In this Briefing, Dave Elliott establishes the basic sustainable energy options. However his main aim is to look at potential problems ahead in the short, medium and long term, and deal with the counter-arguments. No technology is entirely benign. Renewable energy technologies may have far less impacts than the global impact of fossil-fuelled plants, but they do have some local impacts. How do we trade off local and global impacts? The author looks at the UK wind farm issue and at the problems facing hydro power and waste combustion. The medium term example concerns a sustainable transport policy: whether we can develop a green energy system to meet that demand as well. This means looking at changes in the way we live and behave. The final example concerns the longer term limits of the sustainable energy approach: whether it is possible to use renewable sources to sustain economic growth indefinitely.