Geothermal Energy Has Massive Potential as a Renewable Source

Geothermal energy has been around for over a hundred years but is harvested through conventional methods.

With new technology, geothermal energy can possibly be harnessed anywhere on earth—next-generation geothermal. In the past, geothermal energy, the heat emanating from the earth’s bowels, could only be accessed in areas with naturally occurring heat, which was limited to a few places.

Geoplat lists the top 10 countries with the highest installed geothermal power generation capacity in 2023:

1. United States – 3,900 MW.
2. Indonesia – 2,418 MW.
3. Philippines – 1,952 MW.
4. Turkey – 1,691 MW.
5. New Zealand – 1,042 MW.
6. Kenya – 985 MW.
7. Mexico – 976 MW.
8. Italy – 916 MW.
9. Iceland – 754 MW.
10. Japan – 576 MW.

With next-generation geothermal technology, accessing and generating geothermal energy will be possible almost anywhere in the world. This innovative approach utilises fracking, or hydraulic fracturing, traditionally used in oil and gas extraction to retrieve fossil fuels from rock formations.

The process involves injecting high-pressure fluid into underground rock layers to create fractures, allowing oil or gas to flow more easily to the surface. Now, this technology can also be applied to geothermal energy production through a concept known as Enhanced Geothermal Systems (EGS).

EGS involves drilling wells into hot rock formations, typically in areas where natural fluid or permeability isn’t sufficient for heat extraction. By injecting water at high pressure, fractures are created in the rock, forming pathways that allow water to circulate, absorb heat, and be brought to the surface to generate electricity or provide heating.

Fracking can help tap into geothermal potential in regions without abundant natural geothermal activity, such as areas lacking sufficient hot springs or accessible steam.

EGS offers exciting possibilities for unlocking geothermal energy in areas not naturally suitable for geothermal power production, thus increasing the share of renewable energy in our energy mix.

Hot springs possible source of geothermal energy

Hot springs can be found on every continent and in almost every country around the world. Like deep-well geothermal plants, hot springs are part of a hydrothermal system that can be used for power generation. Utilising energy from hot springs presents a practical approach to achieving a sustainable power supply for the future.

A 2021 study titled “Guideline for electricity generation from hot springs (natural energy storage systems): A techno-enviro-economic assessment,” published in the journal Sustainable Energy Technologies and Assessments, offers a framework for harnessing power from hot springs with varying temperatures and discharge mass flow rates. The study also evaluates the technical, economic, and environmental feasibility of exploiting hot springs for power generation.

According to the paper, nearly 80% of primary energy comes from fossil fuels, and projects aim for half of energy generation to derive from renewable sources by 2030. Indonesia, one of the world’s largest producers and consumers of coal, is projected to exhaust its fossil fuel reserves in a few years.

This situation highlights the enormous potential of geothermal energy as a renewable energy source, which remains underutilised worldwide.

Geothermal energy potential

The study highlights the incredible potential of geothermal energy just 3 kilometres beneath our feet. Recent estimates suggest that approximately 43 × 10¹⁵ gigajoules (GJ) of energy is stored at this depth. To put this into perspective, the total energy consumed globally in one year is around 500 exajoules (500 × 10¹⁸ J). This means that 43 × 10¹⁵ GJ is vastly larger, representing about 86,000 times more energy than the global annual consumption.

In 2018, the world’s total geothermal power generation reached 116,000 gigawatt-hours (GWh), and this figure is projected to more than double to 282,000 GWh by 2030.

Geothermal energy primarily exists in dry steam, liquid water, and a mixture of steam and water at various temperatures. Extraction technologies, such as deep drilling, can increase the total cost of typical geothermal power projects by up to 50%. However, harnessing power from hot springs as a heat source can significantly reduce the overall cost of a geothermal project.

For a spring to be classified as a thermal or hot spring, its temperature must be above the average human body temperature, ranging from 21°C to 149°C. Thermal springs are found in more than 80 countries. In the United States, 1,072 thermal springs have been identified across 23 states, while China boasts 3,398 known hot springs. Each of these springs presents a promising opportunity for implementing direct or indirect power generation.

The study evaluates the power generation potential of hot springs as a heat source for the Organic Rankine Cycle (ORC).

The Organic Rankine Cycle (ORC) is a thermodynamic cycle that converts heat into mechanical or electrical energy. A key feature of the ORC is its ability to utilise low-temperature heat sources for small and medium power generation. Additionally, ORC systems emit fewer greenhouse gases (GHG) due to lower operating temperatures, making hot springs an ideal heat source.

A study evaluating the technical, economic, and environmental viability of using hot springs for power generation found that hot springs with temperatures ranging from 60°C to 90°C and a discharge mass flow rate of 5 to 50 kg/s can enhance power generation capacity from 9.3 kW to 303 kW. The thermal efficiency also improves from 4.2% to 7.2%.

The results indicate that increasing the hot spring temperature and discharge mass flow rate leads to better thermal efficiency and power generation capacity of ORC plants, while the Payback Period (PP), Levelized Energy Cost (LEC), and Specific Investment Cost (SIC) decrease.

For more information, read the study: Guideline for Electricity Generation from Hot Springs (Natural Energy Storage Systems): A Techno-enviro-economic Assessment.

Geothermal energy is a remarkable renewable resource derived from the Earth’s internal heat. This sustainable energy source has the potential to provide reliable power and heating solutions while significantly reducing carbon emissions.

Governments, businesses, and climate change advocates should explore this option more deeply. Investing in the vast untapped geothermal energy reservoirs beneath our feet can harness a cleaner and more sustainable future for generations to come.