Capacity Adequacy and Flexibility as the Missing Reserve

TL;DR. Sweden’s resource adequacy is deteriorating — ERAA 2025 puts Loss-of-Load Expectation at 6.5–10.3 hours/year through 2035, six-to-ten times the 1 h/year norm — yet Sweden has deliberately chosen not to build a capacity market, relying on an energy-only market plus a thin strategic reserve. The reserve’s first procurement failed outright (winter 2025/26): every bid exceeded the CONE price cap, which was set to household demand response — the cheapest theoretical flexibility — while only expensive production-side resources actually bid. That failure is the whole story in miniature: demand flexibility is now the named adequacy mitigation in Svk’s reports, but the flexibility the system needs (cheap, abundant, demand-side) is not the flexibility that shows up. This page connects the adequacy gap, Sweden’s policy choice, the strategic-reserve saga, and why flexibility is the structurally right answer that is not yet bankable for adequacy — drawing on Balancing Markets, Demand Response, Svenska kraftnät, Bidding Areas, and The Swedish BESS Business Case — Revenue Stacking and the FCR Saturation Problem.

The adequacy gap is real and growing

ERAA 2025 (the EU-wide European Resource Adequacy Assessment) shows Sweden well above the adequacy norm for the whole horizon (Source - Svk Kraftbalansen Vår 2026):

SE3 and SE4 carry the risk. SE1/SE2 have surplus hydro but inadequate transmission to move it south — the same north-south constraint that drives the bidding-zone debate. The structural drivers are familiar: nuclear closures (Ringhals 1–2, Oskarshamn 1–2), variable renewables displacing dispatchable capacity, rapid electrification demand, and the binding north-south transmission limit.

This is the “missing money” problem in concrete form (Balancing Markets › The missing money problem): zero-marginal-cost wind and solar clear first and compress wholesale prices during high-VRE hours, so dispatchable plant cannot recover capital at average prices, capacity exits, and adequacy risk rises.

Sweden’s choice: energy-only market plus a thin strategic reserve

Sweden has rejected a market-wide capacity mechanism. The Elmarknadsutredningen (SOU 2025:47) examined the question and recommended a strategic reserve instead — a small, ring-fenced volume held outside the market and activated only in scarcity, rather than capacity payments across the whole fleet.

This aligns with the EU framing: capacity mechanisms are a residual instrument, permissible only when proportionate to an ERAA-demonstrated adequacy problem and when market reforms cannot resolve it (Source - Capacity Mechanisms (EC DG ENER)). The 2024 EMD Reform softened the stance — mechanisms are no longer “last resort,” approvable for up to 10 years (Art. 69(3), Regulation 2024/1747) — but the “market reform first” principle holds. Sweden’s bet is that energy-only price signals plus flexibility plus interconnection deliver adequacy, with the strategic reserve as a narrow backstop.

The strategic-reserve saga — failure, then a quiet success

The mechanism’s first two seasons are a natural experiment in whether that bet holds.

The setup. The old effektreserv (standby, mostly fossil, ~20 years in operation) was terminated March 2025. Its replacement, the strategisk reserv under Lag 2025:50, received EU state-aid approval in July 2025 (Source - Svk Kraftbalansen Höst 2025).

First procurement (autumn 2025, for winter 2025/26): FAILED. Every submitted bid exceeded the CONE (Cost of New Entry) price cap, so no capacity was contracted. Sweden entered winter 2025/26 with no contracted strategic reserve. Svk judged the ~1,000 MW normalvinter surplus meant no immediate adequacy threat — but the mechanism designed to backstop adequacy had simply not functioned.

Second procurement: succeeded. 350 MW was contracted for 15 January – 15 March 2026 from Mälarenergi Kraftvärme and Sydkraft Termisk Kraft. It was held at 100% availability and never activated — the market balanced without it (Source - Svk Kraftbalansen Vår 2026).

