Direct coupling of a fixed-pitch variable speed aerogenerator to PEM electrolysers in a wind-hydrogen system for remote area power supply

Wind-hydrogen systems for remote area power supply are an early niche application of sustainable hydrogen energy. Optimal direct coupling between a wind turbine and an electrolyser stack is essential for maximum electrical energy transfer and hydrogen production. In addition, system costs need to be minimised if wind-hydrogen systems are to become competitive. This paper investigates achieving near maximum power transfer between a fixed pitched variable-speed wind turbine and a Proton Exchange Membrane (PEM) electrolyser without the need for intervening voltage converters and maximum power point tracking electronics. The approach investigated involves direct coupling of the aerogenerator with suitably configured generator coils to an optimal series-parallel configuration of PEM electrolyser cells so that the I-V characteristics of both the aerogenerator and electrolyser stack are closely matched for maximum power transfer. A procedure for finding these optimal configurations and hence maximising hydrogen production from the system is described. For the case of an Air 403 400 W aerogenerator located at a typical coastal site in south-eastern Australia and directly coupled to an optimally configured 400 W stack of PEM electrolysers, it is estimated that up to 95% of the maximum achievable energy can be transferred to the electrolyser over an annual period. The results of an extended experiment to test this theoretical prediction for an actual Air 403 aerogenerator are reported. The implications of optimal coupling between a PEM electrolyser and an aerogenerator for the performance and overall economics of wind-energy hydrogen systems for RAPS applications are discussed.