Planning permissions and consents for onshore wind farms in the UK generally require decommissioning and restoration after a 25-year lifetime. With some of the earliest windfarms being built in the early 1990s we are starting to look at what happens next. With proper operations and maintenance, there is no reason that windfarms can’t operate past this lifetime, especially if they’re receiving ROC payments.
It is important if we want to continue to decarbonise the economy that these existing consented sites continue to produce low carbon electricity and this is represented in Scottish Planning Policy:
‘Proposals to repower existing wind farms which are already in suitable sites where environmental and other impacts have been shown to be capable of mitigation can help to maintain or enhance installed capacity, underpinning renewable energy generation targets. The current use of the site as a wind farm will be a material consideration in any such proposals.’
We are now coming to a stage where many of the first windfarm sites using small clusters of 600KW turbines at around 70m in tip height are coming to the end of their operational lifetime. In many cases, and in eventually in all cases it will be more economic to “repower” the site.
There are numerous benefits in utilising a site, which is already powered: they are grid connected, planned for and there’s years of real data that can inform new design. There can be some difficulties if bases needed replaced or grid connection needs upgraded, the key however is that the sites have the planning permissions in place, if not for larger turbines.
Some sites might even be economically viable to repower before the 25-year lifetime is achieved due to the financial performance of the site and the rapid evolution and increase in wind turbine size. The progress in the last 20 years has been phenomenal with prices tumbling as hub height increases and economies of scale are seen.
There are many options for repowering sites such as maintaining the grid connection capacity by increasing turbine size but lowering numbers. Some sites may wish to maintain turbine numbers but increase the size and capacity but how do these large turbines affect the visual requirements of the area? Sometimes few larger turbines are deemed more acceptable.
Although many sites will not be considered for repowering before the mid-2020s the procedures need to be put in place now and trialled on some of the earliest Highland wind farms. Given the time it has taken to consent these original windfarms there can’t be considerable downtime between decommissioning and repowering considering the ambitious decarbonisation targets the Scottish Government has set.
In an ideal world, we would move to planning for perpetuity.