Guest post by WUWT moderator Andi Cockroft
This has little to do with my beliefs (or otherwise) in CAGW, but more to the fact that I am tight with money and this project offers the ability to run my 5 litre SUV for free ! Please note however, this is only suitable for Petrol/Gasoline Engines – most definitely NOT for diesels
Now I should also state that I live on a block of “Native Bush” (read indigenous trees) in New Zealand, so I have a carbon sink of my very own. I also have access to an almost unlimited supply of pine from plantation operations where logging operations leave huge amounts of uneconomic timber behind – myself and several hundred souls benefit from this bountiful resource to heat our homes in winter.
Now I want to run my SUV on it as well.
So what is “Producer Gas”? Well our dear friends over at Wikipedia have an overview here. Unfortunately it is long on references, but short on detail.
So, I will define what I mean by Producer Gas, as a combination of various gasses obtained by “cooking” dry wood. Heat it enough, without burning it, and it will give off a mixture of primarily Carbon Monoxide and Methane – plus a few nasty bi-products such as tar etc. What remains we know as charcoal.
There are many different mechanisms for manufacturing Producer Gas, most concentrate these days on stationary platforms – however they are just as easily made for mobile use aboard a vehicle.
This image of a Ford Truck conversion, (courtesy of Per Larsson’s Museum) shows one of the many ways it can be achieved – here strapped onto the side of the truck.
Note the extra radiator in front, required to cool the Producer Gas after its manufacture by “cooking” – internal combustion engines work better with cooler fuels (think of this as an inter-cooler).
But looking at this doesn’t really gel with the aesthetics I want to achieve for my SUV – so how can it be done that bit better?
Let’s just look at how Producer Gas is made.
There are different designs, and I have researched many over the years I have been contemplating this project – brought to a head now simply by exorbitant fuel prices. Here is my preference for a “Stratified Downdraft Gassifier”
OK, so how do we convert our fuel (pine for me) into Producer Gas?
Here courtesy of http://www.gengas.nu/byggbes/index.shtml is the version I choose to build. On the right is the main Gassifier – here’s where all the magic happens – but do visit their site, it is a goldmine of information.
Wood Fuel in the form of dried pellets of wood (about 1” cube) are stacked in the hopper at the top, and feed under gravity into the fire tube. At the base of the tube is a dish or grate riddled with air-holes – much like a colander. Both the fire tube, and the grate must be made of pretty heat tolerant material such as stainless steel. We need a small opening in the Gassifier so we can actually set fire to the material in the grate – and for reasons we will see later, this will normally have charcoal in it.
But before we set fire to things, note the other components. In the middle is a filter unit that can be of many designs, but meant primarily to prevent nasty stuff such as tar reach our engine, Use sawdust, oil, water or sand to trap the stuff you don’t want, and then our gas heads off to the left to be mixed with air and on into our engine.
You may notice there are actually 2 throttle controls – one the master throttle, the other to control air. This is OK for an engine that will run at constant speed such as a generator, but for a vehicle it would be far better if these could be linked together – something I am working on right now.
OK, before we can start our engine, we need to light our Gassifier. Easily done, with some charcoal in the grate, add a little lighter fuel if you feel brave, and light it. At the same time, note the provision of a blower – this is only used during this phase to get air flowing into the Gassifier from above, provide oxygen to the charcoal on the grate and start the process rolling.
I am told to expect 10 to 15 minutes for this to begin – but note THIS IS CARBON MONOXIDE – DO NOT DO THIS IN A CONFINED SPACE.
Also, you should include springs to hold the lid firmly on the Gassifier – not welded on. Just in case of a back-fire, the lid will momentarily lift, allow the built-up gasses to escape, then reseal itself.
My plan is to add a spark-plug to the funnel, so I can ignite the gas with ease. Once it is burning with a very pale blue flame then we can look to start the engine – just turn off the blower first.
It has been suggested that starting with petrol/gasoline and then switching to Producer Gas is far easier – but we will see.
The beauty of this design is that the production of gas is totally dependent on demand – ie the suction provided by the engine – put your foot down and it will draw and manufacture more gas. Ease off and it will slow down. And best of all, turn the engine off and it will simply go out – but that takes another 10-15 minutes, so restarting in that time should be just a matter of turning the ignition key.
I am in the process of building the Gassifier right now, and I have a pickup SUV, where I can mount the Gassifier outside on the back and run all that plumbing outside the cab as well. I will keep you apprised of my progress.
I am also working on a stationary engine coupled to a 20Kw alternator that will not only supply all my needs, but allow me to sell the excess (at 3x retail) back onto the grid – heck if they pay subsidies to windmills, then why not to me!
Up until now, I have only mentioned pine as a fuel source, but depending on where you live, you could use left-overs from many agricultural products – corn stalks, sugar cane, coconut husks – even coal if you really want to.
Also on the design-table is a device to take large pieces of pine and chop them into the ideal sizes required – and if I can run that directly of the engine, I just about have perpetual motion – well at least motion at zero cost.