Take out the middle turbine (above) for a better idea on how far apart turbines should be for optimal power production, based on this new research. Photo: FranceHouseHunt.com/Creative Commons
Some new research on the importance of proper spacing in getting the most out of commercial-scale wind farms: Currently wind farms space turbines with 300' rotor diameter about seven rotors diameters, roughly four-tenths of a mile apart. What engineers from Johns Hopkins University and Katholieke Univeritet Leuven in Belgium determined is that an optimal spacing for turbines of this size is more like 15 rotor diameters apart, just under a mile.
Earlier computational models for large wind farm layouts were based on simply adding up what happens in the wakes of single wind turbines, Meneveau said. The new spacing model, he said, takes into account interaction of arrays of turbines with the entire atmospheric wind flow.
Meneveau and Meyers argue that the energy generated in a large wind farm has less to do with horizontal winds and is more dependent on the strong winds that the turbulence created by the tall turbines pulls down from higher up in the atmosphere. Using insights gleaned from high-performance computer simulations as well as from wind tunnel experiments, they determined that in the correct spacing, the turbines alter the landscape in a way that creates turbulence, which stirs the air and helps draw more powerful kinetic energy from higher altitudes. (Science Daily)
Some ways to think about this:
- Oh great, now big wind farms have to take up even more space to optimize electricity production and getting the biggest of these approved now can be difficult balancing the needs of clean energy production, conserving ecologically sensitive areas, not ruining important views, and keeping neighbors happy (and if they live too close by, perhaps, healthy). But maybe not.
- Maybe wider spacing actually reduces visual impact a bit, even if overall area occupied wind turbines for the same amount of power increases. Think about it, from a distance half a mile is far closer together than a mile. Perhaps the lesser density will actually sway some wind farm NIMBYs.
- It may seem like the wind power potential on a given area of land now goes down, but perhaps the power boost from better spacing makes up for the lower turbine density--at least from what I've seen the researchers didn't give a specific figure for how much more power is produced.
- Maybe this lower density actually means that the number of turbines needed to generate a given amount of electricity actually drops. Remember that even if a project is rated at x megawatts that it only produces a fraction of that in electricity due to the fact that wind speeds aren't always optimal, maintenance, and a variety of other factors.
Lots of variables here in terms of interpreting what this means outside of the computer model and wind tunnel.