Geothermal energy is one of the least-utilized forms of renewable energy globally. Of the 6,586 TWh of electricity generated by renewables in 2018, only 1% was produced by geothermal sources, according to The International Renewable Energy Agency. Renewable sources such as hydro, wind and solar energy have dominated media headlines —and investor wallets— due to their relative ease of implementation, proven track records, and typically lower costs than geothermal production. Geothermal plants require access to a high-temperature resource inside the Earth like steam or very hot water.
One main impediment to building geothermal power plants is the necessity of drilling through hard to break igneous and metamorphic rock, and the associated costs of specialized drilling. This contributes to the capital required to develop a plant. For example, a 40 megawatt (MW) power plant was estimated in 2001 to cost between US$42.5 and $67.7 million to build. As early as the 1980s—which saw an increase in geothermal energy interest due to the global gas crisis—the technology was thought of in terms of providing gigawatts of power.
This made the expensive-to-build plants unsuitable for many smaller applications. But small-scale geothermal power plants can now be developed to provide under 5MW of power. And while this technology has been available for some time, low costs and a high degree of flexibility are now making it an increasingly attractive option. Like any technology, the explosion of mini-geothermal began when it found its niche, either backing up existing large-scale geothermal infrastructure or offering a real chance at energy independence for remote or off-grid communities.