Wind is one of the cleanest energy sources available, and the US is sitting next to a gold mine. A new study has found that wind speeds over the oceans could allow offshore turbines to generate far more energy than a land-based wind farm – with the North Atlantic, in particular, theoretically able to provide enough energy for all of human civilization.
In tapping into wind as an energy source, the US has for decades lagged behind Europe and UK, which are home to the largest offshore wind farms in the world, including the London Array and the Netherlands' Gemini wind farm. But the US is catching up: the country's first facility opened up off the coast of Rhode Island last year, and if the Trident Winds project goes ahead, it could snatch up the title of world's largest wind farm.
In addition to being safer to bird life and less disruptive to humans, the main advantage of setting up wind farms offshore is the fact that the wind speeds are higher out there. In theory, those speeds mean there's five times as much energy blowing around over water than there is over land, but whether that would translate to electricity production gains was another question. Researchers from Carnegie Science set out to find the answer.
"Are the winds so fast just because there is nothing out there to slow them down?" asks Ken Caldeira, co-author of the new study. "Will sticking giant wind farms out there just slow down the winds so much that it is no better than over land?"
The team used computer models to compare the output of existing land-based wind farms in Kansas to huge, theoretical facilities out in the open ocean. According to their results, turbines in the ocean wouldn't drag down the wind speeds as much as those over land would, and in some areas, they could generate three times as much electricity as their land-based counterparts.
The mechanism behind that is a result of atmospheric conditions differing over land and sea. The energy that turbines tap into starts as faster winds at higher altitudes, which are brought down towards the surface. Over land, those winds tend to stay up high, but over the ocean – and paticularly over the North Atlantic – surface warming of the seawater brings them down to within reach of the turbines.
"We found that giant ocean-based wind farms are able to tap into the energy of the winds throughout much of the atmosphere, whereas wind farms onshore remain constrained by the near-surface wind resources," says Anna Possner, co-author of the study.
As rich as the North Atlantic is for wind energy, the team also found that its productivity would vary by the season. In the summer, such a huge, theoretical offshore wind farm could be capable of powering the entire United States or Europe, but in winter, the team says there's enough energy on offer to meet the needs of the whole world.
The research was published in the journal Proceedings of the National Academy of Sciences.
Source: Carnegie Science
