Steadying the wind

An ‘exergy’ analysis of wind turbines sited in two cities in Iran, Tehran and Manjil, where wind speeds are very different, promises a boost in efficiency by 20 percent and 80 percent decrease in wasted energy! The scientists’ formula offers optimized values for wind turbine rotation speed, which can be altered depending on wind speed.

Exergy is a term from thermodynamics that measures the energy in a system that is available to do work.

Turbine design must meet load requirements and produce energy at a minimal per dollar cost. In order to address this cost issue, performance characteristics such as power output versus wind speed or versus rotor angular velocity must be optimized. Exergy analysis looks at the "quality" of the energy produced by a system.

The Iranian scientists have now developed an improved exergy analysis for wind turbines, which considers the kinetic exergy of the wind in much greater detail. Their approach offers a way to optimize a wind turbine's three main parameters, cut-in, rated, and furling wind speeds, so that usable energy is maximized at any given wind speed from the gentlest breeze to a roaring gale; within the safe working parameters of the turbine.

Meanwhile some cheer for the sector. Large amounts of capacity of hot standby is not the only way to deal with variability of wind or solar energy. The variability of renewable energy sources such as wind, often cited as the sector’s Achilles’ heel, does not have to be a problem, according to a report by National Grid, the electricity operator in UK.

New network technology could play a strong role in managing renewable energy variability instead of back-up generation alone, it says.

Smart meters and grid would allow electricity demand to be actively managed – for example by automatically shifting demand to off-peak times. Electric vehicles, flywheels, compressed air, etc are also considered as storage options in the report.