h a l f b a k e r yNot so much a thought experiment as a single neuron misfire.
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Renewable energy has the problem that it's intermittent.
So, capture energy and store it.
Batteries are one solution, but they're expensive.
Why not a hydraulic accumulator ? A simple, safe, well-known technology, achieved by using hydraulic rams to lift a heavy weight against gravity. The energy
can be retrieved quickly, at a variable rate, by using a turbine.
A windmill can drive a hydraulic pump directly. Solar panels can drive an electric pump. All that's needed is a very heavy object.
Well, the house is there already. Pour a concrete raft and fix hydraulic rams, supporting a base of girders. Use some of the dead space for a water tank. The ram diameters are small, so they work at very high pressure; thus the volume of water required is also small.
The pistons of the rams are fixed to the raft base. The ram cylinders stick up inside the house, concealed within walls - this means that the lift height is from near zero to arbitrarily high, if you're happy with ram casings poking out through the roof.
When renewable energy is in surplus, the rams slowly lift the entire building. When energy is required, it descends. Importantly, the energy is available as direct mechanical rotation, or it can be converted into electricity via an alternator.
In tornado areas, just vent the system and the building can literally duck and cover until it's safe to come out again.
Electric Mountain
http://www.electricmountain.co.uk/
[hippo, Jul 24 2017]
The Mekarsky system
http://www.douglas-...rair/comprair.htm#m
french. [8th of 7, Jul 24 2017]
How does a propane refrigerator work?
http://homeguides.s...dge-work-84254.html
[Ling, Jul 25 2017]
[link]
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//ram casings poking out through the roof.// sp. "bell towers". |
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Do you think this could be retrofitted? Admittedly we've only got bell towers on three of the four corners, but the fourth could be built easily enough. I'm imagining the energy storage available from 27,435 cubic metres of granite and two-thirds of an acre of leadwork. Would the system cope with significant fluctuations in the mass if, for example, Sturton visits for the weekend? |
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Since that neutron-bombarded potato experiment disaster,
hasn't he had to register his travels with the Geologic Service? |
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This suggests an alternative: just lift Sturton. |
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This begs for an intricate Halfbakery variable staircase where the tread/rise ratio stays constant. Queue the special musical accordion steps. |
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D'oh, Didn't I mean constant tread and rise size for varying height. |
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Do you want Baba Yagas' house?
...because this is how you get Baba Yagas' house. |
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No, it isn't. The KFC is next door ... |
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// This begs for an intricate Halfbakery variable staircase // |
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Feel free to design one ... but the simplest solution is a walkway resembling a ship's gangway. One end is fixed to the house; the other is on rollers, on an embankment with a concrete pad, at half of the maximum height of the building. As the house rises and falls, so the rollers allow the walkway to smoothly change its angle to adapt. This also improves access for wheelchair users and Daleks. |
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Note that self-razing houses are baked by the
London apartment authority. |
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//The KFC is next door...// |
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Did a tile repair job in a KFC once, haven't really been back there since but I do appreciate the advice. |
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//Sp. "Cue"// What, pushed with a long pointy stick? Queue works also, especially if there are many designs. |
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A 100t house raised 10m will give 2.7KW for an hour.
It's surprising how much weight needs to be raised to
store the kind of energy that households need. |
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If the system were pneumatic rather than hydraulic, it would store considerably more energy due to compression of the gas, no? |
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No, because of heating losses during compression. With a gas, the process isn't adiabatic; but liquids are almost incompressible. |
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// It's surprising how much weight needs to be raised // |
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"You're going to need a bigger house ..." |
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//No, because of heating losses during compression.// |
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Wrong, I think. After all, compressed gas is a viable means of storing energy, so clearly the thermal losses on compression/expansion are not equal to all the energy stored by the compressed gas. |
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So, you end up with at least some useful storage in the form of compression (even if some of that energy is wasted as heat), _plus_ the same amount of energy stored as houselift that you would have stored with hydraulics. |
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Also, of the pistons are insulated, you will not lose all of the thermal energy arising from compression - some of it will be retained as heat, and will be recoverable when the gas is vented through the turbines. |
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So, a pneumatic system will store more energy (for a given degree of liftage) than a hydraulic one, at the cost of slightly greater losses. |
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Given that the issue appears to be the amount of energy that can be stored by lifting a typical peasant house weighing only 100 tones, I think pneumatics are the way to go. |
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Of course, a rupture in a pneumatic system will be more explosive than in a hydraulic one, but that's just an added bonus. |
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What you're doing there is asking a reciprocating-piston compressor to operate at very high temperatures. |
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Consider the General Gas Law (PV=RT). Work is done compressing the gas, thus as the volume is reduced and the pressure rises, the temperature also rises in proportion. |
