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General Chat Thread, kickstarter.. in General; Originally Posted by Greenbeast there fixed that for you Err, if you have normalised to Wh, the surely all your ...
  1. #76


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    Quote Originally Posted by Greenbeast View Post
    there fixed that for you
    Err, if you have normalised to Wh, the surely all your figures should be the same, 1 minute of 54Wh is still 54wh (or 0.015W) (or watt seconds if you must)

    The scheme sounds a bit like SheerWind’s Invelox rig. I'm not sure I see any real advantage over the swept area a standard blade turbine or VAWT.

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    featured_spectre's Avatar
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    A standard blade turbine and a *standard* VAWT doesn't allow for much up or down draft...my design does.

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    Quote Originally Posted by pcstru View Post
    How much energy is there in a meter cubed of our lovely atmospheric gas mixture moving at 10ms-1 anyway?
    I do so hate it when interesting questions are allowed to writer around on teh floor and die due to lack of nourishment. So let's see :

    Air at sea level @15deg C has a density of around 1.2Kg per m^3. So energy wise, if that is moving at 10ms-1, it has 117 joules (KE) and at 100% conversion efficiency that would be 117watts. So in a 22mph "fresh breeze" (5 on the beufort scale), a 1m ^2 area can't do any better and will in all cases be considerably worse - I think 50% efficiency from that wind energy to electrical power out would be remarkable. Apart from anything else, 100% conversion involves the air stopping dead (you just extracted the energy) - which means the next lot has to push that out of the way. So typically for that 1m^2 in a fresh breeze, you will be able to get around 30watts maximum, if you optimise your genset for that scenario. To run a two bed house from four of those you can see your average consumption cannot exceed 120 watts. If you want to use a kettle or immersion, you are going to have to add a stack of batteries or export to the grid and import any peak above that.

    Of course, if you live in a universe where passing trains can power the turbines without expending any energy themselves, then normal physics may not be playing any part - so scratch all that and carry on. And the very best of luck to you!

  4. #79

    plexer's Avatar
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    hmm ok so train rushing past station creating gust of wind what happens to that excluding having a turbine there?

    Ben

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    Quote Originally Posted by plexer View Post
    hmm ok so train rushing past station creating gust of wind what happens to that excluding having a turbine there?
    If we look at the train, it is having to push the air out of the way. The air in front of the train will be accelerated by the train, but will tend to be pushed to the side. So you get a kind of bubble of air moving along with the train - it has a nice rounded front that extends out ahead of the train and a sort of ragged pointy tail that finishes somewhere behind the train. So without the turbine, that bubble kind of moves along with the train in it's optimal for that train configuration.

    The easy way to visualise the effect of the turbine is to imagine the train passing through a hole in a wall exactly the size of the train. In that case the train effectively hits a wall of still air as it emerges from the hole. It has to make a new bubble by accelerating a whole load of air (the optimal bubble sized volume). Nothing else will do the work for it, so the energy must be supplied by the train.

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    Quote Originally Posted by pcstru View Post
    Err, if you have normalised to Wh, the surely all your figures should be the same, 1 minute of 54Wh is still 54wh (or 0.015W) (or watt seconds if you must)

    The scheme sounds a bit like SheerWind’s Invelox rig. I'm not sure I see any real advantage over the swept area a standard blade turbine or VAWT.
    sorry I was just heading out to lunch.
    I'm a member of a renewable energy forum and we're always seeing people mucking their units up

    Too be fair, Watts don't scale up over time, i.e. it wouldn't generate more watts of power the longer it was left on, it would generate a fixed quantity of watts for a particular size of turbine (in identical conditions)

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    Quote Originally Posted by Greenbeast View Post
    sorry I was just heading out to lunch.
    I'm a member of a renewable energy forum and we're always seeing people mucking their units up
    We have bizarre hobbies. I'm a (founder) member of a forum which is fascinated by free energy devices. We see people mucking their units up quite deliberately. We have a whole lexicon (with con being the operative word) for mis-measurement!
    Too be fair, Watts don't scale up over time, i.e. it wouldn't generate more watts of power the longer it was left on, it would generate a fixed quantity of watts for a particular size of turbine (in identical conditions)
    I was really just commenting that (say) 3600Wh is 3600Wh, if you measure the instantaneous power (W(s)) it's 1W, but that's still 3600 if you express that as Wh. So when you 'corrected' the figures into Wh :

    Scaled to 1 minute this equates to 0.9Wh.
    Scaled to 1 hour this equates to 54Wh.
    The figures should all be 54Wh. I think.

