What Does It Actually Cost to Produce Green Hydrogen with Solid Oxide Electrolysis?

Green hydrogen gets a lot of attention. So does the cost of producing it.

But conversations about hydrogen economics often stay at a frustrating level of abstraction — “costs need to come down,” “renewables will drive the price,” “scale is the answer.” What is harder to find is a clear, grounded explanation of what actually determines the cost of hydrogen produced by solid oxide electrolysis, and what it would take to hit the targets that matter.

The OUTFOX project has been working on exactly this question. Here is what the numbers actually show.

The metric that matters: levelised cost of hydrogen

The standard measure for comparing hydrogen production economics is the levelised cost of hydrogen (LCOH), expressed in euros per kilogram. It captures the full cost of producing hydrogen over the operational lifetime of a plant — capital expenditure, operating costs, maintenance, and component replacement — divided by the total hydrogen output.

The EU’s Clean Hydrogen Partnership has set a target of €2.7/kg for SOEL-based hydrogen production at 100+ MW scale. That number represents the point at which green hydrogen from solid oxide electrolysis becomes broadly competitive. Understanding what drives the LCOH — and what moves it up or down most significantly — is the question the OUTFOX techno-economic analysis has been designed to answer.

The single biggest variable: electricity price

The most important finding from the OUTFOX modelling is also the most direct: electricity cost is the dominant variable in hydrogen production economics, by a significant margin.

At European average electricity prices of around €100 per MWh, the electricity cost alone accounts for the majority of the total LCOH. Capital expenditure — the cost of the electrolyser system, balance of plant, and installation — is a secondary factor in this scenario.

At lower electricity prices, around €40 per MWh (achievable in high-renewable locations such as solar-rich southern Europe or high-wind sites), the picture shifts. Capital cost becomes relatively more important, and a second variable emerges as critical: capacity factor, meaning how many hours per year the system actually operates.

The practical implication is clear. Solid oxide electrolysis produces the most competitive hydrogen when it can access low-cost electricity and operate at high utilisation, which means co-location with reliable, low-cost renewable generation, ideally coupled with some form of storage or flexibility to maintain high operating hours even when generation is intermittent.

Why heat integration changes the economics

One advantage of solid oxide electrolysis that is often mentioned but less often quantified is its ability to use waste heat or steam from industrial processes. OUTFOX modelling puts a concrete number on this: when an industrial process provides steam, the electrical energy required to produce a kilogram of hydrogen can be reduced by around 30% compared to a configuration that relies on electricity alone to generate steam from liquid water.

This is not a marginal improvement. A 30% reduction in electricity consumption directly reduces the largest single cost component of the plant. It is the primary reason SOEL is particularly well suited to industrial applications — refineries, chemical plants, steel facilities, ammonia production — where hydrogen demand is large and waste heat is available as a by-product of the process.

The configuration matters too. More advanced heat integration — matching fuel-side and air-side heat recovery, optimising recuperator design — can push system efficiency further. But even basic heat integration delivers a substantial benefit, and the OUTFOX analysis suggests that identifying and capturing this heat is one of the most impactful levers available to system designers.

The stack is not the whole story

A common assumption in discussions about electrolyser cost reduction is that bringing down the stack cost is the primary objective. The OUTFOX analysis adds important nuance to this.

At current manufacturing scales, the stack does dominate the cost structure — accounting for roughly 50% of total system cost at low production volumes. But as manufacturing scale increases toward the gigawatt-per-year range, the stack’s cost share falls substantially. Economies of scale in manufacturing bring stack costs down significantly, shifting the relative weight of other components.

Two components emerge as the next targets for cost reduction once manufacturing scale improves: high-temperature recuperators and the hydrogen compressor.

The compressor deserves particular attention. SOEL systems typically operate at near-atmospheric pressure, which means hydrogen needs to be compressed to around 20-30 bar to be comparable with other production technologies and suitable for most end uses. At current system scales, compression is a significant cost item. Centralising compression across multiple modules — rather than one compressor per unit — can reduce this cost by around 20%, and this is one of the system architecture decisions the OUTFOX project has been examining.

System modularity also affects capital cost in ways that are not always intuitive. By increasing the number of stacks per hot box — using larger cells, or more cells per stack — OUTFOX modelling shows potential CAPEX reductions of up to 40% from the baseline configuration, independently of manufacturing learning rates. This is the direct economic argument for the cell scaling work the project has been pursuing.

The installation cost multiplier

One aspect of hydrogen plant economics that receives less attention than it deserves is the gap between equipment cost and fully installed cost.

OUTFOX analysis, drawing on industry data and literature, finds that total installed costs can range from 1.5 to 3 times the bare equipment cost. Engineering, procurement, and construction (EPC) charges, insurance, contingency, and site-specific costs all contribute. For first-of-kind plants, these multipliers tend to be at the high end — costs are uncertain, insurance is expensive, and contractors price in risk.

This has an important implication: bringing down the equipment cost of the electrolyser stack, while valuable, captures only part of the total cost picture. Reducing the installed cost multiplier — through standardised modular design, factory-built units, and accumulated EPC experience — is equally important and becomes a larger priority as stack costs fall.

What the pathway to €2.7/kg actually requires

The OUTFOX modelling shows that the €2.7/kg LCOH target is achievable — but it requires several conditions to align simultaneously.

Low-cost electricity is necessary: the modelling consistently shows competitive LCOH only when electricity costs are well below European average prices. Stack manufacturing needs to scale toward the gigawatt-per-year range, bringing the stack cost share down and shifting attention to other system components. The plant needs to operate at high capacity factor, which in turn requires either a stable, low-cost electricity supply or flexibility mechanisms — energy storage, grid connection, or demand-side management — that maintain high operating hours. And heat integration needs to be designed in from the start, not added as an afterthought.

None of these conditions is unrealistic. But none of them is automatic either. The path to competitive SOEL hydrogen is a systems engineering and deployment challenge as much as a materials science one.

That is precisely what OUTFOX was designed to address.