Monday, 16 October, 2017

Open Ocean Presents Considerable Opportunity For Offshore Wind Energy Generation

Statoil's floating wind turbines surrounded by ships at dusk There's enough wind energy over the oceans to power human civilization, scientists say
Theresa Hayes | 10 October, 2017, 20:23

Anna Possner and Ken Caldeira modeled the electricity generation rates of potential wind farms in open-ocean environments. The authors point to other research which has concluded that the maximum rate of electricity generation for land-based wind farms is limited by the rate at which the energy is moved down towards the ground from high up in the atmosphere.

Scientists at the Carnegie Institution for Science in Palo Alto, California, wanted to know whether turbines installed in the open ocean-where air currents are 70% stronger than on land-would also face wind shadow problems.

The study found that such a huge wind farm could capitalize on low-pressure systems throughout the winter which more efficiently combine the upper atmospheric winds with the surface level winds, producing greater yields in wind farm power generation potential. At onshore facilities, each turbine weakens the power generation potential of each additional turbine downwind of it in a phenomenon known as a "wind shadow". "Will sticking giant wind farms out there just slow down the winds so much that it is no better than over land?"

"The real question is", Caldeira said, "can the atmosphere over the ocean move more energy downward than the atmosphere over land is able to?"

Computer simulations showed that wind turbines in the North Atlantic would be able to generate at least four times more energy per square metre than their counterparts on land. 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.

The whole world can be powered by a single offshore wind turbine farm in the North Atlantic, reports actualno. Scientists, however, state that wind power from the North Atlantic would be seasonal, falling to 1/5 of the average annual rate in the summer.

The authors say their findings should spur companies to try to overcome those obstacles, however, estimating that offshore wind farms in the North Atlantic alone "could potentially provide civilization- scale power".

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.