Uppdrag 3.1 — quantifying the volume gap and bridge measures

Svk’s June 2026 government assignment report Planering för ett leveranssäkert elsystem gives the most detailed quantitative picture of the gap between what ERAA requires and what can realistically be procured (Source - Svk Uppdrag 3.1 Leveranssäkert Elsystem (2026)):

Strategic reserve: need vs. procurable

The implication: at the 1h norm, the strategisk reserv alone cannot close the gap. If Ei’s autumn 2026 norm review relaxes to ~3h, the gap largely disappears — making the Ei norm review the single most consequential near-term decision for Swedish capacity adequacy.

Production resources outside ERAA model (~1,100 MW combined)

ERAA2025 does not capture several existing plants — Karlshamnsverket (330 MW oil, care-and-maintenance), Öresundsverket (448 MW gas, partly decommissioned), Ryaverket (300 MW), and a 45 MW TVL mothandelsreserv — that could contribute in specific scenarios. Their utilization is constrained by contractual, environmental, and operational conditions.

Bridge measure: överbelastningshantering (1,350 MW)

1,350 MW is contracted through the end of December 2029 across 20 resources at 10 plants for real-time activation in SE3/SE4 to prevent overload. These are dispatched without prior notice by Svk, outside normal market mechanisms — funded from flaskhalsinkomster (520 mnkr in 2027). This is not capacity for the strategisk reserv; it is emergency balancing capacity that happens to reduce immediate adequacy risk in the bridge period before grid reinforcement. (Source - Ei Beslut Flaskhalsinkomster 2027 (2026))

Long-term volume trajectory

At the 1h norm, the gap widens dramatically to 2033 — making the norm review even more structurally significant over the longer horizon.

Kapacitetsåtgärder — the TSO-DSO bridge concept

Svk and Vattenfall Eldistribution jointly developed a concept to procure temporary flexibility (production, storage, demand reduction) to bridge connection gaps before grid reinforcement is complete. A pilot in Västra Götalandsregionen was launched in 2025 but concluded without procurement — industrial plans shifted and Svk’s transmission expansion covered the need to 2035. The methods and tools developed remain available for future applications.

Stöd till icke-fossil flexibilitet

Regulation (EU) 2024/1747 requires member states to set national non-fossil flexibility targets (via the FNA process) and permits financial support mechanisms — auction-based procurement — for non-fossil flexibility that also contributes to adequacy. Svk coordinates the Swedish FNA, with results to government/EC/ACER in 2026. This is the EU-framework route to subsidising storage, demand response, and dispatchable renewables in ways that address both adequacy and the flexibility market simultaneously. (Flexibility Need Assessment)

Fixed-price contract concern

Svk identifies fixed-price electricity contracts (long-term contracts at predetermined prices, as used in neighboring countries) as an adequacy concern: when buyers lock in prices regardless of real-time scarcity, they remove demand elasticity from the system at precisely the scarcity hours. Demand response from neighboring countries is a component of the ERAA model — its erosion tightens Sweden’s effective adequacy envelope.

The CONE paradox — what the failed procurement actually revealed

The reason the first procurement failed is the most analytically important fact on this page. The Swedish CONE was calculated using household demand response as the reference technology — the cheapest theoretical new-entry resource. But the actual bidders were production-side units (generators, diesel/gas) with substantially higher true entry costs. All production bids exceeded a cap benchmarked to cheap flexibility, so nothing cleared (Source - Svk Kraftbalansen Höst 2025).

Read carefully, the failure is a measurement: the price cap is set to the flexibility the system wishes it had; the bids reveal the capacity the market actually offers. The gap between them — household DR’s notional cost vs. real production-side entry cost — is the precise size of Sweden’s flexibility shortfall expressed in price terms. The instrument meant to procure adequacy instead quantified the absence of cheap demand-side flexibility. Until demand response is abundant and cheap enough to bid below CONE, a reserve benchmarked to it will keep mispricing the resources that do exist. The revised CONE methodology is an open policy question and a tracked data gap.

