Waste cooking oil-to-biodiesel conversion for space heating applications

Transesterification is a process that converts triglycerides, like vegetable oil, into fatty acid methyl esters, commonly known as biodiesel. This conversion reaction requires the triglyceride feedstock, an alcohol, and an alkali-catalyst to produce the biodiesel. Biodiesel is a versatile biofuel that is renewable, biodegradable, and environmentally beneficial in the sense that combustion adds only biogenic carbon to the atmosphere. The main limitation of commercialization of biodiesel is cost. However, developing closed-loop systems that have an available triglyceride supply, such as waste cooking oil, as well as demand for diesel based fuels, can achieve substantial emissions reductions and energy avoidance, while simultaneously solving a waste disposal issue. Thus, an analysis of the development of a closed-loop waste cooking to biodiesel fuel production process is warranted.;A waste-to-energy (WtE) system like this offers great potential to institutions. Thus, this analysis includes the development of a waste cooking oil to biodiesel fuel program utilizing the available waste cooking oil of a university, the production of the fuel, the internal use of the fuel, and subsequent analysis of the fuel characteristics, emissions, and the life cycle environmental and energy impacts of the production process and ultimate use.;The results show that the waste cooking oil derived biodiesel meets the required American Society for Testing and Materials (ASTM) standard specifically for biodiesel, ASTM D6751. The produced biodiesel was blended with commercially available fuel oil, which met the ASTM specification D396-13b. Therefore, a blend of these two ASTM compliant fuels also met the required ASTM standards. The ASTM standards require high quality fuel characteristics and ensure proper utilization and combustion.;Biodiesel blended heating fuels were utilized in two distinct heating facilities, both showing comparable emissions to conventional fuel oil. Small (500 mL) and large (1L) volume biodiesel blends were utilized in a conventional residential furnace. Emissions data were obtained through the exhaust ducting with a combustion gas analyzer. The same fuel blends were utilized in a lab-scale burner apparatus without a heat exchanger, which enabled near-flame interrogation and visualization of the combustion process. The emissions of both heating facilities were comparable to the incumbent fuel oil.;The life cycle assessment results demonstrate the benefits of increasing the approved blends of biodiesel heating fuels. Currently, most oil burners are only approved up to a B5 blend (5% biodiesel, 95% fuel oil). The results show higher blends achieve substantial life cycle reduction in global warming potential and cumulative energy demand, as well as an energy return on investment of above 4, indicating more energy is obtained from the fuel than required to produce it.