# The Role of Clean Coal Technologies in the Development of Renewable Energy Sources
## 1 Introduction  
Poland's energy security has so far been based on coal. From 1985 to 2018, the contribution of coal to electricity production in Poland was not lower than 130 TWh per year. In 2019, this share dropped for the first time in 35 years to 120 TWh. The reason for this state of affairs is certainly the European Union's climate policy and Poland's Energy Policy. These documents assume the so-called decarbonization of the energy sector. This means that the EU will achieve carbon neutrality by 2050. Coal is to be replaced by renewable energy sources in this process. These provisions are included in the European Green Deal, as well as in the RED (Renewable Energy Directive) [1]. Implementing decarbonization in Poland will require a special amount of work and investment due to the specific nature of the country's energy mix. Figure 1 presents primary energy consumption in Poland in 2022. It should be noted that coal plays the dominant role. This is mainly due to Poland's favorable geographical location in terms of access to coal resources.  
This has naturally shaped the energy system, and easy access to coal fuel influenced decisions to build subsequent coal-fired power plants. Figure 2 presents the structure of energy carriers used in the electricity production process. Once again, coal is of key importance, in this case with a share of over 70%. At the same time, attention should be paid to the share of renewable energy sources (RESs). In both cases it is small, 9% in the case of demand for primary energy and 19% in the case of electricity production. Despite the RES share level in 2022, it should be mentioned that this share is growing very dynamically every year, and in 2007 it was close to zero [3].  
However, in order for renewable energy sources (RESs) to take over the role of coal in the energy generation structure, it is necessary to intensively develop them further. This is not an easy task and it will require many support mechanisms, both from the EU, Member States and the private sector. Renewable energy technology is still not perfect and requires technical and organizational development. Some of the problems that hinder the development of renewable energy sources are as follows:  
* Investments necessary to build the capacity to a level that could take over the role of coal.
* Access to the materials necessary to build this capacity.
* Storage of the obtained wind and solar energy and using it when needed.
* Ensuring stable and uninterrupted operation of the power grid.  
Fossil fuels can help to solve all of these issues. For Poland, coal is the obvious choice in this case, but used only in combination with clean coal technologies (CCTs).  
Figure 1: Share of individual energy sources in primary energy consumption, Poland 2022 [2].  
Figure 2: Share of individual energy carriers in electricity production, Poland 2022 [2].  
Clean coal technologies (CCTs) are technological solutions whose purpose is to increase the efficiency of the coal mining, combustion and processing operations [4; 5]. It is assumed that the most effective way is to implement a three-stage technology for introducing clean coal technologies in accordance with the Clean Coal Strategy (CCS) [6]. This strategy can be supplemented with a fourth level, which takes into account the use of waste from the energy production process for the development of renewable energy sources (Figure 3). Gaseous waste, mainly CO2, and solid waste such as fly ash can constitute a reservoir of materials necessary to develop renewable energy sources.