In this paper we examine the inevitable interconnection between engineering, economics and environmental impact in the electricity industry, and how they shape the roles engineers can and should play in designing the energy systems of the future. Involvement of engineers needs to happen in two ways: engineers can bring a technological awareness to the policy debate; and engineers need to be able to identify and re-think their own assumptions about engineering problems, particularly during times of economic and regulatory change. In other words, engineers must help others re-think their assumptions, and engineers must allow others to help them re-think their own. But how do we know which assumptions are valid or invalid in times of change? Often qualitative methods and interdisciplinary collaboration can help.