20 thoughts on “Weekend reflections

  1. The backflip on Wilkie (which really was not a surprise) does raise a serious point with me and how our political system works, especially with independants. Up until now Wilkie has sided and agreed with the governments bills (whether he agreed with them or not), on the presumption that Gillard will follow through on his signed agreement on pokie reform. But with the backflip he is threatening to withdrawl his support on the Medicare rebate. So what we should be asking of independants is Bills should be voted on by them on the basis of their representations at their election, is it benficial for Australia, and is it beneficial for my electorate. But what this has demonstrated is you vote for this and I will vote for this, irrespective on whether you would have voted one way or the other. Now reality will start to hit home for many Independants (or Minor Parties) are really not truly indepeandant and can really mess up a country.

  2. @TerjeP

    Oh no, TerjeP, now you won’t get that beloved nuclear power plant over your back fence!

    Seriously though, it’s good news. This illustrates the simple but effective advances that are still possible in renewable energy.

    I am waiting for someone to build a vertical solar chimney turbine structure that uses both wind and solar convection from a tarmac-greenhouse to get the synergy of using both together. The tarmac-greenhouse would have shutters that auto-open on the windy side and auto-close on the downwind side. Plus the tarmac would heat the air too and make it rise faster.

  3. @Ikonoclast

    What you outline is pretty much what I imagined some years ago would be a popular approach to despatchable “solar” power. I had in mind a kind of black metallic “apron” over the tarmac with concentrating reflectors onto the apron, and the tower making use of the rising hot air to turn a turbine. Underneath, a heat-absorbant material would retain surplus heat allowing continuing operation outside of daylight hours.

    If the tower were high enough at the top (say 500m), the differential in pressure between the base and the exit would ensure an updraft, so even in the middle of the night, without external heat, there should be output.

  4. I wasn’t able to watch the video for the wind lens because I don’t have the bandwidth for it (I’m in Australia). A standard wind turbine will extract about 44% of the energy from wind passing through the circular cross section made by the rotating blades. A donut wind lens effectively increases the cross section of wind captured, but I don’t see how this is a better solution than just making the blades longer. After all, there is only so much energy to be captured in a given cross section and the lens isn’t going to change that, so I don’t think we’ll be seeing these lenses on large wind turbines, but they might be good for micro turbines or turbines built in populated areas.

    One type of wind lens I thought might catch on is building a slope around the base of the wind tubine, but again, probably easier just to make the blades longer. (But it’s still nice to know that we have a simple, low tech solution to getting more electricity out of existing wind turbines if there is ever some sort of energy crisis.)

  5. @Ronald Brak

    Speaking as someone with a long term interest in turbines, there are advantages to producing the same output with shorter blades. Most obviously, one has greater site flexibility since they can be placed closer together, and of course maintenance is simplified. Having the turbines at lower elevation allows acsess to a denser air mass and in this design, wind-shear ought not to be a problem. The scope of the hazard to birds/bats is also reduced. Also, the pressure at the bearings is reduced and one can build smaller and cheaper bearings. Transport is also simplified and one can manufacture components in a wider variety of places.

    Having watched the video (I’m in Australia too, so I don’t get the bandwidth constraint comment) it seems they are trading in part on the “differential draft” effect, so that low pressure on one side of the turbine sucks air through. I imagine the same might be achieved with marine turbines, and since the Japanese are looking at placing these turbines on floating pontoons on a bay, one can imagine that one might try adding some similar marine turbines.

  6. According to my service provider I have 23 gig data allowance left and it just took me 8 minutes and 47 seconds to almost download a 4 minute 5 second, low quality Janis Joplin youtube video. (Damn Janis Joplin is good! Why didn’t anyone tell me this?) I didn’t get the whole video because the connection died towards the end. I am close enough to the telephone exchange to walk to it in half an hour and give it a good kick. Sometimes my connection is fast, but often it is slow. So, is it reasonable for me to complain, or is this sort of thing normal?

  7. @Ronald Brak

    Currently $50 per month; 50GB (peak) 70GB (off peak) per day with Optus. It’s cable but speeds aren’t brilliant, though adequate for short youtube clips or similar.

  8. Thanks, I’ll have to give my service provider a call. Except my phone hasn’t worked since I got connected to the internet. It looks like I have fallen into their trap.

  9. Yes! It’s fast again for no adequately explained reason! Are they monitoring my online comments and sped it up so I wouldn’t complain? No wonder they charge so much. The surveillance costs must be phenomenal.

  10. It’s probably the case that variations in speed are a function of demand at your nearest switch or similar. If people near you are also doing bandwidth intensive stuff thrm your capacity will vary Then again, it might reflect hoe busy tje server carrying the data is or problems with your own modem/router.

  11. It was basically fine up until the start of this month, then it started really dragging. Being a surly misanpthrope I assumed my service provider wasn’t paying for enough lines. But one thing I noticed is a lot of work being done on the mobile phone tower across the road. I really don’t know if that could have an effect, but it make me decided to give my service provider the benfit of the doubt.

  12. Oh no, TerjeP, now you won’t get that beloved nuclear power plant over your back fence!

    I’m not ideological about the source. However there are still two issues that make me tilt towards nuclear over wind even if the virtues of the wind lens do end up halving the cost of wind power.

    1. There is a lot of scope for innovation in the nuclear industry. My favourite prospect is the LFTR.
    2. Wind suffers significant diseconomies of scale in terms of utility operation.

    That said I’m happy if clever people can make wind cheaper.

  13. @Ronald Brak

    “A donut wind lens effectively increases the cross section of wind captured, but I don’t see how this is a better solution than just making the blades longer.”

    If you had been able to see the video, you would have seen exactly why the wind lens works. It works by deflecting air that misses the blades away outwards from the downwind swept area of the blades and creates a low pressure turbulence area. (It’s clearer in a diagram. See Wikpedia http://en.wikipedia.org/wiki/Wind_lens ) This reduces pressure on the downwind side and speeds up the wind going through the turbie blades.

    It’s a kind of shunt. Slowing air flow outside the blades and speeding it up and shunting more air through the blades.

    I wondered at first that they did not go further and put an opening-up cone on the upwind side. However this would necessitate a down-wind rudder and in shifting winds, the whole assembly would shift, including the huge blades, and destroy the turbine blades with severe gyroscopic forces (is my guess).

  14. I’ve been told on another blog that the power gains shown in the video don’t scale so well. A small rotor blade will get a bigger boost from a wind lens than a large rotor blade.

  15. @TerjeP

    That sounds possible. Whilst the deflection from a “wind lens” can set up a low pressure turbulent area behind a small swept area it may not be able to do that so effectively for a large swept area.

    The scaled-up concept design still shows a wind lens on each prop. Have they tested a large prop and/or calculated the effects? I wonder. Still, any incremental gain is good.

  16. I will mention that wind lenses are not a new thing. Here’s one from a few years ago:


    They are not something that has so far been shown to be practical for large wind turbines. Building a huge moveable lens tens of metres across that can survive storms is tricky and expensive. They might be useful for some applications, but I think big wind tubines will continue to look much as they do now for the forseeable future, although they might be groovier with blades that feather, change shape, or extend like go-go Gadget arms.

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