Climate Action 2011-2012

Carbon Capture
steps to sustainability
Biochar use: a
productive alternative
to carbon storage
By Bruno Glaser, Institute of Agricultural and Nutritional
Sciences, Martin-Luther University Halle-Wittenberg, Germany
Efforts to control the release of greenhouse gas emissions
into the atmosphere have included a number of options
for sequestration and storage of carbon dioxide. About
10 per cent of the EU’s carbon emissions could be offset
by more productive use of biomass and crop residues
through pyrolysis. This would provide stable carbon in the
form of ‘biochar’, that could be used as a soil improver,
and as a source for other carbon uses such as construction.
Since this technology is fully developed, the author argues,
it must be added to the armoury of weapons against
climate change, and deployed without delay.
© Valter Campanato/ABr.
Greenhouse gases such as carbon dioxide (CO 2
), methane
(CH 4
) and oxides of nitrogen (especially N 2
O) are the basis
of human-induced atmospheric pollution. The major human
contribution to the global greenhouse effect comes from the
emission of unimaginably high quantities of CO 2
into the
atmosphere. This corresponds to 11 petagrams of carbon
(Pg C a -1 , corresponding to Billions tons of C per year), of
which about nine are caused by emissions from fossil fuel
burning (about 60 per cent for electricity production and
transport, and 25 per cent for cement and steel production)
and about 2 petagrams by land use – mineralisation
of organic matter resulting in soil degradation and
desertification (Figure 1). Carbon dioxide is emitted from
deforestation, biomass burning, conversion of grassland
Figure 1. Sources and potential human-made sinks for
atmospheric carbon dioxide.
Note: Data in Pg (petagrams, 10 15 g) equal to billions of tonnes of carbon.
Note that conversion into CO 2
data requires multiplication by 3.67.
Amazonian tribes created Terra Preta 2,000 years ago.
These soils are still used today for sustainable agriculture.
to agriculture, drainage of wetlands and soil cultivation in
general. Due to increasing population growth, greenhouse
gas emissions will continue to rise.
In addition, climate change itself will influence terrestrial
and marine ecosystems’ capacity to act as repositories for
CO 2
. For instance, soil organic matter mineralisation is
expected to increase due to increasing temperature; and the
potential of CO 2
storage in the ocean is expected to decrease
with increasing temperature, both adding to the greenhouse
effect. Therefore, sustainable solutions for the removal
(sequestration) of atmospheric CO 2
are needed for global
climate change mitigation.
Carbon sequestration
Carbon (C) sequestration is the long-term removal of
CO 2
from the atmosphere, long-term implying at least
hundreds of years, preferably thousands. Current available
agricultural techniques such as conservation tillage, no
tillage or desertification control will contribute only little to
carbon sequestration into soil (Figure 1). Only conversion
of agricultural land into grassland (pasture) could cope at
least with agriculturally derived CO 2
emissions; however,
this would merely make the present problem worse because
of the tremendous loss of energy from the conversion of
plant into animal food. Therefore, potential options for C
sequestration are:
• Carbon capture and storage (CCS);
• Carbon capture and use (CCU) including C sequestration
in soil (biochar), construction materials and infrastructure;
137 climateactionprogramme.org