In this study, a comparative Life Cycle Assessment has been performed with the aim of finding out how the environmental impact derived from biodiesel production (using raw sunflower oil or waste cooking oils) could be affected by the degree of decentralization of the production (number of production plants in a given territory). The decentralized production of biodiesel has been proposed for several reasons, such as the possibility of small scale production, the fact that there is no need to use high technology or make large investments, and because small plants do not need highly specialized technical staff. Thus, hypothetical territories (considering scenarios in which the production and area were theoretically modified), as well as real territories, have been analyzed to determine which environmental indicators were most affected. Results showed that the optimum degree of centralization was different for each analyzed case. In general, in small territories centralized production was more suitable for the environment, decentralization being more advisable as the territory increased in area. For each of the cases analyzed, an optimum number of plants, which minimized the environmental impacts, was found. This work illustrates the importance of considering the number of industrial plants in the production design, not only from an economic aspect but also from an environmental point of view.