Status of Canada's lignocellulosic ethanol: Part I: Pretreatment technologies

Canada is endowed with abundant lignocellulosic biomass from agriculture and forestry. These sources provide a foundation for the development of Canada's cellulosic ethanol biorefinery concept which is supported by government renewable energy policy initiatives. However, the chemical structure of lignocellulosic biomass comprising carbohydrate polymers and lignin makes the structure recalcitrant to deconstruction, thereby constraining the ability of enzymes to convert these polymers into fermentable sugars without expensive and highly capital intensive pretreatment processes. The challenges are further compounded by the diversity of lignocellulosic biomass available in Canada, which typically necessitates commercial pretreatment pathways optimized for each feedstock type. In turn, these conditions constrain the development of viable business models for the commercialization of Canada's cellulosic ethanol biorefinery concept. In order to address these challenges, Canadian researchers have continued to undertake research to develop pretreatment technologies applicable to several Canadian lignocellulosic biomass sources. The objective of this paper is to review contributions by Canadian researchers vis-à-vis the development of bioconversion pretreatment technologies needed to advance the commercialization of Canada's cellulosic biorefinery concept. These pretreatment technologies include physical, physico-chemical, biological, and processes that combine these methods. This paper also highlights the role of multi-institutional science and innovation collaborative approaches for advancing Canada's cellulosic ethanol biorefinery concept further downstream.