Underground coal gasification (UCG) allows for the utilization of coal reserves not exploitable due to unfavorable geology and economic boundary conditions. The present study examines underground coal gasification economics converting deep-situated coals into a high-calorific UCG synthesis gas. Utilizing UCG synthesis gas to fuel a combined cycle gas turbine (CCGT) considering CO2 capture and its subsequent storage (CCS) in the underground voids resulting from coal consumption, the coupled process offers an economic low carbon option to coal fired power generation for a study area in Bulgaria. The selected coal deposit is not suitable for conventional mining due to great depths, but it may be exploitable by UCG. Cost-effectiveness, CO2 emissions and energy demand of the coupled process are analyzed using a techno-economic model specifically developed for that purpose. Capital and operational expenditure are ascertained from calculations considering six dynamic sub-models describing the UCG-CCGT-CCS process flow and aiming at determination of the costs of electricity (COE). Calculation results show that COE account to 71.67 €/MWh considering 20.5% CCS costs and 79.5% emission charges. The results show that the coupled UCG-CCGT-CCS process should be considered as an economic and low carbon option for power generation for the selected study area

Excess electricity from wind and sun can be transformed into hydrogen and with carbon dioxide subsequently into methane. When needed, electricity is regained in a combined cycle plant burning the methane. To close the carbon cycle carbon dioxide is captured on site. Two subsurface storage formations for both gases are required for the technology. Our regional showcase of two German cities, Potsdam and Brandenburg/Havel, demonstrates that about 30% of their electricity demand can be provided in that way, using 17.2% of renewable electricity generated in the State of Brandenburg. The overall efficiency of the system is 27.7%

UCG facilitates deep-seated coal seam utilization in the Jamalganj deposit (Bangladesh) by producing synthesis gas for electricity and fertilizer production. Based on previous studies which assessed UCG combined with carbon utilization in a urea process, we further investigated excess CO2 utilization by means of enhanced gas recovery (EGR) at the Bahkrabad gas field. Our techno-economic modeling results demonstrate that an economic and carbon neutral UCG operation with urea production and EGR is feasible. Thus, this approach introduces a bridging technology that can tackle Bangladesh's fertilizer and power supply shortages in addition to increasing gas recovery from Bangladesh's depleting natural gas deposits

This paper presents the outcome of a feasibility study on underground coal gasification (UCG) combined with direct carbon dioxide (CO₂) capture and storage (CCS) at a selected site in Bulgaria with deep coal seams (>1,200 m). A series of state-of-the-art geological, geo-mechanical, hydrogeological and computational models supported by experimental tests and techno-economical assessments have been developed for the evaluation of UCG-CCS schemes. Research efforts have been focused on the development of site selection requirements for UCG-CCS, estimation of CO₂ storage volumes, review of the practical engineering requirements for developing a commercial UCG-CCS storage site, consideration of drilling and completion issues, and assessments of economic feasibility and environmental impacts of the scheme. In addition, the risks of subsidence and groundwater contamination have been assessed in order to pave the way for a full-scale trial and commercial applications. The current research confirms that cleaner and cheaper energy with reduced emissions can be achieved and the economics are competitive in the future European energy market. However the current research has established that rigorous design and monitor schemes are essential for productivity and safety and the minimisation of the potential environmental impacts. A platform has been established serving to inform policy-makers and aiding strategies devised to alleviate local and global impacts on climate change, while ensuring that energy resources are optimally harnessed.

Underground methane (CH4) gas storage offers capacity and state of the art technology to temporarily store and reuse wind and solar energy. Carbon dioxide (CO2) for methanation can be readily provided in the same way and used in a closed cycle with CO2 separation at the power plant. With enhanced gas recovery employed, CH4 and CO2 could be placed in the same reservoir to be mutually working and cushion gas for each other. Selected gas storage sites of Germany show that they already have the potential to take up 20-60% of the 90-270 TWh excess energy estimated for 2050