Re: Solar space heating idea

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Ah Ha !! Very Interesting Nick. The only thing with this is, will it work in a British winter ? This system would be great for hot air heating during the winter months, but do we get enough sunny days to make it viable ?
Me thinks me needs more research into this subject.
I may be back.
--
BigWallop

http://basecuritysystems.no-ip.com
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Well, in the link I posted the guy's system produces an average of 0.25 kw from a collector of size 2.8 sqm on an "overcast winters day". I don't know where he lives but it's snowing there!
I guess the main benefit will be in spring and autumn where the central heating will hopefully not come on much at all. Come the middle of winter, I'm sure it will be on a lot.
However, I was looking at my site this morning and realised that the garage roof might get shaded in the winter when the sun is low. It gets sun all day in the summer...
Here is a photo of the site (looking east so the garage is north of the house):
http://home.no.net/enaasen/back_garden_from_gate.JPG
So I might have to rethink :-(
If it's a non starter, I'll see if I can persuade the wife to have removable panels on the ground at the front of the house...
Nick
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work
during
It looks loverly Sir, and I am now jealous. I live in an Edinburgh Tenement, but have to say that these houses are very cosy all year round. Not to hot in the summer and well insulated for the winter months.
I see what you mean about the garage being in the shade, and the picture was taken on quite a clear day which is ideal for your idea. So it may have to be portable panels out the back door.
What the neighbours and I have done here, is put a small wind generator on the roof, shhh, don't tell anyone 'cause it needs planning permission, which runs the door entry system and a light at the bottom of the stairs, from a rechargeable car battery system, that's how small it is. If we'd gone down the, so called, correct route, we'd have had a big electric meter and fuse blocks right at the bottom of the stairs or someone running cables through the common stair to one of the houses, and no one here wanted that. So the pyro' runs down the outside of the building and up to the front door, and it only cost me a day a year to check that it's all OK. Which it has been now since 19 dot and a bit.
Have you thought about going with a wind turbine ? Nothing to huge, just something that would give enough power to run your hot water tank and maybe a few outside lights at night from a battery storage system. It would help cut at least something off the bills a bit. In the picture it looks like the perfect spot for a small turbine not to far away from the back of the house, and disguised by the trees in the background.
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BigWallop wrote:

Current prices mean that small wind turbines are not economically viable. I'm not taling about a tiny thing that generates a few W, I'm talking about a big one which produces enough power to power a hot water tank.
--
Grunff


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snipped-for-privacy@bt.com (NickW) wrote in message
Hi
Good one.
Regards, NT
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I have considered a wind turbine... there are plans for DIY ones which don't cost too much. I have also been thinking about direct drive heat producing ones, ie: convert the kinetic energy into heat using a heat pump or stirling engine rather than into electricity first. This would remove the efficiency loss of converting to electricity and also produce something like 2-3 times more heat that the kinetic energy taken to drive it.
Solar thermal however, I think should be exploited first as it seems to yield the big numbers for something as simple as heating air. I worked out at the weekend that I have enough space for an 8 square meter freestanding collector on the south side of my house. Hopefully enough to average 1.6kw during daylight hours during the winter.
BTW: you can get sizeable grants for solar/wind/hydro projects (yes, even on a domestic scale). The only downside is that you must have an approved system (not homemade!) and it must be installed by an approved installer who will cheerfully jack up his labour cost to eat up your grant. I know this because I got a quote to have solar matting installed for my pool and the guy wanted to charge me 1000 quid for a <10 hour job. >:-(
Regards
Nick.
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snipped-for-privacy@bt.com (NickW) wrote in message

