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Greenhouse gas removal and zero emissions energy production 57

Fig. 2.7 Global land cover.
Based on data from Latham J, Cumani R,
Rosati I, Bloise M. Global land cover
share (GLC-SHARE) databasebeta-
release version 1.0-2014. Rome: FAO;
2014.

and disposed of. Each step increases the handling requirement. For mineralization
(e.g. Mg 2 SiO 4 +4CO 2 +4H 2 O¼2MgCO 3 +SiO 2 +2CO 2 +4H 2 O), the multiples are
even higher with each gigatonne of sequestered carbon requiring the handling of more
than 15Gt of minerals, and 6Gt of water.
The second challenge concerns the permanent sequestration of the GHG. To give
some sense of scale, 1Gt(C) stored as liquefied CO 2 requires almost the same space as
3
current global annual oil production ( 5km ). If the chosen route is biochar, the same
2
12
2
1Gt(C) implies about 3.5Gt biomass, more than 4 10 m (4Mkm ) of land to grow
it (ignoring the use of recycled waste), some 20 million standard container shipments,
and if this level of production were to be reached in say, 50 years, the construction of
six biochar plants a week until 2067 [8]. (These figures should be treated with some
caution as they are dependent on a number of highly variable input parameters, includ-
ing yields per hectare, pyrolysis technologies and efficiencies, and access to waste
biomass. The figures presented here are median figures.)
It is premature to establish plausibility ranges for such an inchoate set of technol-
ogies. The amount of GGR in terms of captured and sequestered carbon is a dependent
variable in the calculator. It is for policymakers to determine what is plausible since
they control the determining factors, namely, research and investment, and the access
to key resources such as land, labor, energy, and finance. The amount of GGR that is
feasible is likely to increase as the science progresses. References to high values of
GGR should not be taken to imply that they are, or might ever, become feasible.
On the other hand, much that we do today would not have been thought feasible,
or even conceivable, a century or two ago, and in many cases, even 50 years ago.
If something similar to Moore’s Law were to apply to this new technology, it seems
plausible that in a few decades, volumes of GGR that today we might consider fan-
ciful, could become a reality.