The processes at work behind harnessing wind and converting it into electric power are more complex than a quick surface glance might reveal. It isn’t simply placing a wind turbine in a windy area and letting the wind do its job, although that is the gist of it. Other factors are taken into account that dictate how fast and when the rotors of a turbine will spin so that wind is used as efficiently as possible.

One of the biggest recurring issues behind maximizing wind’s potential is working around one of the wind’s inherent qualities: namely, its intermittency. Since wind speeds fluctuate over the course of the day, researchers are investigating methods to help turbines generate a consistent flow of electricity that doesn’t vary as wildly as the wind speeds. A recent study from a team at Iran’s University of Science and Technology, for instance, takes a more detailed look at the “exergy” of wind power at various wind speeds. For those without a doctorate in thermodynamics, exergy is simply the available energy to do work within a system. By taking a more nuanced look at the wind potential at various wind speeds through improved exergy analysis, the Iranian researchers hope to better define a wind turbine’s cut-in, rated, and furling wind speeds, so that usable energy is maximized at any given wind speed. Based on exergy analyses at two Iranian wind sites, one in Tehran that experiences slower wind speeds and one in the windier town of Manjil, the Iran University of Science and Technology researchers formulated optimized values for wind turbine rotation speed, which can be altered depending on wind speed. Utilizing these values to manage rotation speed would theoretically yield a 20% increase in efficiency and an 80% recover of otherwise “wasted” energy.

Researchers at the University of Wisconsin – Milwaukee’s Department of Electrical Engineering and Computer Science are also working to improve wind turbines’ handling of intermittency. The Milwaukee researchers have taken a similar “exergistic” approach in addressing how to maximize a turbine’s energy output, in this case, using the inertia of the spinning rotor as an energy storage component. Using a braking control algorithm that adjusts the rotor speed, the rotor is allowed to speed up when incoming wind power is greater than average so that it can store the excess energy as kinetic energy rather than generating a surplus of electricity. This energy is released when wind power output falls below average, helping combat inefficiency by keeping the power produced steady and usable on the electric grid.

Of course, an updated and modernized transmission network would go even further in combating inefficiency and creating a more robust energy market. However, advances in technology that help turbines harness the variable wind energy in a more consistent fashion further show that the problem of intermittency isn’t insurmountable. We just haven’t been thinking “exergistically” enough.

Advertisements