One of the most established suppliers of second-hand turbines, Netherlands-based Windbrokers, had a total turnover of EUR 30 million in its first ten years. But in the first four months of 2013, it has already received orders worth EUR 5 million. Henk van den Bosch, the firm's managing director, says that it is becoming a lucrative market due to private buyers financing projects.
Given that turbines are designed to last around 20 years, many are prematurely made redundant when wind-farm owners repower projects with bigger, more powerful turbines, as is increasingly the case in countries such as Germany and Denmark, where all the windiest sites have already been developed. "These are the ones that are interesting for a second life in countries where space limitations are not an issue. This is our business," says Van den Bosch.
Windbrokers only sells turbines that are less than 12 years old, because it would be difficult for the new owner to recoup the investment on older machines. A ten-year old turbine still has half its lifetime to run. And if a turbine is younger than 20 years, the original certification stating its ability to function is still valid.
No typical buyer
There does not seem to be a typical buyer. Suppliers say that every transaction is unique, and they have interest from all over the world. However, the majority of used turbines that Windbrokers sells go to eastern Europe and Latin America.
Some countries are easier than others for used turbine import. Windbrokers does not sell to the US because its 60Hz grid frequency differs to the 50Hz used by European power grids. Van den Bosch explains that it is too difficult and costly to convert the turbines to make the US a viable market.
So what are the advantages of investing in used turbines? The main one is that they are cheaper than new ones. For developers who want to keep costs as low as possible and still generate a good income, they may be worth considering.
However, there is still limited knowledge of how long and how well they will function. Therefore, banks and financial institutions are nervous about investing in second-hand machines. To help allay the fears of financiers and buyers, Windbrokers provides its used turbines with a two-year product warranty, but the majority of buyers still use their own money and take on the risks themselves.
Oxana Danilevich, project manager at used-turbine supplier Blue Planet, says her clients are often unwilling to take out insurance as they want to keep costs as low as possible, and warranties increase the price. "We try to give warranties to our clients so that banks will be more willing to take a risk, but most of our clients want to pay as little as possible, which is why they are after a second-hand product."
Danilevich would like to see a financial institution that would be willing to co-operate with his company by providing insurance or warranties that the used-turbine supplier could offer cheaply to bargain-hunting customers, which would make the turbines a less risky investment for banks.
Difficult to value
Klaus Hansen, a senior engineer at certification body Germanischer Lloyd (GL) says that one problem is that it is very difficult to put a value on a used turbine. Manufacturers and operators have limited experience to actually know for sure how long these turbines can operate. "Only time will tell," he says.
For its part, Windbrokers has developed a formula that provides the theoretical value of a used turbine. "Prices are however determined by the market, and are always going up and down. There are some models like the Vestas V47 and V52 which are always in demand," adds Van den Bosch
In Hansen's experience, only manufacturers and not operators have the technical documentation to be able to make estimates of the life expectancy of particular models of turbine. In order to provide some clarity, GL published guidelines in 2009 to help assess the condition of a turbine. One method is a desk-based analysis of turbine data, which also takes into account site-specific conditions. An alternative is to inspect the turbine in person in the same way a car would be inspected to test its roadworthiness.
If a second-hand turbine needs spare parts, these are generally available to keep them running. Vestas says that it can offer spare parts to all turbines it has in service. Many wind-turbine manufacturers make use of third-party components. One exception to this is Enercon, which produces everything itself, making it harder to source spare parts and technical documentation for its equipment, says Van den Bosch. For this reason, Windbrokers has not sold any Enercon machines, says Van den Bosch.
Fit for the grid
Another obstacle to the second-hand wind market is that many grid operators will not accept power from older turbines on to the grid. Since the turbines are typically being sold to buyers in locations where wind energy has never been installed before, grid operators are not familiar with wind turbines and can be scared of turbines producing power when not required and tripping the grid.
This can easily be avoided by installation of low-voltage ride-through (LVRT) technology. Newer turbines tend to be equipped with LVRT as standard to enable them not to trip when the voltage on the grid is temporarily reduced due to a fault or load change on the grid.
Van den Bosch says a solution to this problem would be to make it obligatory to retrofit second-hand turbines with a switch which immediately cuts off the turbine from the grid as soon as the grid goes down. He says this would allay the main fear of grid operators that a turbine will continue to produce power on to the grid even if it is down. This switch can easily be installed between the main switch of the turbine and the transformer.
If the market for second-hand turbines is able to overcome these challenges, one question remains. Could second-hand turbines compete with cheap new machines from China to supply emerging markets? Even Van den Bosch is not that optimistic. "The quantity of available used wind turbines is too limited to play a significant role in these emerging markets."