PEM or AEL electrolyzer

PEM electrolyzers have a stable efficiency over a wide range of power input and follow load changes in seconds. You can even connect PEM to photovoltaics directly without any electronics in between. Sounds great, but there are severe disadvantages: shorter usage of the equipment and high prices due to extremely expensive materials like iridium and platinum. The world production of gold is 3,000 to 3,500 t/a, and platinum is 180 to 200 t/a. We have only 7 to 8 t/a Iridium. Even the complete world production of iridium would be only 11 GW PEM electrolyzers.

Surprise, we have again detected a missed profitability transition. There had been a time when photovoltaics and batteries had been extremely expensive. No batteries are necessary at a PEM electrolyzer, making the best usage of the expensive photovoltaic. In this scenario, the high price per kW of PEM electrolyzers did not matter. In this scenario, the scarcity of iridium did not matter. But here again, we have a missed profitability transition. How can this happen so often in the area of the energy transition? Best explanation is the “It doesn't make economic sense” trauma. In the time before 2009, people working for the energy transition heard again and again, “It doesn't make economic sense”. Over several years, this developed into a severe trauma. The reaction was, “We have to do it, whatever it costs”. This trauma-induced reaction brought the energy transition in a bad situation.

Abstract
	To meet the necessary cost optimization targets, we cannot hold the energy problem separate from all other problems: another major problem is housing.

Introduction
	Many imaginations about our future had been created in the past with completely different parameters. Unchecked conclusions from the past endanger our future with unbearable costs.

My personal experience with a profitability transition
	Birds can fly without knowing all the terms of aerodynamics. I reacted with my design change to an ongoing “profitability transition” without knowing the term at this time.

Energy transition
	The long way from random electricity from sun and wind towards 24×365 electricity. Overseen profitability transitions have to be considered as major accidents.

The GEMINI principle: double usage of land
	No better solar power plant, no better housing possible on the same ground is the ultimate target of the GEMINI principle.

Off-grid fast charging settlements
	It can start small, somewhere in a village, with a single GEMINI house with a big PV carport and 100 kW DC charging.

Energy-intensive industry
	I once developed a scale for off-grid solar possibilities depending on photovoltaic size. But now is to make a big jump upwards on this scale: running, energy-intensive industry.

Agriculture: How many square meters does a human need for his food?
	Mankind started as hunters and gatherers. 12,000 years ago, 500,000 m² to 2,500,000 m² per human. With the agricultural revolution, the land use was reduced by 2 magnitudes.

Conclusion
	All parameters are in a constant state of change. We have to check all the parameters and predict the development for the predictable future.

References
	Roland Mösl: Energy Optimised Settlements – Enabler for Necessary Civilization Targets, Graz 2025