Integrated Gasification System for Power and Hydrogen Production

The growth of economic and living standard leads to more electricity demand. Unfortunately, due to more limitation of power station area and electricity grid development, energy delivery issue is rising up; hence, new method of delivering the power by different energy carrier is necessary to investigate. Hydrogen has the promising potential as an energy carrier due to its high gravimetric energy density and cleanliness to the environment. For comfortable storage and transportation, hydrogen is covalently bonded to methylcyclohexane (MCH) and liquid organic hydrogen carrier (LOHC). In this chapter, novel integrated gasification systems for coproduction of electricity and MCH from low-rank coal and microalgae have been proposed. The total energy efficiency is improved by applying enhanced process integration (EPI) technology to minimize exergy losses throughout the integrated system. The integrated system for microalgae is capable to provide more than 60% of total energy efficiency, while the integrated system for low-rank coal delivers the total energy efficiency of 84%

Highly energy-efficient combination of dehydrogenation of methylcyclohexane and hydrogen-based power generation

Hydrogen (H⁠2) has been well studied for its potential use in energy storage, which is particularly related with the intermittent characteristic of renewable energy sources. However, the gas form of H⁠2 at standard pressure and temperature (STP) poses a challenging problem in terms of storage, transportation, and low volumetric energy density. An effective and reversible method for H⁠2 storage is chemically bonded H⁠2 used in the toluene (C⁠7H⁠8)/ methylcyclohexane (MCH, C⁠7H⁠14) cycle. This study investigates a power generation system from H⁠2 storage in MCH, involving the dehydrogenation process and the combined cycle as a power generation process. An adequate analysis of the heat circulation was performed through an enhanced process integration (EPI) to ensure the high energy-efficiency of the proposed system. A highly endothermic reaction of dehydrogenation was supplied by utilizing the energy/heat from air-fuel combustion to ensure the effective heat recovery of the system. The proposed system was analyzed through an adjustment of the main operating parameters, namely, the GT inlet pressure, GT inlet temperature, and the condenser pressure, to observe their effects on the efficiency of the system. It was found that these parameters have a significant influence on the system performance and provide the possibility of further improvement. Under optimum conditions, the proposed system can realize a very high system efficiency of 54.6%. Moreover, the proposed system is also compared to a Graz cycle-based system, which has been reported to achieve an excellent power generation cycle from H⁠2. This result implies that the proposed integrated system leads to a significantly higher power-generating efficiency. Numerically, the proposed system demonstrated a system efficiency of 53.7% under similar conditions as the Graz cycle based system, which achieved a system efficiency of 22.7%