Offshore Wind Decommissioning: The Bad End of a Bad Technology

“The month-long decommissioning project was the first in the world for an offshore wind farm, but more projects will soon follow as early turbines reach the end of their two-decade lifetimes.”

– Sonal Patel, “Vattenfall Completes World’s First Decommissioning of an Offshore Wind Farm.” Power magazine, April 1, 2016.

“… many calculations of the much relied on measure of levelized hourly cost assume a 30-year lifetime…. As a result, many publications of levelized costs for wind turbines are understated by a factor of about two.”

– Kent Hawkins (below)

The April 2016 issue of Power Magazine contains a very likely revealing story on offshore wind plants. Given the political correctness of wind power, the revealing story can be interpreted in two ways:

1. It is critical of offshore wind plants, but in a way that is not clearly so, or
2. It is not critical, but the writer was not careful about what was being said.

The article has the above quotation in its initial paragraph, which can be seen as a warning. It also contains a comment–the two-decade lifetimes–which is not consistent with other information in the article and elsewhere (see below).

The piece is largely about the recent decommissioning of the Yttre Stengrund wind concentration in Sweden, which has been in operation since 2001 and was purchased by Vattenfall in 2006. It consists of five large 2 MW turbines, which are much the same type being extensively installed world-wide today. These consist of about 100 tonnes of machinery on top of a tower multiple hundreds of feet high.

This means it has lasted only 15 years, which appears to be generally true of wind plants, according to a Renewable Energy Foundation article. However the design lifetime is assumed to be about 20–25 years according to the article. Both are inconsistent with the two-decade reference in the above quote. In any event, it appears actual experience continues to point to a 15 year lifetime.

It is important to remember that most of the wind turbines in operation world-wide were installed after the year 2000. So a rapidly increasing number of these should soon start to show signs of a much reduced lifetime.

As an aside, many calculations of the much relied on measure of levelized hourly cost assume a 30-year lifetime. This is the cost per MWh produced over the plant lifetime. As a result, many publications of levelized costs for wind turbines are understated by a factor of about two.

Another interesting, and potentially cryptic, remark from the person who managed the project to dismantle the wind plant for Vattenfall is:

…we’ve learned a lot over the almost 10 years that we’ve been operating it.

If there were good lessons, it is likely that examples would be provided. As none are this suggests that the lessons learned were adverse ones.

The reasons given by Vattenfall to not replace the turbines were summarized as ‘financial and technical’. This represents two of the three factors in assessing overall feasibility. The one not mentioned in this comment is operational, which is also problematic here. The article goes on to quote Vattenfall:

The difficulty in getting hold of spare parts [for these older turbines, which were produced in small numbers] and the huge cost in upgrading the turbines and gearboxes meant that it wasn’t financially viable to replace the turbines…  

That knowledge, combined with the prohibitive cost and technical difficulty of replacing the turbines, made this a relatively straightforward decision.

Don’t miss the use of the word ‘huge’ in the first quote. ‘That knowledge…’ in the second quote refers to ‘…we’ve learned a lot…’ above.

Decommissioning or refurbishment costs of wind turbines is about the same as the initial implementation costs as discussed in the Power magazine article and also shown in this study by Queen’s University in Canada.

The article also mentions the planned de-commissioning of the world’s first offshore wind plant installed in Denmark in 1991, which has much smaller wind turbines (450 kW). It does not point out that Denmark halted offshore deployment in 2003 for a number of years. It started again a few years ago, likely in response to strong competition from China for land based turbine exports. China probably has that answered that too, as mentioned in the article by reference to China’s first offshore wind plant in 2011.

Conclusion

The full story of this earlier wind plant is not clear. As well, there may be more to the story than reported in the Power article on both sides of the realities of offshore wind plants. Subject to amazing revelations to the contrary, it is not easy to discount the very likely warnings in this article.

Locating wind turbines offshore makes even less sense than on land for other issues including:

(1) Accessibility for maintenance, both scheduled and unscheduled. Weather conditions can notably interfere with these, especially in circumstances of unscheduled breakdowns. The extent of equipment, including large cranes, which must be deployed to effect repairs, is a factor that might dictate against responding to a few turbine failures. It might make economic sense to wait until more are inoperative before attempting repairs, and

(2) Environmental, including ultrasound noise impact on sea life.

All of this should give considerable pause to any thoughts of deploying wind turbines offshore anywhere.