Winter 2025/26 reality check — passed on margins, not on flexibility

The winter that followed was a genuine stress test, and how Sweden passed it matters (Source - Svk Kraftbalansen Vår 2026):

• Coldest in decades in Norrland; peak load 24,800 MWh/h on 12 January 2026 (up from 22,470 the prior year).
• Nuclear at 99% utilization at peak; wind at only 18% (vs 63% the year before) — low wind during the cold snap was the defining stress.
• Prices rose sharply: SE4 winter average 90 EUR/MWh, day-ahead peak 493 EUR/MWh (SE4, 19 Feb), and a balancing energy price of 7,363 EUR/MWh (7 Jan).
• Svk made 11 manual mFRR price adjustments — flagged as a structural concern that the balancing mechanism needs intervention at extreme scarcity.

Sweden met demand through high nuclear output and Nordic interconnection (Aurora Line lifted SE1–Finland export from 2.1 to 4.9 TWh) — not through demand flexibility or the strategic reserve (unactivated). The system held, but on the strength of baseload and imports, exactly the resources the adequacy outlook says are getting scarcer.

8 June 2026 — a reserve-exhaustion event in miniature

A second, sharper data point arrived outside winter. On 8 June 2026 two independent faults hit simultaneously — an SE2↔SE3 line de-energised when people climbed a transmission tower, and a −500 MW loss on the Swe-Pol Link (SE4↔Poland) — dropping frequency to 49.80 Hz. The response is the tell: Svk activated mFRR until every bid in SE3 and SE4 was exhausted, then had to start four gas turbines and lean on imports (200 MW each from Lithuania and Norway). mFRR activation peaked at 701 MW (SE3) + 255 MW (SE4) in the 15:30–15:45 quarter. (Source - Svk Driftstörningar 8 Juni 2026)

This is the missing-reserve thesis observed live, and on an ordinary June afternoon rather than a winter peak: when a real two-contingency event hit, the bid stack ran dry and the fallback was fossil gas turbines plus Baltic imports — not demand-side flexibility, which was absent from the response entirely. It also extends the winter signal of balancing-market fragility (the 11 manual mFRR adjustments above): here too the activations drove high mFRR and imbalance prices in SE3/SE4 that Svk will likely adjust down, on the stated principle that major grid incidents should not economically harm BRPs. That ex-post correction is the settlement-layer backstop (eSett, BSP and BRP Roles) — but it is a financial patch after the fact, not added physical reserve depth. The structural reading: SE3/SE4 reserve depth is thin enough that a non-extreme double fault can exhaust it, and the only fast firm capacity that answered was fossil and foreign.

Flexibility becomes the named mitigation

Against this backdrop, Svk’s spring 2026 report did something new: it explicitly named demand-side flexibility as a key adequacy mitigation, alongside new production and grid investment — the first Svk government adequacy report to give demand flexibility a named role rather than treating it only as a market participant (Source - Svk Kraftbalansen Vår 2026).

The technical potential is large (Source - FlexAbility Delrapport 1 (2025), Demand Response):

On paper, this dwarfs the adequacy gap. The problem is not potential but deliverability for adequacy specifically.

Why flexibility is the right answer but not yet bankable for adequacy

Adequacy needs capacity that is firm at the scarcity hour — cold, still, dark winter evenings. Most flexibility revenue today comes from the wrong places for that:

• Batteries chase FCR, not scarcity. As the BESS business case shows, batteries earn ~86% from FCR capacity at 0.8 cycles/day — they are optimized for frequency containment, not for discharging through a multi-hour winter peak. Most are 1-hour FCR batteries, not the 2–4h+ duration adequacy needs.
• Local flex markets are thin and congestion-driven, not adequacy-driven (Why Swedish Local Flex Markets Are Thin — Structural Causes).
• Demand response at the scarcity hour is the least developed segment — the electric-boiler potential (975 MW) is outright policy-blocked by energy tax, and household DR (the CONE reference) is precisely what failed to materialize in the reserve auction.

The bankable bridge is emerging in two places, both narrow:

1. Svk capacity-service contracts (Hisingen/Stenungsund, ~2027) — multi-year bilateral payments that give BESS firm, financeable revenue for being available in scarcity, the first structured adequacy-adjacent revenue outside FCR and spot (Energy Storage › Svk capacity services for Hisingen-Stenungsund).
2. The strategic reserve itself — once the CONE methodology is fixed so demand-side and production-side resources can compete on comparable terms.

