Twice a day the tides rise and fall along coastlines. Increasingly, engineers are trying to harness these regular currents for clean energy. Tidal turbines spin during the fastest flows, turning a rotor that powers an electrical generator. Compared to wind and solar energy, tidal energy is expensive, but it’s also predictable — a feature wind and solar lack.
Previous investments in clean energy have reduced costs as technologies mature, and proponents expect this will hold true for tidal turbines, as well. The machines face difficult conditions: salt and water are notoriously tough on equipment. Right now that makes large-scale facilities impractical. Instead, most projects are on a smaller scale, often focusing on powering remote rural coastal communities that currently rely on diesel for their electricity. These projects provide immediate benefits to the community while serving as a proving ground for the technology as a whole. For more, see this Physics Today article. (Image credit: Nova Innovation; see also Physics Today)