Offshore wind turbines

Offshore wind leads the way in renewable energy

The winning bidders for the nine zones for offshore wind in the UK have been announced, and as E&T discovers that has changed the playing field dramatically for renewable energy and the UK's plans to alleviate climate change by reducing its carbon emissions.

The announcement of 32GW of offshore wind energy for the UK under the Crown Estates Round 3 offshore wind programme ensures that the UK continues to lead the world in this emerging technology. But the schedule ahead will be incredibly ambitious and fraught with both engineering and commercial challenges if it is to be successful.

The UK offshore wind Round 3 is a critical piece of the low-carbon puzzle and fundamental to the country's ambitions to achieve its 20/20 carbon reduction targets as set by the EU.

It is also important to recognise that the amount of investment being poured into offshore wind in the UK creates a great economic opportunity and a huge employment opportunity for the UK as well. But to achieve these aspirations then the whole process needs to be faster, cheaper and safer.

'If offshore wind is going to be the success that it can be, it needs to be able to do things faster, cheaper and safer,' Benj Sykes, senior technology acceleration manager at Carbon Trust, says.

'I have a background in the oil and gas industry. I spent 20 years in an offshore environment and doing it fast and cheap is not enough. We do have to do it safely, so that everyone can go home to their families at the end of the working day. In the offshore environment that is not a trivial challenge.'

The background figures are well known, and are fundamental to the dizzying array of policy that is being churned out at both national and European level. The UK has been set a target by the EU that 15 per cent of our energy use be delivered by renewable sources. At present the three biggest categories of energy use are transport (45 per cent), gas and heating (33 per cent) and electricity generation (19 per cent).

Not all sectors have the same scope for reduction so it is clear that the strategy is for electricity generation will bear the brunt of the demands, with almost 40 per cent of our electricity generation needed from renewable sources by the end of the decade. '40 per cent of electricity from renewables is a big jump from the current 2 per cent,' Sykes says. 'It is a 20-fold increase in renewables over the next ten years.'

So what are the options for renewable electricity generation? 'We see that the vast bulk 151tWh will come from offshore wind,' Sykes explains. 'Quite a bit from onshore wind, which is more advanced, but capacity restrained, where offshore is not.' According to Sykes wave and tidal are going to have a role to play, but that will be well beyond the 2020 timeframe.

'The capacity anticipated from Round 3 is a breathtaking figure, which illustrates the unprecedented size and ambition of the overall project,' Alan John, head of renewables at solicitors Osborne Clarke explains. 'To put this in context, the current total generating capacity in the UK overall for 2009-10 is in the region of 80GW.

'This announcement should give the UK renewable energy industry a huge lift, particularly after the Copenhagen summit failed to produce any meaningful announcements on renewables. However due to the sheer scale of the developments, the announcement is just the starting point as many complex engineering, financial and legal challenges lie ahead.'

Daunting scale

There cannot be many people by now who have not seen an onshore wind farms, and they are quite impressive in scale. But these structures will be dwarfed by the massive offshore turbines that will need to be constructed over the next ten years.

'It is not easy to grasp the scale of the challenge in terms of the amount of capital required, the size of the structures and how quickly we need to install these things,' Sykes says. 'The operating areas that the Round 3 sites are offering are extremely challenging for a number of reasons, but particularly the water depth and the distance from shore two factors that are completely different to the offshore farms that we have seen in the UK and elsewhere in the world to date. It is estimated that around 29GW of capacity is required by 2020 to deliver the 40 per cent renewable target, which equates to around 75bn amount of capex the equivalent to building around eight Channel Tunnels over the next ten years. 'It is a big engineering challenge, but also a huge funding challenge raising the project finance required,' Sykes adds.

'In terms of the engineering challenge it is probably bigger than the offshore oil and gas industry in the 1980s.'

But what about speed of installation? 'We will move very rapidly from where we are delivering a turbine every fortnight or so to having to install one turbine a day by 2012,' Sykes says. 'There is a huge step change required and within eight years we will need to be delivering and installing two or three turbines each day this is an immense challenge compared to where we are today. This is a huge change in the level of activity and should deliver 5-6,000 turbines offshore, ten years from today.'

Getting the proven technology in place over the next couple of years will be vital because technology choices will have to be made by the developers by 2013 for the first developments.

'There isn't actually much time for offshore technology development before then that can be proven, because you are not going to install unproven technology offshore in a wind farm with 300 turbines.'

Engineering challenges

As for the engineering challenges, they are fairly self explanatory when you look at the geographic location of the Round 3 sites. The Round 1 and 2 wind farms are typically in the 0-25m water depth range, and most of the activity seen to date is in water less than 20m deep. The deepest site is the two Beatrice turbines that stand in 45m of weather, but at the moment the capability is around the 0-25m depth.

Round 3 changes that scope dramatically. Around half of Round 3 sites are in 20-40m and the rest are in 40-60m. This presents an entirely different engineering challenge to working in shallower waters. 'You have 500t of turbine and blades on the top of 100m tower, if you then add another 50m underneath that for water depth you have a very big cantilever when you put large wind forces on that it creates very big engineering challenges to put it mildly,' Sykes says.

That is the vertical dimension, the water depth, but then you have the horizontal challenge, the distance that the wind farms will be from shore. At present developments are very close to shore. Round 1 and 2 are up to 25km from shore, but most are considerably less than that. The average for round three is 65km, but in the case of Dogger Bank that extends to 205km.

Not everyone views the rush for wind in such a positive light. Andy Cox, energy partner at KPMG tempers his optimism with a note of caution. 'This is a really positive step forward for the UK as it strives towards its renewable energy commitments of 2020. However, whilst any move to encourage a greener and more secure supply of energy to the UK is to be welcomed, there still remain major issues around offshore wind farms.

'These projects are not just hugely expensive and require a significant amount of capital but, given their size and the technical challenges faced in their construction; these projects are considered very risky by the investment community.' Maintenance for a wind farm 100km out to sea can be very costly and, once operational, gearbox failures could be difficult to resolve in winter.'

The current offshore wind farms are already having challenges with the physical and mental state of engineers by the time they reach the turbines, after spending two or three hours in a small boat bobbing around in the sea.

It is a very real problem, if you get your turbine engineer offshore and they can barely stand because they are seasick, they can't safely get on to the turbine and if they could they can do no useful work. Even in the calm summer months there are sea swells.

With the wind farms 200km offshore it will not be feasible to spend a day and a half in a boat to fix even the smallest of problems. In all likelihood what will transpire is the growth of an offshore operations and maintenance community living on floating support platforms, much like in the oil and gas industry.

'There is no longer a question over whether there is a market for offshore wind energy, but the real unknown is how the technical and financial implementation can be achieved,' Cox says. ''With construction scheduled for beyond 2014, when the current subsidy regime expires, the long-term level and nature of Government support is unknown. This is a crucial variable that will need to be fixed before investors will be prepared to commit the significant levels of capital to fund construction.'

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