Sir, – Chris Horn’s article on the sustainability of offshore wind energy (“Offshore wind farm technology is not particularly green when its ‘whole of life’ is considered”, Innovation, May 25th) ignores the progress in reliability, cost and sustainability which has been made over the past two decades of offshore wind deployment in Europe. First, it is important to consider the context of the transition to renewable energy. A single 12 megawatt offshore wind turbine could be expected to generate a million megawatt-hours of electricity over a typical lifetime of 20 years. If that electricity was generated by in a conventional natural gas-fired power station it would require the extraction and combustion of approximately 178 million cubic metres of fossil gas, and around 350,000 tonnes of CO2 would be added to the atmosphere. Offshore wind farms typically pay back the carbon “debt” incurred by their fabrication and installation within one year of operation.
Second, the end-of-life of wind turbines can be managed sustainably and cost-effectively. Early offshore wind farms in the Baltic Sea have already been successfully decommissioned.
It is true that the blades of most present-day turbines are mainly composed of glass fibre reinforced plastic, a difficult material to recycle. However, our US-Ireland research project Re-Wind has demonstrated the economic, technical and environmental feasibility of repurposing blades from decommissioned wind turbines. Re-Wind has designed and built a bridge on the Midleton-Youghal Greenway in Co Cork which uses two 25-year-old decommissioned blades as the main load-bearing elements, significantly reducing the quantity of steel needed for the bridge.
Repurposing also keeps blade materials out of landfills or incinerators.
No form of energy exploitation is entirely free of environmental impacts, but offshore wind energy has two major advantages – it can be installed at large scale, and as a technology with very low total lifecycle emissions it can make the greatest contribution to decarbonising our energy system in the next decade. – Yours, etc,
School of Engineering
University College Cork.