There were some rare blue skies over Renfrew last Thursday as the top brass of the offshore wind industry gathered at the Westway industrial park.

Nearly 50 years after the closure of the Simons and Lobnitz shipyard, once renowned for building sand dredgers, First Minister Alex Salmond had come to talk up the site's role in Scotland's new industrial revolution on the back of Steel Engineering's expansion into a second of the park's giant sheds.

The fast-expanding Steel makes most of its money building structures for the oil and gas and power plant sectors, but this shed – originally used to build Trident submarines – will be used to manufacture devices for the marine energy industry, particularly offshore wind. To that end, the Scottish Government announced a £500,000 investment in the Westway docks a couple of months ago for work to accommodate the vast barges that will move heavy machinery in and out of the site.

"This is a contribution to the re-industrialisation of our country," said the First Minister of the Steel move. "Scotland has never ceased to excel in high-quality skilled engineering - [but this is about] grabbing back the re-industrialisation process."

Yet despite such moves, all is not well in the UK offshore wind industry. The Westway investment is the Scottish Government's first from its £70 million National Renewables Infrastructure Fund – but a year ago it had been promising three such announcements before the end of 2011. Whether or not the authorities have been dawdling, this mainly reflects the reality that turbine manufacturers are not ready to commit to building factories.

The problem is that the wind farms are taking longer to reach fruition than planned – above all the vital Round Three projects that comprise the biggest part of planned capacity for the sector. Danish turbine maker Vestas recently scrapped a plan to build a factory in Kent and despite memorandums of understanding for manufacturing in Scotland from the likes of Gamesa and Samsung, the sector has been ominously quiet of late. Several major farms – notably Greater Gabbard, off Suffolk – have has serious technical problems that have rattled investors. People are looking nervously at Europe, where the Germans among others are finally getting their act together. Given that there is likely to be less banking finance available than before the markets crash, some wonder whether the great offshore wind dream might be starting to slip away.

Rick Eggleston, managing director of REpower UK, a German-owned turbine supplier that will set up a factory in the UK if it gets the orders, says: "In the UK, I don't think we are particularly good at doing things quickly - When Round Three was announced, people thought it would start ramping up from 2014. Now it will be 2016 or 2017 before it really gets going."

The trouble is that offshore wind is supposed to be the best hope for guaranteeing the country's electricity supply and meeting EU commitments to make 15% of energy renewable by 2020, particularly now that plans for building new nuclear plants look increasingly shaky.

The Crown Estate, which manages UK territorial waters, has allocated concessions for nearly 50GW of capacity from the sector. This amounts to the equivalent of 20 Longannet power stations or almost enough to power the entire country, requiring something like 10,000 of these giant turbine structures at a cost of almost £200 billion.

Nearly 2GW worth – 568 turbines – are in place already; more than half the European total according to RenewableUK (though only 180MW are in Scotland, whose waters were seen as too deep and choppy for the early-stage developments). Forecasters were previously reckoning that there might be 40GW by 2020. Now few believe there will be as much as 30GW, and only if everything goes right between now and then.

Though there are differing views about how bad the situation has become, projects have been held back by a combination of the economic crisis and over-optimistic predictions a few years ago.

In Scotland, for example, as recently as 2009 there were many in the industry who thought that numerous developments would start construction in 2011 and 2012. At that time, the country had been given 10 concessions, amounting to more than 6GW of capacity in the so-called Scottish Territorial Waters (STW) round. In 2010, it got another two allocations in Round Three, worth nearly 5GW between them.

So far, none has got anywhere near the water. Five of the original 10 STW projects have been cancelled for various reasons, from business strategies focusing elsewhere to developers discovering a site was less windy than expected. Of the remainder, two have applied for planning permission (Beatrice in the Moray Firth and Neart na Gaoithe in the Firth of Forth), another two are doing pre-planning environmental work (the Argyll Array off Islay and Inch Cape off Angus) and another Islay project is at an even earlier stage. Of the Round Three projects, Moray has applied for planning permission and Firth of Forth is in pre-planning.

None of the frontrunners are likely to get planning permission until well into next year. After that comes the lengthy process of detailed designs and supply chain assembly to make construction possible, which is thought will take another two years. That suggests there will be no construction in Scotland before 2015 at the earliest, and only then if companies take the final decision to go ahead, raising the money where necessary.

Gary Webster, development director at Wood Group, which provides support services to developers, is not surprised by this timescale. "When we looked into the industry a couple of years ago, we thought that predictions were a little optimistic. It's going to be a much slower burn than some people thought," he says.

Investor confidence has meanwhile suffered from the fact that the Coalition Government decided to change the subsidy system when it came to power and has been missing its deadlines for completing the work. It was supposed to tell the industry about its new contracts-for-difference system months ago, but the vital numbers have not yet been released and no-one knows exactly when this will happen. According to press reports, the Coalition has been battling over how generous the system should be, with the Liberal Democrats apparently wanting greater subsidies and the Conservatives wanting a better deal for the taxpayer.

Because the new subsidy system will only apply to projects built from the 2017-18 financial year onwards, this has had several consequences. As Paul O'Brien, a renewable energy manager at inward investment agency Scottish Development International, says: "One of the things that has happened because of the uncertainty is that some of the developers have decided to go for it under the existing system. So the likes of EDP Repsol, Mainstream and SSE [which each have Scottish projects] are looking to maximise their activities."

Other developers have taken the view that there is no point in doing anything until the new system is clarified. This will partly explain why only 588MW of unbuilt UK projects have consents at this stage. The German equivalent is 8.7GW. One investment banker told the Sunday Herald about a shortage of investors willing to take on construction projects in the UK at present.

Rick Eggleston of REpower, which has about one-third of the UK onshore wind supply market but no offshore turbine orders this year, says: "Projects are continuing to slip to the right. Offshore is still perceived as quite high risk and expensive as a venture - We are fortunate we are seeing a lot of offshore activity in the German market."

So how serious is this situation? O'Brien makes the point that many more German projects need external finance than British ones. "About 70% of the UK offshore market is owned by big utility companies. With Germany, only about 40% is in that category," he says. "The plan for the utilities in the UK is to use their balance sheets to build out the first of the projects, sell them on to institutional investors and recycle the project finance."

The second point is that the Government is not yet hopelessly late with its market reforms. O'Brien believes that the problems in the nuclear sector will mean that the Government will have no choice but to offer a deal soon that will be attractive to developers (and presumably more onerous to taxpayers).

Webster of Wood Group adds that taking slightly longer to get projects off the ground will mean that developers will benefit from efforts to make construction cheaper. The industry's Low Carbon Innovation Co-ordination Group produced a report earlier this year that laid the groundwork for getting costs down from levels of around £140 per megawatt hour to £100/MWhr by 2020 – about £30 more than a gas-fired power station but on a par with the level that senior voices in the nuclear industry had forecast.

Webster says: "The longer it takes to get going, the more the cost-savings and the more the local supply chain will have had a chance to build capacity. I don't think it's all negative that things are a bit delayed."

O'Brien adds that Scotland also has the advantage of having a single planning authority – Marine Scotland – dealing with developers' planning issues, whereas down south there are four to five authorities per application. Several private voices in the industry agree that Scotland has done a good job in this respect.

So, these are uncertain times for the industry. The big picture could still fracture and fall apart if the Coalition gets the subsidy system wrong or developer confidence is dragged down by a worsening economy. For now, though, most observers still maintain that the cup is just about half full.

Alex Salmond, for one, will drink to that.