In other words: flexibility is the structurally correct adequacy answer, the technical potential is more than sufficient, but the contracting and revenue architecture that would make flexibility firm at the scarcity hour barely exists. That gap — not a shortage of MW on paper — is Sweden’s real adequacy problem.

The NRAA pivot (end 2026)

Sweden’s first NRAA (National Resource Adequacy Assessment) is due end 2026 under the Art. 19e–19f EMD Reform framework, with ERAA 2025 as its baseline (Source - Svk Kraftbalansen Vår 2026, Flexibility Need Assessment). It is the document that will formally determine whether Sweden’s adequacy gap justifies a larger mechanism — and whether demand flexibility is credited quantitatively or only qualitatively. Closely linked: the Art. 19f non-fossil flexibility targets due ~2027 (six months after the first FNA), which would for the first time set national flexibility volume objectives (Electricity Market Design Reform 2024, Regulatory Calendar).

What to watch

• Ei reliability norm review (autumn 2026) — whether the 1h LOLE norm is relaxed to ~3h; a change here is the single decision most likely to make the strategisk reserv viable without structural reform. At 3h, ~350 MW procurement could close the gap; at 1h, 750–1,100 MW is needed with only ~350 MW procurable.
• Revised CONE methodology — the single most important fix for the strategisk reserv mechanism; whether the reference is re-set so demand-side and production resources compete fairly.
• NRAA end-2026 — whether it quantifies a demand-flexibility contribution or leaves it qualitative; whether it triggers a move beyond the strategic reserve.
• Svk capacity-contract expansion beyond Hisingen/Stenungsund — the main route to firm, financeable flexibility for adequacy.
• Electric-boiler energy-tax reform — unlocks 975 MW of dispatchable demand reduction currently policy-blocked.
• mFRR manual-adjustment frequency and bid-stack exhaustion — a running indicator of how often the balancing market hits its scarcity limits (11 manual adjustments winter 2025/26; SE3/SE4 bids fully exhausted on 8 June 2026).
• Strategic-reserve volume trajectory — whether 350 MW grows as LOLE worsens toward 2033; this is the key annual procurement question.
• Non-fossil flexibility support mechanism — whether Sweden implements financial support (auction-based) under Regulation 2024/1747 to accelerate demand-side and storage resources that improve adequacy.

Data gaps

• Revised CONE methodology for the strategisk reserv — new reference technology / whether demand-side resources can clear
• NRAA 2026 content — whether demand-flexibility contribution is quantified or qualitative
• Whether the strategic-reserve volume scales with the worsening LOLE trajectory (350 MW today vs 10.3 h/year LOLE in 2033)
• Realized contribution of demand response at the actual scarcity hour (cold, low-wind winter peaks) — potential is large but scarcity-hour firmness is unproven
• Targeted energy tax reform for district-heating electric boilers — general tax reduced Jan 2026 (−7.9 öre/kWh); specific elpanna/fjärrvärme targeted reform (~1.2 GW potential, ~500 MSEK/yr cost) remains unapproved; Energiföretagen advocacy ongoing

Related pages

• Balancing Markets — strategic reserve, missing-money problem, ERAA LOLE, reserve volumes and prices
• Demand Response — demand-flexibility potentials and the scarcity-hour deliverability question
• Svenska kraftnät — Kraftbalansen reports; strategisk reserv operation; elberedskap
• Bidding Areas — SE3/SE4 as the adequacy-risk zones; north-south constraint
• The Swedish BESS Business Case — Revenue Stacking and the FCR Saturation Problem — why batteries optimize for FCR, not scarcity; capacity contracts as the adequacy bridge
• Why Swedish Local Flex Markets Are Thin — Structural Causes — why local flex is congestion- not adequacy-driven
• Flexibility Need Assessment — NRAA baseline; Art. 19f flexibility targets
• Electricity Market Design Reform 2024 — capacity-mechanism rules; Art. 19e–19f adequacy framework
• Energy Storage — battery duration and the Svk capacity-service contracts