Coupling an energy storage facility with a wind farm can improve that wind farm’s interaction with the power grid. This can be crucial, as recent estimates put the cost of integrating wind energy into the grid at 5 to 30% of the cost of generation. Energy storage can benefit wind power in many ways, including providing a balancing function for a rapidly changing load and wind output, smoothing the ramp rates so the power flows are more gradual, and providing reliable, firm output from the wind farm at any time. Sizing and choosing the correct storage technology and operational profile depends upon a number of factors – one size does not fit all.

By Richard Baxter, Senior Technology Analyst, Ardour Capital Investments, USA

Design Considerations and Approaches

In the pursuit to increase the megawatts per surface area and to maximise the megawatts/hour output per project dollar the size of wind turbines has been increasing steadily. To capture the higher winds and to accommodate the larger rotor diameter the hub heights have also been steadily increasing. Wind park prospectors and promoters are now required to measure at greater heights than ever before. From 40 to 50 then to 60 metres, the minimum level now seems to be the 80-metre level. The traditional tubular anemometric masts have not been able to go beyond the 60-metre level without becoming inordinately heavy. However, by revisiting the 250-year old Euler column equations and by using the aircraft design approach, a new lightweight structure is now able to achieve the 80-metre measurement at a fraction of the cost of the traditional lattice tower.

Global component shortages, rising project costs and the risks of ‘offshore’ have hampered a much-anticipated Pan-European offshore wind market. These market inhibitors have provided a reality check for the industry and have stalled plans for new offshore entrants. Meanwhile the US offshore market, which does have some high profile projects in the works, has yet to take off and the Asia Pacific market is still years away from large-scale offshore development.

Economic and social use of the sea has been fundamental in human history. Offshore wind farms are the most recent development and are a major change to the marine environment. They need to safely share the sea with many other users.

Optimising the layout of an offshore wind farm is an iterative process, and adds expense to wind farm development. The Offshore Wind Farm Layout Optimization (OWFLO) project seeks to streamline this process by uniting efficient optimisation algorithms with models of offshore farm costs and energy production. Most software configures farms for maximum energy production, but this does not account for the significant, site-specific costs of components such as the support structure and electrical interconnection. The OWFLO software instead models the levelised production cost to identify the combination of maximum energy production and minimum cost of energy that best suits the site. This article summarises the initial scope and progress of this project and presents a comparison with data from an actual offshore wind farm. The overall energy and cost of energy estimations compare well with the real data, and methods for further improvement of the models are described.