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If the cylinder and delivery pipework are insulated to deliver the heated air, retaining its energy, to the rams, then the cylinder and piston will get progressively hotter. Eventually, they will get so hot that Bad Things will happen, even with superb lubrication. |
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While the combustion temperature of an IC engine is high, the cylinder walls are cooled, as is - in some cases - the lubricant. That means that the actual liner temperature stays low. Heat is continually removed, usually by a circulating fluid. |
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Compressor cylinder housings are typically finned, with fan-assisted air cooling on larger units. This is not just for show - hot air isn't a probem per se - but to ensure that the compressor doesn't get hot enough to destroy the temper on the piston rings, and melt the outlet valve. |
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When the pressurized gas is released through the turbine, it in fact becomes extremely cold - so much so that icing can be a problem. |
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Well, I wasn't planning on operating this system at 2500rpm. Moreovermore, the compression will be quite slow, likewise the decompression, allowing both heat and coldth to be transferred away from critical points and distributed more uniformly. |
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If needs be, the heat arising during compression could be bled off into the domestic hot water system, and the coldth arising from decompression could be siphoned off into a freezer or air conditioner. |
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And in any event, the total energy density of the system at full capacity will be higher. |
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As a bonus, the system could be driven over and above the pressure needed to elevate the house, with the travel of the pistons limited by some sort of stop pin. In an emergency, the stop pin can be pulled, launching the house and its contents safely out of the way of an approaching meteorite, elephant or Jefuckinghova's Witness. |
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Ram end cap, held on with explosive bolts, MUHWHHAHAHA ! |
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Oh, very well. But only if I can have one of those big red buttons under a liftable cover, and a lever marked "ARM". |
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You have to break a glass panel to get a key. A yellow beacon starts to rotate, and a warbling alarm starts to sound. Then you put the key in a lock and turn it. |
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Enter the eight-digit code on the keypad and open the access door. Pull out the pin, and grasp the yellow-and-black striped handle. Press and hold the catch, push the handle in until you hear a click, then pull the handle sharply out and down. |
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The amber beacon is replaced by a red one, and the warble becomes a klaxon. You can now ift the cover over the main controls until it latches. Set the desired time delay on the thumbwheels. |
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Flip the red cover up on the "ARM" toggle switch. The emergency red lighting will come on. Then lift the protective covers on the two red firing buttons labelled "FIRE" and place a thumb on each one. When the annunciator display shows "ARMED", press both buttons simultaneously and hold down for a count of three. |
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"ARMED" will disappear, and the countdown will commence and be displayed. |
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What you do next is entirely up to you. |
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To abort the countdown, follow the abort procedure*. Be aware that when the coundown goes below 5 seconds, it can not be stopped. |
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*Which is completely different from the arming procedure. |
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Get the butter and marmalade, and get ready to transfer the toast to your plate before it cools? |
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Ah, OK. You mean like the system we've got on the East Absinthe Cellar door? Only I'm a bit worried that Sturton might get confused and accidentally launch the house at an inconvenient time. |
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Back to the energy storage, imagine the 100t MB
gatehouse
(outhouse?) is suspended on a 10m long pnuematic
cylinder of
area 1m2. Initially
the pressure is atmospheric, but the house drops until the
pressure in
the cylinder is enough to support the gatehouse. You can
see that the
drop in height gives the energy input. It works out around
9m drop and
Isothermal compression will store more energy as long as
the heat is
somehow returned on expansion.
But if the gatehouse finally rested at 10m height, this
would give initial conditions of 100m for the same
compression. So, the energy storage could be boosted 9
or 10 times. |
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It might prove to be even more effective to get some
really good
double glazing,
and pressurise the gatehouse itself. Although some
caution ought to
be advised for pressurising outhouses, as all sorts of shit
might
happen. |
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// Isothermal compression will store more energy as long as the heat is somehow returned on expansion // |
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That's the killer - how to keep the heat in the gas until the energy is wanted. Even if the cylinders are heavily insulated - maybe even being a Dewar construction - the material they're made of is going to have a much higher specific heat than the gas, so energy will pass from the hot gas to the cooler cylinder. The cylinder and piston would have to be machined from a strong material with a very low thermal conductivity, like SilON. |
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I kind of reasoned like this: |
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If the house compresses the air Isothermally, then it would drop
further than if it compressed the air adiabatically. This is due to the
adiabatic compression having hotter gas and therefore building
pressure more rapidly. |
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Since energy storage must be initially related to how far the house
drops, then isothermal compression must receive more energy.
However, much is lost as heat. The reverse action must gain heat from
the environment in order to return as much energy upon
decompression. |
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The great thing about this kind of energy storage
is
that it provides power very quickly compared to
other
kinds of power station - e.g. "Electric Mountain"
(see link) can go from 0 to 1,320 MW in 12 seconds.
