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Sunday, September 23, 2018

Small-scale gasifiers for solar hybrid gensets

So-called "intermittent" renewable energy can be used in two or more ways to make synthetic methane from any material (straw, waste plastic, coal, etc) containing carbon.

One way is to use renewable energy when supply exceeds demand to power a plasma gasifier.

Another way is to use renewable energy to produce hydrogen by electrolysis of water - and combine that hydrogen with carbon from one or more sources.

Each kilogram of wheat straw with about 7% moisture content is made of 48% cellulose by weight (of which carbon is 44%) and 25% is lignin by weight (of which carbon is 65%) ... (((1000 x (48 / 100) x (44 / 100)) + (1000 x (25 / 100) x (65 / 100))) = 374.

That is 374 grams of carbon in each kilogram - sufficient to manufacture about 500 grams of synthetic methane which has a heating value of 50-55.5 megajoules per kilogram (MJ/kg).

The carbon in 2 tonnes of wheat straw would be sufficient to manufacture 1 tonne of methane with a heating value of 50-55.5 gigajoules (GJ). Natural gas has a wholesale price of $10-$12 per gigajoule in Australia. 

Over 500 million tonnes of wheat straw are produced annually world, the majority of which are burnt in the field. See "Physical Properties of Wheat Straw Varieties", American Journal of Engineering and Applied Sciences, 2012, 5 (2), 98-106.

Small-scale biomass gasifiers are one more renewable energy generation option for Australian farms that need affordable, reliable 24 hour a day electricity supplies.

For example, a seller on Alibaba in China has a biomass gasifier offered for $500 - $1,000 per unit.
Environment Friendly Biomass Gasifier
Environment-Friendly Biomass Gasifier

Another offers gas-fueled electric generators for $550 - $1,250 per unit.

Teenwin biogas electric generator

Teenwin biogas electric generator