In this work, we address the problem of reducing the environmental impact of biodiesel plants through their integration with a solar thermal energy system that generates steam. A mathematical model of the solar energy system that includes energy storage is constructed and coupled with a rigorous simulation model of the biodiesel facility developed in Aspen Plus. The solar energy system model takes the form of a bicriteria nonlinear programming (biNLP) formulation that accounts for the simultaneous minimization of cost and global warming potential (GWP). A detailed cost and environmental analysis of the integrated facility is presented based on data available in the literature. The environmental impact is quantified in terms of contribution to GWP using the CML2001 methodology, a framework based on life cycle assessment (LCA) principles. Numerical results indicate that it is possible to reduce the current natural gas consumption required in the biodiesel facility by more than 94.87% compared to the initial base design, which results in an improvement of 19.88% in green house gases (GHG) emissions.