Hi Dawie
>Surely it is something one can detail out if the building is
>designed from the start to have a 16' turbine on top of it?
If the energy gained figured against the energy (and carbon) costs of
any extra construction required, I suppose.
Dawie, AFAIK, where you live at the Cape of Storms, the roofs are (or
were) built to withstand the ungentle ministrations of the Cape
Doctor, gusts and all. Maybe they could reap some of it too without
falling down. Well, for about half the year anyway. Pity it's the
same half that the sun does most of its shining as well.
I haven't heard anything about the Western Cape's wattle tree
infestation for a long time, is it still a problem? Isn't it a
problem that might have an energy solution(s)? I know that in the 80s
poor people living in squatter huts in wattle forests were making
charcoal for sale, and being harrassed for it by the authorities
rather than aided and abetted. I think poor communities can get a lot
more than charcoal out of a wattle forest.
Long ago I worked at the Rand Daily Mail with your Premier and
ex-mayor Helen Zille, though not on the same beat (she did politics
and I did the Soweto edition). Does she have anything much of a
policy on issues like these? Helen wasn't brought up in Cape Town,
she's from Joburg. The South-easter's okay if you were born to it,
then you just accept it, but for foreigners the incessant gales take
a little getting used to, it's not exactly something you don't
notice. Maybe it'd be nice to have something good to say about it for
a change (and the wattles) (and the squatters).
Erm... you do still get the South-easter don't you? Climate change
didn't change it into a zephyr yet or something?
All best
Keith
>Indeed. The conventional wisdom with wind turbines is, "the bigger
>the better", and with reason.
>
>The interesting thing is the claim of rooftop suitability, which the
>same conventional wisdom warns us against. I wonder if that is
>purely a function of the small size: the literature does not
>elaborate. And I wonder if the problems with vibration apply only
>(or more particularly or equally) to North American timber and/or
>steel construction. I am not aware of any experience with
>heavy-masonry construction. Surely it is something one can detail
>out if the building is designed from the start to have a 16' turbine
>on top of it?
>
>Best regards
>
>Dawie Coetzee
>
>
>________________________________
>From: David House <[EMAIL PROTECTED]>
>To: sustainablelorgbiofuel@sustainablelists.org
>Sent: Saturday, 20 June, 2009 18:05:56
>Subject: Re: [Biofuel] A wind turbine for your home
>
>
>Friends,
>
>Responding to myself:
>
>David House wrote:
>> One can assume a standard sea level air density (0.0024 slugs per
>> cubic foot), in which case the equation becomes 0.0001423 AV^3 , where
>> A is expressed in square feet and V is in MPH. This results in a
>> figure for instantaneous power in watts. Area is of course pi times
>> the radius squared.
>
>My math is wrong there. I was taking information from something I had
>written 30 years ago ("Wind and Windspinners", p. 99), and 0.0001423
>AV^3 assumes an efficiency of 20% in the turbine. One hundred percent
>efficiency would be 0.0012 AV^3 .
>
>My apologies for the error. The basic point remains, which is that there
>is not much power in low winds to extract, and thus very modest reasons
>for trying to do so.
>
>
>d.
>--
>David William House
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