Giant turbines could be key to reducing renewables costs

BUILDING giant 8-megawatt turbines will be one way to reduce the cost of offshore wind farms to make sure targets can be hit, according to research.

Onshore turbines are usually a maximum of 3MW, but inventing offshore turbines more than twice the size will help slash costs, the study by the Crown Estate concludes.

The report, based on evidence from more than 100 companies, argues that offshore wind turbines will “radically change” between now and 2020, from those that have been altered from onshore turbines to those built for offshore purposes.

Whereas visual impact has limited the size of onshore turbines, this is not such a constraint offshore, the report argues, meaning “taller structures are more acceptable”.

Due to noise constraints, onshore turbines have a blade tip speed limit of 80 metres per second, offshore turbines will be able to spin faster at 100 metres per second, it suggests.

The report, “Offshore Wind Cost Reduction: Pathways Study”, points out that at least 12 manufacturers are developing bigger offshore turbines, including Mitsubishi, which is creating a 7MW turbine, with a diameter of 165 metres.

Increasing the size of turbines was just one way the report argued costs can be cut. Others included growing the supply chain and reductions in the cost of finance.

These changes would enable the UK to hit targets of slashing costs by more than 30 per cent to £100 per megawatt hour by 2020, saving more than £3 billion per year, it argued.

And it would mean the UK government target of generating around 20 per cent of the UK’s total electricity demand from offshore wind can be met by the same year.