Carbon solution: cotton farmer turns waste to biochar

Carbon solution: cotton farmer turns waste to biochar

  • AUGUST 13, 2015 12:00AM
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Rierina cotton farmer Tim Commins with biochar. Picture: Vince Bucello

Watching a mountain of cotton waste burst into flames, threatening the local $25 million cotton processing gin at Whitton and thousands of Riverina growers’ unmilled cotton bales, was incent­ive enough for NSW farmer Tim Commins to think there had to be a better way.

It’s also why the cotton farmer turned steel fabrica­tion businessman is well ahead of the game — and ahead of Tony Abbott — when it comes to tackling­ carbon emissions from agri­cul­­tural proces­sing plants and helping farmers store carbon in their soil.

Mr Commins, part-owner and director of the Southern Cotton gin south of Griffith, started thinking about using the stalks, leaves and lint left over after processing local cotton, to both power the gin — replacing LPG gas — and produce a high-carbon byproduct farmers could use to restore soil fertility and carbon content.

“This was never about carbon credits for reducing emissions or getting payments from the governmen­t for carbon sequest­ration; I wanted to solve a problem with a solution that would make commercial sense not just to us at the gin, but to other agricultural and food companies around here with a big waste problem too,” Mr Commins said.

“If by burning waste products we can get rid of unwanted and dangerous trash piles, partly replace LPG gas that is used as a heat source in dryers in many processing plants, and end up with high-value biochar or charcoal to sell, that is a win-win-win situation.

“Any government mechanisms that add carbon reduction payments or carbon storage credits into that equation would be a bonus, the icing on the cake.”

The smouldering, two-month fire destroyed Southern Cotton’s vast cotton waste heaps, releasing tonnes of carbon-laden smoke and destroying the composting system that has been costing the company $250,000 a year to maintain.

It was a similar story near Mildura, when a giant pile of waste almond­ hulls spontaneously combusted at a new almond processing plant, while Australia’s biggest walnut company, Websters, faces the same risk with its walnut shells.

Mr Commins and specialist engin­eer James Joyce have since developed a hi-tech furnace based on continuous carbonisation, which can turn nut, cotton, grape, citrus and wine waste — all prod­uced in large quantities in the Murrumbidgee Irrigation Area around Griffith and Leeton — into rich black biochar.

Mr Commins estimates the ­cotton gin can slash its heating and gas bill in half — saving $500,000-$700,000 a year — by burning the 8000 tonnes of plant trash left after a big cotton harvest.

Companies that burn food or agricultural waste such as nut shells or grape marc to heat their drying machines rather than using LPG gas would get benefits not just from gas cost savings but also meet future mandatory carbon emission reduction targets.

As well as removing the fire risk, the 1000 tonnes of biochar likely to be produced at the Whitton gin is valued at $700 a tonne by the mining indust­ry, where it is used in extract­ion processes, and when sold at large gardening ­retailers such as Bunnings.

But the big nut and wine companies around Griffith are likely to want to return any resulting valuable biochar to the soil.