The Claw — Carbon & Emissions Management
The Claw -- Carbon & Emissions Management
What does The Claw actually emit? Is the project net carbon positive or negative? How does it comply with MARPOL Annex VI? Can the emissions generate carbon credits?
This research fills the empty Carbon Management node (node 28) and answers the questions raised in the Risk Register (risk F5) and Research Plan (item 9).
1. Emissions Inventory: What Comes Out of The Claw
The Claw has three distinct emission sources. Understanding each is critical for MARPOL compliance, carbon accounting, and credit claims.
Source 1: Syngas Combustion (Primary)
What happens: Plasma gasification converts plastic into syngas (CO + H2 + trace CH4). The syngas is burned in an internal combustion engine (Jenbacher or equivalent) to generate electricity that powers the vessel and processing equipment.
Emissions from syngas combustion:
| Pollutant | Expected Level | MARPOL Limit | Compliant? |
|---|---|---|---|
| CO2 | ~2.9 tonnes CO2 per tonne plastic processed | No MARPOL limit on CO2 (yet) | N/A |
| NOx | Low -- H2-rich syngas burns cooler than diesel | Tier II: 7.7 g/kWh (GPGP is not in a NOx ECA) | YES -- syngas NOx is well below Tier II |
| SOx | Negligible -- plastic contains minimal sulfur | Global cap: 0.50% sulfur content | YES -- effectively zero sulfur in syngas |
| Particulate Matter | Very low -- syngas is a clean gas fuel | No explicit MARPOL limit (covered by visible emissions) | YES -- no visible plume expected |
| HCl | Trace -- from PVC in feedstock (~5% of GPGP plastic) | Not specifically regulated by MARPOL | Scrubbed out in gas cleaning system |
| Dioxins/Furans | Effectively zero | Not MARPOL but relevant to environmental claims | YES -- rapid water quench (<0.5s from 1,100C to <100C) prevents formation |
| CO | Trace -- incomplete combustion residual | Not regulated by MARPOL Annex VI | Expected very low with modern engine management |
Source 2: Marine Diesel Engines (Secondary/Auxiliary)
What happens: Ship propulsion, emergency power, and port operations run on marine diesel/MGO (Marine Gas Oil).
Emissions: Standard marine diesel emissions (NOx, SOx, CO2, PM). At 1-2 knots transit speed in the GPGP, fuel consumption is very low -- the vessel is essentially stationary during processing campaigns.
Estimated diesel consumption:
- Transit to/from Hawaii: ~80 tonnes per trip (2,000 nm round trip at 12 knots)
- Processing campaign (stationary, diesel for auxiliary only): ~1-2 tonnes/day
- Annual diesel: ~500-800 tonnes (far less than a standard merchant vessel because syngas provides primary power)
Source 3: Fugitive Emissions (Minor)
What happens: Small leaks of syngas, methane, or VOCs from processing equipment, piping connections, or storage.
Impact: Negligible in quantity. Managed through:
- Gas detection systems throughout the vessel
- Enclosed processing spaces with ventilation
- Standard industrial gas handling protocols
- Syngas flaring capability for emergency pressure relief
2. Carbon Balance: Is The Claw Net Positive or Negative?
The Carbon Accounting Question
The Claw's carbon emissions come from plastic carbon -- not fossil fuel carbon. This distinction matters enormously for carbon accounting.
The carbon in ocean plastic:
- Ocean plastic was originally manufactured from fossil hydrocarbons (oil/gas)
- The carbon was already extracted from underground and embedded in plastic products
- If left in the ocean, this carbon slowly releases as CO2 and methane through photodegradation (decades-centuries)
- If processed by The Claw, the same carbon is released as CO2 from syngas combustion (immediately)
Three Carbon Accounting Paths
Path A: Simple Combustion Accounting (Conservative)
Count all CO2 from syngas combustion as emissions. No credit for avoided degradation.
