re: free energy inventions !
8 jun 1999
anthony matonak wrote:
>...i have heard the number 1,000 watts per square meter bandied about as
>the amount of sunlight hitting the ground...
in the sahara desert, at noon, with the square meter aimed at the sun.
in philadelphia, nrel says about 1000 btu/ft^2 (3.2 kwh/m^2) of sun falls
on a south-facing wall on an average january day, when it's 30 f outdoors.
a south wall of a sunspace or greenhouse that's double-glazed with plastic
film with a 90% solar transmittance and r2 thermal resistance gains about
800 btu/ft^2-day. at 130 f, it loses about 6h(130f-30f)1ft^2/r2 = 300, for
a net gain of about 500 btu/ft^2 (1.6 kwh/m^2) per day.
>...how big would a thermal storage bank be to power [a 3 kw minto wheel]
say minto wheels were 50% efficient, regardless of the temperature
difference, unlike other heat-to-motion devices, with limits like
carnot's (thot-tcold)/thot, using absolute temperatures...
we might store 6kw(24h-5h) = 114 kwh or 389k btu of useful heat by
concentrating a lithium chloride solution in a pool in a greenhouse,
something like a solar still. licl is a dessicant that costs $4/pound
and absorbs about 10x its weight in water vapor. it takes about 1000 btu
to evaporate a pound of water, so we need about 400 pounds of water and
40 pounds of licl in a single plastic 55 gallon drum, about $200 for
storage, with no heat loss over time. to recover the heat and provide
a cold sink, we might evaporate water from a damp basement floor, and
absorb the water vapor upstairs.
add another $500 or so for the 800 ft^2 plastic film greenhouse components.
the greenhouse might also form the roof of a house, and provide daylight and
winter heating and solar air conditioning in the summer.