Crucible is also technology partner in the Rainbow Bee Eater project (named after the bird) in Western Australia's wheat belt, backed by a prominent farmer, Ian Stanley, and the WA Agriculture Department. The project aims to convert agricultural residues and woody crops into biochar and renewable energy.

About $1.5 million has been invested in the project over the past 18 months, by among others listed miner Alumina Ltd, which is interested in offsetting its own emissions using biochar.

Alumina believes 20 million tonnes of carbon dioxide a year could be stored using biochar by 2020. In January, its chief executive, John Bevan, said he was "not aware of any other potential large scale mitigation option that could commence capturing and storing carbon in this way within several years".

Stanley says field trials applying biochar to wheat crops are already demonstrating the agricultural benefits.

It is just one example. Lukas van Zwieten, of the NSW Department of Primary Industries and Energy, helped organise last week's biochar conference and presented a paper showing the greatest potential market for biochar was as a soil amendment, valued at between $100 and $1000 a tonne.

That's a big range, which just shows it is early days. The char can be used to improve the efficiency of fertilisers and also can be a physical amendment to the soil. Its value depends heavily on the type of application - the type of biomass used as feedstock, the soil it is applied to, the crop being grown etc.

The department extrapolated from a one-tenth scale trial to conclude that a pyrolysis unit processing four dry tonnes an hour of waste from a chicken facility (mainly manure and sawdust) could yield 2.3 megawatts an hour of electricity, saleable to the grid for $750,000 a year (assuming a price of $40/MWh). Renewable energy certificates could be sold for another $1 million (assuming a price of $55 per MWh).

The unit would also produce 12,000 tonnes of biochar a year worth - this is the big part - up to $6.4 million based on the extra sweet corn and fava beans yielded after application of biochar in the department's trial. The productivity increase was substantial - almost double, in some cases.

The trial used a pyrolysis unit made by BEST Energies, the most established Australian company in the field.

BEST is also raising money to build an $8 million-$10 million commercial-scale plant with backers including Transfield Services. The plant will turn green waste from Sydney councils into electricity and biochar.

BEST director Adriana Downie told GBIZ the most exciting potential for biochar was to be "carbon negative" but the emissions trading schemes proposed in Australia were skewing the application of the technology towards renewable energy generation, because there was no recognition of the carbon sequestered using biochar.

In Canberra this week, Downie pushed for recognition of carbon offsets using biochar under the draft Carbon Pollution Reduction Scheme, and in the position Australia's climate negotiators will take to next week's pre-Copenhagen meeting in Bonn.

The International Biochar Initiative is lobbying for the same thing globally. In an open letter to the initiative last year, Flannery, the environmental campaigner and former Australian of the Year, said biochar "may represent the single most important initiative for humanity's environmental future".

In a recent New Scientist interview, the British scientist and conservationist James Lovelock - after summarily dismissing the efficacy of carbon trading initiatives, renewable energy and carbon sequestration - was effusive: "There is one way we could save ourselves and that is through the massive burial of charcoal.

"The biosphere pumps out 550 gigatonnes of carbon yearly; we put in only 30 gigatonnes. Ninety-nine per cent of the carbon that is fixed by plants is released back into the atmosphere within a year or so.

"What we can do is [get] farmers to burn their crop waste at very low oxygen levels to turn it into charcoal, which the farmer then ploughs into the field. A little carbon dioxide is released but the bulk of it gets converted to carbon.

"This is the one thing we can do that will make a difference, but I bet they won't do it."

But maybe we will.