The Department of Energy says California has the potential to generate enough power for 14 million homes if its wave and tidal power were developed fully. Even if it was only half of that, it would be a substantial new source of clean renewable energy; all produced a few miles off California coasts.
DOE studied ocean power nationwide and concluded that up to 15% of all US power could be generated from waves and tides if the west and east coasts plus Hawaii and Alaska were fully utilized. That’s a whole lot of untapped power just waiting to be used. Their estimates also include the neglected powerhouse of renewable energy, hydropower. For some reason hydropower often gets studiously ignored. Yes, dams can have deleterious effects. But Hoover Dam has a nameplate capacity of 2 GW, equal to a big coal or nuclear plant, and supplies power to Arizona, Nevada, and California. Without big hydro, the southwest would be a very different place indeed.
There are actually three types of ocean power, not two. They are wave, tidal, and Ocean Thermal Energy Conversion (OTEC.)
Wave power is generated by the movement of moored devices on the ocean surface. The passing waves move the devices and power is created by hydraulic rams, peristaltic pumps, hydroelectric turbines onshore powered by compressed sea water, and other ways too.
Tidal power is created by devices sitting on the ocean floor. They generate power when the tide comes in and out. While tidal power generation is variable it is also completely predictable. We always know when the tides will be. They too come in a variety of configurations. Some look like giant clam shells, others resemble wind turbines.
OTEC uses the difference in temperature between deep and surface water to run a heat engine. It works best in areas with big temperatures differential. Hawaii is an ideal location and has an OTEC site on the Big Island.
California has tried before with wave power but was unsuccessful. Lt. Governor Gavin Newsom is a big proponent for ocean power and tried to implement it while mayor of San Francisco. However, PG&E killed test projects after cost overruns and opposition from environmentalists and the fishing industry. The ocean is an unforgiving place. The turbulence is unending and salt corrodes whatever it can. This technology is still in its infancy. So that explains some but not all of the reasons why the US is not using all its many natural resources.
Scotland recently said they plan to be 100% renewable energy by 2020. They are already well on their way. Not only will they be able to power their entire country with renewables, they will (and already are) selling it to other countries. With their abundant wind, wave, and tides they are fast becoming the “Saudi Arabia of Renewable Energy.” They have huge amounts of power coming from offshore wind and are on the verge of commercial-scale wind and wave power. The US by contrast, still has no offshore wind. Why is this? We are falling behind Great Britain, Europe, Japan, and China in renewable energy generation and we don’t need to be.
Hopefully the DOE report will spur development of wave and tidal in California and elsewhere. The power is there. We just have to harness it.