Alternative fuel put to the test

The Saskatchewan Research Council is demonstrating a machine this summer that turns waste wood into electricity.

The machine converts waste wood into a synthesis fuel that can be used to run a modified three-litre natural gas engine.

Power produced by the engine runs a electrical generator that can be hooked up to any building’s circuitry via the service panel.

It is capable of producing 20 kilowatts of electrical power.

The PP20 Power Pallet is manufactured by AllPower Labs in Berkeley, California. Base units start at about US$25,000.

The unit’s price tag makes it an unlikely choice for most people who own properties that are serviced by an electrical grid.

However, it could have practical applications in locations that aren’t serviced by an electrical grid, such as northern communities, wilderness cabins or remote rural areas.

“Basically, it converts wood chips and gasifies them into a synthesis gas, which is hydrogen, carbon monoxide, some methane and a bit of carbon dioxide and water,” said Darren Anweiler, process development manager with the SRC.

“That syn gas then gets cleaned up and is fed through an engine that is hooked up to a (generator).”

The Power Pallet model produces about 20 kilowatts of energy, which is enough to run about three houses, assuming average consumption levels.

Wood that fuels the unit must be chipped into small chunks, approximately one inch across.

AllPower also makes other gasified units with different specifications and output capacities.

Gasifying biomass is different than burning or combustion.

Combustion involves burning a fuel source entirely using unlimited amounts of oxygen. The resulting byproducts of combustion are primarily carbon dioxide and water.

Under gasification, oxygen is limited and fuel sources are thermally decomposed and broken down into gaseous components rather than burned.

“Under gasification, you have a certain amount of oxygen … but not a lot,” said Anweiler.

“What it does is it partially decomposes the wood, so you have a fairly high temperature — somewhere around 700 C or above — and it breaks down the biomass … into energy and gas that you can then feed into an engine where it is fully combusted.”

The engine on the Power Pallet requires only a few minor modifications.

The standard engine on the unit is a four-cylinder General Motors Vortex, originally manufactured to run on natural gas.

Modifications to the engine’s timing and intake system allow it to run on a synthesized gas containing hydrogen, carbon monoxide and methane.

Heat generated by the engine can be re-directed from the radiator and passed through a remote radiator unit that uses a forced-air fan for interior heating.

Jordan Wicks, the SRC research technologist who has been demonstrating the machine in Saskatchewan, said the unit is well suited to remote areas that aren’t serviced by electrical utility companies.

The fuel hopper holds 50 kilograms of dry fuel, and the unit consumes about one kilogram of wood per hour per kilowatt produced.

Moisture content in the wood should be less than 20 percent for optimal performance.

“It’s a pretty basic machine,” said Wicks.

“At the end of the day, it’s just like a diesel generator, but it runs off wood.”

Anweiler said the SRC is exploring other gasification applications, such as producing fuel from municipal waste, cardboard and straw.

“The technology is certainly applicable to any type of straw waste,” he said.

“Flax is one straw that we are very interested in.”

brian.cross@producer.com

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