Carbon-neutral liquid fuel from sunlight, air, and water

Abstract

We propose a system that produces carbon-neutral liquid fuel using only sunlight, air, and water. Our proposed system involves electrochemical capture and separation of carbon dioxide from the atmosphere, and generation of hydrogen gas via the electrolysis of water using photovoltaic-generated electricity. The hydrogen is used to catalytically hydrogenate the captured carbon dioxide to generate methanol or other liquid fuels using well-established methods [1]. We will discuss our experimental progress toward energy-efficient electrochemical CO2 separation from the atmosphere. First we will discuss the latest results from an ongoing project that uses a modified-fuel-cell-based approach towards CO2 separation [2]. Using this approach, we have demonstrated CO2 separation from atmospheric concentrations with an energy consumption of less than 400 kJ/mol(CO2). We will also discuss progress on a second approach to electrochemical CO2 separation: a novel pH-controlled, high-pressure electrodialysis system that allows energy-efficient, high-rate CO2 separation from the atmosphere [3]. [1] K. Ushikoshi, “A 50 kg/day class test plant for methanol synthesis from CO2 and H2,” in Advances in Chemical Conversions for Mitigating Carbon Dioxide, T. Inui et al., eds., Studies in Surface Science and Catalysis, 114, 357 (1998). [2] Karl Littau et al., “An ‘Atmospherically Healthy’ Recipe for Carbon-Neutral Fuels: A synthetic fuel made from sunlight, CO2, and water,” CTSI Clean Technology & Sustainable Industries Conference & Trade Show, Boston, MA, June 1-5, 2008. [3] Karl Littau, “System and method for recovery of CO2 by aqueous carbonate flue gas capture and high efficiency bipolar membrane electrodialysis,” patent pending.