Overview
ARBOK-MethaneTrap captures methane from streams too lean for any existing commercial route and delivers it as a saleable gas rather than as heat. Coal mine ventilation air carries 0.1–1% methane at enormous flow rates; the entire installed technology base for this stream is thermal flow-reversal oxidation, which destroys the resource and needs above 0.6% to pay for itself, while a typical mine runs 0.3–0.4%. MethaneTrap holds methane selectively on TEGA, ARBOK's graphene-like material, releases it under deep vacuum, and hands the operator an enriched methane stream. Nitrogen and oxygen pass through. The sorbent is hydrophobic, so saturated mine air does not kill it — the failure mode that closes this application to zeolites and activated carbon.
Applications
Primary: ventilation air of gassy underground coal mines; shafts of abandoned mines that keep emitting after closure; landfill gas; off-gas from wastewater treatment.
Secondary: glacial forefield springs and Arctic sites, where meltwater carries dissolved methane and no grid, foundation or pipeline exists.
Industries and users: coal operators under EU Regulation 2024/1787, landfill operators, municipal utilities, Arctic and polar programmes.
Scale: containerised, modular; line-up configured per shaft flow rate.
Operating Principle
Ventilation air passes a wet scrubber that strips coal dust before the sorbent. The washed air enters a TEGA bed, which selectively retains methane while the bulk nitrogen and oxygen pass through. The unit is multi-chamber: while one chamber is capturing, another is on regeneration, so the process runs continuously and the ventilation network sees no interruption. Regeneration is done under deep vacuum — the methane is drawn off as an enriched gas and the sorbent returns to working condition without being consumed.
The process runs at ambient temperature. No heat is supplied from outside, there is no heating circuit, and no process temperature setpoint exists — the process temperature equals the temperature of the incoming ventilation air.
Chambers are built for minimum hydraulic resistance so that the trap does not raise the pressure drop across the mine's ventilation network. Control is automatic: cycle switching, vacuum maintenance, outlet methane concentration.
The scrub water carries the coal dust into an ARBOK separation train. The scrubber itself is a standard node; the recovery of rare-earth and other critical elements from the separated dust is ARBOK know-how. Whether the dust is worth processing is decided per site by feed composition.
Key Parameters
Feed concentration: 0.1–1% CH₄ (design case 0.3%); works below the 0.6% economic floor of thermal oxidation.
Sorbent: TEGA, working surface 2,400–3,600 m²/g — around 10x that of activated carbon.
Sorbent behaviour: hydrophobic, unaffected by saturated air; material working range to 450 °C.
Process temperature: ambient; no external heat input.
Cycle: multi-chamber capture and vacuum release, continuous.
Pre-treatment: wet dust scrubbing upstream of the sorbent.
Outlet: enriched methane stream to boiler, heat generator, or vacuum module for further enrichment to fuel quality.
Sorbent production: mobile units in 20-ft containers, up to 1 t/h, diesel-driven, off-grid.
Architecture and Components
Wet dust scrubber → scrub-water line to ARBOK separation and critical-materials recovery; multi-chamber TEGA capture section with low-hydraulic-resistance internals; vacuum release line; enriched-gas offtake to boiler / heat generator / vacuum enrichment module; on-site mobile TEGA production unit in a 20-ft container; SCADA/PLC control.
Advantages
Technical: works at 0.3–0.4%, where thermal oxidation does not pay; hydrophobic sorbent survives saturated air; no catalysts, no membranes, no consumable filters; ambient temperature; sorbent regenerated, not consumed.
Economic: output is gas, not heat — a saleable product instead of a compliance expense; the ventilation fan is already running by law, so moving the stream costs the operator nothing extra.
Environmental: converts a vented greenhouse gas into fuel; removes an explosion hazard from the shaft; captures coal dust that would otherwise leave with the air.
Strategic: sorbent produced on site from a diesel-driven container, which is what makes remote and polar deployment possible at all.
Integrations
TEGA sorbent platform; ARBOK critical-materials recovery for scrub-water dust; ARBOK vacuum module for further gas enrichment; ARBOK gas-in-water technology for degassing methane-supersaturated meltwater in the glacial-forefield case.
Deployment & Operation
Mounted at the ventilation shaft; modular line-up sized to shaft flow. Continuous, automated. No consumables in the core process; scrub water is recirculated; sorbent regenerated in place. For abandoned mines the same unit works on shaft outflow without any active mining infrastructure. For glacial forefields a water-degassing stage is required upstream.
TRL
R&D. Working principle and material parameters are established on the ARBOK vacuum and TEGA platforms; the methane configuration is at pilot definition stage.
Market Potential
Coal accounts for 43 Mt of methane per year worldwide; around 60% of that leaves through ventilation rather than drainage — 26 Mt, equal to 36.4 bcm of natural gas or 11.5% of EU-27 annual gas consumption, and about €11 bln per year at 30 €/MWh. Abandoned underground mines in the EU closed since 2015 emit a further 298 million m³ per year — Poland 110, Czechia 90, Germany 55. Total fossil-fuel methane worldwide is 124 Mt per year: oil 45, coal 43, gas 36.
Regulation opens the window: EU Regulation 2024/1787 bans venting from mines emitting above 5 t of methane per kt of coal from 1 January 2027, tightening to 3 t from 1 January 2031. The operator's alternatives are closing the face, paying the penalty, or installing recovery.
Competing technology is a single category — thermal flow-reversal oxidation. It is self-sustaining at 0.3–1.0% but only pays back above 0.6% with a carbon price at or above 20 $/t, and it destroys the gas. Membranes lose selectivity at 0.3%; cryogenics would chill the whole stream for 3 molecules in 1,000; zeolite and activated-carbon adsorption drowns in the moisture of mine air.
Typical Project Economics
Modelled case — one gassy mine, ventilation flow 300 m³/s, methane 0.3%, capture 70%:
- Methane captured: 14,200 t/year — 1.6 t/h, 2,265 m³/h
- Energy: 197,700 MWh/year — 22.6 MW continuous
- Gas revenue at 30 €/MWh: ~€6 mln/year (~$7 mln), about $18,900/day
- Avoided obligation: ~400,000 t CO₂-equivalent on the 100-year horizon; at €75/t a further €29.8 mln (~$34.5 mln)
- Additional revenue line: critical materials from scrub-water dust, per feed composition
Payback: 5–7 years.
Risk Factors
Dust loading in real mine air and its effect on sorbent life over long cycling. Offtake for the enriched gas at sites with no local heat demand. Coal-dust composition varies widely, so the critical-materials line is a per-site decision rather than a standing revenue item.
Related Technologies
ARBOK Critical-Materials Recovery · ARBOK-Scandium-REE · ARBOK-VC (Vacuum Cracking) · ARBOK-Gas · Ammonia Trap