[en] The European power sector is transforming due to climate policies and an increased deployment of intermittent RES. The sector will require thermal power plants for the decades to come, but their business cases are (negatively) affected by this transformation. This study presents a novel tool to quantify the effect of policy, price and project-related uncertainties on power plant business cases. This tool can support policymakers in stimulating necessary investments in new thermal generation capacity. We find that these investments are currently unsound (power plants recoup on average –12% to 59% of their initial investment). Future climate policy, i.e. the CO_2 price, has a very strong impact on business cases (affects the profitability by 5–40%-points). The impact of the deployment of wind power is average (2–8%-point difference between 10% and 21% wind penetration). Variations in annual wind power production barely affect the profitability (variation of ±1%-point). To stimulate new investments, policymakers should first decrease the uncertainty in business cases caused by policy. Durable climate policy is especially important. Also, policies to increase the profits of thermal power plants should be carefully considered and implemented. This combined approach will reduce the revenue gap that needs to be bridged by supportive policies. - Highlights: • The operation of thermal power plants is affected by CO_2 prices and wind power. • A new tool quantifies the effect of their uncertainty on power plant profitability. • New power plants are unprofitable and show a large spread in expected profits. • Uncertain future climate policy is a key factor in all business cases (±56% change). • Increasing wind power penetration (10–21%) decreases profitability by 14%.