At Laragon Almonds in north-western Victoria, the processing plant is dwarfed by the piles of leftovers that sit alongside it.
The hulls and shells are normally sold as livestock feed, but with the almond industry expanding rapidly over the past decade, that market is oversupplied.
"A couple of years ago, we were achieving $200 a tonne," managing director Brendan Sidhu says.
"This year, we'll probably average $30 a tonne for [the] hull, so it's a significant difference."
With that in mind, he went looking for an alternative and landed on biochar, a type of charcoal that's rich in carbon.
"We think that there's a great demand for it in the future," he says.
"But we think there are also great spin-offs."
What is biochar?
Biochar is made by heating organic material with limited oxygen through a process known as pyrolysis.
SDA Engineering, which is supplying Laragon with its pyrolysis plant, has been trialling more than a dozen agricultural residues from nut, forestry, broadacre and wine industries.
Company co-founder Leon Daych says generally the leftovers sit in a paddock and deteriorate and release carbon dioxide into the atmosphere.
Instead, the carbon is locked up in the biochar, which Mr Daych says is a very versatile product.
"It can be used as a pharmaceutical ingredient, as a road building material, as concrete for bricks and so on, so the applications are really unlimited."
Benefits to agriculture
One of the biggest beneficiaries of turning agricultural leftovers into biochar could be the agricultural industry itself.
Agricultural and environmental scientist Melissa Rebbeck, who ran a year-long trial at a commercial dairy, says there are many benefits to using biochar.
"When you do feed it to an animal, we found benefits for improved milk yield, and we've also found better feed conversions," she says.
Ms Rebbeck says there is also a lot of research that shows it can improve soil productivity and yields.
"For every 1 per cent you increase the soil carbon, you increase the water holding capacity by 10 to 30 tonnes per hectare," she says.
"It's a no-brainer in a country like Australia."
But that productivity comes at a cost.
On average, biochar sells for about $800 a tonne in Australia at the moment.
And there are reports it doesn't always work.
But influential economist Professor Ross Garnaut, who spoke at the recent Australia New Zealand Biochar Summit, says "of course, there'll be sceptics".
"Australians are like that, they don't believe it until the farm next door has done it and is making money from doing things better, and then they change and do it themselves," he says.
Multiple income streams
A growing number of agricultural companies are investing in pyrolysis plants because they are starting to make business as well as environmental sense.
In fact, it's the by-products that come with biochar that are often the big selling point.
Mr Sidhu says Laragon Almonds plans to harness the excess heat produced in pyrolysis to dry its almonds and generate power for the rest of the de-hulling plant.
"From an emissions saving, obviously we're not generating and using coal-generated power, so that's a huge plus for us," he says.
"We no longer need the LPG gas that we currently use, so that's again another big savings.
"So we think our savings on site will be north of $500,000 a year."
Then there's what's commonly called wood vinegar.
It's the liquid by-product of pyrolysis, which NSW company PyroAg sells as an agricultural tool that can reduce the need for fertilisers and pesticides.
According to company co-founder Chad Sheppeard, the benefits are great.
"It actually feeds the microbes in the soil and helps the bugs in the soil grow in diversity and population, which then helps the plants' uptake nutrients out of the soil," he says.
Selling carbon credits
On top of the by-products, there's another increasingly lucrative source of income.
Biochar is now recognised in some carbon markets.
So producers that are certified as negative net emitters can sell carbon credits to companies that want to neutralise their own emissions.
"Since we started looking at this market, the value of the carbon credits are tripled and it's probably worth in excess of $200,000 a year for our business," Martin Jeffries, whose family business in South Australia turns household green waste into agricultural products like compost and fertiliser, says.
Momentum in the biochar industry is building.
In South Australia, there's a parliamentary inquiry into the industry.
Ms Rebbeck has big plans to convert Kangaroo Island's bushfire-affected timber.
"There's six and a half million tonnes of partially burnt timber on Kangaroo Island that is rotting at the moment that produces 50 per cent of its waste as carbon dioxide," she says.
"All of that could be turned into biochar."
But to achieve these goals and make biochar more affordable, the industry needs to scale up and that's going to push Australian manufacturing.
Professor Garnaut believes the movement is gaining momentum.
"The next five years will be a period of innovation and learning, increases in scale, reductions in costs and in five years time, we'll be in a strong position to run fast," he says.
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