Biochar - menace or benefit?
Renfrey Clarke
Biochar is the
latest concept that has been bandied around as a solution to
climate change. While it may be beneficial in certain
circumstances, commercializing it could pose social and
environmental problems. |
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?
Suspicions
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
internatio
nally 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:
o”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.
o”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.”
Meanw hile, 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 Gmagazine.com.au on
March 26. Studies have found that in some soils, nitrous oxide emissions
decline by as much as 80%.
o “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.
- Third World Network Features
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