This article is a broad literature review of materials used and defined as potential for heat storage processes. Both single-phase and phase-change materials were considered. An important part of this paper is the definition of the toxicity of heat storage materials and other factors that disqualify their use depending on the application. Based on the literature analysis, a methodology was developed for selecting the optimal heat storage material depending on the typical parameters of the process and the method of heat transfer and storage. Based on the presented results, a solution was proposed for three temperature ranges: 100 °C (low-temperature storage), 300 °C (medium-temperature storage) and 500 °C (high-temperature storage). For all defined temperature levels, it is possible to adapt solid, liquid or phase-change materials for heat storage. However, it is essential to consider the characteristics of the specific system and to assess the advantages and disadvantages of the accumulation material used. Rock materials are characterised by similar thermophysical parameters and relatively low prices compared with their universality, while liquid energy storage allows for greater flexibility in power generation while maintaining the operational parameters of the heat source.

The European Union aims to be climate neutral by 2050. To achieve this ambitious goal, net greenhouse gas emissions must be reduced by at least 55% by 2030. Post-combustion CO₂ capture methods are essential to reduce CO₂ emissions from the chemical industry, power generation, and cement plants. To reduce CO₂, it must be captured and then stored underground or converted into other valuable products. Apromising alternative for CO₂ reduction is the use of humic acid salts (HASs). This work describes a process for the preparation of potassium (HmK) and ammonium (HmA) humic acid salts from oxidized lignite (leonardite). A detailed characterization of the obtained HASs was conducted, including elemental, granulometric, and thermogravimetric analyses, as well as 1H-NMR and IR spectroscopy. Moreover, the CO₂ absorption capacity and absorption rate of HASs were experimentally investigated. The results showed that the absorption capacity of the HASs was up to 10.9 g CO₂ per kg. The CO₂ absorption rate of 30% HmA solution was found to be similar to that of 30% MEA. Additionally, HmA solution demonstrated better efficiency in CO₂ absorption than HmK. One of the issues observed during the CO₂ absorption was foaming of the solutions, which was more noticeable with HmK.

Since fossil fuels still dominate industry and electricity production, post-combustion carbon capture remains essential for decarbonizing these sectors. The most advanced technique for widespread application, particularly in hard-to-abate industries, is amine-based absorption. However, increasing energy efficiency is crucial for broader implementation. This study presents pilot-scale results from the Tauron Power Plant in Poland using a mobile CO₂ capture unit (1 TPD). Two innovative process modifications—Split Flow (SF) and Heat Integrated Stripper (HIS)—were experimentally investigated; they achieved a 10% reduction in reboiler heat duty, reaching 2.82 MJ/kg_CO2, along with a 36% decrease in overall heat losses and up to a 28% reduction in cross-flow heat exchanger duty. The analysis highlights both the advantages and challenges of these modifications. SF is easier to retrofit into existing plants, whereas the HIS requires more extensive modifications in the stripper section, thus making HIS more cost-effective for new installations. Moreover, as heat consumption constitutes the primary operational cost, even a moderate reduction in heat duty can lead to significant economic benefits. The HIS also offers substantial potential for thermal integration in industries with available waste heat streams. The pilot data underwent validation procedures to ensure reliability, which provides a robust foundation for process modeling, optimization, and scaling for industrial applications.