[GBlist] GRAVITY POWER

["Eli Fishpaw" <eli.fishpaw@rockbridge.net>]

I have a steep hillside behind my house.  My wife and I have developed a
simple trail up the wood hillside for quick exercise.  Because the hill is
fairly steep, walking at a simple pace has the effort required of running.
I want to use the potential energy I am storing by moving up hill to
transport me back to the house.  I want to set up a steel zip line from
large tree near top of hill to large tree near bottom of hill.  What I am in
need of is an engineered cable break.  I would like to ride in a harness
connected to a pulley that would have a brake that can grip the cable.  I do
not know of such a device.  However, it may be out there.  I have some ideas
for developing a brake.  I would rather buy a well engineered device if I
can find one.

Beyond simple entertainment (although staying healthy greatly reduces energy
use in health care) I can anticipate this device supporting a cart that I
could load firewood from dead trees.  Gravity would move my wood in the cart
down the hill to the wood processing area for final cutting and splitting to
then drop on a plywood slide into the wood shed.

Because we have a wooded hillside, leaves collect behind the house as they
seek to move by gravity to the bottom of the hill.  I am placing a tarp at
the low point behind the house that can be rolled up to collect the leaves
for use in the Garden.  Since the Garden is 20 vertical from the back of the
house, there is potential to hook it up to a zip line running to the Garden.

Actually by continually applying the breaks (which is what we do when we
walk back down) we are coverting a lot of energy to heat. In keeping with
the concept of storing gravity energy a counter weighted cart of slightly
less weight could carry mass up the hill for storage.  In some cases, this
could represent material you want up the hill such as compost for an
orchard.  In my case, it is more likely to carry materials to service the
trail.

Another concept of tapping the gravity energy would feature a loop that
would turn a shaft for a water pump.  If the load on the line could be
sufficent to slow the cable, riding down off the hill would have the affect
of pumping water (building potential energy for future use).  Water up hill
is very useful for a lot of things.  Although if you were dependant on going
up the hill to pump water, you would probably live a lot longer.  We have
access to plentiful, though not potable water from a nearby creak.  If when
you dropped fire wood or an old body like mine, water could be flowing up
hill to slow the speed of decension.  The water itself could be a
counterweight on demand for when you want to carry compost, building
materails or a lazy body up the hill.

All these are fanciful ideas that are a lot of fun.  However, the main
barrier to building the simple zip line is finding a break that can grab a
steel cable.  The line I have surveyed is just over 300' diagonal (cable
run) which is near 150' vertical and 270' horizontal which is just under 30
degrees.  The candidate trees can support a platform 20'-30' up to deal with
the line sag.  I do not know how much that would be.  The closer to the
trunk, the more tension can be put on the line.

I am looking for a cable break.  I hope there are expericens in the list
that can give me ideas for developing this concept.

Eli Fishpaw
Lexington, VA
eli.fishpaw@rockbrdige.net


______________________________________________________________________
This greenbuilding dialogue is sponsored by REPP/CREST, creator of
Solstice http://www.crest.org, and BuildingGreen, Inc., publisher of
Environmental Building News and GreenSpec http://www.BuildingGreen.com
______________________________________________________________________