The biodiesel production process has been widely studied and had many improvements regarding reaction conversion and cost reduction. However, most processes in this field share a common problem, the formation of glycerol as the side product. There are still many concerns involving glycerol use and demand, as the growth in biodiesel production inevitably raises glycerol formation as well. Nevertheless, the rapid growth in glycerol availability has led to price fluctuations, and, sometimes, the crude glycerol formed is even discarded as a waste product. Considering this constant problem, one option would be to indirectly use glycerol inside the biodiesel production process. One way to achieve this proposal is to convert this product to mainly hydrogen, carbon monoxide, and carbon dioxide and then convert these gases to methanol. In this study, a biodiesel production process from residual oil is proposed as well as glycerol processing to convert this side product to methanol, using it as a reactant in the same unit. The proposed process will minimize waste production by recycling the raw materials in excess from the biodiesel reaction and also the converted side product. Here, the biodiesel and glycerol processing units are thoroughly analyzed and optimized. Energy integration is also considered to reduce utility usage. A final economic evaluation is made to verify if the conversion of glycerol to methanol is economically feasible and compare the economic aspects of glycerol processing instead of selling or disposing it. The use of a circular biodiesel industry is a promising reality that could help reduce waste disposal and encourage new findings and alternatives to improve the conversion of such wastes into value-added products.