By Gary Thomas
Helping Nature Help Us
Farming Benefits of Biochar
Limitations of Biochar
Sources and Further Reading
Helping Nature Help Us
In the fight to reverse the worsening effects of climate change,
there is no one quick-fix idea that will magically save the world.
Rather, a combination of methods needs to be utilised and integrated
One such idea that may be used is ‘biochar’. Biochar is essentially
charcoal, except it is given different name when used in
environmentally oriented applications.
It is formed in roughly the same way, i.e. by the thermochemical
decomposition (or pyrolysis) of living or recently living organic
material (biomass) in the absence of oxygen. This process has been used
for thousands of years to produce charcoal, by burning wood (as other
bio waste such as plant stalks and roots). This eventually results in
only carbon and inorganic ash. And because there is no oxygen involved
in the process, it means that the carbon will not combust.
Remnants of this process are seen in the Amazon rainforest, in the
dark soils known as ‘terra petra’. It is thought that ancient
Amazonians used a method of pyrolysis to produce better soils for
There are numerous benefits of using biochar in everyday
applications and also on a larger scale to help significantly reduce
carbon dioxide in the atmosphere. Like many clean technology ideas
biochar is not a new one – research on its potential started as far
back as 1947. However, with the aid of modern practises there has now
been resurgence in interest in the potential of biochar.
The prominent environmental benefit of biochar is that is can trap
carbon dioxide and hold it for a long time. Plant material and animal
waste will naturally decompose if left alone, and this ends up
producing a large amount of CO2 which then becomes a
greenhouse gas in the atmosphere. This is of course a natural part of
the carbon cycle, but with the huge amount of farming that occurs
globally, agricultural waste is a huge contributor to the greenhouse
effect via this decomposition.
However, if this waste in converted into biochar, the carbon is
locked within it and will not enter the atmosphere. Furthermore, the
carbon in biochar is very resistant to degradation, meaning that if
this is buried in the ground, it could stay there for centuries. It is
thought by using this simple method of creating biochar from farm waste
and burying it in the ground, up to 2.2 gigatons of carbon could be
stored in the ground by the year 2050. Emissions of nitrous oxide and
methane, two more potent greenhouse gases may also be reduced via the
production of biochar.
Sewage treatment is also a significant producer of greenhouse gases,
but if pyrolysis is used to convert the sewage to biochar, it has been
shown that up to 60% of the carbon in the sewage could be locked away.
The entire process ends up being carbon negative and would help to
stall the amount of anthropogenic CO2 entering the
atmosphere. The technique of burying biochar in the ground can be seen
as a form of CDR
Farming Benefits of
The second independent benefit of biochar is that it makes soil
appreciably more fertile. The native tribes of the Amazon still search
for ancient ‘terra preta’ because of the fertility of this land. The
reason that soil containing biochar is so good for farming is that when
the biochar is created, it becomes a highly porous solid, but because
of its fine grained nature it is not very permeable. This means that
biochar can retain a relatively large volume of nutrients and water
within the soil, allowing better crop growth.
Moreover, the good retention of nutrients and chemicals means that
biochar use on farmland can lead indirectly to better quality water in
the area, as the retention of the chemicals in the soil means that they
will not leach into groundwater supplies and cause pollution.
Furthermore, the pyrolysis process can also form biofuels. Biochar
is produced at temperatures between 400-500oC, but if
biomass is heated to over 700oC, then it can be used to
produce syngas, which could potentially be used as fuel.
Limitations of Biochar
One of the prominent issues when discussing biochar production as a
large-scale solution to climate change is that there are few financial
rewards currently for the production of biochar. Most money in this
sector is given out for work involving the production of energy via
biowaste, rather than storing it in the ground.
The Royal Society has questioned how effective biochar would be in
reducing carbon emissions in the long term and also suggested that
widespread production of biochar may inadvertently lead to a rise in
food costs and a lack of crops.
Lastly, some people are advocating plantations specifically for the
production of biochar, which would be detrimental to local ecosystems
and native populations.
Sources and Further
Lovelock on biochar: Let the Earth remove CO2 for us – The
must cool enthusiasm for setting fire to the planet – The Guardian,
Is the hype justified? BBC News, 16/03/09