| Introduction | Background | Features | Availability | Further Information | Future Development | References |
Wind energy is emerging as one of the few serious contenders for the generation of clean energy. In recent years, improvements in the reliability and cost-effectiveness of land based wind turbines have been remarkable. Some commentors now argue that wind derived electricity is cheaper than that produced by gas fired CCGT plant [1].Wind energy is not without disadvantages however. The Northern European public are becoming increasingly unwilling to tolerate even the relatively small environmental impact of wind turbines. Locating wind turbines offshore provides an appealing solution. Moreover, the offshore wind energy potential of Northern Europe is enormous - large enough to satisfy it's entire electricity demand [2].
Building turbines offshore presents several challenges not present on land. In addition, offshore operations are considerably more expensive than their land based equivalents. What effect does this have on the economic viability of offshore wind energy? How can offshore wind farms be designed to produce the most economic energy?
The CEC Joule funded Opri-OWECS project (JOR3-CT95-0087) set out to provide some preliminary answers to these questions. To assist the work, a novel 'offshore wind energy cost model' was developed.
In a limited way, the cost model attempts to simulate the desgn process for an OWECS. Based on an outline farm specification provided by the user, the model sizes and then costs the components required. An estimate of the annual energy production is made, and used to calculate the cost of energy produced by the farm.
The model is written in the Visual Basic for Applications (VBA) language of Microsoft Excel. Using VBA allowed considerable flexibility in programming the model, yet the user is able to interact with the model through a familiar spreadsheet interface as shown below.
There are many possible uses for the model. The authors have used it for the following:
It is important to emphasise that the model was prepared specifically for use in the Opti-OWECS project. As such, it is tailored for the investigation of the engineering economics of large scale offshore farms, with installed capacities in the range approximately 80MW - 400MW. The model may be of use to those interested in smaller scale developments, but be aware that this would involve using the model outside of its intended range. Using the model in this range will have a serious impact on the reliability of the results.
Please note also that the cost model is not a wind farm design tool. The broad nature of the model means that many of the calculations it performs have to be simplified, and the results are necessarily approximate. Considerable work and expertise would be required to turn the model output into a realisable wind farm specification. Having said that, the model is of value to offshore wind farm designers, as it allows rapid evaluation of several design options. It also allows designers to optimisers the overall specification of a wind farm, with respect to minimising the cost of energy.
All versions of the model run within Microsoft Excel 5/95. In general, the model should run on more recent versions of Excel, but this is not guarenteed.
If you would like to use the model as part of your work, then you must buy the full version, which gives you access to most of the Visual Basic source code. We negotiate prices on an case by case basis for the full model. As a guide, commercial organisations should expect to pay in the region of £200. Academics and non-commercial researchers can expect a substantial discount - again these are negotiated individually, please contact me for details.
If you would like to obtain a copy of the model, or have other questions, please contact me at tim.cockerill@sunderland.ac.uk.
Further information about the model and the Opti-OWECS project in general is available as follows:
[1] Milborrow,D. Wind is now cheaper than gas?
[2] Offshore Wind Energy in the EC, Report on European Project JOUR-0072
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