Google & Siemens Show What's Possible in Green Energy
The IntegralBlade design has no glue joints in the turbine blade. The commercial version of this rotor will have a diameter of around 154m and a total sweep area of 18,600 square meters. (Source: Siemens)
Wind turbines are deceptively complicated. The image included with this article caught my eye first; I was surprised to see the entire rotor assembly lifted as a whole instead of being assembled one blade at a time on the nacelle. But weight and balance means the first blade on makes the other two much more difficult.
The nacelle hides another complex mechanism - the gearbox. The rotor spins relatively slowly (even if those blade tips are really hauling!), the gearbox output shaft turns much faster to run at speeds useful to a generator.
The mass of the rotor assembly and gearbox is substantial; I'm pretty sure one could not use simple weather-vane control of pointing direction. I've seen some fascinating laser-based systems to detect air particle motion to give wind direction.
As with most technology development, there are often wrong directions taken and too much effort put into making the deficiencies acceptable. These sorts of wind turbines – horizontal axis - have major issues, few of which are mentioned much, especially not in these items. The deficiencies they have may, or not, be overcome in time, but there are much better designs of turbine that have been sidelined - a sort-of repeat of Beta v VHS thing.
The development work done to overcome the deficiencies is generally good - it adds to the body of knowledge available, as long as someone remembers to apply it in other areas of endeavour and not 'reinvent the wheel'!
Wind is actually not a great source of energy anyway - I live in NZ where we have quite a few wind farms - on a clear air day, I can see a farm on the ridge line if some hills around 50km away - often, they are not turning, even though the wind is blowing sufficiently - Why? Because there isn't the load required and the generation company didn't bid a supply price low enough to 'win' capacity. As they stand, wind farms, of the size they currently are, cannot supply base load, the wind is just not steady enough or predictable enough in most places around the world. This leaves them to provide the next layer up in load, but there needs to be 'rotating capacity' that can pick up load as the wind farm drops off or, more importantly, can quickly be dropped off as load falls.
The key to 'intermittent' alternative and 'green' energy is efficient storage. The Snowy Mountains Hydro Scheme in Australia is a step in the right direction – pump water up to a lake using 'off-peak' low value electrical energy available from large base load generators and alternative energy generation that is out of sync with demand load and then let the water run through a hydro station to generate power for peak demand load. They make money from the difference in price paid and received and do quite well too.
Unless pumping can be more efficient, then I don't see this as a major solution, just a pragmatic solution for now.
In the future – and not too far either, wind turbines will probably be seen as 'not such a good idea', unless politics and silly amounts of money are used to skew matters.
And the issues with horizontal axis wind turbines? Infrasonics and their harmonics, vaguely reasonable efficiency (good enough to be interesting, but probably could not be made to be much more efficient without radical technology improvements), shadow flicker, airspace hazards and ugly.
Pump storage for hydroelectricity. That is a tried and true option. However, quite a bit is lost in simple evaporation. But is any system lossless?
It's green-ish. Turbines, like most green generators, take several years to re-coup the costs i manufacturing. It takes approximately 9 months to generate the amount of energy used to create the turbine. But then it take years to get a return on the investment.
Without government subsidies, I doubt anyone would use them.
I don't think green energy is ever really stored. Just like electric vehicles the battery (whether electrochemical or mechanical) is always the achilies heel of the whole idea of alternative energy. Green energy only supplies on demand (i.e. it saves by lowering the amount of carbon or nuclear energy needed).
I think that in terms of alternative energy, it will be a LONG time before we have generation capability that exceeds demand so it's not really a problem. Even if you did, such massive amounts of energy would require a whole new technology to store. Perhaps massive flywheels or hydroelectric lakes above dams (when generating electricity use the excess to pump water back up to the higher altitude storage lake).
Better yet, have wind farms generate NO electricity, just pump water up (put a bunch up near niagra falls and Hoover Dam). This would make the energy conversion more efficient as well. You used to see such things on farms all the time (way back when it was the only way to get running water out of a well that didn't involve a hand pump).