The working paper summarizes results of a research project on company behaviour in the EU Emissions Trading Scheme. The study looks at the first trading phase of the EU ETS and combines quantitative surveys with qualitative case studies in four different countries: Germany, the UK, Denmark and the Netherlands. In this paper, we look at seven company case studies in Denmark and Germany to analyze how emissions trading might trigger sustainable innovations within companies in the energy sector in a systematic way. Four potential channels are identified: the allocation of emission rights by the legislator, the CO 2 trading decisions within the companies, the make or buy-decision in the electricity market, and sustainable innovations through technologies or new organizational processes. We conclude from our case studies that the EU ETS has a potential to trigger sustainable innovations in the electricity sector, but that the outcome of the first trading phase is disappointing in this respect.