Technoeconomic Analysis of an Artificial Photosynthesis Fuel Plant Supplied by Raw Biogas

The objective of this collaboration between the Joint Center for Artificial Photosynthesis (JCAP) and Sempra Energy is to work towards development of a comparative analysis of net life-cycle energy use of a renewable fuel plant at pilot scale using water (H₂O), carbon dioxide (CO₂), sunlight and grid electricity as inputs. The work builds upon existing and ongoing analysis at JCAP examining hydrogen and hydrocarbon fuel production systems. We define “pilot scale” as a total fuel output of ~200 m³/hr., equivalent to ~1-2 MW continuous output (depending on the distribution of products). Note that we assume plant operation during non-sunlit hours using lowcarbon grid electricity to maximize plant capacity factor and utilization of expensive capital.

Electrochemical (EC) or photoelectrochemical (PEC) CO₂ reduction using a copper catalyst results in a variety of fuel products, including hydrogen (H₂), carbon monoxide (CO), methane (CH₄), ethylene (C₂H₄), other hydrocarbons and oxygenates (e.g., ethanol, propanol, acetaldehyde, formate ion/formic acid, etc.) (e.g., Hori et al., 1994, 2003), as well as oxygen (O₂). All of these products have some commercial value and will result in multiple revenue streams, depending on purity.