A serial system of multi-stage reverse electrodialysis stacks for hydrogen production

Salinity gradient energy is converted to hydrogen energy by integrating reverse electrodialysis (RED) and electrolysis of water to produce hydrogen. In this work, a serial system of multi-stage RED sacks is proposed to improve the energy efficiency and working performance of direct hydrogen production. The experimental results show that, compared with a single-stage system, the multi-stage RED stack system showed significant improvements in both hydrogen production and power output. Appropriately reducing the working current while increasing the number of RED stacks was beneficial to net power output and energy conversion. Total hydrogen production was almost unaffected when the number of RED stacks was large. Maximum energy conversion efficiency occurred at an optimal feed solution velocity. Under these conditions, the maximum net output power, total hydrogen production, and total energy-conversion efficiency were 2.06 W, 881.88 mL h(-1), and 7.74%, respectively. The results are of relevance to investigation of the thermal-energy-driven reverse-electrodialysis heat engine for hydrogen production.

Automated summary

In this study, a serial system of multi-stage RED sacks was proposed to improve the energy efficiency and working performance of direct hydrogen production. Experimental results showed that reducing the working current while increasing the number of RED stacks improved both hydrogen production and power output significantly.