Industry Insight: Offshore wind costs have plummeted. Energy storage will improve performance further still
These are positive times for the wind sector, which has confounded critics to deliver some remarkable performance improvements.
Notice was served earlier this month at the UK government’s Contracts for Difference auction, where wind operators strike prices fell as low as £57.50/MWh from 2022-2023. This would make wind cheaper than new nuclear, where the backers of Hinkley Point in Somerset promised £92.50/MWh.
So, what’s gone right for offshore wind? The improvement in performance is the result of a dramatic reduction in costs, dropping by half in less than two years. This can be attributed to the convergence of several engineering-related factors, with relevance throughout the supply chain.
Firstly, wind turbines have got bigger and more powerful. Back in 2000, the average height of an offshore turbine, base to tip, was somewhere in the region of 100-metres. Today, they can be anywhere up to 200-metres tall. Subsequently, output has grown from 2MW to 8MW – with plans to build even larger structures that could achieve up to 15MW per turbine.
More aerodynamic blading, intelligent clustering of towers, and the use of more efficient cabling have also played a valuable role in improving the efficiency of new developments.
Construction costs have fallen, too. Companies have managed to cut the steel content in conventional monopile foundations, or have moved to latticed jacket designs instead. Floating turbines are also being planned for next-generation windfarms, which would slash construction costs further still.
Operational savings have also been achieved. Maintenance firms have invested in new access structures on board offshore wind turbines, meaning workers can be winched down rather than having to be ferried out by boat. And drones are now being used increasingly to survey offshore wind structures, reducing the need for physical checks.
This all bodes well for the future of wind, as it does for other renewable sectors such as solar, which are also on a path of incremental development. But the shift to renewable energy is causing problems in other areas – namely with grid stability.
Both wind and solar are intermittent, there is no certainty that the wind will be blowing or the sun will be shining when the peaks occur. National Grid pays companies to help maintain transmission system frequency at 50Hz. If it drops down or moves up beyond a certain threshold (too much wind, for example), it could, in the worst-case scenario, cause the power system to fail.
So, the wind industry is being forced to prove its ingenuity once again. Dong Energy has announced plans to integrate a hybrid battery system into its Burbo Bank offshore wind farm for the delivery of frequency response. The addition of the 2MW battery stack, set to be installed by the end of the year, will enhance the capability of the 90MW wind farm. It will be the first time an offshore wind farm is integrated with a battery system to deliver frequency response to the grid.
Of course, combining energy storage with new wind infrastructure adds complexity, and MW-scale battery systems don’t come cheap. But the prize is surely worth pursuing. Research firm GlobalData predicts that installed offshore wind capacity in the UK will rise from 6GW in 2017 to 23GW by 2025.
That’s a staggering increase. And if some of that new capacity can be optimised through energy storage, then the era of cheap and reliable wind power will have truly arrived.
Lee Hibbert, Industry Analyst and Content Director, Technical Associates Group (Editor of Professional Engineering, February 2010 - January 2016)
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