Abstract
This paper presents a discussion of the development of wind energy generation in the United Kingdom and the challenges faced by the wind industry including reliability, performance and condition monitoring, particularly in the offshore environment. The worldwide installed capacity of offshore wind has now risen to over 7 GW, with an ever increasing deployment rate of new assets. About 90% of the global currently installed capacity is in Northern Europe, with the United Kingdom having the world's largest share at 4 GW. Capacity factor data from UK offshore wind farms is presented, providing an insight into the current performance of large Round 2 offshore wind farms compared to the earlier Round 1 farms and to onshore farms. The data reveal that the United Kingdom's Round 2 offshore farms are achieving an average monthly capacity factor of 38.3% with a peak value of 75.8%. The older Round 1 farms have a lower average capacity factor of 33.6% while large onshore farms with capacities above 100 MW have achieved 25.6%. Offshore wind turbine performance has improved over time, and the industry is applying the learning from early experiences to achieve better performances at the more recently installed farms. Despite these improvements in turbine availability, the cost of energy from wind, particularly offshore, remains too high for it to be a commercially viable form of generation without subsidies. Reducing the cost of energy from wind to economically sustainable levels is the most important challenge facing the industry today. Operation and maintenance costs constitute up to 30 % of the total cost of energy from wind in large farms. The industry must overcome the challenges associated with improving component reliability and the development and adoption by operators of appropriate condition monitoring systems and maintenance strategies, in order to reduce costs to sustainable levels. Research and development work carried out with these goals in mind is also reviewed in the paper.
Highlights
The challenges of climate change, energy security and cost of energy are becoming ever more present for governments across the world
Unscheduled maintenance at day-rate costs of up to 1000 per operative[35] has been shown to account for approximately 70% of the Operating and maintenance (O&M) costs.[36]. These high figures emphasise the need for optimising the O&M strategy for unmanned offshore wind farms to reduce unexpected turbine downtime, avoid lost revenue and improve the availability, so that competitive prices for the produced electricity can be achieved.[37]
An analysis of large UK offshore and onshore wind farm capacity factor data has been reported in this paper
Summary
The challenges of climate change, energy security and cost of energy are becoming ever more present for governments across the world. The performance of offshore wind farms is explored in this paper by making use of extensive capacity factor data from large UK onshore and offshore wind farms. The launch in 2001 of the ‘Offshore Wind Capital Grants Scheme’ by the UK Department of Trade and Industry led to investment in five farms of 60–90 MW scale (North Hoyle, Scroby Sands, Kentish Flats, Barrow and Burbo Bank) All of these have been fully operational for at least 7 years. The Beatrice wind farm, in the Moray Firth, features two 5 MW REpower turbines These were constructed in order to assess the feasibility of installation and operation in deeper waters than the United Kingdom had previously experienced. Capacity factor data has been reported by each of the wind farms in Table 1 through a number of different schemes:. Number of Farm capacity Award Capacity Reported manufacturer capacity (MW) turbines (MW)
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