National Geographic : 2015 Jan
EXPLORE Planet Earth Can the “Emerald Isle of the Caribbean” be the first to go green? Montserrat is trying. Nearly 20 years after the Soufriere Hills volcano began erupting—rendering much of the island nation uninhabit- able and exiling two-thirds of the population—the same geological forces could provide reliable, renewable geothermal energy. Like much of the Caribbean, this British overseas territory runs on costly oil and gas imports. But as on other islands, plate tecton- ics and volcanic activity bring magma close enough to the surface for geothermal wells to tap into the heated reservoirs just below. A single well can cost several million U.S. dollars, though. Last year, with U.K. funding, University of Auckland researcher Gra- ham Ryan and an international team of scientists and engineers mapped two promising spots. Initial findings suggest there’s enough geothermal juice there to power the grid, warrant a third well—and maybe even sell to neighbors. — Jeremy Berlin A Geothermal First? Hot water Cool water Steam Very hot water is brought to the surface, turning to steam as pressure decreases. At a power plant, steam is separated from water. Steam flows through a turbine, powering a generator that produces electricity. Cool water is pumped down into a natural reservoir. 1 2 3 4 1 2 3 4 Generator Condenser Steam separator Ground Electricity Natural water reservoir Warmwater Wells Underground reservoirs are usually a complex system of porous rocks and heated water. That makes the drilling process (shown generally here) a major challenge on Mont- serrat and other Lesser Antilles islands with geothermal potential.