What is the minimum rate of return that investors require to extend the lifetime of a renewable energy facility?

The Flemish Energy Agency supports both investments in new renewable energy facilities and investments to extend the lifetime of existing facilities through its certificate scheme. Investors may however accept a lower rate of return for investments to extend the lifetime of an existing facility as several risks do not apply anymore. For example, risks around permitting may no longer apply as the permit has already been obtained and the risks around construction are much smaller as the site and its infrastructure has been prepared already. The objective of the study was to assess how significant any changes in risk profile and required rate of return are and advise whether or not it would be appropriate to apply a different IRR assumption in the calculations to estimate the required level of support.