New offshore wind turbines strategy from partnership Megavind

In May 2006, the Danish Government presented a report on promoting environmentally effective technology and established a number of innovative partnerships. The partnerships intend to strengthen public-private cooperation between the state, industry, universities and venture capital to accelerate innovation for a number of green technologies. The partnership for wind energy is called Megavind.

Megavind’s vision is to maintain Denmark as a globally leading hub in wind power. The following partners represent the sector:

• Vestas Wind Systems A/S

• Siemens Wind Power A/S

• DONG Energy

• Grontmij I Carl Bro

• The Technical University of Denmark

• Risø DTU – National Laboratory for Sustainable Energy

• Aalborg University

• (observer)

• Danish Energy Agency (observer)

Megavind’s strategy for offshore wind energy describes the offshore challenges and suggests research, development and demonstration (RD&D) priorities to enable offshore wind power become to competitive with other energy technologies.

The strategy lists key recommendations as well as key thematic priorities and for each of these a number of RD&D priorities. Under each thematic priority references are made to the European Strategic Energy Technology plan (SET-plan), which prioritises offshore wind RD&D in Europe.

The strategy content and recommendations are based on inputs from a long list of Da-nish offshore players both from industry and research organisations.

The Danish Wind Industry Association functions as secretariat for Megavind and Risø DTU has co-authored the strategy.

Megavind’s vision is to maintain Denmark as a globally leading hub in wind power. The Megavind target for offshore wind is to drive down cost of energy (CoE) from offshore wind farms and to half the CoE from new installations on comparable sites before 2020.

This will make offshore wind competitive with newly built coal-fired power, and in the process most likely achieve cost-competitiveness with all other new-built electricity generation, except for onshore wind. This ambitious target may be met through concerted effort from industry, research and governments.

Three main achievements must be realised by industry and research between 2010 and 2020. Firstly, newly built offshore wind farms must be able to produce roughly 25% more electricity per installed MW. Secondly, the capital expenditure including costs per installed MW must be reduced by approximately 40%. And thirdly, the cost of operation and maintenance per installed MW must be reduced to about half.

Cost efficiency gains at this scale are considered necessary to maintain public and political support for large-scale implementation of offshore wind energy in Europe and globally, and to maintain the competitive edge of Danish actors in this market.

Three important preconditions must be met by governments to reap the full benefits of the technology gains proposed. Policy makers and planners have a very direct impact on the future CoE and competitiveness of offshore wind farm.

Firstly, economies of scale and industrialisation are the main drivers and technology development the enabling factor in reducing CoE. The reduction target presumes a high degree of political certainty for gradually increasing the annual new build rate over the period towards 2020 to allow the industry to make planned investments in industrialisation.

Secondly, governments must deliberately improve their planning systems and enable use of more cost-efficient sites. The European pipeline for offshore wind towards 2020 is for political reasons planned further from shore, and at greater water depths, compared to the average operating wind farm installed prior to 2010. The described technology driven cost efficiency gains could well be offset by higher cost related to the site selection.

Thirdly, governments must put in place the necessary core funding for RD&D as described in this strategy. The vision and target achievements are considered necessary and feasible by the key sector organisations.

Denmark’s stated vision is to continue to be world leading in green energy technologies, including offshore wind power. At the same time, other governments in Europe and elsewhere are keen to attract these industries and are raising considerable support.

The strategy report describes 7 thematic priorities and lists specific RD&D priorities for each. These are selected by Megavind on the basis of their potential to contribute to the 50% CoE reduction target. Several of the specific RD&D activities described in this report are about enabling economies of scale and industrialisation. Government funding for these priorities will help drive down the CoE from offshore wind farms and will help increase the competitiveness of actors taking part in the activities.

More than ever it is important for any government to ensure that increased government programmes will in fact attract investments in private RD&D. Therefore, there is an increased need for targeting government programmes towards the specific needs of the sector.
Danish government RD&D programmes are negotiated annually as part of Government’s fiscal budget. This creates unnecessary uncertainty for companies planning RD&D investments in Denmark.

It is recommended that government RD&D funding programmes instead have a longer term framework, e.g. rolling three-year budgets.
Public RD&D expenditure on wind energy remains low compared to the private RD&D expenditure. Studies indicate a RD&D intensity of 2.6-3.0% of annual turnover in the wind industry. For the Danish wind energy industry with an annual turnover in 2009 of 51 billion DKK, this would amount to 1.3 – 1.5 billion DKK. Effectively, the sum invested by Danish actors is considerably higher but more precise figures are not available.

In the same year, the sum total of all Danish public energy RD&D expenditure was approximately 1 billion DKK, of which 131 million DKK was granted to wind energy RD&D projects. This corresponds to just 8-10% of the private RD&D wind energy investment in Denmark. The EU Strategic Energy Plan (SET-plan) recommends a 50/50 ratio for public/private investment in RD&D.

Effectively, the Danish government funded RD&D for wind energy is matched 10 times over by private research, development and demonstration activities in Denmark. While private RD&D investments will continue to be the main source of investments in offshore wind RD&D, a general recommendation is that Danish government RD&D programmes for energy RD&D should be gradually increased from its current approximately 1 billion DKK annually to at least 4 billion DKK annually in 2020.

