Biodiesel in Circular Economy

Recently, waste to energy projects regained international interest due to environmental concerns and sustainability agenda oriented to reduce waste generation while using these materials as feedstocks to produce low carbon energy. Biodiesel is a renewable fuel derived from vegetable and animal triglycerides. It is obtained through a transesterification reaction between a triacylglycerol and alcohol in the presence of a catalyst. Nowadays, the primary commercial feedstocks are edible vegetable oils. However, waste cooking oil (WCO) and residual fats are alternative feedstocks that can also produce biodiesel. They are available at a reasonable cost in urban areas, where food processing residues, either from residential, commercial, or industrial sectors, are relevant sources. These feedstocks have the lowest carbon emissions per litre of produced biofuel compared to fresh oil biodiesel. In 2019, the Mexico City government launched a Sustainable Energy Strategy to increase the contribution of renewable energies in its energy matrix. Particularly, in the case of the transport sector, the government has promoted, in alliance with Academic Institutions and public companies, the production of biodiesel from WCO to be consumed as a B10 blend in a pilot program for public transport. This model is expected to maximize the environmental, economic, and social benefits from the production of biodiesel since the four steps of the life cycle system would be located at the city perimeter, minimizing transport and distribution burdens. Thus, this chapter analyses the Biodiesel Program for Mexico City as a case study of biodiesel in the circular economy.