The  most common forms of marine renewable are outlined below and through the tabs on the left. Marine renewables are covered by the REA's Ocean Energy Group

Wave Power

This involves using wave energy that occurs due to movements of water near the surface of the sea to generate electricity. See Wave power section for more information.

Tidal power

This involves using tidal energy that occurs due to large movements of water within in the sea. Tidal power is a more predictable and reliable source of renewable energy than some alternatives, such as wind or solar power, as tide movements can be calculated more reliably than weather. The department of Business Enterprise and Regulatory Reform has estimated that 10% of the UK's electricity needs could be met by tidal power.

Tidal stream energy

This energy is most commonly captured using tidal stream turbines, which work like wind turbines underwater. See section on Tidal stream energy for more information.

Tidal barrages and lagoons

A dam or barrage is built across an estuary or bay that experiences a tidal range of more than 5 metres. As the tide comes in it flows through the barrage. When the tide is fully in the barrage gates are closed, trapping the water. As the tide recedes, gates containing turbines are opened and as the water comes through these gates it drives turbines which generate power.

Ocean Thermal Energy Conversion

This involves using the temperature difference that exists between shallow and deep waters to run a heat engine. This engine converts solar radiation absorbed by the ocean, into electric power.

This energy conversion only produces a significant amount of power in tropical seas, where the surface temperature of the water can differ from the deep water by about 20^oC.

Every day 23 million square miles of tropical seas absorb the same amount of heat energy from solar radiation as is contained in 250 billion barrels of oil.