Energy Storage Via Carbon-Neutral Fuels Made From CO2, Water, and Renewable

R. J. Pearson, M. D. Eisaman, J. W. G. Turner, P. P. Edwards, Z. Jiang,
V. L. Kuznetsov, K. A. Littau, L. di Marco, and S. R. G. Taylor


Abstract—Fossil fuels are renewable only over
geological time scales. The oxidation, via combustion,
of considerable amounts of carbonaceous fuels since
the dawn of the industrial revolution has led to a rapid
accumulation of CO2 in the atmosphere leading to an
anthropogenic influence on the Earth’s climate. We
highlight here that a versatile energy carrier can be
produced by re-cycling CO2 and combining it
chemically with a substance of high chemical bond
energy created from renewable energy. If CO2 is taken
from the atmosphere a closed-loop production process
for carbon-neutral fuels is possible providing an
energy-dense and easily distributed storage medium
for renewable energy.
The rationale for reduced carbon or carbon-neutral
energy carriers made from re-cycled CO2 is described,
focusing on, for transport applications, their
manifestation as energy-dense carbonaceous liquid
fuels. Techniques for the separation of CO2 directly
from the atmosphere are reviewed, and the challenges
and advantages relative to flue-gas capture are
discussed. Pathways for the production of
carbonaceous fuels from CO2 are discussed. An
integrated system is proposed where renewable energy
is stored in the form of synthetic methane in the gas
grid for supply to the power generation and heat
sectors while methanol and drop-in hydrocarbon fuels
are supplied to the transport sector.
The use of atmospheric CO2 and water as feed stocks
for renewable energy carriers raises the important
prospect of alleviating a dependency on imported fossil
energy with the associated large financial transfers.
Their application in the transport sector yields a highvalue
end product. The synthesis and storage of
carbon-neutral liquid fuels offers the possibility of
decarbonising transport without the paradigm shifts
required by either electrification of the vehicle fleet or
conversion to a hydrogen economy. They can be
supplied either as drop-in hydrocarbon fuels for
existing reciprocating and turbine-powered
combustion engines or, at lower energetic cost and
using simpler chemical plant, in the form of lowcarbon-
number alcohols which can be burnt at high
efficiency levels in optimized internal combustion
engines. The suitability of these fuels for conventional
engines enables the continued provision of globally
compatible, affordable vehicles.

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