Researchers say ocean winds could power all of human civilization
Though such a vast engineering project would face huge challenges, it would provide enough sustainable energy to meet the whole planet's electricity needs, scientists say. Wind turbines in the open ocean could in theory intercept more than five times as much energy as wind turbines over land.
The study notes that wind energy gathered on land has an upper limit due to how structures on the land, both natural and manmade, can slow wind speeds. Also, open-water wind farms were seen as better able to capture energy that originates high up in the atmosphere and is transported down to the surface, where turbines may extract it. "These wind turbines have a lot of moving parts which need to be maintained", he said. In some areas, particularly the North Atlantic, ocean-based wind farms would be far more potent because the drag introduced by wind turbines would not slow down winds as much as they would on land. The research article, by Anna Possner and Ken Caldeira, was published by the Proceedings of the National Academy of Sciences of the United States of America.
Power generation from a giant North Atlantic wind farm would be seasonal, dropping significantly during the northern hemisphere summer.
But extracting efficient energy from wind involves more than putting turbines in the path of gale-force winds.
The pair set to work using modelling tools to compare the energy generation of a theoretical open-ocean wind farm with a wind farm in Kansas. 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. This contrast in surface warming along the US coast drives the frequent generation of cyclones or low-pressure systems, that cross the Atlantic and are very efficient in drawing the upper atmosphere's energy down to the height of the turbines. Land or close-to-shore farms merely "scrape" energy from the lowest level of the atmosphere, said Caldeira; open ocean installations could "tap into the kinetic energy reservoir of the entire overlying troposphere", he claimed. Although it is a very hard target to achieve and has several environmental consequences, the study seems to be quite interesting and reveals the true capability of wind energy over the ocean.
"Wind speeds over open ocean areas are often higher than those in the windiest areas over land, which has motivated a quest to develop technologies that could harvest wind energy in deep water environments".