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    ah I get you.

    yeah we get the free energy lot in all the time. Usually much fun is had stringing them along

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    54Wh over a 1 hour period is 54W. Over a 24 hour period this is 1296W. 4 of the "turbines" at 54Wh over a 24hour period, would be close to 5KW (just over). Please tell me how 5KW is not enough to run a house over a 24 hour period? Unless my maths is wrong here...

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    I think it's just units mixed up there, i.e. 54W over 1 hour is 54Wh, not other way around

    happy to be corrected

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    Depends what you are doing in you house. 5KWH would let you run 3.6 60W light bulbs all day! Switch on the kettle (3 KWH) a few times, watch TV, run a computer (~100W) idle, maybe 500W if I crank it up to play a game. Oh - you want to cook dinner using multiple 3KW rings and a 4KW oven - better make it quick then! Immersion heater for a bath (3+KW) - might be a bit tepid if you have a large tank so better take a power shower (10KW) but don't linger! Washday might eat into your allowance and the average energy consumption for heating homes in the UK will easily exceed 5KW (I think it's around 7KWH per day) before you even switch on an appliance.

    Then you have the wind. 5KWH per day would assume the wind is Beaufort 5 all day , every day. Pull the data for anywhere in Bedford and you will have to revise your calcs right down - probably by an order of magnitude. One of the problems for domestic settings for turbines is the houses tend to act as windbreaks - your device might be better at dealing with turbulence but it can't make wind that isn't there.

  12. Thanks to pcstru from:

    featured_spectre (4th July 2013)

  13. #87

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    I am ridiculously festidious about energy saving.

    All bulbs in my house are 1.7w max (LED bulbs FTW)
    My kettle rarely goes on, if we need to boil water, then yes it goes on, otherwise we hardly use it.
    Cooking - granted, cookers use a lot of energy but again, we tend not to cook much, we prefer fresh veg and fruit and not much meat in my house. Only time I ever use the oven is if I am baking something or roasting meat (again, rarity).
    Immersion - never been on in my house since I've moved in.
    No power shower in my house either!

    And granted, it can't make wind that isn't there I agree. However you have given me things to think about.

    In your estimations, it could provide 25% of the household energy needs, and if a person uses solar as well, happy days, surplus energy!

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    Quote Originally Posted by nephilim View Post
    In your estimations, it could provide 25% of the household energy needs, and if a person uses solar as well, happy days, surplus energy!
    Well no. In my estimation you will get a .5KWh daily average out of 4 units IF you are lucky. How that stacks up as a % of your consumption should be easy enough to determine by looking at your electric bill. IMO you would do better (per £ invested vs the return) with solar - you can DIY your own panels reasonably cheaply and configure them so they will generate even on an overcast day. Every day has light - but not every day has wind.

    I've made two wind turbines - a 3 blade (blades made out of waste pipe) driving a custom generator and a VAWT using the same generator. They were quite fun to build and I learned a lot from them. They don't figure in my energy generating future though and there is a reason for that! Perhaps you will do better and in that, I wish you luck.

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    plexer's Avatar
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    Ah so the caveat is that anyone using 2 to power the house have to use naff all power

    Ben

  16. #90

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    Quote Originally Posted by nephilim View Post
    we tend not to cook much, we prefer fresh veg and fruit and not much meat in my house. Only time I ever use the oven is if I am baking something or roasting meat (again, rarity).
    Really? I am sure you have posted before about buying lots of meat from local butchers? Have things changed then?



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