“Money machines don’t exist — not for long, anyway.“ Arbitrage is the technical term for money machine. In well functioning capital markets there are no opportunities for arbitrage. A Pumped Storage Power Plant (PSPP) may violate this law. The “TIMES” model (The Integrated MARKAL-EFOM System) is simply spoken a sophisticated decision tree. Consequently, it opens up a battle of wits because decision trees are like grapevines: They are productive only if they are vigorously pruned. That includes, determining an appropriate discount rate. While in 2023 nuclear stocks turn into alternative energy stocks, also the demanded return has to change. Consequently, the objective of the Master’s thesis is to evaluate the extension of Pumped Storage Power Plant (PSPP) in the village Glems (Germany) and do a Net Present Value analysis. Parts 2 to 3 of the Master’s thesis are concerned with the German energy concept, its effects on electricity prices and explain how a Pumped Storage Power Plant (PSPP)works. Part 4 focuses on forecasting cash-flows and its analysis. Part 5 looks at the company cost of capital. Part 6 calculates the net present value of the investment and Part 7 is the Conclusion.