Wave energy captures the motion of ocean surface waves. Waves are created by wind blowing across water. The energy is concentrated and consistent compared with wind or solar, though it varies by location and season. The global resource is enormous, but the technology remains immature.

Devices come in many designs. Point absorbers bob up and down with the waves, driving a generator. Oscillating water columns trap air in a chamber and push it through a turbine as waves rise and fall. Attenuators are long hinged rafts that flex with the waves and pump hydraulic fluid.

Wave energy faces hard engineering problems. Saltwater corrodes metal. Storms destroy devices. Mooring lines break. Maintenance at sea is expensive. Early projects have mostly failed or been abandoned. A few survive, including a plant in Portugal and test sites in Scotland. The potential is real. The path to commercial viability is not yet clear.

Common device types

• Point absorbers
• Oscillating water columns
• Attenuators
• Overtopping devices
• Submerged pressure differentials