Life-cycle fossil energy consumption and greenhouse gas emissions of bioderived chemicals and their conventional counterparts

Production of chemical compounds from biological feedstocks has attracted interest from industries seeking to reduce the environmental footprint of their products and supply chain.  Additionally, integrated biorefineries may produce bioproducts along with biofuels to improve economic performance.  It is important to understand the life cycle impacts of these products, assess whether they offer environmental and energy benefits over their petroleum-derived counterparts, and identify life cycle stages with the greatest impact.

A comprehensive life cycle analysis (LCA) of ten bioproducts produced either from algae or corn stover was conducted using Argonne National Laboratory’s Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET^TM) model.  Based on a market analysis, the following bioproducts were selected: propylene glycol, 1,3-propanediol, 3-hydroxypropionic acid, acrylic acid, polyethylene, clean sugars, succinic acid, 1,4-butanediol, l-lactic and ethyl lactate.

The first step of the analysis was to develop process models for the production of each of these compounds in Aspen Plus.  The material and energy flow data for each bioproduct production process were incorporated into the GREET bioproduct module along with flows for conventional processes synthesized from the literature to produce the same products from fossil sources. 

All the bioproducts offered greenhouse gas (GHG) emissions reductions compared to their fossil counterparts ranging from 18-93% on a cradle-to-grave basis.  Key drivers were natural gas and enzyme consumption in the conversion processes.