[q]This morning I met a guy with a sheet metal business and talked Stirlings and Tesla turbines with him for about an hour. He showed me some really fine stainless steel fabrication work, all Tig welded. I then visited a small saw mills, that converts about 20 tonnes of trees into timber, and then into garden furniture. The proprieter told me all about his mountain of sawdust problem, and how there is no market for the 5 tonnes or so he produces in a week. This type of operation generates about 40% waste from straight logs.
We talked gasification for half an hour, as I looked around his mill. He has no 3 phase so all his plant is driven by the PTOs from farm type diesel tractors and he has a small 2 cylinder Petter diesel driving a buzz-saw bench.
Idea? Small scale demonstrator of gasification on a petrol tractor or landrover to drive the 30 hp bandsaw, using the saw dust as it is consumed. I estimate that gasifying 5 tonnes a week at just 10% efficiency IC engine will give 80hp at the shaft for the 40 hour working week. I’m in a similar position. I make flooring from logs on a micro scale, and I’m about to launch a certified (FSC) product. I have green waste slabs & sawdust from the mill, dry shavings from the moulder, and dry blocks from trimming. The trim blocks go in my mom’s woodstove but pile up in boxes through the summer in an unruly way.
My kiln is a dehumidifier, and heat for my shop & home is electric hydronic. I don’t have 3ph power, but a phase converter works great for the moulder. The mill is 13hp Honda gas (great engine). Electricity here is still cheap CAD$0.059/kWh (4centsUS), but I still have breathtaking bills in the winter (up to 10,000kWh/month).
I am thinking of selling the kiln guts (Nyle dehumidifier & controller) and buying a two-stage combuster (a la Pacific Western or Garn) for the slabs and a shovelful or two of green sawdust per load for kiln energy, space heating, and maybe a hot tub or something.
Shavings feed seems too complicated and risky so I am thinking of somehow using shavings to run my 3/4 ton flatbed Dodge. I am wondering if a guy can do Methanol on a small scale or should I haul a gasifier around on my deliveries? Either way I would make darn good use of it for publicity. (The things a guy hasta do to compete with the big boys!!) What kind of comments, help/dissuasion, ridicule can you share? [/q]
[a]
Is this ALL as sawdust? In that case it would simplest to burn it direct – it’s fairly easy to handle powders of uniform size. Or is there a fair amount of offcuts of irregular size and shape? (This would be the normal situation in most woodworking plants) In that case it will be hard to design machinery to feed it reliably. In fact, if the long-term idea is to handle ANY kind of carbonaceous waste, whatever comes along, this will be the situation.
The choices would then be:
- Grind or shred the material. It would not be easy to shred input material of very different properties.
- Ferment it to alcohol. This would again be dependent on the properties of the input material, it would be a big, stationary, plant, need skilled management and a plant of viable size might be so large that there cannot be enough material in a viable catchment area.
- Convert it to charcoal. Very little dependent on the properties of the input material, The convertor could be small enough to mount on a vehicle and take it to the soures of material, and the output material can easily be crushed fine enough to feed mechanically without problems. And it is high enough value to be worth transporting
ALL these options consume some energy to process the material. But energy costs are not the dominant consideration in many applications; reliability of running and ease of starting, and generally “well-mannered behavior” are necessary. [/a]
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