If you don’t know your free air gravity from your Bouguer maps, now is a good time to find out. When combined, the global maps form a one-two punch that could knock the geothermal industry out of the ballpark, so to speak.
Although the geothermal industry has stalled out here in the US, globally, the geothermal energy sector has been growing steadily, and the two maps provide a tool that could cut way down on exploratory expenses and help the industry really take off.
Global Geothermal Energy Potential
One thing that came out of the 2014 United Nations Climate Summit last September was a working group called the Global Geothermal Alliance. Its mission is to find a way around the main stumbling block to geothermal development, that being the enormous expense, risk, and uncertainty of exploratory drilling.
Let’s pause here and note that we’re not talking about small-scale geothermal heat pumps. We’re more interested in utility-scale geothermal energy, and that presents something of a quandary since, depending on the technology, it can involve significant industrial infrastructure attended by land, air, and water resource issues.
In other words, a geothermal power plant isn’t necessarily “clean,” at least not as far as local impacts go, so we’ll temper our enthusiasm by advocating for careful site selection and mitigation measures.
A Shortcut To Geothermal Energy
The new geothermal energy tool comes to us courtesy of our new best friends: IRENA (the International Renewable Energy Agency) and ESA (the European Space Agency).
Here’s the money quote from IRENA policy and finance Director Henning Wuester:
These maps can help make a strong business case for geothermal development where none existed before. In doing so, the tool provides a short-cut for lengthy and costly explorations and unlocks the potential of geothermal energy as a reliable and clean contribution to the world’s energy mix.
The Global Bouguer and Free Air Gravity Anomaly Maps are provided by ESA. Together, the satellite-derived gravity measurements help pinpoint features that look promising in terms of geothermal potential, without the hassle and expense of other exploratory measures, including drilling.
Those features include areas where the Earth’s crust is relatively thin, “young” magnetic activity, and subduction zones, which is fancyspeak for areas where the edge of a denser tectonic plate is slipping under the edge of the adjoining one.
Who knows why nobody ever thought of this before, but apparently this is the first time that ESA’s gravity data has been deployed as a tool for preliminary geothermal energy exploration.
Since this is just the first go-around, you can expect the next iteration to include more detail, partly gleaned by combining the satellite findings with other data gathered on Earth.
If you want to see the whole shebang, visit the Global Atlas portal where all the goodies are stored.
So, What Are These Geothermal Energy Maps?
We went over to the folks at LithoFLES.org for an explanation of the two maps.
The map above is assembled from free air gravity disturbance data gathered by GOCE, aka the Gravity field and steady-state Ocean Circulation Explorer satellite launched by ESA back in 2009. It’s a means of charting superficial density variations in the Earth’s crust.
GOCE also collected data to form the Bouguer anomaly map, below. These calculations involve subtracting the effect of elevated land mass and water-filled ocean basins, resulting in a fine-tuned picture of variations in the thickness of the crust.
The two maps form a complementary pair by integrating gravity with heat flow, as described by LithoFLEX (breaks added):
Generally speaking, thicker crust produces more negative Bouguer values, thin crust more positive Bouguer values. This is seen very clearly in the high Bouguer values in the oceanic areas and negative Bouguer values for mountain ranges. The free air field allows mapping of geologic structures, from which borders separating rock types are identified.
Although GOCE met an untimely death in 2013 (well actually it ran out of fuel as anticipated), the data it collected has continued to inform studies on climate subjects including ocean circulation, sea levels, and polar ice, as well as practical applications such as surveying — and most recently, geothermal energy exploration.
Onwards And Upwards For US Geothermal Energy
Of course, the new tool doesn’t do all the work for you, but it does provide a quick way to weed out unpromising, high-risk sites and focus on sites where the risk is worth the investment.
Meanwhile, the US geothermal industry sure could make good use of something like that. Back in 2009, the International Energy Agency put the US at the top of the geothermal list, generating 16,600 gigawatt-hours annually from an installed capacity of 3,093 megawatts. The only country that even came close was the Philippines, clocking in at 10,311 gigawatt-hours.
Fast-forward just a few years and you find the US geothermal energy industry lagging behind while other countries — Kenya, for example — are leaping ahead, thanks partly to supportive government policies.
However, it looks like the Obama Administration is set to awaken the sleeping US geothermal energy giant.
Last July, the Energy Department threw down $31 million to start up a next-generation geothermal demonstration site called FORGE for Frontier Observatory for Research in Geothermal Energy, in pursuit of 100 gigawatts of geothermal potential.
The agency followed up the next month with another $18 million in funding for a new group of 32 geothermal projects, adding to an existing lineup of 150 active projects.
Image Credits: IRENA and LithoFLEX.org.
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