RE: [cdn-nucl-l] " Norway tries underwater 'windmills' "

[George Stanford <gstanford@aya.yale.edu>]

Jaro:

        Thanks for the additional info and comments. 

        Your 3,000-kWh number for the Ontario house means an average consumption rate for February of (3000/28/24) = 4.5 kWe, somewhat higher than the 2.6 kWe that the Norwegian house would get if all its energy came from the watermills.  The tide flows no faster in winter than in summer, so without another source of heat, the annual-average daily energy available is also the maximum for any given day (with some fluctuation because some tides are higher than others).

        To supply 30 Ontario houses with watermills alone, they would have to have an annual capacity of 30x4.5x365x24 = 1.2E6 kWh, which is 39,000 kWh per home per year.  Actual annual consumption, of course, would be a lot less than that (as you implicitly point out), since much of the capacity would go unused, most of the year being warmer than February.

        Also, the above leaves no reserve for a below-normal cold spell.   In practise, absent efficient energy storage, , watermills would only be used in conjunction with other sources of power. Although their output is more predictable than windmills', it does fluctuate between zero and maximum with a period of 6.2 hours. As with wind power, it's not clear to what extent the need for installed capacity of other types would be reduced.  For space heating, perhaps the power supplied to the heaters could be synchronized with the tides, assuming heaters with high thermal inertia.

        In view of its cost, periodic nature, and possible ecological consequences, the technology does not seem promising for anything but very limited niche applications.

        Cheers,

                        George
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jaro Franta wrote:
Date: Sat, 27 Sep 2003 09:49:29 -0400

If one just divides
700,000 kWh by 30 homes, its 23,300 kWh per home per year. 
That's very high.
Here in Canada, the average annual consumption per home (Ontario) is just
under 12,000 kWh.
(in the coldest month (February), a large electrically-heated home
consumes something like 3,000 kWh)
But as you point out, the price per installed kW is astronomical -- and
doesn't even cover (or at least there's no mention of it in the article)
electrical batteries for energy storage during periods when the tide is
turning around, thus there's no, or little, current.
 
One thing that I find
appealing in the concept though, is that the flow past the
"underwater windmill" is always in a predictable direction, so
you don't need to have a rotating cab on top of your tower and, even
better, you can brace the tower in the plane of high overturning moment,
instead of the omnidirectional resistance one must build into ordinary
dry-land windmills....
 
But I'm not so convinced
of the harmlessness of such installations to cetaceans & other large
marine animals, as claimed in the article (I suppose the Norwegians have
a different perspective on this subject, since they're one of the last
countries in the world still practicing whale hunting...).

 Jaro 
^^^^^^^^^^^^^^^^^^^^^

-----Original Message-----

From: cdn-nucl-l-admin@informer2.cis.McMaster.CA [mailto:cdn-nucl-l-admin@informer2.cis.McMaster.CA]On Behalf Of George Stanford

Sent: Friday, September 26, 2003 10:34 PM

To: multiple cdn

Cc: trandall@mishoreline.com; gmarsh@anl.gov

Subject: Re: [cdn-nucl-l] " Norway tries underwater 'windmills' "

                The article mentions "700,000 kilowatt hours of non-polluting

energy a year, or enough to light and heat about 30 homes."  If my

arithmetic is correct, that's an average output 80 kW, or 2.6 kW

per home.  Is that enough for a house in a Norwegian winter?.

        "The plant in the Kvalsund channel, which had cost about

$11 million by Saturday's launch . . . " Again if my arithmetic is

correct, that's $137,000 per average installed kWe.  Compare

some $600 for a gas-fired plant, and maybe $1500 - $2500 for

a nuclear plant (or is my estimate for nuclear high?).

        George Stanford

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

At 04:35 PM 9/24/2003, Jaro Franta wrote:

Date: Wed, 24 Sep 2003 17:35:20 -0400

Something weird with the numbers in this article...  (installed capacity,

for one, seems very small, even assuming a low CF).

....but they sure don't mince words, when they state flatly that "Aboveground

windmills, by contrast, are useless in calm weather and have to be built to

withstand hurricane-force winds."

Wonder what the maintenance list includes... cleaning barnacles off the

blades ?

 Jaro

^^^^^^^^^^^^^^^^^^^^^

http://www.msnbc.com/news/969748.asp

Norway tries underwater 'windmills'

Tides turn blades, providing power to local homes