Environmental and techno-economic considerations on biodiesel production from waste frying oil in Sao Paulo city

Biodiesel is a renewable and biodegradable fuel that reduces the greenhouse gas emissions and global warming. However, the use of food oils in biodiesel production is severely criticised because its impacts on food prices, increase in crop area and deforestation. Thus, the production of biodiesel from non-food sources should be encouraged. This study was aimed at producing biodiesel from waste frying oil from residences and restaurants in an economically and environment-friendly manner. Therefore, a kinetic study of the transesterification reaction was carried out for each frying oil source. Energy and greenhouse gas emission efficiency values were measured in a diesel oil engine. Managers and residents answered some questions for evaluation of the environmental and economic sustainability of the city of Sao Paulo. The results of measurements showed that the biodiesel kinetics were zero order relative to frying oil concentration, leading to a 90.10% yield, and biodiesel physicochemical properties were in compliance with the Brazilian standards. For blends up to 30%, net power of each biodiesel was equal to that of diesel oil, but the reduction in greenhouse gas emissions were reduced by 33% compared to diesel oil. The statistical survey revealed that the city of Sao Paulo has a production potential of more than 8800 m(3) per month, which can generate savings of US$ 5,000,000 per month and an additional profit of US$ 7,000,000 per month owing to the sale of excess biodiesel, glycerin, and carbon credits. Thus, this work shows how to make the city more sustainable and contributes to the improvement of its image. (C) 2018 Elsevier Ltd. All rights reserved.