The First Minister of Scotland, Alex Salmond, recently switched on a machine for converting wave energy into electricity. The machine, called the Oyster, is simple: it’s a hinged contraption with one end that rises and falls with the waves, an action that pumps water to an onshore hydro-electric turbine. There are no electronics or generators in the water, which should make it easier to maintain.

Yet, we’ve got a long way to go before wave power makes any sort of dent in our need for fossil fuels. At two megawatts of power per Oyster, it would take about 400 of them to replace a coal plant, assuming the wave power is as reliable as a coal plant–that’s yet to be proven.

Another recent wave project didn’t fair too well. The snake-like Pelamis system was installed off of Portugal last year, only to be discontinued after economic and technical difficulties (the latter of which the company says have been addressed).