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Gravity Battery
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Tarrel



Joined: 29 Nov 2011
Posts: 2447
Location: Ross-shire, Scotland

PostPosted: Fri Feb 07, 2014 2:01 pm    Post subject: Reply with quote

In the "Big House" example:

Assume a large (10 tonne) weight that could conceivable be hoisted by several able-bodied people using some form of gearing mechanism.

The contraption is in the central stairwell of the house, giving a drop of, say, 15 metres.

g = 9.81 ms-2

Potential energy gained = 10,000 x 9.81 x 15 = 1,471,500 J

Assume the weight is allowed to fall over a four-hour period, to keep the lights on from, say, 6.00 pm to 10.00 pm (14,400 secs). Ignore losses.

Power delivered = 1,471,500 / 14,400 = 102 Watts approx.

So, it wouldn't exactly have been Piccadilly Circus, but it is just about feasible! More so if you had a tower built over the stairwell to increase height, and the able bodied people were prepared to work for a little longer.

(10 tonnes is 5 or 6 builder's bags of rock)
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Tarrel



Joined: 29 Nov 2011
Posts: 2447
Location: Ross-shire, Scotland

PostPosted: Fri Feb 07, 2014 2:05 pm    Post subject: Reply with quote

PS_RalphW wrote:
When I was in India in a remote mountain village, they had at great expense and considerable effort installed a diesel powered mill to grind their grain, because otherwise the locals had to carry the grain thousands of feet down the mountain and the milled flour back up again, on their backs. No roads.

Unfortunately the locals couldn't afford the charges the miller asked, diesel being so expensive (even when heavily subsidised, 15 years ago) so they had a plan to build a water mill instead. No local stream to power it, so they were going to use their rainwater capture tank, up on the hillside, with a bucket and chain arrangement to drive the mill. However, of course they realised that they would quickly run out of water, so they decided to arrange the buckets to be filled up again, nearly full, so that most of the water would be carried back up the hill again to the top reservoir....


Neat. So the energy extracted out of the system to run the mill was compensated for by the fact that the buckets were going back up not quite full. (If you wanted them to go back up full it would have to be an imaginary loss-less system). In an ideal situation, the amount of water retained at the bottom would just equal the water-needs of the people down there!
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adam2
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Joined: 02 Jul 2007
Posts: 6206
Location: North Somerset

PostPosted: Fri Feb 07, 2014 2:24 pm    Post subject: Reply with quote

Tarrel wrote:
In the "Big House" example:

Assume a large (10 tonne) weight that could conceivable be hoisted by several able-bodied people using some form of gearing mechanism.

The contraption is in the central stairwell of the house, giving a drop of, say, 15 metres.

g = 9.81 ms-2

Potential energy gained = 10,000 x 9.81 x 15 = 1,471,500 J

Assume the weight is allowed to fall over a four-hour period, to keep the lights on from, say, 6.00 pm to 10.00 pm (14,400 secs). Ignore losses.

Power delivered = 1,471,500 / 14,400 = 102 Watts approx.

So, it wouldn't exactly have been Piccadilly Circus, but it is just about feasible! More so if you had a tower built over the stairwell to increase height, and the able bodied people were prepared to work for a little longer.

(10 tonnes is 5 or 6 builder's bags of rock)


102 watts, less losses would not be much use, say a single 60 watt lamp, and remember that electric lamps were then much less eficient than those available today.

In fact I believe that the engineers recollection was correct, but that the lights were not electric but petrol vapour.

Petrol vapour lighting was popular at one time for isolated premises.
Air under moderate pressure was passed over mesh saturated with petrol, and the vapour thus produced was piped to each room or area and burnt in more or less standard gas lighting equipment.

The machine for producing the petrol vapour was rather a fire risk and was preferably placed in an outbuilding in case of accident.
The petrol vapour itself was relatively safe, perhaps suprisingly. It already contained a lot of air with the result that any escape into the air of a room tended to produce a mixture well below the explosive limit.
The petrol vapour also had a strong smell which facilitated the prompt detection of any leakage.

The machine was usually driven by a very small water turbine, clockwork or a falling weight being alternatives.
The principle energy input was of course the petrol, not the mechanical power to drive the fan.

Although primitive by todays standards, such systems compared well against electric lighting plants, or the building of ones own coal gas plant.
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