With 1341 MW installed, the UK is the world leader in offshore wind but with many more turbines still to be built and deployed, where they will be built remains a key question.

Speaking in March this year, UK climate change minister Chris Huhne said that the UK would have to see a, "five-fold increase in the current rate of deployment of renewables," in order to meet its targets for 2020.

Continuing, he said: "It would be crazy to support producers generating low-carbon energy, businesses selling low-carbon products, consumers installing low-carbon measures — and not try to capture some of the original value."

But despite the scale of Round III investment, the UK lacks a volume turbine manufacturing capability, with the majority of large turbine parts built in Germany or Scandinavia.

Although the UK does well from small turbine manufacturing — supplying 25% of the global market — it doesn't even make the top 10 when it comes to large wind turbine production.

After the much-criticised review of the country's solar feed-in tariff, UK chancellor George Osborne took various measures in the UK's March government budget to stimulate the country's domestic renewable industry, including an extra £2 billion to establish the much-mooted Green Investment Bank. The bank will fund early-stage technical development in key areas such as marine renewables.

However, it is wind power that's in the spotlight, with a successful UK wind manufacturing sector potentially creating 60,000 jobs by 2020, according to RenewableUK.

Reducing the cost of wind power deployment is also a key goal for Round III and building factories at ports from where turbines can be easily loaded has the potential to be more efficient, along with a host of other benefits.

Smoothing the path for factory development, Prime Minister David Cameron confirmed last October that the £60 million grant earmarked by the previous Labour government for investment in English and Welsh ports will go ahead as part of the National Infrastructure Plan. Another £70 million will go to Scotland.

Three of the biggest turbine manufacturers are already committed: Gamesa will spend up to £133.7 million on various facilities including a factory, while shifting its head office to London, and GE has plans to invest up to £100 million. Siemens chose Hull as the preferred location for its turbine factory in January this year.

Other notable recent investments include Mitsubishi and Doosan in Glasgow and Clipper in Newcastle, while Vestas is putting £50 million into its new technology park on the Isle of Wight.

Vestas has also hinted that it might build its new 164 metre rotor diameter 7 MW turbine in the UK. But further investment will only happen if the manufacturers believe that future market demand warrants it and — crucially — that the market will be stable.

'The number one thing that will attract Vestas to manufacture the new turbine in the UK will be if there is a visible order pipeline to justify the significant investments,' said Matthew Delany, director of government relations at Vestas Offshore.

'The state of the [country's] infrastructure is secondary to [the]order pipeline. The £60 million port investment fund certainly signals the government's belief in the industry and is a step in the right direction,' he added.

Addressing uncertainties over financial support is the key point, while clarifying and accelerating the implementation of the Electricity Market Review (EMR) is another priority.

There are currently no firm offshore wind funding plans beyond 2017, and statistics released in March by the influential American Pew Charitable Trust claim the UK's private investment in the renewable sector fell by a worrying 70 percent in 2010.

'Over the last decade, successive governments have provided welcome financial support, but the pace of investment now needs to change. Around 1 GW of wind generation was added in 2009, compared to over 3 GW required annually by the end of the decade,' said Alstom's UK president and head of power Stephen Burgin.

'This step-change needs to take place at a time when many other countries and sectors are also chasing a limited pool of capital, so the government has to do all it can to make the UK one of the most attractive places to invest.'

'We've just consulted on the EMR package,' said a spokesman for the UK's Department of Energy and Climate Change (DECC). 'We know that certainty and clarity in the long-term is important for those people investing hundreds of millions of pounds. This is about the decades ahead, not just 2020.'

Other long-standing challenges include finalising the regulatory framework for offshore transmission, agreeing investment for the onshore transmission network and reducing the planning application periods for onshore renewable projects. The latter is a bete noire for manufacturers and symbolises the uncertain future of UK development.

'Urgently addressing delivery barriers such as planning and grid issues should help create more market certainty, which in turn should help create the visible order pipeline we need for a turbine facility to be viable,' said Delaney.

Chancellor Osborne tackled planning in his budget statement, with a new presumption in favour of sustainable development.

The default answer to planning applications is now 'yes', although what this means in practice is yet to be defined.

Osborne also guaranteed that any renewable planning application would produce a result within 12 months. How planning authorities are to meet this goal is unclear.

The UK government is trying hard to persuade more turbine manufacturers to set up here, but if it wants to make a clean sweep of all the big players, it needs to do more to assuage their concerns.

Ultimately this means taking some tough decisions about how offshore wind will be funded, built and run in future — and taking them soon.