Phil. Trans. R. Soc. A (2010) 368, 1091–1108 doi:10.1098/rsta.2009.0216 R E V I E W The path to fusion power† B Y C HRIS L LEWELLYN S MITH AND S TEVE C OWLEY* Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon OX14 3DB, UK The promise, status and challenges of developing fusion power are outlined. The key physics and engineering principles are described and recent progress quantiﬁed. As the successful demonstration of 16 MW of fusion in 1997 in the Joint European Torus showed, fusion works. The central issue is therefore to make it work reliably and economically on the scale of a power station. We argue that to meet this challenge in 30 years we must follow the aggressive programme known as the ‘Fast Track to Fusion’. This programme is described in some detail. Keywords: energy; fusion; power 1. Introduction Global energy use is expected to increase 45 per cent by 2030 (World Energy Outlook 2008). Meeting this demand will be extremely difﬁcult; meeting it in an environmentally responsible manner will be an enormous challenge. Currently, 80 per cent of the world’s primary energy is generated by burning fossil fuels—a resource that is rapidly dwindling. Consider coal reserves. It is often said that there is enough coal for some 200 years—but that assumes current use. Continuation of the current 4.5 per cent per annum growth in coal use reduces 200 years to 50. And it is well established that burning fossil fuels has adverse effects on climate and the environment (Intergovernmental Panel on Climate Change 2007). All experts agree that a portfolio approach is needed to decrease dependence on fossil fuels and to meet increased world energy demand—there is no single ‘solution’. Improved efﬁciency will be vital, and needs to be encouraged by ﬁscal measures and regulations. But, even if efﬁciency can reduce demand in the developed world, it cannot provide the growth in total energy use that is needed to deliver a decent standard of living in the developing world, where 1.5 billion people still lack electricity. Renewables should be deployed to the largest extent *Author for correspondence (steve.cowley@ccfe.ac.uk). †General information on fusion can be found in McCracken & Stott (2005), Weisse (2003), or on the CCFE Culham website (www.fusion.org.uk). One contribution of 17 to a Theme Issue ‘Personal perspectives in the physical sciences for the Royal Society’s 350th anniversary’. 1091 This journal is © 2010 The Royal Society