We study the impact of environmental regulations on the patent activities for wind turbines between 1980 and 2008. We explicitly control for energy market liberalisation and take a potential interaction between liberalisation and policy instruments into account. We find a strong and highly significant effect of environmental tax revenues, which we regard as a proxy for the extent to which energy prices changed in favour of renewable energies, as well as foreign demand for wind turbines on innovation activities. In addition, we find that price-based policy instruments are more effective in fostering innovations in the wind turbine technology when energy markets are fully open to competition. In contrast, non-price-based policy instruments such as grants or low interest rate loans are largely independent from whether or not energy markets are liberalised.