14 votes

IEA Report: The future of geothermal energy

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    Comment box Scope: summary, information, personal analysis Tone: neutral Opinion: yes, at the end Sarcasm/humor: none Geothermal energy could be a foundational part of the energy mix by 2050,...
    Comment box
    • Scope: summary, information, personal analysis
    • Tone: neutral
    • Opinion: yes, at the end
    • Sarcasm/humor: none

    Geothermal energy could be a foundational part of the energy mix by 2050, replacing a huge portion of baseload, round-the-clock energy needs currently met with fossil fuels. From the executive summary of this December 2024 report from the International Energy Agency:

    With continued technology improvements and reductions in project costs, geothermal could meet up to 15% of global electricity demand growth to 2050. This would mean the cost-effective deployment of as much as 800 GW of geothermal power capacity worldwide, producing almost 6 000 terawatt-hours per year, equivalent to the current electricity demand today of the United States and India combined.

    Geothermal can provide around-the-clock electricity generation, heat production and storage. As the energy source is continuous, geothermal power plants can operate at their maximum capacity throughout the day and year. On average, global geothermal capacity had a utilisation rate over 75% in 2023, compared with less than 30% for wind power and less than 15% for solar PV. In addition, geothermal power plants can operate flexibly in ways that contribute to the stability of electricity grids, ensuring demand can be met at all times and supporting the integration of variable renewables such as solar PV and wind.

    New drilling technologies exploring resources at depths beyond 3 km open potential for geothermal in nearly all countries in the world. Using thermal resources at depths below 8km can deliver almost 600 TW of geothermal capacity with an operating lifespan of 25 years.

    Geothermal can also provide a continuous source of low- and medium-temperature heat for use in buildings, industry and district heating. Global geothermal potential from sedimentary aquifers at depths up to 3 km and temperatures greater than 90°C is estimated around 320 TW. This is consistent with the requirements of existing fossil fuel-fired district heating networks, which could be decarbonised by switching to geothermal heat. For lower temperature requirements, the potential for geothermal increases about tenfold.

    And there is an economic incentive or opportunity for this, from an industry perspective:

    Up to 80% of the investment required in a geothermal project involves capacity and skills that are common in the oil and gas industry. The industry has transferable skills, data, technologies and supply chains that make it central to the prospects for next-generation geothermal. Diversifying into geothermal energy could be of great benefit to the oil and gas industry, providing opportunities to develop new business lines in the fast-growing clean energy economy, as well as a hedge against commercial risks arising from projected future declines in oil and gas demand.

    We estimate that, with the right support, costs for next-generation geothermal could fall by 80% by 2035. At that point, new projects could deliver electricity for around USD 50 per megawatt-hour, which would make geothermal one of the cheapest dispatchable sources of low-emissions electricity, on a par or below hydro, nuclear and bioenergy. At this cost level, next-generation geothermal would also be highly competitive with solar PV and wind paired with battery storage.

    I have been hearing about people getting geothermal energy installed for their home in a relatively cost-effective way. Geothermal seems like a bit of a "dark horse" energy technology to me, with a lot of potential and very little attention. Almost all attention is focused on solar (rightly) and wind, perhaps because those projects are physically higher-profile than something like geothermal. But modern geothermal techniques develop existing industrial processes and have, as far as I am aware, significantly less general opposition than solar/wind. I can see the geothermal industry really taking off, in its dark horse way, to serve as a consistent foundation for renewable energy generation.

    3 votes
    1. skybrian
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      The technology that's useful for heating or cooling a home is sometimes called "geothermal" but more properly called a "ground source heat pump." It uses electricity to pump heat. The advantage...

      The technology that's useful for heating or cooling a home is sometimes called "geothermal" but more properly called a "ground source heat pump." It uses electricity to pump heat. The advantage over an air-source heat pump is that it's more efficient, but it's much more expensive to install.

      The geothermal energy that this article is about is useful for generating electricity. That's utility-scale power, since it's like drilling an oil well, but more challenging.

      8 votes
    2. davek804
      Link Parent
      I heat and cool my entire home with a closed loop ground source heat pump. Which is geothermal. Two wells, 425' deep, spaced ten feet apart. Into each well goes two 2.5" HDPE pipes, with a u bend...

      I heat and cool my entire home with a closed loop ground source heat pump. Which is geothermal. Two wells, 425' deep, spaced ten feet apart. Into each well goes two 2.5" HDPE pipes, with a u bend at the bottom. These come into my basement, and connect to a pump. They're filled with a water/glycol solution. Then, the actual unit is just an air conditioner that can run forwards or in reverse.

      I use between 50--150kWh to heat or cool my home in a month. Which, at first, was scary and potentially expensive.

      But I also installed 32 solar panels on the roof, generating a maximum of 9.6kW of AC power to the grid, which is net metered. That system has generated a max of about 88kWh on a perfect day. So, with two reasonably good/perfect solar days, I cover the electricity cost of heat or cool my home during one of the peak winter or summer months.

      The geothermal system has 6 heating power levels and 8 fan levels. It's shockingly efficient and dramatically quieter to run than my old propane system.

      5 votes