Some areas of the ocean have enough offshore wind energy to power the world, but that "civilization-scale power" will not be harnessed until commercial-scale deep water wind farms are feasible, according to new research from the Carnegie Institution for Science.
Anna Possner, a postdoctoral researcher, and Ken Caldeira, a senior scientist and a professor at Stanford University, found that some regions of the open ocean can produce triple the amount of wind power that is generated in a similar area on land. This is because the skies above these deep waters have circulation patterns that allow wind farms to harness more energy in the atmosphere, rather than the limited amount of kinetic energy available at the ocean surface.
Researchers had previously thought offshore wind farms could generate an annual 1.5 watts per square meter at most. But parts of the North Atlantic, for example, have the potential to generate more than 6 watts per square meter annually, which could open the door to more ambitious offshore wind projects.
"What we did here is not a projection," Possner said in an interview with S&P Global Market Intelligence. "We're not saying that you can extract 10 TW or 1 TW of power in the Atlantic. ... This is a study looking at the limit of wind power extraction that's set by the air currents in the atmosphere."
In order to meet current worldwide annual energy demand of 18 TW, there would need to be turbines evenly spread across about 3 million square kilometers — an area roughly the size of India. And the offshore wind industry is nowhere near that level of technological development and economic feasibility. Current commercial offshore wind turbines are still limited to shallower waters. Wind developers would need floating turbines or another turbine design to extract more energy above the open ocean.
On the upside, floating turbines been gaining more traction in offshore wind research and development; of the 26 floating wind projects under some phase of development, 11 projects with a combined capacity of 229 MW are now either under construction, approved or have significant resources backing them for more development, according to a recent Department of Energy report on offshore wind technology.
Most existing and planned offshore wind farms have fixed feet in waters close to shore. In September, the U.K. government reported that costs for offshore wind projects coming online in the early 2020s have fallen by half since its last auction in 2015. China added nearly 600 MW of offshore wind capacity in 2016 alone and has been working with Denmark to further develop its industry.
In the U.S., offshore wind has been slower to pick up. The country's first offshore wind farm, the 30-MW Block Island Offshore Wind project, came online in December 2016. A handful of wind developers, including Statoil ASA and DONG Energy, have been working on offshore wind projects and several states including Massachusetts, New York and Maryland have issued requests for proposals to incorporate more offshore wind into their energy mix.
"There are some prototypes out there and people are doing tests, but they're a lot closer to shore than we're considering in this study," Possner said. "A huge amount of innovation is still required."