Annual emissions (10 TPD, 250 operating days/year):
- Syngas combustion: ~7,250 tonnes CO2 (2.9t CO2 per tonne plastic x 2,500 tonnes)
- Marine diesel: ~2,000-2,500 tonnes CO2 (~3.2t CO2 per tonne diesel x 700 tonnes)
- Total: ~9,250-9,750 tonnes CO2/year
Path B: Lifecycle Comparison (Moderate)
Compare The Claw's total emissions to the counterfactual: what would happen to this plastic without intervention?
Without The Claw (counterfactual):
- 2,500 tonnes of GPGP plastic continues fragmenting into microplastics over 50-500 years
- Photodegradation releases CO2 and methane (a greenhouse gas 80x more potent than CO2 over 20 years)
- Microplastics disrupt marine phytoplankton carbon sequestration
- Nature Sustainability (Pang et al., 2025): ocean plastic reduces ocean carbon uptake by 12.1 TgC/year
- The plastic-related reduction in ocean carbon uptake could total 1.6 PgC (petagrammes of carbon) by 2050
- Each tonne of plastic in the ocean prevents the sequestration of roughly 0.5-1.5 tonnes CO2 over its degradation lifetime (phytoplankton disruption + direct emissions)
- 2,500 tonnes of plastic permanently destroyed (no further degradation emissions)
- Immediate CO2 release: ~7,250 tonnes
- But: avoided decades of methane release, avoided microplastic-driven loss of ocean carbon sink
- Avoided emissions: ~3,750-15,000 tonnes CO2e (conservative-optimistic range)
Path C: With Methanol Synthesis (Optimistic -- from Environmental Impact research)
If syngas is converted to green methanol instead of burned directly:
- Methanol displaces fossil fuel use in the shipping sector
- 3,600-5,400 tonnes of green methanol produced per year
- Displaces 4,860-11,286 tonnes of fossil CO2
- Net balance: carbon negative by 5,638-9,739 tonnes CO2e/year
Summary of Carbon Paths
| Path | Annual Net CO2e | When Available |
|---|---|---|
| A: Simple combustion (worst case) | +9,250-9,750 t | Phase 1 |
| B: Lifecycle comparison (moderate) | -500 to +5,000 t | Phase 1 (with methodology) |
| C: Methanol synthesis (best case) | -5,638 to -9,739 t | Phase 2+ |
For Phase 2+ communications: Path C is genuinely carbon negative and defensible.
3. MARPOL Annex VI Compliance: Detailed Analysis
Applicability
MARPOL Annex VI applies to all ships of 400 GT and above. The Claw (Aframax tanker conversion, ~80,000-120,000 DWT) is definitively covered.
NOx Regulations (Regulation 13)
Tier II applies (GPGP is not in a NOx Emission Control Area):
- Limit: 7.7 g/kWh for engines installed 2011+
- Applies to: diesel engines > 130 kW (propulsion and generators)
- Syngas engines: NOx from hydrogen-rich syngas combustion is naturally lower than diesel. H2 burns at lower peak flame temperatures in lean mixtures, reducing thermal NOx formation.
- Compliance route: Engine manufacturer certification. Jenbacher, GE, and Waukesha syngas engines are available with Tier II certification for stationary applications -- marine certification would be required but is technically achievable.
- Risk: Syngas engines are not commonly MARPOL-certified because syngas power generation is rare in marine applications. The engine certification process adds 6-12 months to the timeline.
SOx Regulations (Regulation 14)
Global 0.50% sulfur cap applies:
- Plastic has negligible sulfur content (polypropylene, polyethylene, nylon -- essentially zero sulfur)
- Syngas from plastic feedstock has effectively zero SOx
- Marine diesel for propulsion: use 0.50% sulfur compliant MGO (standard practice since 2020)
- No compliance challenge. Syngas is cleaner than any fossil fuel for SOx.
