Vast and efficient ocean wind farms 'could power human civilisation'

Vast wind farms in the North Atlantic could tap enough power to power the entirety of human civilisation, researchers have claimed.

Open ocean sites thousands of kilometres from Europe or North America could hit far higher efficiency than equivalent land installations thanks to strong marine winds and optimal spacing, said the team from the Carnegie Institution for Science in Washington DC.

Anna Possner and Ken Caldeira examined ocean farms’ ability to beat electricity generation from land farms – which they claimed is limited to approximately 1.5W/m² – or offshore installations, which can operate at around 3W/m² with wind speeds of about 50km/h.  

“The question was, is there something about the atmosphere or the ocean that allows it to bring down more wind energy to wind farms? The answer was basically yes,” said Caldeira to Professional Engineering. The team ran simulations to test the potential efficiency of open ocean sites.

“There is something special about some ocean environments and there are places like the North Atlantic where the Gulf Stream and all of its heat is pouring into the atmosphere,” said Caldeira. “That heat creates contrasts in temperatures… which brings more wind energy down to the surface where the wind turbines are.”

The heat difference means more air currents flow down to the surface, constantly replenishing the potential wind which can be harvested. 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.

This property of open ocean wind means operators could pack turbines closer together and generate more than 6W/m² on average, the simulations found. The team claimed farms spread over approximately 3,000,000km² – bigger than Argentina but a tiny fraction of the 107,000,000km² Atlantic Ocean – could theoretically generate 18TW (terawatts), which they said is equivalent to total global energy demand.

The study is a “green light” for operators to invest in suitable open ocean technology like floating turbines, said Caldeira, who claimed the main challenge to commercially successful open ocean farms is the low cost of oil and gas. “These wind turbines have a lot of moving parts which need to be maintained,” he said. “These things are more like aeroplane technology, so you have to make generating electricity with aeroplane technology as cheap as burning rocks, which is tough.”

Other main challenges include turbine maintenance and the logistical and economic difficulties of transferring electricity thousands of miles to shore said Stephen Wyatt, research director at ORE Catapult, the UK’s innovation and research centre for wind, wave and tidal energy.

“Floating wind isn’t yet fully developed,” he added to PE. “There are a handful of trial sites at the moment, most notably the Statoil project off Peterhead, which is looking at five spar buoy type floating turbines. That is a real sort of watershed moment, if that project is successful I think we’ll see a lot more… that will help us unlock deeper water sites, many of which have got better wind regimes [resources].”  

The Carnegie research was published in the Proceedings of the National Academy of Sciences.