Alternative Power sources - AEH - cogeneration & credits

Author

AEH - cogeneration & credits

Ecnerwal

2007-04-18, 3:25 am

If there are still a few other people actually interested in home power
generation here, as opposed to all the fricking trolls...it's getting to
be time to take the electric cattle prod under the bridges around this
newsgroup, flush them into the sun and turn their troll behinds to
stone. We might try the "AEH" prefix on subjects actually relevant to
the group's purpose.

I recently got moving a bit on my power generation, after years of
seeking ideas and waffling on spending the money, with the coincident
effect of crystallizing whatever choice I was waffling on. I bought two
liquid-cooled 1800 rpm generators - a 1952 Kohler gas unit, and a 1988
northern lights marine diesel, recently rebuilt (less than 300 hours on
the rebuild). This leaves me a bit more cash loose for other parts of
the system than the new low-speed diesel I was thinking of getting.

The Kohler is a bit funky, but was inexpensive, and appears in overall
mostly good shape, plus there's lots of info and support over at
smokstak, so I expect I can get it back on line, and/or trade it
for/towards another diesel. Or I might see about running it on woodgas,
as I have plenty of wood, and think that might be good for a
supplemental generator (a bit fiddly for prime and reliable power, IMHO).

The NL is supposedly in good shape, but I need to hook it up yet. I'm
planning to do co-generation with the generators, as during the worst
sun-time it's also heating season in Vermont, and I like getting double
use from my fuel, if I need to burn fuel. In summer when the
hot-water-heater is hot I'll have a radiator arranged to dump excess
heat if the generators need to run.

My intent is to hook the cooling systems (perhaps via exchangers) into
the radiant slab loops and a hot water storage tank. I'm also hoping to
recover additional heat (particularly from the diesel) by piping the
exhaust though a moderately old, but intact oil-burning boiler, set up
to act as a heat exchanger - exhaust going in where the burner used to,
and out the chimney. Probably put an induced draft fan on the chimney
for good measure, though the whole setup is in a separate shed, with the
heat being piped across, to reduce issues of carbon monoxide and fire in
the main building.

At present the diesel is set up with a heat exchanger and wet exhaust.
I'll want to change to a dry exhaust, but I'm not sure if I wish to lose
the heat exchanger at that point (as is typical for a "keel-cooled"
setup), or retain it as a way of isolating the engine loop from the
cooling loop.

Still undecided between 24 and 48V for the battery/inverter side of the
system. More stuff works directly on 24, lower resistive losses and
fewer strings in parallel for the same storage at 48. I'll have to
decide it soon enough - I'm getting close to spending that money, so as
to try to occupy and take the PV & Thermal credits in 2007. At my usual
rate of progress, missing the credits by missing the occupation date is
a real possibility, but it's enough to make trying hard worth it. Has
anyone filed for the credits this year, and if so, did you run into any
"gotchas" from that? I plan to review this (tax) year's paperwork with
an eye towards next (tax) year - the information available on it last
spring was alarmingly vague, and I partly feared spending a bunch only
to have it not count when the actual forms were written.

--
Cats, coffee, chocolate...vices to live by

nicksanspam@ece.villanova.edu

2007-04-18, 9:25 am

Ecnerwal <LawrenceSMITH@SOuthernVERmont.NyET> wrote:

>At present the diesel is set up with a heat exchanger and wet exhaust.
>I'll want to change to a dry exhaust, but I'm not sure if I wish to lose
>the heat exchanger at that point (as is typical for a "keel-cooled"
>setup), or retain it as a way of isolating the engine loop from the
>cooling loop.

Why change this out and then add your own exhaust gas heat exchanger?
Sounds like it might help get the engine heat into the slab/tank water.

Nick

Ecnerwal

2007-04-18, 9:25 am

In article <f04trf$nsm@acadia.ece.villanova.edu>,
nicksanspam@ece.villanova.edu wrote:

> Ecnerwal <LawrenceSMITH@SOuthernVERmont.NyET> wrote:
>
>
> Why change this out and then add your own exhaust gas heat exchanger?

The heat exchanger in question does not add anything to exhaust gas heat
extraction - it just transfers heat from the engine loop (coolant) to an
outside loop (seawater). Any exhaust gas heat collection which is not
already in the coolant loop (that loop does include the exhaust manifold
- one reason a marine set seemed a good choice, plus I could find a used
marine set to suit me, and could not find a used land set to suit me) is
done in the wet exhaust.

A marine wet exhaust involves sucking up water from the ocean, sucking
heat off the coolant in the engine loop via the heat exchanger, and then
dumping the somewhat heated water into the much hotter exhaust stream
and back over the side into the ocean (thus cooling the exhaust). It is
an open loop with no heat recovery, and based upon a more or less
infinite supply of water.

--
Cats, coffee, chocolate...vices to live by

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