Cracking “Economies of Scale”: Biomanufacturing on Methane-Rich Feedstock

Abstract

Methane is considered a “dream energy package” for chemical production. The large amount of energy stored in methane (CH₄) and the current market trend toward lower CH₄ price make the use of CH₄ as a carbon and energy source for higher-value chemical production desirable. With a substantial stored energy capacity of 47 MJ/kg as determined by the lower heating value (LHV), CH₄ represents a driving force behind only hydrogen (120 MJ/kg) as a high-energy feedstock for chemical production (Boundy et al. 2011). Recent natural gas prices put methane costs around $5/thousand cubic feet in 2016, one of the lowest trends since the early 2000s (Fig. 17.1a; U.S. Energy Information Administration 2017). While CH₄ production volumes are increasing, due in part to transitions in oil and gas recovery techniques (Fig. 17.1b), the distributed and small-scale nature of many sites, together with CH₄’s inherent chemical properties including flammability and gaseous nature, complicate its recovery and transportation using conventional technology (Fig. 17.1c; U.S. Energy Information Administration 2016). Rather, standard protocols at distributed or small-scale sites typically rely on flaring or venting of CH₄ to the atmosphere to remove the gas (U.S. Environmental Protection Agency 1991). Remote CH₄, however, represents a potentially lucrative opportunity given the viable technology to recover and transform CH₄ into a more readily transportable form, such as a liquid or solid value-added product (Haynes ans Gonzalez 2014; Conrado and Gonzalez 2014; Clomburg et al. 2017). Unique opportunities for industrial biomanufacturing that are not considered to be feasible for chemical manufacturing via traditional routes may be well-suited to address several challenges associated with remote CH₄ recovery, such as utilizing small feedstock volumes, erecting compact facility operations at or near well sites, pursuing biological mechanisms for direct conversion of CH₄ to higher-value fuels and chemicals in liquid or solid form, and considering early separation requirements during process design for efficient scale-up to commercial operation.