Review on the thermal neutrality of application-oriented liquid organic hydrogen carrier for hydrogen energy storage and delivery

The depletion and overuse of fossil fuels present formidable challenge to energy supply system and environment. The human society is in great need of clean, renewable and sustainable energy which can guarantee the long-term utilization without leading to escalation of greenhouse effect. Hydrogen, as an extraordinary secondary energy, is capable of realizing the target of environmental protection and transferring the intermittent primary energy to the application terminal, while its nature of low volumetric energy density and volatility need suitable storage method and proper carrier. In this context, liquid organic hydrogen carrier (LOHC), among a series of storage methods such as compressed and liquefied hydrogen, provokes a considerable amount of research interest, since it is proven to be a suitable carrier for hydrogen with safety and stability. However, the dehydrogenation of hydrogen-rich LOHC materials is an endothermic process and needs large energy consumption, which hampers the scale up of the LOHC system. The heat issue is thus essential to be addressed for fulfilling the potential of LOHC. In this work, several strategies of heat intensification and management for LOHC system, including the microwave irradiation, circulation of exhaust heat and direct LOHC fuel cell, are summarized and analyzed to provide suggestions and directions for future research.