Prospects for Producing Low Carbon Transportation Fuels From Captured CO2 In a Climate Constrained World

The climate implications of emerging technologies that capture CO₂ to produce transportation fuels (CCTF) are investigated by studying two examples: biodiesel from microalgae and Sandia National Laboratory’s S2P process. Simple performance and economic models for each technology are examined in the context of a bifurcated – “pre-decarbonization” vs. “post-decarbonization” – climate regime in which CCTF uses CO₂ that is captured from, respectively, power plant flue gases vented to the atmosphere or taken from CO₂ in pipelines destined for geologic storage. CCTF promises to improve domestic energy security by converting sunlight and waste CO₂ into transportation fuels; in addition, these fuels are roughly climate neutral when CO₂ is captured from either flue gases or directly from the atmosphere. However, after the power sector becomes largely decarbonized under a stringent climate policy, large point sources of concentrated CO2 are likely to be relatively rare, and unfortunately, fuels made from pipeline CO₂ do not have markedly reduced net GHG emissions. Thus, absent the development of economical CO₂ capture from air, it is difficult to see how CCTF can play a significant long term role in decarbonizing the US transportation sector (and thus reaching US climate goals).