Focusing devices channel waves into an elevated reservoir. Then they apply standard hydropower technologies to generate electricity from the water as it flows back out.

The oceans cover two-thirds of the world and could potentially provide a limitless supply of renewable energy. But the technology to harness wave power is still in its infancy, and its impact on marine ecology and coastal erosion and deposition are not yet fully understood.

Figure 15 Focusing device Source: U.S. Department of Energy