Solar energy is not a marine renewable energy technology because it does not harness energy from the ocean.

Tidal energy is generated by harnessing the energy of the tides, which is caused by the gravitational pull of the moon and sun on the Earth's oceans.

Tidal barrages are tidal energy technologies that use a barrage to create a difference in water level between two bodies of water, which is then used to generate electricity.

Wave energy is more predictable than other marine renewable energy technologies because waves are generated by the wind, which is a relatively predictable force.

The Pelamis wave energy converter is a type of wave energy technology that uses a floating buoy to generate electricity. The buoy is connected to a hydraulic system that drives a generator.

The main challenge associated with current energy generation is the low speed of ocean currents. This means that large turbines are required to generate significant amounts of electricity.

Horizontal axis turbines are the most common type of current energy technology. They use a horizontal axis turbine to generate electricity, similar to wind turbines.

Marine renewable energy technologies can have a variety of environmental impacts, including noise pollution, habitat loss, and visual impact.

Tidal energy has the lowest environmental impact among marine renewable energy technologies because it does not require the construction of large structures in the ocean.

The potential of marine renewable energy to contribute to the global energy mix is estimated to be up to 20%.

The United Kingdom is a leader in the development of marine renewable energy technologies, with a number of large-scale projects in operation or under construction.

La Rance Tidal Barrage is the world's first commercial tidal barrage, located in France. It was commissioned in 1966 and has a capacity of 240 MW.

Ocean thermal energy conversion is still in the early stages of development, as it requires large temperature differences between the ocean surface and the deep ocean.

The development of marine renewable energy technologies faces a number of challenges, including high cost, environmental impact, and lack of infrastructure.

The future of marine renewable energy is uncertain, as it depends on a number of factors, including technological developments, cost reductions, and government policies.