Patricia Gill,  Denmark Bulletin

A biochar project of over three and a half years at the Shire Waste Transfer Station has the potential to develop a world-first industry for Denmark.

Through a pyrolysis unit, which heats waste in low oxygen, green waste, silage wrap and food organics would potentially be converted into a carbon-rich product capable of improving soils and animal health.

Wilson Inlet Catchment Committee or Green Skills would possibly run the $3 million project which is the focus of a forum to be held on June 17 at the Denmark Country Club. Australia’s pre-eminent biochar specialist Professor Stephen Joseph, among other speakers, will address the forum.

In recent years, WICC executive officer Shaun Ossinger headed a $74,000 pilot project in partnership with Murdoch University which has examined the science and economics of local biochar production.

The university discovered that green waste could be converted into a safe, stable, solid carbon through a pyrolysis unit which can fit into a shipping container and be set up at the Waste Transfer Station.

The pilot project has also looked at adding other waste streams such as food organics and silage wrap with dairy effluent discharged into a pond adjacent to the pyrolysis unit.

The pond will feed water into the pyrolysis unit and through adding microalgae to the pond it could gather more carbon-rich products.

In capturing three streams of waste via the pyrolyser and algal ponds, 80 per cent of carbon from the wastes would be captured.

“Currently these are not being managed what so ever,” Mr Ossinger said.

He said producing biochar was ‘a bit like baking a cake’ with different biochars produced for different purposes at varying heat.

Studies had shown that a 150g a day biochar feed additive in dairy cattle could reduce methane by 22 per cent, increase live weight by 5-10 per cent and lift milk production by 1.4 litres a head.

Only 1g of biochar has the surface area of two basketball courts with microscopic holes in which bacteria clings.

When added to soil, it helps retain water in the soil profile, increase soil fertility and reduce the leaching of nitrogen from the root zone.

“It improves the rate of growth in plants and the gut health in ruminants,” Mr Ossinger said.

High demand predicted for locally made biochar

For the future project to be viable, the production of biochar needed to be reduced from $2000 a tonne to $500/t.

Behavioural economist Colin Ashton Graham’s research of 115 gardeners and 78 farmers in the Denmark shire showed these people were willing to pay $1000 a tonne for biochar.

In the Denmark shire, 800 tonnes a year of green waste is collected.

Demand for the biochar processed from this green waste would be so high consumers would have to wait up to three years fto receive a delivery.

So, Mr Ashton Graham’s research illustrates three scenarios.

The first uses green waste only in the shire, the second, green waste plus the same from two other shires of similar size and, third, the shire’s green waste with FOGO.

The best result was a scenario of shire green waste with FOGO.

The Shire of Denmark has tried composting green waste, sending it to Albany and now burning the material.

Silage wrap and food organics are sent to landfill and have a lot of plastic in them.

In the pilot project, samples of pyrolysed green waste and silage were analysed and the resultant biochar did not contain heavy metals, therefore, could be used as a feed and soil additives.

In recent years, the Shire considered processing of food organics but this was found to be too expensive.

It was estimated to cost $200 a tonne to send the material to Albany for processing and would have an adverse financial impact on Shire rates.

The pilot project will show if it is posssible to cost-effectively keep the carbon and nutrients in the green waste and FOGO within local farmland and gardens, and safely remove plastic contamination at the same time. 

This article appeared in the Denmark Bulletin, 30 May 2024.