Advisory body the Carbon Trust estimates that to get close to this, some 6,000 turbines will have to be installed between 2010 and 2020 (including the remainder of Round 2 construction). That amounts to one turbine a day from now until 2017, and 2.5 turbines a day from 2017 to 2020, compared to a historic rate of one every 11 days.
This target also has to be seen in the context of the paucity of installation resources. Early offshore wind developments have had to rely for the installation of turbine foundations, turbine construction, cabling and surveying on vessels from oil and gas industries, with varying degrees of conversion and refitting required.
Since 2007, there has been a surge in demand for vessels, prompting RenewableUK (formerly the British Wind Energy Association) to conclude in a 2009 report: "This trend has continued for the last year culminating in a ‘vessel crunch' for projects deploying in the 2009 and 2010 build seasons."
That demand will increase as 2015 (the estimated start of Round 3 construction) approaches, and developers will need ready access to these vessels, rather than waiting for their availability during downtimes in other industries.
Targets under threat
Bespoke installation vessels will be required because turbines will be deployed in deeper water than in earlier rounds. These are likely to be jack-up barges that can operate in 40 metres of water. They have four or six legs that form a stable platform on the sea floor for putting in foundations and installing turbines. Onboard cranes have a capacity of 500-600 tonnes. Also needed are cable-laying vessels and auxiliary boats for crew and equipment.
Worldwide, there are 12 vessels that can be used for turbine installation and foundation work but only about half of them will be able to handle Round 3 construction. Another 10 to 15 vessels will need to be built between now and 2015 but with a four-year commission and build time for new vessels, the timescale looks increasingly tight.
So tight that some commentators believe Round 3 targets are unlikely to be met. "From both an engineering and a financial perspective, the challenge of building 33GW of offshore wind power - approximately 6,000 turbines - by 2020, both in deeper water and further offshore, will be extremely difficult and unlikely to be achieved," says Alex Desbarres, senior renewable analyst at Datamonitor.
Neil Birch, head of strategy and development at supplier Offshore Marine Management, is more optimistic. "The key to securing enough vessels is early engagement with the supply chain to manage and mitigate risk," he says.
Round 3 has provided the long-term stability to encourage new technology and equipment, says Kaj Lindvig, chief sales officer of offshore installation specialists A2Sea. Suppliers now have confidence in the future of the industry and are better placed to attract the investment to develop the necessary vessels.
"I think we'll get a commitment from consortia to charter vessels over a longer period, which means agreements can be made with developers to use the specific vessels for several years," Lindvig says.
The signs are that this is already happening - suppliers such as Fred Olsen Renewables and Beluga Hochtief Offshore are building or planning to build vessels. And RWE npower renewables, involved in the Dogger Bank and Bristol Channel developments, has commissioned two vessels.
Benjamin Sykes, senior technology acceleration manager at the Carbon Trust, is confident the sector can deliver. "Round 3 has given a strong signal to the supply chain that there is a large, growing and sustainable business out there," he says. "As the offshore wind industry grows, you will see a bespoke sector develop."