Idle thoughts re generators

As I was thinking about backup power the other day the following train of thought occurred to me:-

  1. Generators are available powered by diesel or petrol

  1. Petrol car engines are easily converted to run on LPG

  2. My gas hob is easily switched between natural gas and LPG

So I was wondering whether or not it is possible to get a petrol generator running off LPG, and if so, could it be further converted to run off mains gas?

No plans to actually implement this but I'd be interested if it's technically possible/prohibitively expensive/specifically precluded by regulation etc.

Thanks

Neil

Reply to
Neil Jones
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an LPG powered generator off-the-shelf. Don't forget that the exhaust is every bit as poisonous as petrol and diesel exhaust, so you must vent it properly.

CHP (Combined Heat and Power) has been around for quite a while, but the economics of it are really only favourable for industrial use. Mains gas (typically) is used to drive a modified car/truck engine which drives a generator for electric power and the waste heat from the water jacket is used to heat the building. It isn't quite that simple, because there is normally an agreement with an electricity supplier, that you can draw extra power as you need, and if the establishment closes at night + weekends, it can put into the grid for credit. The problem is synchronising with the grid, if you get this wrong, the local distribution system will probably go *BOP*.

John Schmitt

Reply to
John Schmitt

Machine Mart do a kit to convert their Honda petrol sets to run on LPG. How easy it would be to run on natural gas I don't know - suspect with a bit of carb tweaking would be very easy.

Reply to
Grunff

Thanks - from these 2 replies I'm clearly not being as stupid as I first thought :-)

Neil

Reply to
Neil Jones

I'd also wondered about building a generator that runs off mains water pressure...granted it wouldn't be enough to power the whole house but it *should* power the lighting.

sPoNiX

Reply to
sPoNiX

These people do it on a slightly larger scale:

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Reply to
sPoNiX

A turbine in the soil pipe could also recover some of that expended energy :-)

As with the 'mains water' generator you would need to store the electricity (unless you are not on a water meter and plan to run the tap 24/7).

Cheers Dave R

Reply to
David W.E. Roberts

Firstly, it will reduce your mains pressure. You could have it heat an immersion in a cylinder, so every time the tap is on it turns and the immersion will dump some heat in the cylinder water. It is getting a unit that is efficient enough to do it. It would have to a DIY effort.

Reply to
IMM

draw extra power

put into the grid

The best CHP method using an IC engine, is to have the genny power up a set of batteries. this is an auto arrangement that charges them when they are down. When charged the genny is off. Then an inverter takes the DC and converts it into a.c for the house to use. Also the hot water created can be store in a thermal store.

Running an IC genny 24/7 is highly uneconomical, umnless al the power and heat is being used or stored.

Reply to
IMM

It was just an idle thought that you could devise some system that operated a turbine whenever the water supply wasn't being used. The energy could be stored in a series of batteries for use when needed.

Whenever the water pressure is needed somewhere else the water supply could be diverted and the gererator allowed to spin down.

sPoNiX

Reply to
sPoNiX

Wrong. Even without the generous government grants, for large installations (which is where I said they were viable) there are consistent savings to be made.

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uploaded/documents/ACFPLBwLaq7D.doc

The HE sector is moving into CHP in a relatively big way. Not surprising really, as some of the bigger players in the sector have student populations comparable to that of Gibraltar.

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but one example. It is far better to keep the engine running, with scheduled downtime. Think about automotive engines and the most common reasons cars fail to do what they are supposed to. Correct: B*gg*r wont start! Also the lubrication is constant, and the load is stable so that wear is minimised. At least one sewage works I know of goes one stage farther and obtains all their hot water and one third of their electricity from methane derived from their sludge digesters. This also has the advantage of giving them skeleton power to keep the plant going until the rest of their gensets come on stream if the mains goes.

John Schmitt

Reply to
John Schmitt

You could have a large tank at high level and one at low level. The mains water turns the genny to produce power to heat a thermal store of water. The genny turbine would have another pump on the same shaft. This pump, pumps water from the low tank to the high level tank. When the high tank is full the water from the high tank is released to turn the genny and flows into the lower tank. Start all over again. You are getting the power to raise the water free ( the water companies pumps in fact).

Reply to
IMM

installations (which is where

that of Gibraltar.

There are retrofitted oil storage vessels under pressure. When the engine turns the oil is released super fast into the bearings. It prolongs the life of an engine.

one stage farther

methane derived from

skeleton power to keep the

It all depends on usage. Light usage, which is most domestic if you heat, cook and DHW on gas, it is best to use the battery method topping up when required. You are right in that the best usage is from large users. But the inefficiencies of the IC engines is still there.

Reply to
IMM

Problem is that there's no energy in mains *pressure* unless it is accompanied by flow (in the same that there's no energy in voltage without an associated current).

So you could only generate electricity whilst actually *using* water. If you use it just to generate electricity, you waste an awful lot of water - which the Water Board might just notice, even if you're not on a meter.

Reply to
Set Square

I have a Honda petrol generator which can apparently be converted to run on bottled LPG. However, according to Brown Power of Rugby (who supplied the generator) it doesn't work with mains gas. [I asked the question because I bought it mainly to keep the electrical bits of my gas central heating going in the event of a prolonged power cut - and it would have been convenient to run the genny on gas at the same time].

Reply to
Set Square

What you want is a steam turbine. Heat the water with a gas jet.

Reply to
David W.E. Roberts

convenient to

Yes, this is the sort of application I was thinking about - it would be more convenient to let it run off the mains gas than keep having to change bottles or fill jerry cans at the petrol station.

Neil

Reply to
Neil Jones

Sort of miniature power station in my garden shed? What's involved and is this really a practical consideration?

Reply to
Neil Jones

The thought was prompted by memories of a country show where there were loads of old small stationary steam engines.

They did all sorts of things including generating electricity.

AFAICS it wouldn't be difficult to convert a coal fired steam engine to run on gas.

Steam turbine was one step further (too far?).

A steam engine with a rotating flywheel could drive a generator no problem - a lot of older rural houses had diesel gennies which AFAIR were in two parts - engine and generator.

Not as whizzo efficient as a modern petrol generator, I presume, but a quaint and interesting power source none the less :-)

Reply to
David W.E. Roberts

Certainly would be a talking-point!

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Reply to
Neil Jones

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