Orsted Signs Up to Study Liquid Air Storage for Offshore Wind Power
Offshore wind giant Orsted is working with a UK-based startup in an effort to solve one of the most persistent problems for offshore wind power: storage. In stormy weather, offshore turbines can produce so much electricity that they have to be curtailed so as not to overwhelm the grid; in light airs, however, they produce so little that utilities have to resort to other sources of power. Storage could help even out the highs and the lows - if it can be achieved at scale.
According to Highview, the lack of renewable energy storage during peak conditions this past winter meant that the UK had to forego 1.35 TWh of wind energy due to curtailment. If this power had been captured using storage at peak times, it could have powered 1.2 million homes. Over the same period, the UK's utilities had to purchase $75 billion worth of natural gas - some of which could have been saved through stored wind power.
"We believe that energy storage will play a pivotal role in a world that runs entirely on green energy. Our collaboration with Highview Power is an important step in creating effective energy storage solutions that unlock greater value from next generation wind farms," said Duncan Clark, Orsted's managing director for offshore.
Highview's technology is based on the liquefaction and regasification of air. During storage, the plant compressors use excess electricity to compress and refrigerate air down to -196 C, the point of liquefaction. The liquid air is stored in insulated storage tanks in a cryogenic state. At times of peak demand, the plant regasifies the air and blows it through a turbine to generate electrical power.
Grid bottlenecks are one of the major challenges facing offshore wind development in every locality, including the UK. A primary benefit of energy storage is that it smooths out the amount of power that has to be sent down the lines at peak times, reducing the need to upgrade costly transmission infrastructure.
"The UK is an efficient producer of renewable energy, yet if we cannot store our excess energy, we will have no option but to pay wind farms to switch off, wasting valuable renewable energy in the process and costing the tax payer in the process," cautions Highview.
While it is durable, economical to build, and does not depend on the world's finite supply of battery components, liquid air energy storage is somewhat less efficient than a utility-scale lithium-ion battery bank. The round-trip efficiency is about 60 percent, though this can be increased of the plant can tap waste heat or waste cold from other industries. By comparison, grid-scale battery parks are about 85 percent efficient.