Alternatives to Lens Arrays

Hey,

I was thinking about my 12 prototypes in frozen Newark Ohio these
days. I wanted to tell you another way to reduce tracking costs is to
make really big concentrators and move them minimally. This is the
idea behind power towers.

http://en.wikipedia.org/wiki/Solar_power_tower

The problem with those is that you have to securely mount an array of
mirrors in the ground and then power them to move to track the sun, so
they all point to the power top.

The problem is you want to get your cost per sq meter as low as
possible. And while you might be able to get your mirror costs down,
to a few bucks a square meter - putting it on a nice mount with
motors, kicks your costs up to $100 per sq m or more.

One 'big' mirror I created was a strip of PET plastic of very long
length, a strip about 10 inches wide indeterminant length. The first
4 inches of width are mirrorized and coated on the back - which makes
it mylar like. The other 6 inches is molded into stakes every inch.
Think of a flexible big ass comb. lol. You take PET pellets and the
strip continuously in a rotary mold - mirrorize and coat it, and have
a take up reel to store the product of your little machine.

Truck it out to the field - where you've erected a temporary
installation system This consists of an arm 100 meters long rotating
around a central pivot - with the far end running along a circular
track - installed temporarily. The ground has been prepared - we can
go into detail later if I have time - with a bulldozer, grader, and
roller.

You have a 'planter' that takes the roll of plastic from the truck and
pays it out as the arm goes around. You start at the rim and work
your way in in a continuous loop - forming what looks like the groove
of an old LP record.

As the planter unwinds the plastic, two rollers heat the film where
the mirror stops and the comb begins and folds it at an angle between
90 degrees and 68 degrees. The angle of the heated wheels - which
cause the PET to reflow and reform and resolder in place - changes
based on the radius measured from the center. Its 68 degrees at the
rim, and 90 degress at the center. The reformed strip is then planted
vertically into the ground at a precise depth.

In the end you have a 200 meter diameter faceted reflector that
focuses ALL the energy from a large area to a point that moves through
the sky as the sun moves.

Now, please take a look at the following;

http://en.wikipedia.org/wiki/Skycam

I erect three masts to support guy wires for a Skycam like setup. But
instead of an HD Camera, the system has an inflatable hyperbolic
mirror that reflects the light focused by the main array into the sky,
back to a specific point on the ground -

http://origins.jpl.nasa.gov/meetings/ulsoc/papers/meinel.pdf

So, the 31.4 MW of solar energy on a given day, makes its way to a 14
m diameter target on the ground - at over 2,000x solar intensity -
redirected there throughout the day - by the 'floating' hyperbolic
mirror. The mirror like Skycam - pans and tilts - and also changes
its focal length by changing the tensioning ring diameter slightly
across the inflatable mirror (made of mylar)

Our cost for all of this - principally the masts holding the guy wires
- is around $1 million. 3 cents a watt.

Now, what to put in the target?

Well, if we boiled water and made steam, we could drive a 12 MW
turbine generator

When the sun shined - which means the costs are WAAY out of whack.

Here are two we've tried;

(1) A turntable covered with kiln bricks, and atop that, iron oxide.
Half the turntable has anodized aluminum steam lines that spray steam
onto half the hot table - built into an anodized aluminum cover ***
- and other half merely exposes the iron oxide to the intense solar
energy.

(2) Something really different

Both make hydrogen very cheaply.

.

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