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Post by lazarus on Sept 10, 2010 2:09:14 GMT 1
All high-rise flats and office blocks need to pump water up to tanks on various floors. Why not stick a wind turbine on the roof, it wouldn't need to be that big because of the height, and make the tanks larger than required. This would give free pumping of the water that is usually used and once the tanks contain more water than they need a valve could be opened and the water dropped down to a turbine in the basement. That may just be the kernal of a great idea. |
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Post by rsmith7 on Sept 10, 2010 7:01:12 GMT 1
"That may just be the kernal of a great idea."
Really?
Even in a windy city the conversion losses would be high, as demonstrated on another thread. Factor in the extra stengthening required to carry the load of a huge water tank on a tower block and it would be (another) waste of time.
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Post by pumblechook on Sept 10, 2010 10:41:56 GMT 1
People do seem to come up with imaginative ideas. The problem is when you do the sums they tend to fall apart. I would have thought that the amount of energy that could be generated by a tank at the top of a tall building would be small and the costs would be very high.
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Post by marchesarosa on Sept 10, 2010 13:04:08 GMT 1
"the amount of energy that could be generated by a tank at the top of a tall building would be small and the costs would be very high."
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Agreed, pumblechook. Would a better idea be a neighbourhood heating and hot water scheme?
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Post by steveh on Sept 10, 2010 14:46:01 GMT 1
In my experience it's usually windy at the top of most high buildings.
The water has to be pumped up anyway, so if nothing else a wind turbine would save the electricity that usually does that.
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Post by rsmith7 on Sept 10, 2010 16:08:01 GMT 1
Steve,
But you'd spend any savings on strengthening the building and building the tanks and associated gubbins.
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Post by yellowcat on Sept 10, 2010 16:17:56 GMT 1
Steve, But you'd spend any savings on strengthening the building and building the tanks and associated gubbins. Why would you need extra strengthening for a tank that was there anyway? |
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Post by steveh on Sept 10, 2010 16:26:04 GMT 1
You're probably right rsmith.
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Post by rsmith7 on Sept 10, 2010 17:37:40 GMT 1
Yellowcat,
The standard tank would be too small by several orders of magnitude
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Post by pumblechook on Sept 10, 2010 17:59:29 GMT 1
Anyone care to calculate how many litres per second of flow would be needed to generate one kWh. Then multiply that by how long the system
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Post by pumblechook on Sept 10, 2010 18:08:26 GMT 1
Eden Project............
Potential energy gain for 22.71 litre of water up 38m = m.g.h = 8, 466J every second - 8.5kW.
23 litres per second flow. You would need 2 Million litres (2000 tonnes) to generate 8.5 kW for 24 Hours = 204 kWh.
The tank would have to be 2000 cu metres say 13 x 13 x 13 metres. 42 ft x 42 ft x 42 ft in old money.
204 Kwh is enough energy for about 15 houses and if bought normally would cost about £25.
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Post by rsmith7 on Sept 10, 2010 18:34:27 GMT 1
Does that include deduction for generator efficiency at 30%?
That would take the daily output down to about £8.
Hmmmm
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Post by pumblechook on Sept 10, 2010 18:40:04 GMT 1
That is output so takes into account all efficiencies. Alternators are 90+ % efficient.
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Post by rsmith7 on Sept 10, 2010 19:32:34 GMT 1
"Alternators are 90+ % efficient."
True but wouldn't it need to be converted to AC?
Why would tidal generators only be 30% efficient? (A figure I got from an engineer friend).
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Post by StuartG on Sept 10, 2010 20:42:40 GMT 1
"True but wouldn't it need to be converted to AC?"
They produce AC, hence the name. The outside of the alternator are windings of copper wire. In the middle a rotating magnet. On my car [and Yours probably] the magnet is another coil of cu wire, on my 125 Yamaha [and most m/c's] a permanent magnet. To charge the battery a 'rectifier' is used to convert the AC to DC [technically Pulsed DC 'cos the way a rectifier works]. To supply an house the Alternator would have to be kept at a constant speed so that 50 cycles was maintained. So the electricity supply companies are obliged to keep within certain limits of speed [and voltage come to that]. Where does Your electricity come from?
StuartG
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