Sustainable design and optimization of co-processing of bio-oil and vacuum gas oil in an existing refinery

In order to lower the production cost of bio-fuels and add renewable carbon into the fossil fuels, the co-cracking of bio-oil and vacuum gas oil (VGO) has been proposed by utilizing the existing infrastructures in a refinery. The co-processing technique demonstrates an excellent economic viability for its further commercialization. However, the environmental impacts of the co-processing system consisting of the co-processing process and the bio-oil production process remain unclear. In this work, a multi-objective model was built to achieve the optimum biomass raw material and bio-oil production technology by simultaneously minimizing the total cost and the environmental impacts of the co-process system. An investigation was also conducted into the effects of the FCC capability and the bio-oil/VGO feed ratio on the economic and environmental objectives. Two cases were proposed to demonstrate the multi-objective model. The results shown that the optimum biomass raw material and bio-oil production technology were heavily dependent on the objectives. The most efficiency way to reduce total cost was to lower the biomass consumption while the most efficiency way to mitigate the environmental impacts was to decrease the VGO consumption, which is because the impact of the non-renewable raw material remains the most significantly contributory to all the environmental impacts.