The oceans are in constant motion, rippling, swirling, swelling, retreating. As wind blows across the surface, waves are formed. As the gravitational forces of earth, moon, and sun interact, tides are created. These are among the most powerful and constant dynamics on earth.

Wave- and tidal-energy systems harness natural oceanic flows to generate electricity. A variety of companies, utilities, universities, and governments are working to realize the promise of consistent and predictable ocean energy, which currently accounts for a fraction of global electricity generation. Early technologies date back more than two centuries, with modern designs emerging in the 1960s, thanks especially to the work of Japanese naval Yoshio Masuda and his 1947 invention of the oscillating water column (OWC). As a wave or tide rises within an OWC, air is displaced and pushed through a turbine, creating electricity.


The appeal of wave and tidal energy is its constancy. No energy storage is required. And while communities often resist the presence of wind turbines along ridges or shorelines for violating viewsheds, the idea of underwater, out-of-sight wave and tidal systems has proven to be more acceptable to coastal citizens. (Though they can pose concerns for local fisherman, whose livelihoods depend on the same waters.)


The opportunity of marine-based energy is massive, but realizing it will require substantial investment and expanded research. Proponents believe wave power could provide up to 25 percent of U.S. electricity and 30 percent or more in Australia. In Scotland, the number maybe upwards of 70 percent. Wave and tidal energy is currently the most expensive of all renewables, and with the price of wind and solar dropping rapidly, the gap will likely widen. However, as this technology evolves and policy comes into place to support implementation, marine renewables may follow a similar path, attracting private capital investment and the interest of large companies such as General Electric and Siemens. On a trajectory like that, wave and tidal energy could also become coast competitive with fossil fuels.

IMPACT: There are many projections of wave and tidal energy to 2050. Building on these few, we estimate that wave and tidal energy can grow from .0004 percent of global electricity production to .28 percent by 2050. The result: reducing carbon dioxide emissions by 9.2 gigatons over thirty years. Cost to implement would be $412 billion, with net losses of $1 trillion over three decades, but the investment would pave the way for longer-term expansion and emissions reductions.

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