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All: I think a lot of
this is well known to most of you, and I apologize if I just missed
this discussion in the history. However, I think a clarification of
state-of-the-art is required, in the interests of ensuring that AWES
folks proceed with a clear understanding of what they are competing
against. To that end, I put a couple of graphics together, aligning
their scales. This is imperfect, but will provide clarity for
comparison. The key observations of note are
that in areas where wind turbines are erected, HAWTs are already
outside of most ground effect slowing. Observing Pareto's Law, they are
already in clean, strong air, and have a very large swept area in that
zone. The rate of increase of wind speed with increasing altitude slows
substantially. Increases above that level are non-trivial,
especially into the jet stream, but the higher the altitude, the more
difficulty in bringing energy usefully to the ground. The first graphic is modified from a Government of Canada graphic I ran across in the LTA material. http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/cbd/building-digest-28.html
The second graphic is modified from one of many scaled
representations of increasing HAWT heights and swept area diameters,
this one from EWEA from 2007 reproduced in this article. http://www.terramagnetica.com/2009/08/01/why-are-wind-turbines-getting-bigger/ The
following graphic from the successful Upwind project (now superseded by
the newly launched Innwind project) focusing on the increasing the size
of offshore wind turbines is instructive as well. The largest turbine
in the above image is the fourth largest on the image below. The
world's first 7 MW wind turbine was just inaugurated. 8 MW and 10 MW
wind turbines are being built. The Innwind project, with substantial
funding, is assessing the key technical challenges with achieve 20 MW
wind turbines for offshore use. Offshore, obviously, has an even
more drastic increase of wind speed above sea level. The
point of this is that AWES must compete in an area of diminishing
returns. AWES current realistic heights are not in massively stronger
winds than wind turbines today, but marginally stronger ones. HAWTs are
economic and full LCA price per KWH for new generation is now cheaper
than anything except gas generation in countries where fracking is
dominant. For
additional perspective, I've included below the current MAPS sounding
for one of the places I've paraglided recently. The wind speed increase
is in line with the average from the original observation.
Substantially higher wind speeds do exist above 5000', but the
difference between 500' and 5000' is a lot smaller than the difference
between 100' and 500'. Once
again, this is the reality of the space AWES needs to compete in, and
again I apologize for rehashing what is likely obvious to many or most
of you. Cheers, Mike |