If houses had grid feed-in links and were properly
networked, this could be used for meeting national
power demand spikes - so you would see an entire
neighbourhood of houses gradually sink as they fed
in power to meet a sudden demand spike elsewhere. |
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The point about pneumatics rather than hydraulics is not just one of efficiency - a pneumatic system will indeed be less efficient than a hydraulic one, since not all heat will be recoverable. |
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The point was about energy capacity, which will be higher for the pneumatic system. |
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Let's take an extreme case as an example. We raise the house pneumatically, and we just throw away all the heat of compression. So now our house is at the top, and we have a pressurized gas cylinder. |
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We now lock the house in place, and vent the pressure through a turbine, generating X amount of electrical energy. We can now engage a rack-and-pinion system so that the house can be lowered whilst driving a generator. In this way, we can recover the gravitational potential energy of the lifted house. |
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Finally, the house is back on the ground. We have recovered (a) some energy from the compressed air plus (b) as much energy as possible from the gravitational potential of the raised house. |
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So, for storage efficiency go for hydraulics. But for storage capacity, go for pneumatics. |
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// must gain heat from the environment in order to return as much energy // |
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In your 19th century, compressed air was used for motive power - trams were one application. There were problems with icing, and limited power; a heater called a "bouillotte" - a tank of hot water to heat the expanding air. |
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They were quiet, safe, and pollution free, but energetically rather poor. |
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[Max] Alternatively, could the pressurised gas held
in the cylinders not be vented (expanding as it does
so) to provide absurdly expensive and inefficient
air-conditioning for the house? |
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It could. It can also provide some cooling even as it goes through the turbines. |
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Under the house locking system, wouldn't there also be a heavy hydraulic head? |
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Why? With my rack-and-pinion system we're not using any hydraulics. The house is lifted pneumatically, and descends using a rack-and-pinion that directly drives a generator (through some very high gearing). It's not necessarily the best system, but it does show that you can store more total energy. |
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Racks and pinions would be rather costly. A set of ropes and pulleys would do the trick. This concept was baked in grandfather clocks. |
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Brilliant. Should the cats be minced before sealing them in the pyramid chamber, or can they just be roughly chopped, for instance by a tree chipper ? |
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I'm reasonably sure (enough to wager, say, [8th]'s next paycheck on it, should he ever receive one) that you can't generate static electricity purely by interfeline friction. You need some alternative material, in addition to the cats. |
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Technically and theoretically speaking, the most suitable material to act as an electrical counterpart to cats ought to be stac, but I'm not sure where you could get that from. |
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Given that one of the most energy-consuming home
devices is air-conditioning and you most often need
air-conditioning when the sun shines, there is
surely a market for a device which converts solar
energy into air-conditioning without the
intermediate step of converting the solar energy
into electricity. One approach might be to shade
your house with a material which absorbs solar
energy but cleverly converts it into another form,
like chemical energy, rather than re-radiating it.
If this material had moisture-containing
capillaries, the solar energy could also be used to
evaporate water from these capillaries so that
there would be an evaporative cooling effect as
well. |
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// you most often need air-conditioning when the sun shines // |
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Use a parabolic mirror to heat a steam tube. Convert the steam pressure directly to mechanical rotation, and drive a refrigerant compressor. Use a bit of the rotation to drive the feed pump that returns condensate to the steam tube. |
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There are a couple of potential problems: |
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A shaft seal on the compressor might leak. However, this can be overcome by magnetically coupling the drive through the casing via high-speed low-torque gears. |
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The compressor is probably going to need to run at constant speed, so any variation in steam pressure may cause problems. Using a hydraulic or pneumatic reservoir as a buffer may be an answer. |
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Actually, Solar->steam->pump ->hydraulic accumulation may be more efficient than Solar->photovoltaic->motor ->pump->hydraulic accumulation. PV cells aren't particularly efficient. Solar-thermal can harvest a broad E-M spectrum including IR. |
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// The units would require keeping dry. // |
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OK, bake until dry after the mincing process. Got that, thanx. |
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//solar energy could also be used to evaporate water from these capillaries// |
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In places where water is not limiting, it should be possible to design roofs to accommodate a moistening trickle from a plumbed-in device in the ridge. If 5l/hr were thusly evaporated, you'd have something like 10kW of cooling. |
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I would also like to point out that "moistening trickle" is very euphonious phrase. |
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The solar-energy-absorbing and air-conditioning roof
I suggested could also absorb CO2 and supply you with
fruit, if properly designed.
//Actually,
Solar->steam->pump ->hydraulic accumulation may be
more efficient than
Solar->photovoltaic->motor ->pump->hydraulic
accumulation// - yes, that was what I was thinking -
the conversion process is very inefficient. |
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//could also absorb CO2 and supply you with fruit// fantasy, sheer fantasy. |
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All right, it's sheer fantasy. Just as long as there's enough spare energy to drive the cat-mincer; the steam condenser coils can be used for the drying. |
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Refrigeration using a small heat source is economical
and efficient. Propane refrigerators are available, and the
flame could be substituted with focused sunlight. |
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Absorption refrigerators are a well understood technology; and very quiet. They use ammonia and water - both are cheap, and easily available. Even better, there are no moving parts. |
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The Einstein-Szilard design is similar, but operates at constant pressure. However, it is apparently very noisy in operation. |
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//it's sheer fantasy// My first mental recall, stimulated by
this idea, was of Marineville. |
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