In order to assess investment needs different fields of action of the green economy are investigated. Three groups are differentiated. The first group includes renewable energies, energy efficiency and climate friendly transport, i.e. measures to reduce greenhouse gas emissions which show a great potential and high political priority and therefore involve high investment needs which will increase until 2050. The second group includes sustainable water supply, waste water disposal, and agriculture. In view of the increasing quality requirements regarding waste water treatment, the measures according to the water framework directive and the continued introduction of the organic farming the changes to be expected in these sectors are also quite well defined. However, they are linked to comparatively small investment needs. Finally, the raw material efficiency and recycling industry are representatives of the third group. Even though they show significant differences in investment requirements, they have in common that the sustainability targets are not concrete and the scope of application is complex. For this reason, the investment requirements are defined using a top down method, whilst a bottom up approach is used for the first two groups. Overall, the investment needs in the investigated areas range between 1.2 percent of the economic output in Germany in the year 2020 and 1.8 percent in the year 2050. In the next step, a screening of international financing concepts and instruments is carried out, as well as a deeper analysis of selected examples and a discussion of innovative financing approaches from different fields of application. On this basis proposals for financing instruments and policy recommendations are derived.