----- Original Message -----
From: "Jed Rothwell"
In this design, do you envision some sort of wind turbine
mounted above the deck, or only sails, to move the ship along?
No sails - and the drogue turbine plays only a small role. Mounted
on deck is an improved "ladder-mill" (either fixed or rotary)
which has the same capability as about 200 acres of land-stationed
wind turbines. Here is the original Delft concept for a stationary
laddermill:
http://www.lr.tudelft.nl/live/pagina.jsp?id=8d16d19a-e942-45aa-9b52-48deb9312e92&lang=en
Delft has worked out all the numbers. It has almost unbelievable
capacity compared to turbines. This thing promises to be an order
of magnitude more cost effective than present turbines, and
cheaper than every other alternative - but it is more complicated,
perhaps fragile, and needs active computer control. No
technological breakthrough is required. The Dutch are very
practical folks. The video is worth the time but only shows the
stationary version. Turbines would be mounted on the wings of the
stationary version. The rotary ladder-mill turns an axle for the
prime output, but wings may be fitted with turbines as well.
I wish I had the finalized and improved ocean-going rotary version
of that Delft concept firmed-up enough for a nice web-page
presentation, with some drawings and animation - because any
picture, in this case, is probably worth more than a thousand
words. It is not an easy concept to put to words. The big (former)
drawback, which I am trying to make into a "feature" is the
storable-energy-output in the form of liquid air. Obviously there
is no other way to use the idea than with storable energy output
and making liquid hydrogen is too wasteful.
Here is a crude sketch of an airfoil wing attached to a flexible
carbon fiber cable. In a rotating ladder-mill there would be
dozens of these wings pulling 3-4 cables up which then turn
axle-mounted machinery on the ground. The (computer controlled)
wing would tilt into a "dive" for the backside descent. The path
is not circular but an elongated oval flattened on one side. Too
fragile.
http://www.ockels.nl/Images/Concepts/ladder_one_wing_advanced.JPG
Here are kite type airfoils - again not suitable for the ocean
version.
http://www.ockels.nl/Images/Concepts/two%20halves.JPG
These older ladder-mill concepts are usually envisioned for land,
using miles of cable. I envision a less flexible but tiltable
version of about 300-400 meters in height, with a open-strutted
mandrel, built like a radio-transmission tower - attached to the
deck at one end (hinged) - the effect being not unlike the "blade"
of a gigantic chainsaw - only open, and with steerable airfoils
mounted on the chain so that torque is applied on both the lift
side AND on the return side (forced dive). The torque for the
rotary version is easy to calculate and is enormous, as each wing
can lift about 200,000 pounds against gravity at only 30 knots.
There would be 12-18 wings per ladder-mill. In the stationary
version, 2-4 turbines are mounted on the back of each wing, but it
is less cost effective than the rotary version. The catamaran
hulls would be 100-120 meters in length with 40-60 meters between
hulls; and with the ladder-mill hinge mounted fore deck - which
hinged mandrel and wings can fold nearly flat, for allowing the
return to the starting point with little drag when the drogue is
raised. The wingspan of the dozen or so airfoils can be 60 meters,
and the construction similar to but simpler, and with no sweep,
compared to a 747 which has that wingspan ! Probably they can be
of Rutan-type fiberglass construction.
The slight drift movement of the catamaran with the wind can be
analogized to the flotilla being stationary with a slightly slower
wind. IOW if the wind-speed is 30 knots and the drift speed is 2
knots then only 28 knots can be used from the wind. Constant
daytime winds of this speed are the norm in the better locations
on the West coast. The water turbine in the drogue-cone provides
additional energy, but most is provided by the lift of the
airfoils.
Much more torque is available using "lift" than from sails plus a
water mounted turbine. And a traditional bladed turbine is only as
efficient as its diameter, and that is limited by structural
constraints, more so than are true wings. By far the best way to
harness heavy wind is with the pure lift from a number of
large-chorded airfoils, which are nearly identical to an airplane
wing.
A design with only sails might be simpler. The ship would always
go before the wind, which simplifies sailing. (And takes the fun
out of it, too.) These would not be cloth sails, but rather
large, rigid structures which could be retracted or feathered
when the motor is used.
Yes there are a number of simpler options, including privately
owned, robotically controlled ships which make a storable fuel (H2
or liquid air) for companies, or even individuals. If too many
were allowed, ocean shipping would be impacted. Like many, the
search is for lowest net cost for unsubsidized grid electricity.
The Europeans are ahead of us in the USA on advanced wind energy
concepts, and although I "borrowed" from their work extensively in
the present version, I believe this ocean-going ladder-mill
concept is an improvement over anything out-there presently - but
only IF a power-utility company can be convinced or enticed to add
a liquid air expander to a present power plant, using waste heat
for expansion ... and so forth.
It is altogether a very complicated situation, even politically,
in application - and that may be its ultimate downfall - but
hey... it is offered free to all - a re-Dutch treat, so to speak.
It would even be ideal for a country like France - where instead
of adding more nuclear capacity - they could use the existing
waste heat from nuclear to expand liquid air - which has been
manufactured offshore. Having been in Provence during the
'Mistral' that would be an enticing way to benefit from nature's
wrath.
Jones
