John Nagelson wrote:

Hello, I am considering taking a house 'off grid', and would be
grateful for help with some of the following questions:

1) how easy is it to run an generator fuelled by PARAFFIN(known in the
US as 'kerosene', i.e. '28sec', the type of oil used in most oil-
powered domestic heating systems in the UK)?

2) how easy is it to get hold of, and run, a generator fuelled by
SOLID FUEL, e.g. coal or wood or both?

3) how easy is it to run a generator fuelled by DIESEL? And surely if
you do, you don't have to pay petrol-station prices? Is there a legal
way to avoid paying the excise?

4) what about running an oil-fuelled generator on cheapo COOKING OIL?
Is this practicable? Is it legal?

What you are considering can only be practical if you can use the heat
produced by the engine, as in a CHP generator. The problem with small
diesel generators, especially cheap ones, is that they tend to be air
cooled and even the water cooled ones run at a low temperature compared
to a boiler. If they run too hot the engine will fail prematurely and
you will need to change the oil frequently.

To use solid fuel in a steam engine would be grossly inefficient
compared to IC engines, and introduced problems with the use of live
steam if you are aiming for the hoghest efficiency. This would need you
to be trained and certified to operate such machinery. I suspect "forget
it" is the better advice here. It would be possible to use a Stirling
engine generator using the flue gasses from a solid fuel fire but AFAIR
the only Stirling engine generators available at the moment work with
natural gas only, cost a lot and provide very low generating capacity,
typically around 1KVA.

There's no practical difference between running an engine on diesel or
kerosene. And if you use a kerosene stationary engine to provide
electricity for your home you can use the same heating oil as is used in
boiler. However you will effectively be throwing away 60%+ of the energy
content of the fuel, whereas a good oil-fired boiler is 90% efficient.

Using cooking oil is possible but may well damage the engine. Only the
manufacturer can tell you. If you want to use cooking oil in winter it
will have to be either heated or converted to biodiesel by
esterifcation. The process is striaghtforward for a chemist but involves
handling large quantities of strong alkali and is not recommended for
amateurs. You would also need "quite a bit" of kit and to register with
HMCE as a fuel producer in order to qualify for the small fuel producer
fuel duty exemption, although since you don't want to use the fuel in a
car they may waive registration. You'd have to ask them.

Don't even think about any of this unless you can think of a way to
scavenge and use the waste heat from the engine. And when it comes to a
generator your sugestion of a small "Honda" diesel is inappropriate. A
true Honda will cost a lot, generators in an open frame sold as "Honda"
often only have a Honda motor and are incredibly noisy, usually greater
than 109dbA. Regulation on these generators is poor, and you will have
to put up with flickering lights even at the best of times. If you
connect or disconnect a significant load (microwave, kettle) you will
bown out for a time then the engine will really start to hammer as it
takes up the load.

If you are doign this the minimum generator capacity you should be
looking at is 6KVA, it would probably be better to consider 12KVA. You
shoudl also consider an alternator/inverter type generator which is
electronically regulated to give a stable voltage to avoid the brownouts
and flickering. You will also need to get a generator with a decent
sound suppression cabinet, which can get the noise level down below
40dBA. This may still be intrusive at night and if you have neighbours
they will complain, and if you don't do something about the noise they
will take it up with the local authority.

If you were au fait with what you intend to do, I suspect you wouldn't
need to ask these questions. I suggest you go and learn some more about
generators, efficiency, noise and CHP issues before you contemplate such
an installation.