Biochar — menace or benefit?

April 24, 2009

Sometimes you have to hand it to capitalism. It's sheer magic the way the system takes promising concepts, hands them over to the market and turns them into howling social and environmental disasters.

Take biofuels, for example.

Plants use carbon dioxide from the atmosphere to produce sugars and oils, which can in turn be converted into fuel. With fossil fuels warming the planet, why not use plants for fuel instead of petrol and diesel?

We all know where that finished up. A big chunk of the US's corn crop was turned into grain ethanol. Corn prices soared due to the extra demand. Worldwide, food production became far more expensive.

Anyone unable to pay went hungry. When US drivers filled up with bio-ethanol, they were in effect burning the tortillas of the Mexican poor.

However, was it the technology that was the problem? Or the system?


Whatever the case, when activists of the international group Biofuel Watch noted the attention being paid to another attractive concept — biochar — their suspicions were raised immediately.

Biochar is a process of turning plant matter into fine charcoal, and adding it in agricultural soils.

Biofuel Watch prepared a research paper that critically examined biochar and the promises made for it. An international appeal was circulated, titled: "'Biochar', a new big threat to people, land and ecosystems". The appeal opposes plans to include biochar in carbon trading.

So far, the appeal has been signed by more than 145 environmental groups around the world. Among them are Friends of the Earth Australia and the Australian Student Environment Network.

The biochar skeptics have cause to be suspicious. Enthusiasts for biochar now include Liberal Party leader, Malcolm Turnbull.

Considering Turnbull's passion for the Australian coal industry, and the non-existent "clean coal" technology, his support for biochar should set alarm bells ringing immediately.

Added to this, some of the proposals made for biochar are downright barmy.

British writer George Monbiot drew attention to New Zealand environmentalist Peter Read's call for new, worldwide plantations of trees and sugarcane.

Read said the plantations should cover 1.4 billion hectares, with the plant matter then turned into biochar and ploughed into soils. Trouble is, the world's total crop land only comes to 1.36 billion hectares.

Furthermore, and as Biofuel Watch's appeal rightly points out, the effects in the global South of including biochar in carbon trading would be disastrous.

An assured world market for biochar would turn the substance into an internationally traded commodity.

Biochar is non-perishable and can be easily transported. Once it can be cashed in for carbon credits it will become far more profitable. The real likelihood is land now used for growing essential crops in the poorest countries will be used for biochar production for export instead.

In ideal conditions, the growing of tree crops for biochar would be included in village agricultural systems. It would be best used on degraded or marginal land previously used for highly destructive grazing.

Biochar produced in small local kilns would be dug into soils. The dramatic benefits for food yields would aid local nutrition and increase the food surpluses, which farmers could supply to towns.

Carbon trading

Add in carbon trading, and the world capitalist market would destroy this harmonious picture. The biochar would not be used locally, but would be exported.

Large-scale commercial agriculture, often internationally based, would respond to the price signals and move in. The tree plantations, offering higher profits, would spread to occupy the best agricultural land, where they would get first call on resources of water and fertiliser.

As a result, food production would shrink. An array of economic pressures would drive small farmers off their land. Wealth in rural districts would become even more concentrated in the hands of the richest people able to take advantage of the new conditions. Local communities would be ravaged.

The problem, however, would not be biochar, but capitalism.

So should Australian environmental organisations sign up to Biofuel Watch's appeal? As things stand, no. Action against commercial biochar is needed, but the ammunition used against it needs to be of much higher quality.

The science in the Biofuel Watch appeal is dodgy, and many of the arguments are beside the point or overblown. This may seem a harsh judgment, but it is borne out if we look in detail at some of the appeal's claims:

"It is not yet known whether charcoal in soil represents a carbon sink at all …"

In what is a relatively new field of research, many unanswered questions remain. This, however, is not one of them.

In a set of notes posted in March, one of Australia's most respected authorities on biochar, CSIRO Land and Water scientist, Evelyn Krull, points out that biochar "has a chemical structure that makes it very difficult to break down by physical, biological and chemical processes."

"We know", Krull continues, "that biochar is stable over the timescales of any [carbon] abatement scheme" for up to 100 years.

Not all biochars are the same — their individual properties depend on the kind of plant used and on the temperature and duration of the burning process.

Highly fertile, carbon-rich terra preta (dark earth) soils in the Amazon region of South America indicate very strongly that when put into agricultural land, biochar can stay for thousands of years.

Historians believe the terra preta soils were created deliberately by ancient peoples who made charcoal and dug it into the ground along with food scraps and other organic matter.

•"There is no consistent evidence that charcoal can be relied upon to make soil more fertile …."

If this were the case, the Amazonian peoples would hardly have bothered. True, the evidence is not 100% consistent. Still, there is a lot of it.

Trials of biochar in carbon-rich soils in Sweden found that soil fertility actually declined. Scientists think this is because the extra carbon speeded the breakdown of existing organic matter in the soil.

But in poorer tropical soils, and also in the ancient, low-fertility soils common in Australia, the experience has been very different. Evelyn Krull writes:

"We know that biochar application can have positive results, particularly in sandy and infertile soils.

"Due to its chemical and physical nature (e.g. high degree of porosity and absorptive capacity), biochar has been shown to enhance soil fertility, resulting in increased productivity and in turn a build-up of organic matter in soil."

Meanwhile, there is good evidence that biochar, by improving soil structure and keeping plant nutrients, can allow crops to flourish with much lower use of artificial fertilisers.

Nitrous oxide, a greenhouse gas hundreds of times more damaging than carbon dioxide, enters the atmosphere largely through the breakdown of nitrogen fertilisers used in agriculture.

Not only does biochar allow the use of these fertilisers to be cut, but as NSW Department of Primary Industries scientist Annette Cowie observes, the cut in nitrogen dioxide emissions is higher than what would be expected.

"It seems that when you apply the biochar, that nitrogen transformation process is inhibited", Cowie told on March 26. Studies have found that in some soils, nitrous oxide emissions decline by as much as 80%.

•"The process for making charcoal and energy (pyrolysis) can result in dangerous soil and air pollution."

In principle, the burning process used to make biochar is exceptionally clean. Plant matter is heated in an enclosed, oxygen-poor environment at about 500º Celsius.

Unstable carbon compounds are separated, some of them to be turned into a useful bio-oil. The remaining gases are used to power the process, and (in many cases) to generate carbon-neutral electricity.

The exhaust gases that result from this process consist almost entirely of water vapour and carbon dioxide. The small amounts of nitrogen oxides created can be removed (or "scrubbed") from the exhaust stream by the biochar itself.

The solid residues from the process are inoffensive — apart from the biochar they include silica ash, plus nutrient elements including potassium and phosphorus.

Take the market out

Biochar, however, is a "garbage in — garbage out" technology. If you make it out of toxic industrial wastes, you're likely to have problems. Such practices need to be banned. But that is an argument for strong regulation, not for rejecting the technology out of hand.

In its handling of the science, Biofuel Watch's appeal ignores important facts while stretching others to make them seem to confirm particular, preconceived conclusions.

Too many readers will spot this, and will consequently not be encouraged to support the document's correct and necessary criticisms of carbon trading and of other market-based emissions reduction schemes.

The truth is that capitalist markets are a completely unsuitable means for regulating environmental matters. Markets work to secure profits for businesses, not to allow the best possible outcomes in dealing with complex natural systems.

Points such as these can be argued convincingly without giving strained and selective accounts of scientific findings, or creating needless prejudices against potentially valuable innovations.

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