Commercialization of renewable-resource-based routes to chemicals is gathering speed, with major players such as Dow and Dupont already actively involved. Now, studies done at Utrecht University, Utrecht, the Netherlands, indicate that biofeedstocks can play a far wider role and offer significant economic and environmental advantages for producing many bulk chemicals.
The studies focused on 15 chemicals — acetic acid, acrylic acid, adipic acid, butanol, caprolactam, ethanol, ethyl lactate (EL), ethylene, lactic acid, lysine, 1,3-propanediol (PDO), polyethylene terephthalate (PTT), polyhydroxyakanoates (PHA), polylactic acid (PLA) and succinic acid — that realistically could be produced via fermentation and that have substantial potential consumption, at least 200,000 metric tons/year in Western Europe, explains Barbara G. Hermann of the school’s Department of Science, Technology and Society. An industrial panel, drawn from companies including BP, Degussa, DSM, Dupont, NatureWorks, Novozymes and Shell that are in a consortium supporting the research, were involved in the selection. Some of the firms also contributed data from their own large-scale bio-based plants and provided expertise, such as for estimating plant costs.
The first study, which appeared in 2007 in Applied Biochemistry and Biotechnology, analyzed the economics of production using biofeedstocks versus oil or natural gas. Valid comparisons could be drawn, Hermann notes, because she developed a generic approach that allowed all processes to be put on a common basis. Fermentation-based routes included both current technology and what may be possible in the future (assuming continuous fermentation and higher yields, 90 mol.% of the theoretical maximum, because of better genetically engineered micro-organisms).
The analyses, based on constructing a new 100,000-mt/y plant in Western Europe, gave a profited production cost, akin to a market price, for each chemical for each route. She evaluated its sensitivity to varying prices for sugar (70€/mt, 135€/mt, 200€/mt and 400€/mt) and crude oil ($25/bbl and $50/bbl), the nature of the sugar source (sugar cane, lignocellulosics and corn starch), as well as plant size (100,000 mt/y, as well as 200,000 mt/y and 400,000 mt/y for some of the products). The results showed that making many of the chemicals with biofeedstocks was already economically viable.
A second study focused on using a common methodology to assess the environmental impact — namely, greenhouse gas emissions and non-renewable-energy use — for the same 15 bulk chemicals over their entire life cycle. The results, recently published in Environmental Science & Technology, indicate that biofeedstocks provide significant savings compared to conventional petrochemical-based routes for most of the products — fermentation now doesn’t offer benefits only for adipic acid and acetic acid but eventually should (Figure 1). Indeed, Hermann adds that future fermentation technology may reduce greenhouse gas emissions by more than 100% when energy credits are considered.
