Three steps to making onshore wind work

United Kingdom | 18 June 2020
Reading Time : 4 mins

Around the world, the key to the viability of many onshore wind projects is reducing costs. Although there’s no single way to do this it’s usually possible, by looking at the full life-cycle of a project, to identify incremental gains that can add up to a big saving. These fall under three headings: reducing capital expenditure, maximising grid connection potential and extending life

1. Reducing capital expenditure

Standard designs lead to standard costs. Only by challenging traditional thinking can you reduce capital expenditure.
When ENERCON faced high foundation costs due to the remote location of its four-turbine 15MW wind farm in the Peace region of Northern British Columbia, we developed an alternative to a standard gravity-base foundation. Our concept, which uses a combination of precast concrete beams and cast-in-place concrete slab and pedestal, saved CAD$300,000 per foundation.
We’ve also reduced clients’ costs by moving a meteorological mast to reduce the length of the road servicing it. And we’ve found savings by specifying a one-way system around a site – eliminating turning circles.

By challenging every aspect of the design, you can chip away at the capital expenditure. Could you optimise the cable routes? Could you reduce crane time on site? Would the grid operator allow you to use capacitor banks instead of stat coms to regulate voltage? Do you really need such large control rooms or meeting spaces on site?

Kimberley Dewhirst Technology Lead, Wind, WSP

Even reducing the amount of land needed to access the site helps. For one project we adjusted the wheels of the trailers carrying the towers to site, giving them a tighter turning circle and reducing the number of easements the client had to obtain.

2. Maximising grid connection potential

With wind farms typically sited in remote locations, connections to the grid can be difficult to come by and expensive, so it’s important to make the most of them.

A wind farm would usually get a grid connection based on its rated capacity, but losses and intermittency mean it would never use its full connection. There are two solutions to this: overbuilding and colocation.

Our 'Making Wind Work' study showed that, because of losses between the generator and grid, you can overbuild your wind farm by 5% without affecting your grid connection. If you have a 100MW grid connection, it’s fine to build a wind farm rated at 105MW because it will never actually deliver this full capacity to the grid.

Because the wind doesn’t always blow, wind farms typically generate 30-40% of their full capacity at any one time. This is where colocation comes in – build something else on the same site to take up the slack in the grid connection.

Kimberley Dewhirst Technology Lead, Wind, WSP

You could install solar power, which will produce more energy at less windy times of the year. Or you could install battery storage, enabling you to further overbuild your wind farm and store excess energy. This option is growing in popularity as battery costs plummet.

3. Extending life

Wind turbines have traditionally been designed for a 20-year lifespan. Why shouldn’t they be designed to last 25 or 30 years, reducing their overall lifecycle cost and enabling them to go on producing revenue for longer? Life extension is an area we’re increasingly advising clients about, as it can help to make a wind farm viable.

To understand if extending the life of your wind farm is a good option, you need to ask some questions. What is the current state of your asset? If it’s still on the drawing board, what criteria are you designing it against? What are the critical components?

For example, the gearbox or rotor blades may be the limiting factor rather than the foundation or tower. Or maybe data analysis of the designed, expected and actual loads experienced by the wind turbine generator would show that, with careful operation and maintenance, it could carry on for several more years.

Other questions include: Will the wind farm and its technology be redundant in 20 years? What will the future market be like? Power purchase agreements tend to run for only 15 years, and future grid requirements may be very different.

These are the sorts of questions our life-extension team are now helping clients to examine. In conjunction with maximising grid connection potential and reducing capital expenditure, the answers can help make the sums add up for onshore wind farms.

Contact Kimberley to request a copy of Making Wind Work