Liquid Organic Hydrogen Carriers as chemical hydrogen storage – Opportunities and challenges of reconversion into electricity with combustion engines

Durst A, Russwurm T, Strauß L, Wensing M (2019)

Publication Language: English

Publication Type: Conference contribution, Conference Contribution

Publication year: 2019

Event location: Stuttgart

Abstract

Climate change is omnipresent and stricter laws to reduce carbon dioxide emissions are enforced. This work describes the potentials and challenges of the reconversion of hydrogen, stored in liquid organic carriers, into electricity by ICE. Hydrogen stored in LOHCs requires an enthalpy of 65 kJ/mol_H2 at a temperature level of 280-350 °C for direct dehydration without any intermediates. Therefore, an internal combustion engine is used, using the exhaust enthalpy for the dehydration of LOHC. The main advantages of this system are the possibility to store renewable energy, to reduce the carbon dioxide emission and thus making a  ontribution to energy turnaround. The challenge lies in the fact that the enthalpy of the exhaust gases in efficient engines is too small to dehydrate a sufficient hydrogen mass flow from Dibenzyltoluol. For this reason, the engine runs on a mixture of hydrogen and methane. In order to find the best settings for the LOHC system, two operating strategies respectively engine settings are investigated. The first one is the strategy of the best overall efficiency, the second one is the strategy of the best renewable efficiency, what is similar to the lowest methane mass flow for constant conditions. The optimum overall efficiency is reached for the leanest possible combustion (approximately λ=2) and a centre of combustion MFB50 at 8° CA ATDC. But due to low energy losses, the exhaust enthalpy is small, therefore the percentage of hydrogen in the fuel is approximately 5 wt.% (≙ approximately 11,2% of the fuel energy). To increase the percentage of hydrogen at about 20 wt.% (≙ approximately 37,5% of the fuel energy) in the fuel and to minimise the methane flow, a stoichiometric combustion and a late centre of combustion MFB50 at 20° CA ATDC are favourable. Future concepts show potentials to reduce dehydration energy and especially the required temperature level so that a higher share of the exhaust enthalpy can be used and even better efficiencies can be achieved.

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How to cite

APA:

Durst, A., Russwurm, T., Strauß, L., & Wensing, M. (2019). Liquid Organic Hydrogen Carriers as chemical hydrogen storage – Opportunities and challenges of reconversion into electricity with combustion engines. In Proceedings of the 13. Tagung Gasfahrzeuge - eine nachhaltige Alternative. Stuttgart, DE.

MLA:

Durst, Alexander, et al. "Liquid Organic Hydrogen Carriers as chemical hydrogen storage – Opportunities and challenges of reconversion into electricity with combustion engines." Proceedings of the 13. Tagung Gasfahrzeuge - eine nachhaltige Alternative, Stuttgart 2019.

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