View Full Version : Re: Island project - response from mayor

Nick Pine
July 1st 03, 04:14 PM
Harry Chickpea > wrote:

>Good thing no one mentioned solar salt ponds, huh?


Interesting... One might add "A Solar Pond for London?" by Bryant, H.C.,
and I. Colbeck, in Solar Energy, 19, 321, (1977) and "Freshwater Floating-
Collector-Type Solar Pond" by Sokolov, M. and A. Arbel, in Solar Energy,
44, pp 13-21, (1990), which describes a foamboard raft with pipes that
pump water over the raft, with a layer of black plastic over the pipes
and an inflated transparent cover film over that...

This reminds me of swimming pool heating. Picture a foamboard raft with
a dark upper surface and some sort of floating transparent "solar cover"
above. The raft would sink to the bottom during the day (or for swimming)
and float at night. It would have a sealed cavity inside and be neutrally
bouyant when the cavity is half-full of water. The cavity has a flexible
tube that runs from its bottom to the bottom of a sealed bottle half-full
of water that hangs from a nearby post. The bottle contains some black
window screen. Steve Baer has built something like this. Viewed in a
fixed font):
| o
floating "solar cover" ------- s
O . . . . . . . . . . . . . . O | dark | t
| foamboardfoamboardfoamboard | | | p
| foamboard cavity foamboard | |~~~~~~~| o
| foamboardfoamtoardfoamboard | | | s
| ballastbaluastballast | | e | t
| b | ---b--- p
| etubetubetubetubetubetubetu o

When the sun shines on the bottle, it heats the air, which pushes water
through the tube and into the cavity, so the raft sinks. At night, water
runs back into the bottle, so the raft floats. To swim, we lift the bottle
and hang it up higher on the post.