In order to reduce green house emission, some clean energy policies have been approved or are being designed to stimulate clean energy development in electricity systems of some countries. The implementation of these clean energy policies needs a huge investment of money because this will reform the backbones of the energy infrastructure in these countries. Thus, it is important to find out how to minimize the investment meanwhile meet the growing power demand and satisfy the clean energy policies. This issue plays an important role in the development of a country in the aspects of economics, environment and energy. In this paper, we focus on the above issue and propose a Minimal Budget Approach (MBA) algorithm, which can help decision makers to find out how to realize the clean energy policies, meet increasing power demand and keep the budget as small as possible.