Like to the Pontic Sea,
Whose icy current and compulsive course
Ne'er knows retiring ebbs, but keeps due on

(Shakespeare, Othello, III, iii)

Poets have long marveled at the enormous power of the ocean. In the past few decades, scientists have been figuring out ways to convert that power into electricity. I remember a Q&A session eight years ago with a board member of ExxonMobil, talking excitedly about the potential of tidal power. “Imagine,” he told the audience, “a small bay or inlet in Maine with a narrow opening. Now imagine, somehow, putting a hydroelectric gate at the mouth of the bay to harness the immense power necessary to move millions of gallons of water in and out between high and low tide.” It’s a great concept, though, somewhere along the way, the folks at ExxonMobil decided it wasn’t. Thankfully, many of the other big players, like British Petroleum (BP) , have seen the (green) light, investing significant resources into alternative energy technologies and research. BP  now claims its initials stand for ‘Beyond Petroleum.’  Meanwhile, other, much smaller companies are working to make tidal and wave power viable energy alternatives. Pelamis Wave Power, a Scottish wave-energy tech firm, and Australia-based Biopower Systems are two such examples.

Pelamis started operating a modestly priced $13 million wave farm three miles off the coast of Portugal.  According to officials, the converters represent the world’s first commercial wave-power project. The Pelamis energy converters are 460 foot cylinders designed to bob, partially submerged in the waves. The bobbing motion drives the generators, and underwater cables link those generators to power substations on shore and then into the grid. The company plans to add 25 converters for a capacity of 21 MW and the ability to power 15,000 homes. Portugal is investing in wave-power technology as part of its goal of generating 31 percent of its energy from renewable sources by 2020. Here’s a video of the cylinders.

Biopower Systems is making waves by helping to commercialize ocean power conversion technologies. Biopower is developing two designs, both inspired by mechanisms that exist in nature. Biomimicry, as they call it, has inspired the BioWave and the BioStream. The BioWave‘s design, based on the swaying motion of sea plants, involves buoyant blades that oscillate with sea currents. BioWave systems are being developed for 250kW, 500kW and 1000kW capacities. The BioStream mimics the shape and motion characteristics of swimming species such as ahi, mackerel and shark. As their site explains, “in this configuration the propulsion mechanism is reversed and the energy in the passing flow is used to drive the device motion against the resisting torque of an electrical generator.” These videos demonstrate the two designs.