In order to keep offshore turbines light and as energy-efficient as possible, engineers are looking beyond superconductors for a new approach.
According to IEE Spectrum, permanent-magnet technology should help with powerful turbines, potentially lightening the already extremely heavy loads. Typical offshore towers are very powerful, heavy, large, and, as far as gas turbines are concerned, hot. In fact, gas turbines operate at much higher temperatures than steam turbines — typically, at 2,000 degrees Fahrenheit versus 1,200 degrees Fahrenheit for steam turbines.
Conventionally, bigger and more megawatts per turbine have been better. But if the turbine industry doesn’t find new ways to adapt to the growing emphasis on reducing machine weight, bigger turbines will soon become much worse.
A European Union project called InnWind calculated that if a 20-megawatt turbine were to be built with today’s technology, the outer casing of the machine would weigh 2.4 million pounds — which is simply unobtainable. Not only that, but its three blades would have to span a diameter the length of eight blue whales. Again, unfathomable.
“The problem is that there is a limit for constructing with current technology,” said Iker Marino, an electrical engineer at Spanish applied-research organization Tecnalia Corporacion Technologic. “The weight of the top of the machine is too huge.”
Superconductors have worked well for reducing weight, but permanent magnets are seemingly even more successful. These permanent magnets can help replace the direct drive’s magnets with lighter electromagnets made from coils of superconducting wire.
Finding a way to minimize weight and maximize efficiency has been extremely difficult for those working in the offshore energy sector.
“All the engineering around heat extraction is feasible but complex,” added Marino. “Offshore conditions are a problem for complexity.”
Though engineers and energy officials are working tirelessly to reduce the size and weight of the world’s offshore turbines, there are still plenty of projects developing in the U.S. and other major nations that are doing the opposite.
RECHARGE adds that project developers across the globe are increasing their deployment of larger rated turbines, often with larger ratings and longer rotors, in order to improve competitiveness in power auctions.