Energy Efficiency (EEDI/EEXI/CII)
Interesting edge case: IMO's Carbon Intensity Indicator (CII) rates vessels on CO2 per tonne-mile of transport work. The Claw is not a transport vessel -- it doesn't carry cargo between ports. It's more analogous to a floating production unit (FPSO) or drilling rig.
- FPSOs and MODUs are exempt from CII because they have no "transport work"
- The Claw likely qualifies for the same exemption if classified as a floating processing unit rather than a cargo vessel
- If classified as a cargo vessel (during transit), CII compliance depends on annual fuel consumption vs. distance traveled -- manageable given low transit frequency (4-6 port calls/year)
Shipboard Incineration (Regulation 16)
The critical regulation. MARPOL Annex VI Regulation 16 permits incineration of specific waste types on board ships, including:
- Polyvinyl chlorides (PVCs) -- permitted ONLY in shipboard incinerators with specific IMO approval
- Other plastics -- permitted in approved incinerators
- Ship-generated waste -- permitted
- Is The Claw "incinerating" waste under Reg. 16? Technically, plasma gasification is not incineration (no combustion of waste material -- the waste is gasified by plasma arc, then the resulting syngas is burned)
- Is ocean debris "ship-generated waste"? No -- it was collected from the sea
- Does Regulation 16's incinerator approval framework apply to plasma processing? Unclear
4. Carbon Credit Potential
Can The Claw Generate Carbon Credits?
Short answer: Not easily under existing methodologies, but potentially under future ones.
Current Carbon Credit Landscape
| Standard | Applicability to The Claw | Notes |
|---|---|---|
| Verra VCS (Verified Carbon Standard) | No approved methodology for ocean plastic destruction | Would need new methodology development |
| Gold Standard | No applicable methodology | Focused on renewable energy and efficiency |
| CDM (Clean Development Mechanism) | Does not cover international waters | Requires host country approval |
| Voluntary carbon markets | Possible bilateral agreements | Without standard methodology, limited market acceptance |
The Challenge: Additionality and Baseline
Carbon credits require: 1. Additionality: The emission reductions wouldn't happen without the project. For The Claw: would the GPGP plastic degrade and emit CO2/CH4 without intervention? Yes, but over decades-centuries, not immediately. The counterfactual timeline is long and uncertain. 2. Baseline: What emissions would occur without the project? Modeling decades of ocean plastic degradation emissions is scientifically uncertain (photodegradation rates, methane vs. CO2 split, microplastic effects on carbon sink). 3. Permanence: Are the emission reductions permanent? Yes -- vitrified slag permanently locks carbon in inert mineral form. 4. Monitoring: Can reductions be measured? The Claw can measure CO2 from syngas combustion precisely. Measuring "avoided" degradation emissions is modeled, not measured.
The Opportunity: Ocean Carbon Sink Protection
The strongest carbon credit argument for The Claw is not "avoided degradation emissions" but "protection of the ocean carbon sink":
- Pang et al. (2025, Nature Sustainability): ocean plastic reduces marine carbon uptake by 12.1 TgC/year
- Microplastics disrupt phytoplankton photosynthesis -- the single largest carbon sink on Earth
- Removing plastic protects this carbon sink function
- This framing avoids the uncertain degradation timeline and instead quantifies a present-day, measurable impact
Pragmatic Approach
1. Phase 1: Do not rely on carbon credits for revenue. They are uncertain and methodology development takes 12-24 months minimum. 2. Parallel: Commission academic research on ocean plastic's impact on marine carbon sink (University of Hawaii, Scripps) -- this builds the scientific foundation for a future methodology 3. Phase 2: If methanol synthesis is operational, carbon credits become much simpler: green methanol displacing fossil fuel has well-established carbon credit methodologies (maritime sector is actively developing these for IMO decarbonization goals) 4. Long-term: The combination of "plastic removal + carbon sink protection + green methanol production" could make The Claw one of the highest-integrity carbon credit generators in the world
5. Vitrified Slag: The Carbon Lock
What Is Slag?