Hi
Last time I did calcs for wind to heat the figures were incredibly bad. Since solar thermal can actually pay its way and more, it is the clear choice. There is also the fact that its silent, safe, virtually maintenance free, and can go most places. OTOH wind turbines rarely get planning.
Regards, NT
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Air heaters are very efficient. have one on the back wall of a conservatory with the heat rising into the house, or loft and ducted down.
What is very efficient and economical, is a sun tracker focusing the sun via lenses onto a heat exchanger and producing very hot water. These can also produce steam and run a small steam or Stirling engine/generator. Even in cloudy weather very hot useful water can be produced. Steam or Stirling engines can be very small for high large torque. There is research in the USA on sun trackers/heat generators for CHP applications, or cogen as the Yanks say, and it appears more cost effective and efficient than most other methods: PV cells, flat plate collectors, etc.
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Can I ask a couple of questions?
1: If suntrackers are so efficient, why is it that the only one at the Centre for Alternative Technology is about 25 years old? Why haven't they installed more? Is it perhaps that the reflectors are a waste of time?
2: Are you *sure* Stirling engines have high torque? The ones I've seen certainly don't - they are very efficient, but only when operating high speed/low torque.
Just interested :-)
Hwyl!
M.
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conservatory
via
also
in
the
the
other
Lots have happened in 25 years. Do a Goggle on sun trackers. There are some off the shelf versions from the USA.

Specifically steam engines have high torque at low speeds. Steam trucks, which were built up to WW2, never had gear boxes the torque was so high. The highest torque is at stall speed. A team engines does not idle; the old steam trucks just opened up the steam and off she went at an amazing speed for the time. The problem with steam engines is condensing the steam back to water, otherwise the steam has to be released and water used at high rates. Stirling's do not have that problem. So using steam and having a guaranteed cool condenser, such as a large thermal store, may be feasible. Seam engines are used in ships still with a guaranteed endless supply of cool sea water to guarantee the steam turns back to water. The most efficient steam engines are the marine variety , which have been made far more efficient over the past 15 years or so. The cooling problem applies also to Stirling's, which are used in French and Swedish submarines also using cold seas water to cool. The engines are super quiet and virtually vibration free.
R&D using sun trackers using Stirling's and steam engines, and focusing on a metal water filled sphere to produce steam/hot water is going on. many keen armatures using their own home built equipment have reported excellent results.
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[...]
The point I think I was making was that they tend to get the best/most efficient stuff at CAT eventually, and will try (almost) anything in the meantime. Unless something's happened since I was last there, the only sun tracker is this 25 year old thing. If they were so good (in this climate perhaps) then *surely* CAT would have installed a couple more up to date versions? I can understand how they might fractionally increase the efficiency of a system where direct sunlight is the norm, but where diffuse light is the norm (i.e. here) where do you aim your device? On top of that you've the extra mechanicals to maintain, and the extra energy required to cause the thing to track.

[snip the rest which interested parties have probably already read]
I understand that steam engines have high torque - but as far as I understand it, a Stirling engine is *not* a steam engine, though I suppose steam could be used as the heat source.
Unlike a steam engine, the cylinder is sealed.
Unlike a steam engine, the "working piston" isn't actually *in* the cylinder, it is merely attached to it. In models it is often a sheet of rubber, though I see no reason why a piston shouldn't be used.
Unlike a (modern) steam engine, the working fluid in the cylinder (air) must be heated *and* cooled in order to complete one full cycle.
Can you post me some web references to the Stirling steam engine? I'm very interested in the technology since coming across that boiler which uses a Stirling engine on the exhaust to generate electricity. One thing I don't quite understand about that thing though is whether it'd actually get much use in a modern highly insulated house :-)
Hwyl!
M.
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Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
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Trackers have been fixed on sphere that contain the water. they swivel around the ball while focusing the intense suns rays.

I never actually said a Stirling was steam engine. It is a "heat" engine. There are many variations of the Stirling sing differeing gasses to expand. It has in common with "piston" steam engine: eternal combustion (very eco) and a heat and cooling source.

I most yes. the early versions (1830ish) were not. There is also a rotary (wankle type) of Stirling engine.

Virtually all usable Stirling's have a piston in cylinder arrangement.

The working fluid can be air, but the more efficient versions uses various more efficient gasses.

http://www.stirlinginfo.com /
Not available yet.

