3.1.5. Energetic Utilization of Synthetized Gas

Gas with high H2 content (after the purification, shift and CO2 capture) will be mixed with nitrogen (waste product of oxygen production). The mixture of the synthetized gas with nitrogen ensures the high energy efficiency of the whole system. Thus, the net calorific value of the synthetized gas must not be lower than 12.8 MJ/kg (6.9 MJ/m3).

The unique principle of the case study was designed and tailored for the conditions of Czech operational power unit. The whole concept was designed by the biggest energy research company in the Czech Republic (UJV group) for the national project [12]. The advantage of this system is not requiring such a high external energy input. On the other hand, IGCC-CaL system lowers the power generation efficiency to 25.3%.

#### *3.2. Case Study 2—Activated Carbon Adsorption*

Case study 2 considers the thermal power unit with the gross output of 250 MWe connected to post-combustion carbon capture technology based on adsorption. The adsorption unit was designed as a pilot facility to capture CO2 from operational flue gases. It is based on a rotative adsorber of continuous operation. The rotative adsorber operates in three phases of adsorption, desorption, and cooling. In the operation (even with minimum concentration of pollutants in the flue gases entering adsorber), the sorbent will degrade, and it is necessary to periodically it with 23 kg/h of the activated carbon pellets. The source for active carbon production is hard coal. Hard coal is further processed in two steps of (1) carbonization of the raw hard coal without presence of oxygen and (2) activation of the carbonized product by water vapor. The whole process chain can be divided into technological segments as follows:


5. CO2 capture and compression.

The technological details of the whole technology are described in Zakuciová et al. [4] and the technological segments are shown in Figure 2. The advantage of this process is the continuous operation and higher power generation efficiency of 33.73%. However, the activated carbon production requires a process of activation and carbonization that consumes more raw material (hard coal) and energy.

**Figure 2.** System boundaries for Scenario 2 (red marked is the energy returning back to the system; dashed lines with numbers represent technological segments).
