Geothermal energy is often billed as one of “the cleanest energy sources” –and with good reason. It’s carbon-free, renewable, and efficient. Even those stoic anti-hyperbolists over at the United States Department of Energy sing its praises, saying, “this vital, clean energy resource supplies renewable power around the clock and emits little or no greenhouse gases — all while requiring a small environmental footprint to develop.”
While geothermal is one of the superheroes of clean energy production, however, it still has a lot of room for improvement. First and foremost, it needs to be massively scaled up in order to have any real environmental impact or significant market share compared to where it stands now, a speck in the giant shadow of fossil fuels. What’s more, there are significant barriers and high costs to the initial phases of exploration and infrastructure.
“Where to drill?” Science Daily distills the issue into just three words. “This is the basic question in the exploration of underground energy resources, such as geothermal energy. Water in rocks flows along permeable pathways, which are the main target for geothermal drilling. Borehole, core and micro-earthquake data show that the pathways are spatially connected, permeable structures, such as fractures or faults in the rock. However, the geothermal potential of these structures cannot be fully exploited with the techniques available to date.”
Luckily, there has recently been an important breakthrough in the field of geothermal energy exploration and finding those geothermal hotspots (so to speak) thanks to a team of research scientists from the GFZ German Research Centre for Geosciences, based in Potsdam. The scientists’ findings, published this month in a Scientific Reports journal article titled “Geothermal sweetspots identified in a volcanic lake integrating bathymetry and fluid chemistry,” have solved the issue of finding underwater drilling sites by identifying a method that allows the mapping of submerged geological structures in order to determine inflow information essential for developing geothermal energy production.
This development is an essential one, as many of the most promising locations for geothermal energy productions are naturally occurring in volcanic areas that are either near or below the waterline of crater lakes. “However, these lakes hide structures that are important for geothermal energy,” explains research team leader and TU Delft Associate Professor Maren Brehme. “In the study, we showed that volcanic lakes such as the Lake Linau in Indonesia, which we investigated, have so-called ‘sweet spots’, deep holes with fluid inflow from the surrounding rock.”
As paraphrased by Science Daily, “the new approach combines bathymetry measurements with geochemical profiles. In this study, bathymetry (from Greek bathýs ‘deep’ and métron ‘measure’) is used to map fault zones and geyser-like holes in the lake floor. Its most important feature is the echo sounder. The geochemical profiles from data on temperature, salinity, density and pH at different depths show areas in the lake with inflows from the surrounding geothermal reservoir. The combination allows the distinction between permeable and non-permeable structures, which was previously not possible. With this method, promising locations for drilling can be located more precisely.” Geothermal energy has been garnering interest and advancing technologically in other corners of the globe as well. In Nevada, “the Department of Energy has awarded a major new grant to the Nevada Bureau of Mines and Geology to research and expand the use of machine-learning to make the exploration process even more effective” according to reporting by Nevada Today. The new methodology has already resulted in two successful geothermal discoveries in Nevada’s Great Basin where there was no detectable hot water at the surface level.
Meanwhile, on the other side of the globe, Japan has also been investing in geothermal energy with a renewed vigor in the wake of 2011’s Fukushima nuclear disaster, which left both the public and political spheres wary of nuclear energy and in need of new power sources. These simultaneously developing parallel geothermal industries show a bright future for the world’s cleanest energy source, and not a moment too late. In the same month that Donald Trump officially pulled out of the Paris Climate accord, any developments in the world of clean energy are welcome news indeed.