As forest biorefineries increases14. The relationship between
As Canada’s population increases, the demand for large amounts of energy follow suit. An emerging source is the use of lignocellulosics, which are woody plant biomass composed mainly of lignin, cellulose and hemicellulose8, This feedstock proves to be valuable as it removes the dependence on importing foreign oils, and lowers greenhouse gas emissions by up to 90%, among other benefits14. Canada is a prime location for this sector as its forests can produce 200 million m3 of biomass annually, earning the ranking of second largest producer of lignocellulosic biomass in the world5. Additionally, Canada’s pulp and paper mills face increasing competition from lower-cost companies overseas, so the incentive to convert the existing mills into more cost-effective and environmentally friendly forest biorefineries increases14. The relationship between both biological and mathematical concepts must be considered when analyzing the use of biomass as an energy source in Canada.Life SciencesWoody biomass is used to produce biofuels and bioenergy through different means. To convert forest biomass into biofuel, four steps are performed; pretreatment, enzymatic hydrolysis, fermentation and distillation13. Pretreatment makes the hemicellulosic sugars found in plant biomass, mainly xylose and arabinose, accessible. This allows for easier refining of lignin because this polymer’s complex crystalline structure would otherwise make it difficult for the enzymes to reach the sugars2. After pretreatment, an enzyme is combined with the biomass mixture in a liquefaction tower. This lowers the mixtures’ viscosity so it can be pumped into saccharification tanks more smoothly13. In these tanks, the cellulose and hemicellulose are hydrolyzed, or separated into their monomers, glucose and xylose, as well as other sugars. Subsequent to this, the monomers are fermented into ethanol using a strain of Saccharomyces cerevisiae13. The final step to this process is distillation of the ethanol. Whole stillage, or the partially solid residue from distillation, is separated into thin stillage which is a liquid. This liquid is then concentrated through evaporation13. The solid parts of the whole stillage are pressed into a ‘cake’ which is rich in lignin. Both the cake and the liquid are burned to create energy13.The use of ethanol as a biofuel is important as carbon emissions are much lower in comparison to its non-renewable counterparts. For instance, based on data collected from 2007, using ethanol derived from wood biomass would decrease greenhouse gas emissions by 7%, or 2.1 million tons16 compared to the same amount of coal. Bioenergy is created using various methods including cofiring and direct combustion7. In cofiring, biomass is added to coal boilers, converting the biomass into electricity12. This process lowers the release of carbon dioxide and sulfurous gas, as biomass has a lower sulphur content than coal. This reduces instances of harmful effects such as acid rain12. In direct combustion, heat produced from the burning of biomass is used to heat a boiler and generate steam. The steam produced from this process is used in a steam turbine converting this energy to electricity10. As the research on forest biorefineries progresses, many efforts are being made to the improve the fermentation process used to make biofuels. Projects have been performed focusing on the genomics of strains of bacteria like Saccharomyces cerevisiae. The purpose of these investigations is to select for bacteria with greater biosynthetic abilities, and also to find bacteria that can make consortia with a greater ability to convert feedstock into energy and fuels5. A project called the Microbial Genomics for Biofuels and Co-Products from Biorefining Processes, studied the metabolism of different bacteria, as well as their gene structure and function pertaining to the conversion of waste materials and cellulose into renewable forms5. Through this project, they isolated eight new types of bioplastic-synthesizing bacteria which can potentially be used in the future to increase the efficiency of the biorefining process5. Along with the benefits of using biomass for energy come the consequences. A main issue is the subject of sustainability in regard to making and harvesting the biomass3. Most of the wood feedstock is obtained from waste residue found in forests across Canada. This includes leaves, branches, bark and tree tops7. While harvesting these materials may seem advantageous as it is reducing waste, ridding the forests of these types of matter could disrupt ecosystems, soil composition and habitats, leading to long term repercussions. Forest residues in Canada are abundant but not limitless and if handled incorrectly, irreversible damage to resource levels, ecosystems and biodiversity will occur7. To avoid this, current harvesting practices must be supplemented with ways to preserve the natural balance of the environment, while using the resources in an efficient manner3.