Industrial alkaline electrolysers run at something like 200 to 400 volts. Last week (of October, 2026) a team at LUT University in Finland reported running one at 1,000 volts, which they believe is a record. The interesting part is not the number. It’s which part of the plant gets cheaper.
Lower current is the point, not higher voltage
A single electrolytic cell sits at roughly 2 volts, so 1,000 volts takes close to 500 cells wired in series. For a given amount of power, pushing the voltage up lets you pull the current down, and current is what sizes the expensive hardware around the stack: the rectifier, the busbars, the cabling, the switchgear.
LUT reckons electricity supply and power electronics account for about a quarter of a hydrogen plant’s capital cost. If higher voltage and lower current cut that share by half, they estimate whole-system investment cost falls by something like 10 to 15 per cent. That’s a conditional figure rather than a measured one, and the university is clear about the caveats. The real saving depends on where the plant sits and how it runs. A plant following wind and solar availability clocks fewer operating hours, which pushes capital cost per kilogram back up.
The problem is current that goes the wrong way
The reason nobody simply builds a 500 cell stack is stray currents. Electrolyte circulates between cells and conducts, so some current wanders off through piping and grounding paths instead of splitting water. It’s wasted electricity and it drags down current efficiency.
Wiring several shorter stacks in series dodges the worst of that, and the LUT work builds on bench testing done with ABB, which supplied the power electronics and co-funded the research, and Stargate Hydrogen, which built the stacks. Published findings from that earlier two stack rig are blunt about the trade-off: individual stacks held above 95 per cent current efficiency, and specific energy consumption rose by under 5 per cent above half load, but at low power external shunt currents reached 30 per cent of supply current and cost 10 to 20 per cent efficiency against single stack operation. Suppressing those paths without hurting performance is the stated next step.
Why we are watching this at H2Heat
Stargate Hydrogen supplies the 0.5 MW advanced alkaline electrolyser for the H2Heat demonstrator in Gran Canaria, where hydrogen feeds a 100 per cent hydrogen CHP unit and a heat pump serving a hospital run by the Canary Islands Health Service. H2Heat isn’t part of the Finnish experiment, and our electrolyser is a different machine at a different scale. But cost reduction across the value chain is one of the project’s objectives, and the Finnish result points at where some of that cost actually sits.
For a hydrogen system on an island, running on variable renewable supply rather than flat baseload, the economics of balance of plant matter as much as stack efficiency. An electrolyser that needs less copper and a smaller rectifier is cheaper to build and easier to site. On a demonstrator feeding low temperature heat below 100 degrees C to a working hospital, every euro taken out of the hardware is a euro the replication case doesn’t have to carry.