Suggest locations. Estimates costs.

Abstract and paper:

http://iopscience.iop.org/article/10.1088/1748-9326/aaa9c4/meta

The chemical weathering of rocks currently absorbs about 1.1 Gt CO2 a−1
being mainly stored as bicarbonate in the ocean. An enhancement of this
slow natural process could remove substantial amounts of CO2 from the
atmosphere, aiming to offset some unavoidable anthropogenic emissions in
order to comply with the Paris Agreement, while at the same time it may
decrease ocean acidification. We provide the first comprehensive assessment
of economic costs, energy requirements, technical parameterization, and
global and regional carbon removal potential. The crucial parameters
defining this potential are the grain size and weathering rates. The main
uncertainties about the potential relate to weathering rates and rock mass
that can be integrated into the soil. The discussed results do not
specifically address the enhancement of weathering through microbial
processes, feedback of geogenic nutrient release, and bioturbation. We do
not only assess dunite rock, predominantly bearing olivine (in the form of
forsterite) as the mineral that has been previously proposed to be best
suited for carbon removal, but focus also on basaltic rock to minimize
potential negative side effects. Our results show that enhanced weathering
is an option for carbon dioxide removal that could be competitive already
at 60 US $ t−1 CO2 removed for dunite, but only at 200 US $ t−1 CO2 removed
for basalt. The potential carbon removal on cropland areas could be as
large as 95 Gt CO2 a−1 for dunite and 4.9 Gt CO2 a−1 for basalt. The best
suited locations are warm and humid areas, particularly in India, Brazil,
South-East Asia and China, where almost 75% of the global potential can be
realized. This work presents a techno-economic assessment framework, which
also allows for the incorporation of further processes.

Summary/Press Release

https://www.sciencedaily.com/releases/2018/03/180306101711.htm

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