With wind power getting cheaper, wind farm developers are drawing up plans for farms an order of magnitude bigger than anything around today, some with more than 1,000 turbines. But there’s one big problem: the economics of wind farms depends on accurate predictions of power output, and it is far more difficult to model how such large wind farms will behave.

At the scale of several hundred to over a thousand wind turbines, simulating the interactions between so many wind turbines, in a range of different weather conditions, can be too complex for current computer models. The issue could have profound implications for the cost of wind power and its ability to scale up to replace large amounts of fossil fuel.

About five years ago, poor data gathering and ineffective computer models meant wind developers were prone to overestimating the energy production of their farms by over 10 percent, enough to destroy profits and in some cases prevent them from making loan repayments. Models have improved, but the jump to larger wind farms, and the increasing prevalence of ordinary wind farms built close enough together to interfere with each other, is raising the issue again.

Some researchers and industry experts say that while computer models have become good at estimating the production of typical wind farms of between 50 and 100 wind turbines, they will have trouble at much larger scales. "If you were to go to 1,000 wind turbines, the industry’s tools would start to break down," says Keith Longtin, general manager of product management at GE Power and Water.