字幕表 動画を再生する 英語字幕をプリント We all know energy can come from the wind and the sun, but there's a plentiful renewable resource covering more than 75% of the planet that you might not have thought about: our water! The movement of the ocean's waves, tides, and currents carries energy that can be harnessed and converted into electricity to power our homes, buildings and cities. The energy available in this moving water is called kinetic energy. Scientists and engineers are learning to capture clean renewable ocean power using marine and hydrokinetic technologies. Water currents occur naturally all over the planet. Waves crash against coastlines. Tidal currents ebb and flow and large currents move water all around our oceans. We can tap into each one of these sources to generate electricity. It's estimated that along U.S. coastlines, there is enough energy in waves and tides to meet a significant portion of America's power needs. So, how does it work? That depends on what kind of hydrokinetic power you're trying to capture, but the concept is essentially the same: extracting power from moving water. For example, a buoy can harness energy from the vertical rise and fall of ocean waves, as well as back-and-forth and side-to-side movements. Currents and tides can also spin a turbine in various directions as water moves through an ocean power device, generating electricity. The Energy Department is supporting research on a range of innovative turbine technologies to capture energy from waves, river, and tidal currents. Devices that operate in water have to work under turbulent and harsh conditions. They must be built to withstand strong currents and impacts from debris carried in the water. Of course, they also have to be designed to preserve the integrity of the marine environment. One of the greatest benefits of developing marine energy or, ocean power, is that many of our water resources are right where we need them -- near the most populated areas. More than half of all Americans live close to coastlines where the potential for ocean power is the greatest, and some cities and towns can use power from tidal currents. Marine and hydrokinetic technologies are still a ways off from widespread adoption. But today, dozens of organizations are already working to deploy ocean power systems throughout the world. Marine and hydrokinetic technology: a new wave in harnessing clean, renewable energy from all sorts of water resources right here at home.