space.
Heat Dissipation: The heated fluid then flows back into the ground loops, where it releases the absorbed heat into the cooler underground environment. Since the ground temperature remains relatively constant year-round, it effectively absorbs the excess heat.
Cycle Continuation: The cooled fluid then returns to the heat pump, where the cycle repeats. This continuous loop allows for efficient heat exchange without relying on external energy sources, minimising energy consumption.

Overall, geothermal systems provide a highly efficient means of cooling by utilising the Earth’s natural temperature regulation, significantly reducing energy use and environmental impact.

Geothermal energy is perfectly suited for industrial applications, offering a reliable and efficient energy source that enhances productivity while reducing operational costs.

Industries such as food processing, pharmaceuticals, and manufacturing benefit from the consistent heat provided by geothermal systems, which can be used for processes like heating, drying, and sterilisation. Geothermal energy not only lowers energy expenses but also helps companies meet sustainability goals by eradicating greenhouse gas emissions. Additionally, geothermal systems can be integrated into existing operations with relative ease, allowing for a seamless transition from traditional energy sources.

By tapping into the Earth’s natural heat, industries can improve their efficiency, reduce their environmental impact, and promote a more sustainable future, making geothermal energy an invaluable asset in the industrial sector.

Geothermal energy is an ideal solution for domestic heating, providing a sustainable and cost-effective way to maintain comfortable indoor temperatures in both single-family homes and multi-home developments.

For individual houses, geothermal heat pumps can be installed to harness the Earth’s consistent underground temperatures, efficiently heating and cooling the living space with minimal energy consumption. In multi-home applications, such as residential complexes or communities, centralised geothermal systems can be employed to distribute heat to multiple units, maximising efficiency and reducing installation costs.

These systems not only lower energy bills but also contribute to a net zero future, making them an environmentally friendly choice for homeowners. Furthermore, the durability and low maintenance requirements of geothermal systems enhance their appeal, ensuring long-term comfort and reliability for residents. Overall, geothermal energy offers a versatile and effective solution for domestic heating, benefiting both individual households and larger residential communities.

Geothermal energy is an excellent fit for leisure centres, providing a sustainable and cost-effective solution for heating swimming pools, gyms, and recreational areas.

By harnessing the Earth’s natural heat, geothermal systems can maintain comfortable temperatures year-round, enhancing the overall user experience while minimising operational costs. This reduced energy consumption translates to significant savings for local governments and public facilities, allowing them to allocate resources more effectively and reinvest in community programs. Furthermore, by lowering carbon emissions and promoting sustainability, leisure centres utilising geothermal energy can set a positive example for environmental stewardship in the community.

Overall, integrating geothermal systems into leisure centres not only improves public health and wellness through increased access to recreational facilities but also supports fiscal responsibility, making it a smart choice for public investment.

Geothermal energy is an ideal solution for public buildings, including healthcare facilities like the NHS, due to its efficiency and sustainability. By utilising geothermal heat pumps, these buildings can maintain comfortable indoor climates while significantly reducing energy costs and carbon emissions.

In hospitals and clinics, where temperature control is critical for patient comfort and care, geothermal systems provide reliable heating and cooling without the fluctuations often associated with traditional energy sources. Additionally, the long lifespan and low maintenance requirements of geothermal systems make them a cost-effective choice for public budgets.

The integration of geothermal energy in public buildings not only promotes environmental responsibility but also supports the overarching goals of the NHS and other public entities to enhance health outcomes and improve community well-being. Overall, the adoption of geothermal technology in public infrastructure represents a forward-thinking approach to energy management that benefits both the environment and public health. public health.

Geothermal energy stands out as one of the best options for achieving net-zero power generation due to its reliability, sustainability, and minimal environmental impact. Unlike solar and wind energy, which can be intermittent, geothermal power plants provide a consistent and stable energy supply, operating 24/7 regardless of weather conditions.

This baseload energy source significantly reduces reliance on fossil fuels, contributing to a substantial decrease in greenhouse gas emissions. Geothermal systems have a small land footprint and a low risk of environmental disruption, making them an environmentally friendly choice.

As technology advances, enhanced geothermal systems are expanding the potential for harnessing this renewable resource, even in areas previously thought unsuitable. By investing in geothermal energy, countries can move closer to their net-zero targets, creating a resilient and sustainable energy future that supports economic growth while protecting the planet.