carbon limited

As flagged up by Tom at XCO2e, the Warwick wind trial final report (pdf) is out and the results aren’t good. Keeping in mind that the trials included only sub-2kW turbines, there are some important things to take away from the report:

1. We consultants must be cautious – it’s not enough to take an average wind speed or a predicted output from the London Plan and think it has any relationship to reality. It’s becoming even clearer that a lot of site specific analysis is required before considering micro-wind.
2. NOABL isn’t applicable in the built environment – the study found that the NOABL database consistently overestimated wind speeds by around 16x relative to measured data. The study recommends scaling factors for NOABL data that bring the predictions in line with measured data (these are based on a limited sampling period so should be treated with caution – but it’s a good start).
3. Manufacturers can’t be trusted – using measured wind speeds and manufacturers’ power curves overestimated power output by 170% – 340%. As the report points out, there are other reasons why this might be: accuracy of monitoring equipment, response times, etc. But check out the graphs on page 30 of the report showing sampled power output vs. manufacturers’ Cp curves. OUCH!
4. Micro-wind in the built environment may be a bad application of a good technology.

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