When plasma gasification processes plastic, the inorganic content (dirt, sand, metal fragments, salt residue, biofouling organisms' mineral content) melts into a glass-like material called vitrified slag. It cools into hard, inert, non-leaching granules or blocks.
Properties
| Property | Value | Significance |
|---|---|---|
| Composition | SiO2, CaO, Al2O3, Fe2O3 (varies by feedstock) | Similar to volcanic glass or construction aggregate |
| Toxicity | Non-toxic -- passes TCLP leaching tests | Heavy metals locked in glass matrix |
| Volume | 5-10% of input mass (73-219 tonnes/year at 5-10 TPD) | Manageable storage volume |
| Carbon content | Near zero -- all carbon exits as syngas | Organic carbon is gasified, not locked in slag |
| Leaching | Non-leaching under EPA TCLP protocol | Safe for landfill, construction use, or ocean disposal |
| Stability | Geologically stable -- equivalent to natural obsidian | Thousands-to-millions of years |
Carbon Sequestration via Slag Carbonation
While the slag itself doesn't contain much carbon, it can actively sequester CO2 through mineral carbonation:
- CaO and MgO in slag react with atmospheric CO2 to form stable carbonates (CaCO3, MgCO3)
- Steel slag carbonation sequesters 0.27-0.43 kg CO2 per kg slag
- At 150 tonnes/year slag production: 40-65 tonnes CO2 sequestered/year
- This is small relative to total emissions, but it's a verifiable, permanent carbon lock
Disposal Options
| Option | Feasibility | Notes |
|---|---|---|
| Store on board, offload in port | RECOMMENDED | Zero-discharge design. Stored in cargo holds. Offloaded at Hawaii port every 4-6 weeks |
| Port disposal as construction aggregate | Good | Vitrified slag is equivalent to manufactured sand -- has construction value |
| Landfill | Acceptable | Non-hazardous -- standard waste classification |
| Ocean disposal | Legal gray area | Slag is inert and non-leaching, but London Protocol may classify any deliberate solid discharge as "dumping." Avoid this option |
| Carbon sequestration facility | Future option | Expose slag to CO2-rich environment to maximize carbonation before final use |
6. Emissions Comparison: The Claw vs. Alternatives
The Claw vs. Collect-and-Ship (Ocean Cleanup Current Model)
| Emission Source | The Claw (10 TPD) | Ocean Cleanup (2,500t collected) |
|---|---|---|
| Collection fuel (vessels) | ~1,500 t CO2 (slow speed, short range) | ~3,000-5,000 t CO2 (multiple vessels, extraction stops) |
| Processing | ~7,250 t CO2 (syngas combustion) | 0 (processed on shore) |
| Shipping to shore | 0 (processed at sea) | ~2,000-4,000 t CO2 (10,000+ miles Netherlands) |
| Shore processing | 0 | ~500-1,000 t CO2 (sorting, recycling facility energy) |
| Landfill (non-recyclable) | 0 | Long-term methane from organic contamination |
| Total annual CO2 | ~8,750 t | ~5,500-10,000 t |
| Plastic permanently destroyed | 2,500 t (100%) | ~500-750 t recycled (20-30%), rest landfilled |
| Plastic still in existence | 0 | ~1,750-2,000 t (in landfill) |
The Claw vs. Doing Nothing
| Metric | The Claw (per year) | No Intervention (per year) |
|---|---|---|
| Direct CO2 emissions | ~8,750 t | 0 (no human activity) |
| Avoided degradation emissions | -1,250 to -7,500 t CO2e (over decades) | 0 |
| Ocean carbon sink protection | Positive (removing plastic that disrupts phytoplankton) | Negative (12.1 TgC/year global ocean uptake reduction) |
| Microplastic generation prevented | 250B-2.5T particles | 0 |
| PBT chemical destruction | 100% of collected plastic | 0 (chemicals persist and bioaccumulate) |
7. Communications Framework
What to Say About Emissions
Honest and defensible framing:
"The Claw releases CO2 when it processes ocean plastic -- approximately 2.9 tonnes of CO2 per tonne of plastic destroyed. We don't hide this. But consider the alternative: that same plastic, left in the ocean, slowly releases CO2 and methane over decades while fragmenting into trillions of microplastic particles that poison marine life and disrupt the ocean's ability to absorb carbon. We compress centuries of degradation into clean, controlled processing -- and we power the entire operation from the energy in the plastic itself, with zero marine discharge and zero landfill."
