The UK energy technology innovation system (ETIS) has undergone wholesale remaking in recent years, in terms of its aims, funding and organisation. We analyse this process and distinguish between three phases since 2000: new beginnings, momentum building and urgency and review. Within an international trend to ETIS rebuilding, UK experience has been distinctive: from a low starting base in the early-2000s, to system remaking under a strong decarbonisation policy imperative in the late-2000s, to multiple and contested drivers in the early-2010s. Public funding levels have been erratic, with a rapid increase and a more recent decline. The private business sector has played a leading role in this remaking, and as this influence has grown, the role and style of energy innovation has shifted from long term niches to the shorter term mainstream. The UK ETIS suffers from persistent problems: fragmentation, low transparency and weak links to the research evidence base.