This paper argues for “Free Lunch”, a computation architecture that exploits otherwise wasted renewable energy by (i) colocating datacentres with these remote energy sources,(ii) connecting them over a dedicated network, and (iii) providing a software framework that supports the seamless execution and migration of virtual machines in the platform according to power availability. This work motivates and outlines the architecture and demonstrates its viability with a case study. Additionally, we discuss the major technical challenges facing the successful deployment of Free Lunch and the limiting factors inherent in its design.