The unit actually has a burner playing on the Stirling, which has a free wheeling piston with no crank, being the only moving part. The gasses pass through a heat exchanger, Another supplementary burner is used to boost to hot water output.
On existing poorly insulated homes the Stirling boiler is feasible. Any excess electricity produced passes to the grid via a two-way meter.
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pass
More info.... British Gas to launch individual CHP boiler for homes
British Gas has announced that it is developing a household boiler that generates both heat and electricity, which will increase energy efficiency and cut costs for customers, allowing them to sell excess electricity back to the Grid.
The new combined heat and power (CHP) boilers, developed by MicroGen Energy, a subsidiary of BG Group plc, will result in increased energy efficiency, says the company. Normally, only 37% of electricity that is generated at a power station and transferred to customers via the grid is used. However, the new boilers will have an efficiency of around 90% or more, cutting fossil fuel use and reducing the need for gas imports, a British Gas spokesperson told edie. One million of the boilers would be the equivalent to Sizewell B.
The system uses a Stirling engine, invented by the Reverend Robert Sterling in 1816. The pistons are the only moving parts of the engine, which uses gas bearings to minimise wear. The engine is a sealed unit with no requirement for regular servicing or maintenance, says MicroGen. The Stirling engine generates both heat and electricity and additional heat needs are met by a supplementary burner.
The boilers will produce a baseload of 1.1kW, which is sufficient to run most domestic appliances during the day, and any excess is then sold back to the Grid. At times of peak electricity use, the household will have to buy extra electricity, and will receive a net electricity bill at the end of the quarter.
It is also estimated that they will reduce an average household electricity bill by around 25%, and will cut a homes annual carbon dioxide emissions by about 1.5 tonnes and nitrous oxides emissions by an average of 40%.
This could herald the biggest change in British homes since the introduction of gas central heating in the 1960s and 70s, said John Shears, Commercial Director of British Gas. According to Steven Evans, Chief Executive Officer of MicrGen, the prospect of the new technology is already arousing a great deal of interest in the market.
An added benefit, says British Gas, will be for homeowners subject to power cuts, as they will guarantee continued heat and electricity.
The CHP boilers are currently undergoing tests by British Gas, and the first boilers will be available commercially by late 2004/early 2005, said the British Gas spokesperson.
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Some info: Associated Press
1/13/2003 02:15 pm
A solar power demonstration program is making UNLV a hot spot for research into tapping the sun in the southern Nevada desert as an alternative for the nation's energy needs.
"UNLV is quickly becoming one of the leading solar researchers in the country,"said Mary Jane Hale, a senior engineer for the National Renewable Energy Lab in Golden, Colo."And then you have this great solar resource there in southern Nevada."
UNLV researchers are trying to find an affordable way to generate energy using the sun's power, and a parabolic dish array at the edge of the campus helps to spotlight the program.
Two mirrored dishes track the sun, focusing light energy on a tube filled with hydrogen gas that heats and drives the pistons of a Stirling engine.
The unit has been in operation for about a year. It produces 25 kilowatts of power, or enough power for 250 100-watt lightbulbs, every second.
If testing is successful, the technology might justify the cost of putting solar collectors on Bureau of Land Management property in the desert.
Sen. Harry Reid, D-Nev., helped secure $1 million in federal funds in 2002 for the UNLV research program. The University of Nevada, Reno got $1 million of research money for geothermal energy.
However, the technology is expensive, and the nation has resisted alternatives to fossil fuels.
Other solar technologies also are being tested, including a Duke Energy project in Boulder City that uses oil, not hydrogen, to power the engine.
"What we have is a (presidential) administration right now that's not really high on this kind of stuff,"said Bob Boehm, director of UNLV's Center for Energy Research."They are high on oil."
The dishes soak up 30 percent of the sun's rays _ three times as much as conventional solar panels. It would cost the average user triple the price of traditional power sources, according to NREL officials.
But with continued research and use of the technology, costs are expected to go down, officials said.
UNLV's renewable energy program is also training experts in a field where there aren't many experts to go around, Boehm said.
The hope is that UNLV's projects will help make the state a Mecca not only for the collection of energy but also the manufacturing of energy collectors, Boehm said.
"It's not unreasonable that this could lead to some sort of industry here,"he said."We are in a prime location for using the sun and manufacturing these types of things."
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IMM, Just a quickie, because this is turning into one of your religious-type arguments, but
a: the sun tracker you mention is in NEVADA, for Pete's sake, not NEASDEN! We *started* by discussing domestic scale arrangements in this country. It needs DIRECT sunlight to work, hence their suggestion of it being useful in the desert. All large reflector-arrays I've seen to date have been in similar situations. It is very hard to focus a completely diffuse source, which is what the sun is throughout most of the year in this country. Even on only partly cloudy days you begin to reduce efficiency dramatically. There are other technologies which are much more suited to Britain's climate.
b: it is on a very large scale (25kW), when compared with domestic use (and what kind of journalistic rubbish is "25kW per second"?)
c: it involves high pressure hot gasses and doesn't look like something which could be scaled down any time soon.
d: I'm not convinced that an unsealed Stirling engine is really a Stirling engine. It sounds more like a conventional high pressure steam engine. Incidentally, are we actually talking about steam pressure cylinders, or steam turbines when referring to "normal" steam engines?
e: when you say that "virtually all" Stirlings have a piston in cylinder arrangement, I presume you are referring to an "expansion" cylinder somehow attached to the main cylinder which contains the bulk of the working fluid and the displacement piston? This is an interesting compromise and the calculations as to dimensions of this extra cylinder will have to be made very carefully in order to allow maximum heating and cooling of the working fluid which is common to it and the main cylinder.
f: are you aware that the fuel consumption and emmissions figures for Renault's dCi Diesel High Pressure Common Rail engines actually *better* those of Toyota's so-called "green" hybrid car? Ok, it was in a Renault brochure I read this, but it's scary. (We have a large - 1.9l - Renault dCi and it's fantastic. Last time I did the 400 mile round trip to see the parents I averaged 61mpg, and I wasn't trying *very* hard to be economical. The 1.9l dCi Scenic out-accellerates our 1.6l 16V Laguna too).
Hwyl!
M.
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That was just one example, others are under R&D. The same sun actually shines in England too.

