|
| Author |
Message |
Dolph
Member
|
# Posted: 14 Nov 2011 09:16 - Edited by: Dolph
Reply
Hi Folks, I'm Stuart from UK, been checking out some of the great projects on this site, truly awesome. Just like to say that i really admire people who decide to go "off grid", as it takes alot of guts. It is my intention to one day get off grid, but with land prices so expensive in the UK it is very difficult, never the less i will keep searching!
I have been designing a project of my own, not quite in the same league as some of the projects here but it does have potential.
I have experience of fitting biomass boilers and it occurred to me one day that i should build my own and generate electric with it. With wood being a renewable and sustainable resource it would make much more sense to use the local resources than to truck in propane or gasoline/diesel especially when the wild price fluctuations are taken into account, really it's anyones guess what gasoline or diesel is going to cost in another 5 years, but one thing is certain, it will be a lot more.
So the project is to build a wood fueled biomass boiler which can generate hot water and central heating while also generating enough electric to power a small off grid cabin.
To give year round power it would be used in conjunction with solar panels and wind turbine so as not to waste fuel during the summer. During the winter when the heating demand is high then the boiler is used to generate electric and take up the slack when the wind does'nt blow or it is cloudy.
I have started out small, building a very low cost prototype boiler system which will be used provide heat to the electric generation module for testing. My system is similar to a steam engine but instead of using water it uses refrigerant (butane) as the working fluid. Once i have finished testing i can build an improved boiler suitable for indoor use and then locate my electric generation module outdoors.
The electric generation module will charge directly into a battery bank.
The cabin would be heated by the radiant heat from the indoor stove/boiler and also by the heat rejected in the electric module condenser which would heat a water cylinder and radiators.
Would be great to hear from anyone who is interested in this type of system.
More info on website.
Best Regards,
Stuart
PS,
This project will eventually be used to gain my HND mechanical engineering qualification.
|
|
Mtnviewer
Member
|
# Posted: 14 Nov 2011 09:41
Reply
It does sound interesting. In my location I have a pretty much unlimited supply of waste wood piled high in burn piles from area logging. It would be great to use it vs. have them just waste it.
Do you have any pollution controls on the exhaust, such as a catalytic converter, which could ramp up the heat even more. My Blaze King wood stove uses one & it has proven to be excellent. I don't like the idea of adding my wood smoke to the environment & the air that I breath, even though the loggers don't care. This valley used to be incredible for year round air pollution until the local mills went out of business. Now, the air pollution is mainly in winter, down valley from me, 20 kms or so, as the nearest village still has horrible air pollution due to residents using old wood stove technology & many using horrid outdoor biomass burners without pollution controls. I've read in forums that in the USA, these outdoor burners are becoming outlawed in some regions. I'd think that you'd need to address the pollution controls if your burner is at all like other outdoor wood burners?
Tell us more?
|
|
Mtnviewer
Member
|
# Posted: 14 Nov 2011 09:58 - Edited by: Mtnviewer
Reply
How much Butane does your system use? I see that it is a "closed loop", could you explain that more in relation to how Butane is used?
|
|
Dolph
Member
|
# Posted: 14 Nov 2011 10:20
Reply
Quoting: Mtnviewer Tell us more?
Yeah i agree pollution control is very important, modern UK stoves/boiler are very clean, they should emit no smoke if they are working correctly. Old boiler/stoves should be replaced with cleaner burning technology asap. When i build my final boiler it will use secondary combustion chamber to fully burn the wood and its gases.
During prototyping i am focusing on perfecting heat transfer, pollution control will come as a result of development of the boiler.
|
|
Dolph
Member
|
# Posted: 14 Nov 2011 10:28 - Edited by: Dolph
Reply
Quoting: Mtnviewer How much Butane does your system use? I see that it is a "closed loop", could you explain that more in relation to how Butane is used?
Sure, The Butane is part of a sealed system which operates under what is called: The Organic Rankine Cycle. It works in a similar way to a steam engine, however Butane boils at a much lower temperature than water so i don't need >100 degrees C to create vapour.
The Butane never escapes from the system and it does'nt get burned, there is no exhaust so the noise is kept to a minimum. The system holds a small volume of Butane dependant on how much power you want to genearate, the system in my videos hold 2 litres. My final system will hold about 8 litres.
The Heat from the boiler is used to vapourise the butane and thus spin the turbine.
|
|
davestreck
Member
|
# Posted: 15 Nov 2011 17:20
Reply
The world-class scroungers and alt-e tinkerers at Otherpower have built a wood-fired 2kW generator. Very cool stuff. Here it is.
|
|
Dolph
Member
|
# Posted: 3 Dec 2011 14:42
Reply
Thanks Dave,
They're done a good job, very interesting stuff.
|
|
Anonymous
|
# Posted: 3 Dec 2011 21:23
Reply
If your already using propane for boiler, you loose to much that away.
Here in US propane is 3 bucks a gallon. If you insist on propane, just run gas/propane engine genset and be done, simple and cheap. Everything you go from one fuel to another you loose 20 to 30% efficiency. Just like truck with automatic trans has 50hp less than standard trans. The more power goes through the more you loose efficiency and power. Wood is free, and if you loose any efficiency no big deal. Many tree services and sawmills have tons of free wood to burn.
One volcano Eruption causes 200 years of emissions, how can a small fire hurt that burns clean. Also wood is carbon. Trees get carbon from the air.
|
|
|
Dolph
Member
|
# Posted: 4 Dec 2011 08:51 - Edited by: Dolph
Reply
Hi Anonymous,
It will be a great feeling to know that i don't need to burn oil, diesel, propane, gasoline or any other fossil fuel because i can get electricty from wood and i can build it all myself: self sufficient. The point of my system is to free myself from oil and protect myself from oil prices which are out of my control.
Just making sure everyone understands that my system does not burn propane or butane or oil or diesel, it burns wood. The butane is held inside a closed cycle and it never escapes a bit like an air conditioning unit, once you've filled the system it won't need anymore until annual service.
Like you say, my electric generation system would be best used with a free source of energy like waste wood or solar heat, but even if you don't have a cheap source of fuel my system could still be retro fitted into a normal wood/propane boiler system as an emergency backup of electricity.
A backup system would work like this: During normal operation the boiler heats hot water and central heating zones with my system isolated from the flow. Then, during a power outage you could turn the isolation valve so that heated water flows to the electric generation unit first then to DHW and central heating, that way you have peace of mind that as long as you have wood or propane you can generate off grid electricty with no need for a diesel generator. You could survive for months just burning wood to generate electricty and hot water.
yes propane and butane are very expensive, in the UK it costs £11 per gallon (4.5L in a Uk gallon), diesel is at £1.40 per litre and petrol is not far behind it at £1.35. These prices are squeezing the UK bad and are encouraging innovation by back yard inventors!
Wood is really the only answer in the UK and if i can find a cheap source of wood then thats all the better.
If there is lots of wood waste in the US going unused ie sawmills and forestry then utilising that would make a lot of sense as long as it is clean. To burn wood clean you have to burn it hot and transfer the heated into a large storage accumulator. Thats how its done in the UK, smoke free.
Without too much effort you could easily improve many of the outdoor wood furnaces just by adding an accumulator and getting it to burn hot and smoke free instead of cool which = smoke.
As for emissions, just keep them as low as you can, thats my thinking. At this time carbon is the least of my worries, Carbon helps things grow and wood is carbon neutral.
|
|
|
