by Robert F. Service: Rivers could generate thousands of nuclear power plants worth of energy, Green energy advocates may soon be turning blue.
A new membrane could unlock the potential of “blue energy,” which uses chemical differences between fresh- and saltwater to generate electricity. If researchers can scale up the postage stamp–size membrane in an affordable fashion, it could provide carbon-free power to millions of people in coastal nations where freshwater rivers meet the sea.
“It’s impressive,” says Hyung Gyu Park, a mechanical engineer at Pohang University of Science and Technology in South Korea who wasn’t involved with the work. “Our field has waited for this success for many years.”
Blue energy’s promise stems from its scale: Rivers dump some 37,000 cubic kilometers of freshwater into the oceans every year. This intersection between fresh- and saltwater creates the potential to generate lots of electricity—2.6 terawatts, according to one recent estimate, roughly the amount that can be generated by 2000 nuclear power plants.