I was once told by a very experienced engineer, involved in wind turbine
design, that the energy used to manufacture all these devices can actually
exceed the energy they will produce over their lifetimes. I haven't worked
any numbers out for myself, but it would be interesting to see if he
I have no idea if that is true.
However, they are generally reported based on the maximum capacity of the
associated generator. That is misleading as that level of power is rarely
generated.
Most turbines require a wind of 14 m/s to reach rated power. One of the few
caseswhere wind in
1 kW·h = 3.6 MJ (megajoules). Mostly :-)
Stan
- Original Message -
From: James R. Frysinger j...@metricmethods.com
To: U.S. Metric Association usma@colostate.edu
Sent: 09 Sep 04, Friday 14:44
Subject: [USMA:45733] [Fwd: Energy and power]
I recently posted this email to Rick
Of course they will never pay for themselves (otherwise they would have been
all over the place paid for by private money). Their electricity also will
not get relatively cheaper when oil prices go up. Nor will wind mills reduce
foreign oil consumption. Electricity production is unrelated to
Stan,
You provide a figure of 1 W/m2 for a quality site. Is that area in the
denominator the land area, the blade surface area, or the blade-swept area?
You've raised many valid points which one will not see discussed much,
if at all, by green-wind aficionados.
Jim
Stan Jakuba wrote:
I am having trouble relating to Stan's figure of 1 W/m². However, the usual
development of the equations looks at the swept area of the rotor.
The machine can only extract a fraction of the wind power, 30% overall being
GOOD.. This page gives a reasonable development of the equations:
Taken out of context, it was not clear that the W/m² refers to the land. It is
meant to be reflective of the section of the Earth's surface that is occupied
by the towers to the max practical density. The larger the propeller, the
larger the radial and axial distance between adjacent towers.
This did not go thru the previous time
- Original Message -
From: Michael Payne
To: U.S. Metric Association
Sent: Thursday, 03 September 2009 14:48
Subject: Re: [USMA:45721] Measurement in the UAE
I don't think this is an entirely accurate picture. I lived in Abu Dhabi from
1980
Dear All,
The Telegraph at http://www.telegraph.co.uk/education/6138456/Maths-standards-no-better-than-mid-70s.html
and
the Daily Mail at http://www.dailymail.co.uk/news/article-1211345/Maths-skills-standing-thirty-years-GCSE-grades-soaring.html
have both reported that metrication has
