PNNL

Abstract

Viable manufacturing of bio-based chemicals is critical to decarbonize the industrial chemicals sector, and microbial bioconversion and hybrid processes that include subsequent chemo-catalytic conversion can produce many types of compounds to that end. Here, we conduct methodologically-consistent process modeling, techno-economic analysis, and life cycle assessment to highlight sensitivities and trends in economics and environmental impacts for multiple cellulosic sugar-derived chemicals across an array of metabolic space: 2,3-butanediol (2,3-BDO), 3-hydroxypropionic acid, 1,8-cineole, muconic acid, aconitic acid, malic acid, and medium-chain-length polyhydroxyalkanoate (mcl-PHA). We conduct multi-variate analyses to identify key drivers of production costs, greenhouse gas (GHG) emissions, and marginal CO2 abatement costs to identify the minimum performance metrics required for each pathway to compete with or outperform commodity product benchmarks from both economic and environmental perspectives. Except for 1,3-butadiene derived from 2,3-BDO, all assessed molecules could be conceptually synthesized at competitive prices, defined as within 25% of current market prices. Additionally, all compounds have the potential to reduce GHG emissions below those of their respective petrochemical counterparts if a given minimum process performance is achieved. Additionally, our analysis also revealed clear trends associated with large-scale bioproduct manufacturing: namely, 1) molecules derived from anaerobic processes consistently correlate with lower minimum selling prices and GHG emissions compared to aerobic processes, 2) the catalytic upgrading of bioconversion products to final products adds substantial cost and increased emissions either due to the loss of heteroatom mass (e.g. water from dehydration reactions) or from the use of capital- and chemical/energy-intensive steps, and 3) the selected downstream processing technique can help anticipate the economic and environmental impacts associated with bioconversion products. Moreover, because the classes of molecules assessed in this study share key process parameters – such as maximum theoretical yields, aeration demand, and recovery strategy – with other products from the same metabolic node, the economic and environmental results shown here can often be extrapolated to related molecules from that node.