There is direct sunlight in England too.

It will point "exactly to where it should be at that particular time and date.

Cylinders.
Yes and that is why the hybrids have never caught on in Europe. But of course there is a catch. Diesel produces particulates (soot) which is cacogenic and blackens building. Horrible stuff, and diesel engines pollute the environment in the excessive noise they produce. Nasty engines. Best avoided, and I have had two turbo diesels.

I have had one Renault in my life and hated it. Poorly made and rattly.
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religious-type
it
in
*better*
pollute
Best
Renault
rest.
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Service intervals on our Diesel are *exactly* the same as on the petrol versions of the car: 18,000 miles or two years. Free "safety check" every year (so you don't miss MOT tests). The previous generation of engines had 12,000 miles petrol, 10,000 miles Diesel. Hardly a difference.
And, ok, nearly all Diesels these days have Turbos, but nearly all petrols these days have highly complex 16-valve systems with variable valve timing, engine management units and *spit* electrics to go wrong.

Scenic is rather more than a "taller" Megane. Define "dog". What don't you like about it?
[rest snipped as unsubstantiated name-calling]
Hwyl!
M.
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disturbing,
all.
are
about
Not so long ago all diesels had 6,000 mile services when petrol was 9,000 plus. Things have improved.

There are many petrol engines that are quite simple, with 2 valves per cylinder and common fuel injection system. Diesel injection is now electronic/mechanical. Diesel are more complicated with a heavy bill if a turbo packs up.

Cheap nasty, breaks down a lot, lousy styling, lousy interior etc. Best avoided. Renault used to have advanced styling, now they make blurb boxes that looks the same as the next large auto makers blurb box.
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So is a turbocharged petrol engine.
Except that many diesels don't need wastegates, which removes most of the failure-prone components from the turbo.
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