Large Scale Offshore Wind Energy in the North Sea — A Technology and Policy Perspective

Abstract

With the ground breaking 160 megawatt wind farm Horns Rev, off the coast of Denmark in the North Sea, installed and operating, offshore wind energy experts are progressing with optimism. With a portfolio for offshore wind farms in north-western Europe that foresees in an accumulated installed power of more than 3 gigawatt by the end of 2006, the future indeed looks bright. But will the expectations for offshore wind energy be met? Based on experience from technical and market-orientated studies on offshore wind energy (OWE), the Energy research Centre of the Netherlands ECN concludes that the growth of OWE in the next few years will mainly be hampered by insufficient policy support, rather than by technical barriers. The realisation of the first two Dutch offshore wind farms has been delayed considerably. Towards the end of 2004, the Dutch policy will shift to a concession system for the issuing of exclusive rights for plots in the North Sea. For the tendered sites surrounding the UK coast, the financial returns appear marginal. Moreover, according to market models, the incentives for offshore wind energy in Germany are insufficient for successful competition with other electricity supplies in the liberalised European market. The main technical challenges are the increase of turbine availability by improvement of turbine operation and maintenance (O&M) and a further reduction of wind farm array losses by innovation in turbine operation and farm layout. Focusing on The Netherlands, a significant upgrade of the grid is required to feed-in the Dutch goal of 6000 megawatt in 2020 successfully.

A review of geographic information system (GIS) and techno economic (TE) software tools for renewable energy and methodology to develop a coupled GIS-TE software tool for marine renewable energy (MRE)

“…However, the focus is only on offshore wind with data for the Dutch part of the North Sea. 68 It also does not appear to be publicly available for consultation and it is unclear from the literature whether this tool is still in use. 69 ECN also have a wide range of more complex inhouse simulation models for offshore wind but these focus on the TE assessment of a single phase of the project lifecycle, for example, ECN Install and ECN OMCE calculator for installation and O&M respectively.…”

Maintenance optimization and inspection planning of wind energy assets: Models, methods and strategies

“…In Opti-OWECS project, Kühn et al [8,236] showed that unplanned repair and maintenance of the failed wind turbines account for a significant portion of the annual O&M costs. Kooijman et al [14] studied the current state of maintenance for offshore wind turbines in the North Sea. The authors suggest that utilizing an optimum PM policy can potentially minimize the maintenance expenditures.…”

Planned intervention as a maintenance and repair strategy for offshore wind turbines

“…It is reported that for offshore wind power the O&M costs account for typically 23% of the project's total expenditure as summarised in Fig 1, 6,15,14 or alternatively this may be expressed as accounting for between 25-30% of the cost of the energy produced. 4,15,13,9 For an equivalent onshore project, the O&M costs as a percentage cost of the energy is estimated to be between 5-10%. 9 The main reason for such a difference may be attributed to the impact of operating a wind turbine in the marine environment where the wind turbines are 'stressed' in a harsher maritime environment and their accessibility for repair and maintenance restricted by weather and sea-state conditions, and also by their distance to shore which affects accessibility, meaning expedition costs to visit offshore wind turbines tend to be more expensive than visits to onshore wind turbines.…”

“…They conclude by suggesting the reactive response maintenance strategy has not yet shown itself to provide the best economic solution for offshore wind farms. Kooijman et al 13 suggest that the reactive response maintenance strategy as currently applied to existing offshore wind farms is a major factor when explaining why they are economically uncompetitive compared with onshore wind turbines. They suggest an increase of turbine availability is needed to maximise revenue and conclude that the optimisation of wind farm O&M strategy is needed to improve competitiveness so large scale offshore wind energy projects may compete successfully in a liberalised European Energy Market.…”

“…7 Investigations reported in this paper show that the reactive response maintenance strategy is neither practical nor is it desirable for large offshore wind farms when the cost of electricity generation must be competitive primarily because access is dependent upon environmental conditions, ie, weather and sea state. 9,10 O&M costs are known to account for up to 30% of the price of energy produced by offshore wind farms, 4,13,9,14 so reducing the maintenance costs would inevitably mean greater competitiveness of electricity generated by offshore wind turbines in the electricity market.…”