Aquamarine Power has developed an interesting device called oyster that will convert wave power into electricity. The case for marine energy is the high-energy output waves offer and their relative predictability. Potentially, wave power can produce 5 times the global electricity consumption.
The Oyster technology offers many favorable qualities. It as accessible (onshore converter), reliable, high capture factor (uniform wave direction), and maintains economies of scale (one generator, multiple flaps and low cost fabrication). Environmental considerations are relatively low risk. Minimal impact is expected on marine mammals and birds will have no impact (much regulation based on offshore wind farms). Socio-economic impacts are minor but of concern. The device could interfere with creel fisheries, although it would benefit local communities from development.