Sustainable fuels are being promoted as a low-carbon substitute for fossil fuels because they may help to reduce greenhouse gas (GHG) emissions and the associated effects of transportation on climate change. But there are also concerns that if they are used more widely, there might be unforeseen environmental effects. The effects of these fuels on the environment, including climate change, have been examined in a number of life cycle assessment (LCA) studies. However, there is a lot of variation in the estimations, and their results are frequently contradictory. Thus, the aim of this chapter is to review and evaluate the most recent data in order to provide better knowledge of how sustainable fuels affect the environment.