(782d) Life Cycle Assessment of Ethanol Produced in an Integrated Biorefinery From a Forest Product Industry Wastewater Stream

Integrated technology systems are designed based on the concept of “zero waste” to fully utilize natural resources by building industries next to each other when the waste of one is capable to fulfill the input requirement of another. The forest products industry produces wastewater streams of different characteristics, and this study considers the conversion of a wastewater stream from one manufacturing facility. This facility generates a wastewater stream with wood extractives suspended in it, including lignincellulosic components. Integrated with this facility, a biorefinery produces cellulosic ethanol as well as co-products; an organic acid deicer compound and steam.  At the same time, this biorefinery strategy partially displaces the need for a wastewater treatment plant (WWTP) at the forest products facility.

For cellulosic ethanol produced at this integrated biorefinery, an original life cycle environmental impact assessment has been conducted to determine greenhouse gas emissions for a functional unit of 1 MJ fuel. In this analysis, there is a reduction of WWTP impacts and these “credits” have been allocated to the main product - ethanol, and also to a co-product acetate de-icer compound based on mass production ratios.  However, in this analysis other credit allocations have been investigated.  For example, if a carbon market is anticipated in the future, both the original forest product facility and the new biorefinery would benefit monetarily from the reductions of GHG emissions from the avoidance of WWTP emissions. Three scenarios for crediting are analyzed and discussed: i all credit allocated to the original forest products manufacturing facility, ii all to the biorefinery facility, and iii 50%-50% to each. In addition, sensitivity analysis applied to key LCA inputs is also investigated.