With a view to drive innovation and demonstrate skills and competences of Danish energy actors, including industry, research institution and public agencies, the Megavind partnership recommends:
• All government funding to energy RD&D priorities should be awarded according to a well-described potential to reduce CoE. For offshore wind, the Megavind offshore strategy may be used as a guideline.
• A substantial share of future new offshore wind capacity installed in Danish waters between 2010 and 2020 should be reserved for offshore demonstration projects, including 10×50 MW smaller wind farm projects preferably on near-shore locations. New and innovative solutions in several of the focus areas outlined will not be implemented at a commercial scale before these have been demonstrated in full scale. A mechanism to enable and provide co-funding should be put in place.
• The cross-border offshore wind farm at Kriegers Flak is recommended established as the next large wind farm in Denmark. Notably, this project will develop and demonstrate new and innovative solutions needed to realise the planned future offshore grids in the Baltic and North Sea.
• Special attention should be given to ensure and support investments in world class full scale test facilities for large nacelles and critical components.
• The Offshore Wind Turbine Action Plan should be updated, including potential use of near-shore sites for demonstrations purposes. This planning tool already incorporates considerations for choosing sites with lowest resulting CoE, but more comprehensive data, in particular wind, wave and soil data, are needed to lower risks for future developers on selected sites.

The strategy should also be embraced by educating institutions in order to ensure a relevant supply of competent graduates for the sector matching the thematic priorities. The Megavind thematic priorities and RD&D priorities are described in detail in the following chapters.

The Megavind target is to be able to produce electricity at half the cost per MWh, on comparable sites. A site where costs today are 100 €/MWh should be reduced to 50 €/MWh in 2020.

The chosen site for an offshore wind farm determines the harvestable wind resource (annual energy production) and impacts directly on costs per installed MW (CAPEX) and O&M costs (OPEX). Experience so far shows a significant correlation between sea depth/shore distance and CoE. Other met-ocean data, including notably design wind conditions, wave heights, currents and sea bottom, also define the site specific costs. This is primarily a government action area where research and lessons from demonstration projects may be used to improve decision-making.

If government planning pushes offshore wind farms to less optimal sites, the 50% reduction target will not be met. At the same time, selecting more optimal sites prior to 2020 is a short cut to achieving lower costs on those sites and may contribute to reaching the target sooner.

Higher productivity and earnings of the offshore wind farm will contribute positively to reducing CoE of the offshore farm. These gains can be achieved partly through improved optimising design (larger rotors), optimising operation of the farm and exploring potentials within delivery of system benefits, including regulation and stabilisation power to the grid.

This area is therefore primarily driven by wind farm developers, suppliers, owners and operators as well as transmission system operators. It is estimated that this action area will be able to contribute by increasing wind farm production by 25% relative to installed MW.

Research, development and demonstration in lowering construction and installation costs (CAPEX), comprised in the four areas “wind turbines”, “foundations”, “electrical infrastructure” and “assembly and installation”, are estimated to contribute significantly and equally to reducing cost per installed MW. The ambition is to reduce CAPEX by approximately 40% of current costs.

Today’s offshore wind turbines are almost identical with the wind turbines onshore. Offshore wind turbines will, over the next 10 years, become both bigger and more efficient. Bigger and differently designed wind turbines will simultaneously open up for cost reductions for support structures and electrical infrastructure.

RD&D priorities
1. A ccelerated full scale test of wind turbines and components (test and demonstration)
2. Design conditions for reliable and multifunctional wind turbines in wind farms
3. Design basis and methods for large offshore wind turbines in integrated wind farm operated with minimum maintenance (up to 20 MW)
4. New rotor concepts

Accelerated full scale test of wind turbines and components is dedicated test facilities, which are required to manage the risks when up-scaling design and deploying large scale wind. The proposed testing facilities are combinations of full scale wind turbine tests and accelerated component tests under laboratory conditions.

The combination makes it possible to experience real operating conditions and transfer realistic conditions to the controlled environment for detailed analysis. Accelerated full scale wind turbine tests could be obtained by increasing the operational loads by a combination of increased rotational speed, dedicated control actions and operation in complex wind conditions including wake from other turbines. By tailoring the operational conditions to generate increased loads relative to the design load basis, the accelerated lifetime of the different components can be reduced to e.g. a test period of 1-3 months. In particular, there is need for:

• Development of methods for accelerated full scale test of turbines, incl. complex wind e.g. wake conditions
• Establishment of reference test facility, including component test facilities
• Data collection, statistical analysis and data evaluation

Design conditions for reliable and multifunctional wind turbines in wind farms address the overall design requirements for offshore wind. There is need for incremental innovation to improve turbine reliability, increasing component lifetime and developing preventivemaintenance strategies. Research and development should address:

• Measurements, description and modelling of external conditions (wind, wakes, waves, geotechnical topics). Investigation of especially external wind conditions such as mean, turbulence and extremes above 100 m is needed as no measurements currently are available for these heights. Joint probability statistics of wind and wave, with respect to both amplitude, phase and directions
• Establishment and verification of design load basis, incl. wakes, transients and multifunctionality (down rating, over rating, ride through, feed forward)
• Develop probabilistic design and verification methods for systems and subcomponents (life-time, extreme incidents, inspection, service, mean time between failure etc.)
• Improved methods for optimising operation and maintenance
• Improved standards for wind turbine systems

Design basis and methods for offshore wind turbines in integrated park design operated with minimum maintenance involve site specific design process with feedback between turbine, support structure, wind farm design and control, and the impacts on up-scaling.