17 Apr 2015

Mapping geothermal resources from space

8:09 am on 17 April 2015

The hunt for geothermal energy resources is expected to get a boost from new observations made from space.

The satellite's sleek design helped it achieve drag-free flight.

Europe's GOCE satellite mapped Earth's gravity field during a mission from 2009 to 2013. Photo: ESA / AOES Medialab

The data comes from Europe's GOCE satellite, which mapped the Earth's gravity field between 2009 and 2013.

The satellite's data is expected to narrow the search for prime spots to put future power stations, with the International Renewable Energy Agency (IRENA) releasing the information in a special global atlas.

In parallel, GOCE scientists have been discussing the work at the European Geosciences Union General Assembly in Vienna, Austria.

Although a large potential resource, geothermal currently accounts for less than one percent of the world's electricity generation - in part due to the huge costs of exploration.

GOCE's maps are expected to shortcut some of that effort by pinpointing regions with favourable characteristics such as a relatively thin continental crust.

As it flew around the planet, the satellite was able to observe tiny differences in the pull of gravity from one place to the next - a function of the uneven distribution of mass beneath it. The variation in signal was most obvious over large mountains and over deep ocean trenches but, by processing the data in special ways, scientists were also able to tease out details of different rock layers and structures.

This Bouguer model shows thin crust (red), where the planet's hot mantle is relatively shallow, increasing the chance of exploiting geothermal energy.

This Bouguer model shows thin crust (red), where the planet's hot mantle is relatively shallow, increasing the chance of exploiting geothermal energy. Photo: ESA / IRENA

For IRENA, GOCE researchers provided two gravity models: one called "Free Air" and one called "Bouguer".

Free Air gives insights into particular structures that might favour geothermal energy while Bouguer details the thickness of the Earth's crust. Prospectors will still need other types of information but the new portal should be a good place to start, especially in countries where local geological surveys may be difficult to conduct.

Geothermal prospectors have long used gravimeters for point measurements in the field but GOCE provides global information at a high level of resolution.

The satellite's main mission goal was to acquire gravity field information to investigate the movement of ocean currents. It spent four years and eight months circling the Earth, returning when it ran out of fuel.

- BBC