Nowadays, the importance of activities for the protection of the environment is growing. This approach has a major impact on the current energy and mining policy in Poland. On the one hand, the energy policy has imposed several restrictions to which the Polish economy will have to adapt; on the other, however, it raises great social opposition from professional groups that will be at risk of changing or losing their jobs and income, which implies extensive restructuring processes. These processes involve the decarbonisation of the economy and include, among others: sustainable production and consumption, sustainable municipal management and high quality of life in the city, waste management, sustainable transport, and energy management. The aim of the article is to indicate the importance of investment outlays and costs incurred when purchasing alternative fuels that would replace hard coal in Poland. It is part of the process of adjusting to the requirements of the new energy policy adopted by Poland as an EU member. In order to ensure energy security by abandoning coal mining, disproportionately high investment outlays for such a transformation would have to be incurred, as well as significant resources that would have to be allocated in the future to the purchase of alternative fuels. The result of the scenario methods used is the proposition of the proprietary RCAES index, which is to facilitate the transition from fossil fuels to alternative fuels, which the authors will fill in the gap existing in this area.