Saturday, February 27, 2010

Knock on Wood

The observant amongst you will notice that most of my posts are named after song titles. This one is no exception. I have just returned from a week long odyssey to All Power Labs in Berkeley in Northern California to learn all about running engines on wood.

All Power Labs is based at "The Shipyard", a kind of creative artists community workspace, based in a couple of industrial units at the south end of Berkeley. They have a well equipped metal machining workshop with big machine tools and a metal fabrication shop. The artists share the facilities and develop great mechanical art projects such as the "Neverwas Haul" (pictured above) which attend festivals such as "Burning Man". Anyway the Shipyard is a very cool place - and I was lucky enough to hang out there for a week, and sofa surf.

Wood can be converted to a flammable gas, by a process known as wood gasification. The woodgas is then used to fuel a converted internal combustion engine. The technology to do this has been around for over 100 years and it was extensively used for running vehicles during WW2 - as documented in the recent book "Wartime Woodburners".

The aim of my trip was to learn how to make the technology work - so I could then set up a similar system in my Energy Shed and derive most of my household heat and electricity from waste woodchips.

So I flew out to San Francisco and crossed the bay to Berkeley - home of All Power Labs (APL) and the GEK gasifier. GEK is shorthand for Gasifier Experimenter's Kit.

APL is the brainchild of Jim Mason, a self taught gasification guru. When the city of Berkeley authorities tried to evict the artists from the Shipyard, they cut the power supply. Jim and his colleagues took the Shipyard offgrid with solar and diesel power and so they could remain operational.

Looking for an alternative to expensive diesel powered generation, Jim and his team re-discovered old studies on wood gasification and so the GEK was developed.

Over the weekend of 19th to 21st February I attended the Gasification Workshop, with 60 other delegates from all over the world. The workshop was hands on experience in working with the GEK gasifier, and other system components.

The fuel for wood gasification is just chipped wood. This drum load was made in a few minutes by running some old pallet planks through a wood-chipper. This sort of material can be obtained from tree surgeons who make so much they can't get rid of it quick enough.

During the course of the weekend we converted a Lister type diesel engine to spark ignition so that it could be run directly on woodgas. The conversion consisted of fitting a long reach spark plug in place of the diesel injector and devising a spark ignition circuit. A new pair of copper head gaskets were made using the CNC plasma cutter, and these were used to lower the compression ratio down to about 13:1.

The ignition circuit was made from an Arduino and a car ignition coil. A Hall effect sensor was used to detect a magnet on the flywheel, placed a few degrees before top dead centre. The Arduino was used to create the correct timing delay and fire off a darlington power transistor with a multi-burst spark.

A friend in Michigan had made a special wood-gas carburettor, which allows the air and the wood-gas to be mixed in the correct ratio. This fitted right on to the air-intake of the Lister engine.

By the Sunday evening we had the Lister running - in fact amazingly it ran first time without major adjustment.

There's a couple of Youtubes showing the conversion. In the first one, I explain to a small group of people what we are going to do and the second one, shows the engine running.

No comments: