International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Carbon capture, Utilization and Storage (CCUS) technologies are rapidly evolving as a critical component of global decarbonization strategies, particularly in hard-to-abate sectors such as natural gas processing, power generation, fertilizer, cement and steel production industries. Amine-based absorption systems are currently the most established capture method, widely applied in large point sources for natural gas processing and chemical industries. Alternatives such as membrane separation, adsorption, and direct air capture are also emerging, offering benefits for specific applications. CO2 transport is increasingly diversified, with supercritical CO₂ pipelines and liquefied CO₂ shipping offering scalable and flexible solutions. CO₂ storage is focused on deep saline aquifers and depleted oil and gas fields. Carbon capture costs are project-specific and depend on CO2 concentrations, facility size, and technology complexity, with costs ranging from 30 to 120 US$/tCO2. The CCUS chain will undergo substantial development in the next decades, both in technological maturity and economic viability. As of early 2025, the total global CCUS capacity was 50 million tonnes per annum (MTPA) and is expected to reach 1300 MTPA by 2050. Yet, this will cover only 6% of total global CO₂ emissions, far from any net-zero carbon emissions scenario. By 2050, modularization, improved materials, and process integration are expected to reduce investment costs by up to 30%.

The utilization of fly ash (FA) generated by the combustion of coal in thermal power plants instead of its disposal is a critical issue worldwide, which imposes the best available techniques and standards for sustainable practical application of this abundant resource. The present study considers an opportunity for smart utilization of fly ash from domestic Bulgarian lignite coal by its conversion into dualfunctional material with high adsorption capacity to capture carbon emissions and catalytic ability to convert them into synthetic fuel. FА with a high content of iron oxides, obtained as an average sample from the hydroseal of electrostatic precipitators of a Bulgarian coal-fired power plant, is converted by alkaline treatment to a zeolite-like material. Due to its favorable surface characteristics, the obtained material was tested for its adsorption potential toward CO2 at pressure of 5.5 MPa. High content of iron oxides uniformly distributed into the zeolite matrix is a prerequisite for the catalytic properties of the material, which contribute to the conversion of CO2 to methane, proven by infrared spectrophotometry and thermogravimetry combined with gas chromatography and mass-selective detector.