Biochar: An answer to global warming or a menace?

By Renfrey Clarke
May 21, 2009 -- Sometimes you have to hand it to capitalism. It’s sheer magic the way the system takes promising concepts, steeps them in the transformative power of the market – and turns them into howling social and environmental disasters.
Take
biofuels, for example. With fossil fuels warming the planet, why not, indeed,
take advantage of the fact that plants use carbon dioxide from the atmosphere
to produce sugars and oils that can be turned into substitutes for petrol and
diesel?
We
all know where that finished up. A big chunk of the
But is the technology 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 – sequestering carbon by
turning plant matter into biochar (finely divided charcoal), and incorporating
it in agricultural soils – their suspicions were raised immediately. A research
paper was prepared, critically examining biochar and the promises made for it.
An international appeal was circulated -- entitled “‘Biochar’, a new big threat
to people, land and ecosystems” -- and opposing calls to include biochar in the
international carbon trading scheme, the Clean Development Mechanism
(CDM).
So far, the appeal has been signed by more than 120 environmental organisations around the world. Among their number is Friends of the Earth Australia.
Suspicions
The
biochar sceptics have cause to be suspicious. Enthusiasts for biochar now include
Malcom Turnbull, leader of the conservative Australian federal parliamentary opposition.
Considering Turnbull’s other enthusiasms – “clean coal”, for one – his
championing of biochar set alarm bells ringing immediately.
Added
to which, some of the proposals made for biochar sequestration are downright
barmy. British writer George Monbiot records
Furthermore, and as Biofuel Watch’s appeal rightly points out, the effects in the developing world of including biochar in the CDM trading scheme would be disastrous. An assured world market for biochar would turn the substance into an internationally traded commodity. Biochar is non-perishable and easily transported; give it a further boost by allotting it carbon credits, and producing it for export would in all likelihood yield better profits in developing-world settings than growing food crops.
Benefits
In
ideal circumstances, the growing of tree crops for biochar could be
incorporated into village agricultural systems as a superior use for degraded
or marginal land used previously for sparse (and highly destructive) grazing.
The biochar produced in small local kilns would be dug into soils, and its
dramatic benefits for soil productivity (this is well demonstrated) would aid
local nutrition and increase the food surpluses which farmers could supply to
towns.
But
add in carbon credits, 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
superior profits, would spread from the former goat pastures to occupy prime
agricultural land, where they would enjoy first call on resources of water and
fertiliser.
Food
production would shrink. An array of economic pressures would drive small
farmers off their land, and wealth in rural districts would become tightly
concentrated in the hands of the richest entrepreneurs able to take advantage of
the new conditions. Local communities would be ravaged.
The
problem, however, would not be biochar, but capitalism.
Dodgy science
So
should environmental organisations sign up to Biofuel Watch’s appeal? As things
stand, no. Action is needed, but the ammunition needs to be of much higher quality.
The science in the document is dodgy, and many of the arguments irrelevant or
overblown. That may seem a harsh judgment, but it is borne out if we look in
detail at some of the appeal’s assertions:
“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
Not
all biochars are the same – their individual properties depend on the feedstock
and on the temperature and duration of the pyrolysis process through which they
are made. But charcoal can remain intact in nature for more than 10,000 years –
it provides, after all, the basis for carbon dating. Highly fertile,
carbon-rich terra preta (dark earth) soils in the Amazon region of South
America indicate very strongly that when incorporated into agricultural land,
biochar can persist for thousands of years. The terra preta soils are believed to have been created deliberately
by ancient peoples who produced 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 per cent
consistent. But will, say, 90 per cent do?
Trials
of biochar in relatively carbon-rich soils in
“Combinations of charcoal with fossil fuel-based fertilisers made from scrubbing coal power plant flue gases… will help to perpetuate fossil fuel burning as well as emissions of nitrous oxide, a powerful greenhouse gas.”
One
suspects energy companies have weightier reasons for continuing to burn coal
than supplying biochar firms with extracts of flue gases. Meanwhile, there is
good evidence that biochar, by improving soil structure and retention of plant
nutrients, can allow crops to flourish with markedly lower applications of
artificial fertilisers.
Nitrous oxide, which
volume-for-volume has hundreds of times the warming effect of carbon dioxide,
enters the atmosphere largely through the breakdown of nitrogen fertilisers.
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
reduction in nitrogen dioxide exceeds what would be expected from lower
fertiliser use. “It seems that when you apply the biochar, that nitrogen
transformation process is inhibited”, the G-Online
site reported Cowie as saying in March. Studies have found that in some soils,
nitrous oxide emissions decline by as much as 80 per cent.
“The process for making charcoal and energy (pyrolysis) can result in dangerous soil and air pollution.”
In
principle, the slow pyrolysis process used to create biochar is exceptionally
clean. Plant matter is heated in an enclosed, oxygen-poor environment at about
500º Celsius. Volatile carbon compounds are driven off, some of them to be
condensed into a useful bio-oil. The remaining gases are burnt to provide heat
to sustain the process and (in many cases) to generate carbon-neutral
electricity. The exhaust gases that result from this combustion consist almost
entirely of water vapour and carbon dioxide; small quantities of oxides of
nitrogen that are created can be scrubbed from the exhaust stream using the
biochar itself. The solid residues from the pyrolysis process are inoffensive –
apart from the biochar, silica ash, plus nutrient elements including potassium
and phosphorus.
Biochar,
however, is a “garbage in – garbage out” proposition. If you make it out of
toxic industrial wastes, you’re likely to have problems. Such practices need to
be prohibited. But that is an argument for appropriate regulation, not for
rejecting the technology out of hand.
No to market scams
In
its handling of the science, Biofuel Watch’s appeal ignores salient facts while
stretching others to make them seem to validate particular, preconceived
conclusions. Thoughtful readers will spot this, and will not be encouraged to
support the document’s correct and necessary criticisms of the CDM and of other
market-based emissions abatement schemes.
The
truth is that capitalist markets are a completely inappropriate mechanism for
regulating environmental matters. Markets operate to secure profits for private
entrepreneurs, not to allow optimum 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.
[A shorter version of this article appeared in Green Left Weekly.]