Carbon neutral hydrocarbons

Abstract

Reducing greenhouse gas emissions from the transportation sector may be the most difficult aspect of climate change mitigation. We suggest that carbon neutral hydrocarbons (CNHCs) offer an alternative pathway for deep emission cuts that complement the use of decarbonized energy carriers. Such fuels are synthesized from atmospheric carbon dioxide (CO2) and carbon neutral hydrogen. The result is a liquid fuel compatible with the existing transportation infrastructure and therefore capable of a gradual deployment with minimum supply disruption. Capturing the atmospheric CO2 can be accomplished using biomass or industrial methods referred to as air capture. The viability of biomass fuels is strongly dependent on the environmental impacts of biomass production. Strong constraints on land use may favour the use of air capture. We conclude that CNHCs may be a viable alternative to hydrogen or conventional biofuels and warrant a comparable level of research effort and support.

An air–liquid contactor for large-scale capture of CO 2 from air

“…We see AC as a tool for emissions mitigation. Carbon Engineering is focused on using AC to enable production of transportation fuels with low carbon intensity, and, in that context, we see it as competing with alternative transportation fuels such as electricity, biofuels and hydrogen [4]. Like any large-scale industrial facility, it poses local risks, along with a global benefit in the form of low-carbon fuels, but these risks are similar in kind to risks from other energy technology, such as biofuel refineries.…”

CO2 extraction from seawater using bipolar membrane electrodialysis

“…21 We note that CO 2 extracted from seawater can also be used as an enriched CO 2 source in the synthesis of renewable, carbon-neutral algal biofuels. 22 It is important to note that for both the non-biological 16,18 and biological 22 routes to liquid fuel synthesis, CO 2 separation from the atmosphere (in this case indirectly through the extraction of CO 2 from seawater) allows a truly carbon-neutral fuel, in contrast to CO 2 separated from flue-gas, which could produce a fuel with reduced, but not zero, net CO 2 emissions.…”

“…16,17,18 If the entire process (CO 2 extraction, H 2 generation, and fuel synthesis) is powered using a carbon-neutral source such as wind, solar, or nuclear, then no net CO 2 is emitted into the atmosphere during the combustion of the synthesized fuel. While cost estimates suggest that fuel produced in this way could be cost-competitive in the commercial market in the near future, 19 this process also represents a very attractive possibility for on-site, on-demand fuel synthesis at sea for military applications, 19,20 and for remote communities or research stations.…”

Geoengineering: could we or should we make it work?

“…The lack of a clear technological 'winner' warrants equal attention and funding on all potential solutions. (Zeman & Keith 2008) In this paper is a ringing endorsement of inducing technological change with investments in unconventional alternatives to jump start the mitigation process in transportation sectors.…”

“…(Breeze 2008) But, carbon capture and sequestration for coal-fuelled power plants would not do much for transportation systems dependent on liquid fuels. To address this knotty problem, Zeman & Keith (2008) call for a switch of conventional fuels to 'carbon neutral hydrocarbons' (CNHCs), as the 'viable alternative to hydrogen or conventional biofuels and warrant a comparable level of research effort and support'. They call for both direct and indirect methods of producing such CNHCs, using biomass and air capture with chemical plants at massive scales.…”