Flexibility in electrolytic hydrogen production and use

What this is about

DESNZ is asking industry whether the Hydrogen Production Business Model (HPBM) needs rewriting so that electrolysers run flexibly against wholesale electricity prices rather than baseload. The Call for Evidence opens with a concession: under the existing HPBM, operating only during periods of surplus renewable generation is not commercially viable. The department wants evidence on technical constraints, optimal operating patterns, commercial structures, and the role of large-scale hydrogen storage. Findings will feed into future Hydrogen Allocation Rounds and the wider HPBM structure.

The framing matters. The HPBM was designed as a variable-premium contract paying the difference between a strike price and a reference price on every megawatt-hour of hydrogen produced. That structure insulates the electrolyser from the wholesale electricity price: once contracted, the producer captures the spread whether the grid is short of power or drowning in curtailed wind. The predictable result is a fleet that wants to run flat, not chase low-price windows. The consultation is the department noticing that outcome and asking how to bolt a price signal back onto a subsidy designed to suppress it. HAR1 contracts are signed, HAR2 is in train, and the question is whether HAR3 and later rounds can be engineered differently without breaking investor confidence in the rounds already awarded.

Options on the table

Status quo HPBM with flat-load incentives

Keep the existing variable-premium HPBM and accept that contracted electrolysers will run broadly baseload. The strike-minus-reference payment is captured on every megawatt-hour of hydrogen produced, so the rational operator runs whenever the stack is healthy, regardless of whether the grid is constrained or oversupplied. Winners: HAR1 and HAR2 producers, who get a clean predictable cash flow and no exposure to dispatch risk. Losers: levy payers, who fund subsidised hydrogen production during hours when wholesale power is expensive and the system would prefer the electrolyser to be off; and the wider system, which keeps paying constrained-off wind via BSUoS while subsidised electrolysers consume unconstrained power elsewhere. This is the do-nothing option and is the implicit counterfactual against which everything else is measured.

Price-responsive HPBM

Rewrite the HPBM so the production subsidy is conditional on operating in defined low-price or high-curtailment windows. The electrolyser is then exposed to wholesale price signals: it runs when power is cheap and stops when power is expensive. Load factors fall, unit hydrogen cost rises (the same capex is amortised over fewer megawatt-hours), and the offtake contract has to tolerate non-firm supply or sit behind storage. Winners: bill-payers, who stop funding hydrogen production during expensive hours, and the electricity system, which gets a genuine flexible load. Losers: producers without storage or flexible offtake, whose project economics no longer close at the previous strike price, so strikes have to rise to compensate, partially offsetting the levy saving. The transitional question is whether this applies only to HAR3 onwards or whether HAR1 and HAR2 contracts can be reopened, which would damage the credibility of every other administered support scheme.

Storage-coupled flexibility

Pair electrolysers with large-scale hydrogen storage (salt caverns, lined rock, or pressurised vessels) so the electricity-side operating profile can be flexible while hydrogen delivery to the offtaker stays firm. The electrolyser runs when power is cheap, fills the store, and the store discharges to the offtaker on a steady contracted profile. Winners: ammonia plants, refineries, and any offtaker that needs firm hydrogen and would otherwise refuse a non-firm contract. Losers: whoever funds the storage. There is no committed storage support mechanism in GB; a Hydrogen Storage Business Model has been consulted on but is not yet operational, and the capex for cavern-scale storage is large and site-constrained. This option effectively says the answer to a poorly priced subsidy is a second subsidy on a different asset, which is the interventionist spiral in textbook form.

Locational or curtailment-linked flexibility signal

Tie HPBM payments or HAR eligibility to siting in constrained zones or to absorbing demonstrably curtailed renewable output, using curtailment volumes or zonal/nodal prices as the trigger. An electrolyser north of the B6 boundary or co-located with a curtailed wind farm gets paid; one in an unconstrained zone running on baseload power does not. This is the closest the consultation gets to a Coasean fix: the electrolyser is paid for bearing a cost (congestion) it is uniquely placed to alleviate, and the payment is tied to the externality rather than to gross output. Winners: Scottish and northern projects, curtailed wind operators (who get a co-located buyer rather than constraint payments via BSUoS), and bill-payers (who stop paying twice for the same megawatt-hour, once to curtail it and once to subsidise hydrogen made from unconstrained power elsewhere). Losers: projects already sited in unconstrained zones on the assumption of a locationally-blind HPBM, and the administrative simplicity of the current scheme. The mechanism only works if it sits alongside or anticipates locational wholesale pricing; bolted onto a national reference price it becomes another layer of zonal accounting rather than a genuine price signal.

Questions being asked

Technical constraints

- What are the minimum stable load, ramp rate and cycling limits of current and near-term electrolyser technologies? (Tests whether the physical asset can actually follow price signals, or whether "flexibility" is bounded by stack chemistry. Alkaline, PEM and solid-oxide give very different answers.) - What technical constraints limit the ability of electrolysers to follow electricity price signals? - How does flexible operation affect stack degradation, maintenance cycles and asset life? (The unspoken question: who bears the accelerated replacement cost, the producer or the levy? Any answer that pushes degradation cost into the strike price is the producer asking the bill-payer to fund the warranty.)

Commercial structures

- What changes to the HPBM would make flexible operation commercially viable? (Direct invitation for producers to specify the strike-price uplift or contract redesign they would need. Expect submissions asking for a flexibility premium on top of the existing strike.) - How should offtake contracts be structured to accommodate variable hydrogen output? (Goes to whether the offtaker, the producer, or a storage operator bears the supply-firmness risk.) - What role should large-scale hydrogen storage play in reconciling flexible production with firm offtake? (Reads as a leading question towards a future Hydrogen Storage Business Model. Worth flagging if a second subsidy is being pre-justified by the failure of the first.)

System benefits

- How much curtailment could flexible electrolyser operation absorb under plausible deployment scenarios? (Tests the headline rationale. If the absorbed volume is small relative to projected curtailment, the system-benefit case for redesigning the HPBM is weak and the change is really about reducing levy cost, which is a different argument.) - What evidence exists on the wider grid stress and efficiency benefits of flexible electrolysis?

Policy design

- How should flexibility requirements be reflected in future Hydrogen Allocation Rounds? - What transitional arrangements would be needed for projects already in HAR1 and HAR2? (The contract-sanctity question. Reopening signed HPBMs would set a precedent that every CfD, CM and HPBM holder will price into future bids. Grandfathering preserves credibility but locks in the flat-load problem for the contracted fleet's full term, likely 15 years.)

How to respond

The source text does not include the deadline, submission email, or response form. Respondents should consult the published Call for Evidence on GOV.UK ("Flexibility in electrolytic hydrogen production and use", DESNZ, 28 May 2026) for the closing date, the response template, and the dedicated mailbox or Citizen Space link. The department's standard hydrogen policy contact route is hydrogen@energysecurity.gov.uk, but the consultation document is authoritative.