ACI's structural analysis has consistently identified the same failure mode across energy, governance, and computing domains: systems do not fail when capacity is exhausted — they fail when the decision window closes. Applied to the energy transition, this means that the critical risk is not the absence of renewable generation capacity, but the absence of mechanisms that translate surplus generation into durable system value.
CCU is one such mechanism. When renewable generation exceeds real-time demand — as increasingly occurs in Nordic systems during high-wind and high-hydro periods — the economic and physical options are limited: curtailment, export at negative or near-zero prices, battery storage, or conversion to another form of stored energy or material. CCU occupies a specific position in this option set: it is a large-scale, slow-response electricity sink that produces commodities with multi-month to multi-year storage horizons.
This characteristic makes CCU structurally complementary to SGFA-retrofit nodes (WP-019) and to the OGAS2 phase-state model, which already tracks the interaction between dispatchable generation capacity and demand-side flexibility. The Power-to-X pathway — electrolysis, synthesis, upgrading — represents a demand curve that can, in principle, be scheduled against renewable surplus windows.
The CCU process chain can be decomposed into five functional stages, each with distinct energy and material inputs, conversion efficiencies, and institutional dependencies.
The CO₂ input can originate from industrial point sources (cement, steel, pulp mills) or from direct air capture. Biogenic CO₂ from pulp and paper mills is the most strategically relevant source for Finland: it is geographically concentrated in the same forest-industrial regions — Varkaus, Oulu, Kotka — where SGFA-retrofit nodes have been identified (WP-019 §3). Capture from a high-concentration flue gas stream requires approximately 75 kWh of electricity per 100 kg CO₂ recovered, yielding 98 kg of captured CO₂ after parasitic losses.
This is the dominant energy input of the entire CCU chain. Producing 10 kg of hydrogen by water electrolysis requires approximately 300 kWh of electricity. The electrolyser is the primary interface between the electricity system and the CCU process: it can, in principle, be operated flexibly — ramping with renewable surplus, shutting during scarcity periods. Solid oxide electrolysers (SOE) and PEM systems represent the principal technology options, with SOE particularly relevant for co-electrolysis of CO₂ and H₂O to synthesis gas.
Three primary synthesis routes are established at varying technology readiness levels:
| Route | Product | TRL | Transport form | SGFA relevance |
|---|---|---|---|---|
| Methanation | SNG (methane) | High | Pipeline / LNG (costly) | Grid-injectable; FCR-compatible load |
| Fischer-Tropsch | e-diesel, e-kerosene | Medium | Liquid — low-cost transport | HVK strategic reserve; aviation mandate |
| Methanol synthesis | Methanol | High | Liquid — low-cost transport | Maritime fuel; chemical feedstock |
Fischer-Tropsch products require distillation and catalytic processing to reach specification-grade fuels. SNG requires water removal. Methanol is usable directly or as a chemical platform. For polyolefin production — the ForestCUMP pathway — the synthesis output feeds into an existing steam cracker, enabling utilisation of existing industrial capital rather than greenfield construction.
§ 3The production cost structure of CCU products is heavily concentrated in a single input. Across assessed pathways, 80–90% of variable production cost originates from green hydrogen. This is not a temporary condition attributable to immature technology: it is a thermodynamic constraint. Electrolytic hydrogen production is energy-intensive, and that energy cost is the floor below which CCU product costs cannot fall regardless of engineering optimisation.
The ForestCUMP reference case — a 100 kt/a olefin plant using biogenic CO₂ from a pulp mill integrated with an existing steam cracker — yields a base production cost of approximately 3,200 €/t for ethylene and propylene, with total investment of approximately 1.2 billion EUR. This is 2–3× the production cost of fossil-equivalent products at current market conditions.
The implication for OGAS2 integration is direct. The model currently classifies system states by the ratio of available generation to demand. Surplus-phase duration and frequency determine whether CCU investment can achieve viable operating hours. A system that spends 15% of annual hours in deep surplus creates a different electrolyser utilisation profile than one at 8%. This relationship has not yet been parameterised in the OGAS2 state-transition matrix.
§ 4WP-019 maps four SGFA-retrofit sites in Finland: Oulu, Varkaus, Tampere, and a generic coastal CHP node. The Varkaus path currently has 25% SGFA-completeness, with the missing element identified as a PtX branch. The ForestCUMP pathway — biogenic CO₂ from Stora Enso's Varkaus mill integrated with synthesis — is the closest available validated reference for this gap.
| WP-019 retrofit component | CCU correspondence | Status |
|---|---|---|
| CO₂ capture from biogenic flue gas | Stage 1 — pulp mill integration | Piloted; ForestCUMP reference available |
| Electrolyser (40–100 MW) | Stage 2 — H₂ production | Commercial; Oulu 100 MW decision pending |
| Synthesis (e-methane or FT) | Stage 3 — methanation or FT | Bench-scale demonstrated (VTT Mobile Synthesis Unit) |
| Product upgrading | Stage 4 — distillation, catalytic finishing | Technology available; FEED required per site |
| Ecosystem model (Step 4) | CO₂ provider + H₂ producer + offtakers + permits | Analytically mapped; coordination not established |
The SGFA-retrofit advantage over a standalone CCU plant is its three-revenue-stream architecture: (1) reserve market payments (FCR-D, approximately 30,600 €/MW/year), (2) district heat sales from process exothermy, and (3) avoided import cost of the synthesised product. This stack produces an IRR above the standalone CCU scenario, which relies on product sales alone. WP-019 §5 documents this structure; TN-011 adds the explicit process-level correspondence.
