In the Kyoto Protocol each country involved has agreed to reduce the emission of CO2 gases. For Europe the objective is to reduce the emission with 8% compared to the emission in 1990. The Netherlands has an objective of 6% reduction. To achieve these reductions, so-called ‘Kyoto-mechanism’ was launched: Joint Implementation (JI) and the Clean Development Mechanism (CDM). Under the framework of these mechanisms the Netherlands is able to buy ‘carbon credits’ from other countries. One carbon credit equals 1 ton of CO2-reduction each year. Joint Implementation Carbon credits earned with Joint Implementation are called Emission Reduction Units (ERUs). Joint Implementation is possible only between industrialised countries. In practice a company can earn ERUs in Central- and East-Europe. For example municipalities in the Czech Republic have switched their fossil fuel based district heating system into a renewable system with biomass, leading to a substantial reduction in the emission of CO2. The credits derived from the resulting ERUs are used to co-finance the fuel switch project.