Giving wind turbines a “spider sense”
Okay, the “spider sense” part is a bit of a stretch, but being a Spider Man fan I had to throw it in. Actually, what I’m talking about is a new type of LIDAR (Light Detecting and Ranging) device that’s designed to integrate into the nacelle of a wind turbine. The laser system, developed by a Manassas, Virginia-based company called Catch The Wind Inc., projects three beams up to 1,000 metres in front of a wind turbine. The colour frequency of the beams change when dust particles pass through them, and the colour is directly proportional to the distance of the particle — and thus the wind. Using this approach, based on the Doppler principle, the three beams work together to calculate both the speed of the wind and its direction.
Why is this important? Unexpected and sometimes abrupt changes in wind speed and direction can affect wind-turbine efficiency and put a lot of stress on blades and other components. Turbines can be repositioned and blade pitch can be changed to reduce this stress, but currently this only happens after the wind has hit. Since maintenance costs are proportionate to wear and tear, it benefits wind-farm operators to reduce wear and tear. At the same time, improvements to efficiency means improvements in revenue.
By giving turbines a kind of “spider sense” — that is, by integrating the laser sensor into the control system of the nacelle — the turbine can be given advance warning of wind gusts, turbulence, direction changes, etc… before they hit. Catch The Wind has designed its system to give the turbines about 20 seconds notice. Again, this is important because currently turbines only react after they’ve been hit.
Now, there are other LIDAR systems used in the wind industry, but only for collecting field data — either as part of a weather station or by wind “speculators” who are trying to find ideal wind-farm sites. These systems shoot their beam into the sky and measure wind speed and direction directly above. They don’t project horizontally in front of a turbine. Also, existing LIDAR systems are more bulky and rely on precisely positioned mirrors, making them less rugged and unfit for long-term positioning on a nacelle under a variety of weather and temperature conditions.
Catch The Wind’s LIDAR is all-fiber-optic — i.e. no mirrors. The lasers are directed by optical fibers. This makes the system light, small and rugged enough for integration into a turbine. The company still has much work to do to prove its device functions as claimed, and to prove it would provide enough of a return on investment to matter to the wind folks. So far, however, preliminary tests are encouraging.
See article in Technology Review for more information.