Three regulatory frameworks establish the demand-side structure for CCU products in Europe. Their timelines define the market windows against which Finnish CCU investment must be calibrated.
| Regulation | Mandate | Timeline | ACI relevance |
|---|---|---|---|
| RED II/III (Renewable Energy Directive) | Bans fossil CO₂ in e-fuel production for electricity generation | 2036 (power); 2041 (ETS industry) | Creates compliance demand for biogenic/DAC CO₂ |
| ReFuelEU Aviation | Mandates e-fuel share in aviation; EU needs 25–30 Mt/a by 2050 | Market opens ~2030 | E-kerosene offtake anchor for FT synthesis path |
| FuelEU Maritime | Mandates renewable fuel use in shipping | Market opens ~2030 | Methanol offtake anchor for coastal nodes (Oulu) |
The regulatory structure creates a demand floor by 2030–2036 that does not currently exist. This is the temporal window within which SGFA-retrofit investment decisions must be made to capture first-mover position in Finnish e-fuel production. WP-019's investment timeline (2027–2032 construction window) aligns with this regulatory opening.
§ 6The central finding of this note is consistent with ACI's broader diagnostic: the technical components of CCU are individually available and documented. The system is not yet ready because system readiness requires something beyond component availability — it requires coordinated commitment across actors whose decisions are mutually dependent.
An electrolyser investment requires a long-term electricity supply contract, a CO₂ supply agreement, a synthesis off-take agreement, and a permit framework — simultaneously. No single actor can commit without the others. This is the classical coordination trap that SM-010 identifies as the primary barrier to SGFA-cluster formation. CCU does not escape this trap; it is a further instance of it.
| Coordination requirement | Missing element in Finland (2026) | Analogue in SM-010 |
|---|---|---|
| Renewable electricity — long-term PPA for electrolysis | PPA market is shallow; no CCU-specific structure | SM-010 §3: financing instrument gap |
| CO₂ supply — industrial partner commitment | ForestCUMP is research phase; no binding industrial agreement | SM-010 §4: anchor actor missing |
| Synthesis off-take — aviation or maritime fuel buyer | ReFuelEU market opens 2030; no Finnish offtake agreement signed | WP-019 §5: Gap 2 (offtake structure) |
| HVK / strategic reserve policy | No declared role for CCU-derived fuels in HVK framework | WP-019 §5: Gap 3 (policy instrument) |
| FCR-D integration for electrolyser | Electrolyser as reserve asset not tested in Finnish market | TN-010: demand-side loss function not parameterised |
Technology is not the bottleneck. This is now confirmed by an independent Finnish research institution (VTT). SGFA-retrofit's technical feasibility is not in question. The decision window is closing on the coordination layer, not the technology layer.
§ 7OGAS2 currently models phase-state transitions (Surplus / Balanced / Scarcity / Crisis) as a function of generation-demand ratio, shock parameters, and reserve margin. CCU as a flexibility sink introduces a new demand-side actor with the following characteristics:
The electrolyser does not operate as a pure spot-price follower. Synthesis processes have minimum run-time requirements — Fischer-Tropsch reactors cannot be cold-started hourly. This creates a scheduled flexibility profile: commitment blocks of 6–24 hours during projected surplus windows, with advance scheduling against weather-based generation forecasts. This is a materially different flexibility shape than battery storage or demand response, and it affects how CCU demand interacts with the OGAS2 state-transition probabilities.
A proposed extension to OGAS2 would add a CCU demand tier to the Surplus phase model: when the system is in Surplus state for a projected duration exceeding the minimum synthesis campaign length, CCU nodes are activated, converting surplus electricity to stored chemical value. This dampens the price collapse in deep surplus periods and improves the overall system energy balance — reducing curtailment without creating new intermittency-sensitive capacity.
§ 8This note establishes the following propositions for integration into subsequent ACI work:
P1. CCU is a structural flexibility sink, not merely an emissions abatement technology. Its analytical home in ACI is the demand-side of the OGAS2 phase-state model.
P2. The process chain is technically validated at bench-to-pilot scale. The ForestCUMP reference (VTT, biogenic CO₂ + steam cracker integration) provides the closest available validated reference for the Varkaus SGFA-retrofit path (WP-019 §3).
P3. The cost structure is dominated by green hydrogen (80–90% of variable production cost). CCU economics are therefore a function of surplus-phase electricity pricing — establishing direct linkage to the OGAS2 surplus-state duration and frequency parameters.
P4. The coordination gap — not the technology gap — is the binding constraint. All five coordination requirements (PPA, CO₂ supply, offtake, policy, FCR-D integration) remain unresolved in Finland as of 2026.
P5. The regulatory market opens 2030–2036. The investment decision window for SGFA-retrofit nodes to capture this market is 2026–2028.