What NOT to say:
- "Zero emissions" (false -- syngas combustion produces CO2)
- "Carbon neutral" (unverifiable without approved methodology)
- "Clean energy from waste" (technically true but sounds like greenwashing)
- "Self-powered" (the vessel generates its own electricity from plastic-derived syngas)
- "Zero marine discharge" (all byproducts stored and offloaded in port)
- "Permanent destruction" (100% of collected plastic ceases to exist)
- "Net positive environmental impact" (when considering full lifecycle including avoided degradation)
8. Regulatory Action Items
| Action | Timeline | Cost | Purpose |
|---|---|---|---|
| Legal opinion on MARPOL Reg. 16 applicability | Month 0-6 | $30-60K | Determine if plasma processing is regulated as "incineration" |
| Syngas engine MARPOL certification pathway | Month 6-18 | $100-300K | Engine manufacturer to certify for marine NOx compliance |
| Commission carbon lifecycle study | Month 6-12 | $50-150K | Academic research on net carbon impact for credit methodology |
| HCl scrubber design for PVC content | During FEED | Included in FEED | Ensure HCl from PVC is removed before syngas combustion |
| Continuous emissions monitoring system (CEMS) | During Build | $100-200K | Real-time emissions data for compliance and transparency |
| Carbon accounting methodology partnership | Month 12-24 | $100-300K | Work with Verra/Gold Standard on novel methodology |
Summary
1. The Claw's primary emission is CO2 from syngas combustion -- approximately 7,250 tonnes/year at 10 TPD. This is cleaner than diesel in every pollutant category except CO2 total.
2. MARPOL Annex VI compliance is achievable -- syngas has near-zero SOx and low NOx. The main regulatory question is whether Regulation 16 (shipboard incineration) applies to plasma gasification of non-ship-generated waste. Legal opinion needed.
3. Net carbon balance is approximately neutral in Phase 1 (when accounting for avoided degradation emissions) and carbon negative in Phase 2 (with methanol synthesis displacing fossil fuel).
4. Carbon credits are uncertain in Phase 1 but have strong potential in Phase 2+ via green methanol and ocean carbon sink protection methodology.
5. The honest communications framing is the strongest: acknowledge emissions, but contextualize against the counterfactual of leaving plastic to degrade for centuries. 100% permanent destruction with zero landfill beats 30% recycling with 70% landfill.
6. Vitrified slag is environmentally benign and can contribute small-scale carbon sequestration via mineral carbonation (40-65 tonnes CO2/year).
Research compiled March 2026. Based on MARPOL Annex VI regulations (IMO), Pang et al. 2025 (Nature Sustainability) on ocean plastic carbon cycle impacts, PyroGenesis PRRS emissions data, PAWDS Lloyd's MED Type Approval documentation, and The Claw knowledge base (environmental impact node 66, regulatory node 20).
Sources consulted:
- US EPA MARPOL Annex VI overview
- IMO Regulation 16 (Shipboard Incineration)
- DieselNet IMO Marine Engine Regulations (NOx tiers)
- Pang et al. 2025, Nature Sustainability: "The potential impacts of plastic on the marine carbon cycle"
- ScienceDaily: "Microplastics are undermining the ocean's power to absorb carbon" (Jan 2026)
- Frontiers: Steel slag carbonation and CO2 sequestration (0.27-0.43 kg CO2/kg slag)
- Springer Nature: Critical analysis of industrial slags hazard potential
- The Claw Environmental Impact research (node 66)
- The Claw Regulatory & Legal Framework (node 20)