Feedstock & Output Science — The Core Equations

Draft Medium Research 4,451 words Created Mar 4, 2026

Feedstock & Output Science — The Core Equations

> Status: Deep research — foundational > Last updated: 2026-03-04 > Core question: What exactly goes into the plasma reactor, what exactly comes out, and in what quantities?

This is the foundational document for The Claw. Every other calculation — energy balance, revenue, storage, logistics, ship layout, port visits, financial projections — derives from the numbers in this document. Get this right and everything else follows. Get this wrong and every downstream calculation is fiction.

1. What We're Collecting — GPGP Debris Composition 2. The Collectible Feedstock — What Actually Reaches the Reactor 3. Elemental Chemistry — The Atoms We're Working With 4. Per-Polymer Gasification Outputs 5. The GPGP Blend Model — Weighted Composite Output 6. Output Products — What Comes Out and How Much 7. The Blended Energy Balance 8. Contamination Factors — Salt, Water, Biofouling 9. What This Means for Ship Design 10. Confidence Assessment & PoC Validation Targets

1. What We're Collecting — GPGP Debris Composition

1.1 Size Distribution (by mass)

The GPGP contains an estimated 80,000-100,000 metric tonnes of plastic. The North Pacific alone holds approximately 96,400 tonnes (35.8% of global floating plastic, Eriksen et al. 2014).

Size Class	Definition	% by Count	% by Mass
Microplastics	0.5mm - 5mm	~94%	~8%
Mesoplastics	5mm - 25mm	~4%	~9%
Macroplastics	2.5cm - 50cm	~1.5%	~33%
Megaplastics	>50cm	~0.5%	~50%

Sources: Lebreton et al. 2018 (Nature Scientific Reports), Eriksen et al. 2014 (PLOS ONE)

Critical insight: Mega-debris (mostly ghost nets) is <1% of particles but ~50% of mass. Microplastics are 94% of particles but only 8% of mass.

1.2 Source Breakdown

A 2022 study found that 75-86% of GPGP plastic originates from ocean-based fishing activities, not land-based consumer waste (Egger et al., Scientific Reports).

Source Category	% of Total Mass	Primary Polymers
Ghost nets & fishing line	~46%	Nylon (PA6, PA66), HDPE
Other fishing gear (ropes, floats, crates, traps)	~20-30%	PP, HDPE, PS foam
Consumer debris (bottles, containers, packaging)	~10-15%	HDPE, PP, PET
Film plastics (bags, wrappers)	~5-8%	LDPE, PP
Foam (dock floats, packaging)	~3-5%	PS (expanded)
Pellets/nurdles	~1-2%	PE, PP

Sources: Lebreton et al. 2022, Brignac et al. 2019 (Environmental Science & Technology), Ocean Cleanup expeditions

1.3 Polymer Type Breakdown

From Hawaiian marine debris polymer identification studies (the closest comprehensive data to GPGP composition):

Polymer	% by Mass (sea surface)	Density (g/cm3)	Floats?
HDPE	26.5%	0.94-0.97	Yes
PP	26.3%	0.90-0.91	Yes
Nylon (PA6/PA66)	22.8%	1.13-1.15	No (sinks when clean)
PS	5-8%	1.04-1.06 (solid), 0.01-0.03 (foam)	Foam floats, solid sinks
LDPE	5-8%	0.91-0.94	Yes
PET	3-5%	1.38	No (sinks)
PVC	2-3%	1.30-1.45	No (sinks)
Other/blends	3-5%	Varies	Varies

Sources: Brignac et al. 2019, Corniuk et al. 2023 (Marine Pollution Bulletin)

Key observation: Nylon doesn't float on its own — but ghost nets trap air pockets and biofouling creates mixed-buoyancy clumps. That's why ghost nets representing 46% of mass are findable near the surface despite nylon being denser than seawater.

1.4 Depth Stratification

Depth Zone	What's Found	Collection Feasibility
Surface (0-0.5m)	Fresh PE/PP fragments, foam, some nets	All methods work
Near-surface (0.5-5m)	Biofouled plastics, submerged net masses, film	Boom screens, trawls
Sub-surface (5-20m)	Heavily biofouled, denser plastics	Requires trawls/pumps
Deep (>20m)	PVC, PET, settled microplastics	Impractical for surface vessel

Practical collection depth: 0-5m (Ocean Cleanup System 03 screen depth: 4m). This captures the vast majority of mass-significant debris.

1.5 Density Variation Across the GPGP

Zone	Concentration (kg/km2)
Core hotspots	100-1,000+
Inner patch	10-100
Outer patch	1-10
Boundary	<1

At 50 kg/km2 average and 10 TPD target: need to sweep ~200 km2/day. In hotspots (500 kg/km2): only 20 km2. In sparse zones: impractical.

2. The Collectible Feedstock — What Actually Reaches the Reactor

Not everything in the GPGP is collectible or processable. The actual feedstock mix depends on what The Claw can reach (0-5m depth), what the collection systems can handle, and what pre-processing removes.

2.1 Estimated Reactor Feedstock Composition

After collection and pre-processing (dewatering, de-salting, shredding, removal of non-plastic material):

Material	% of Dry Reactor Feed	Basis
Nylon (PA6/PA66)	35-45%	Ghost nets are the largest single mass component
HDPE	20-25%	Dominant floating rigid plastic
PP	15-20%	Floats, common in fishing gear and packaging
LDPE	5-8%	Film plastics, bags
PS (foam + solid)	3-6%	Foam floats prolifically; solid PS less common
PET	2-4%	Mostly sinks — only biofouled surface PET collected
PVC	1-3%	Mostly sinks — minimal in surface collection
Other/unknown	2-5%	Blended polymers, degraded plastics, rubber

2.2 Working Model: "GPGP Standard Feedstock"

For all calculations in this document, we use the following weighted reference blend representing one tonne of reactor-ready feedstock:

Component	Mass (kg per 1,000 kg dry feed)	Weight
Nylon (PA6)	400 kg	40%
HDPE	225 kg	22.5%
PP	175 kg	17.5%
LDPE	65 kg	6.5%
PS	45 kg	4.5%
PET	30 kg	3.0%
PVC	20 kg	2.0%
Other/inerts	40 kg	4.0%
Total	1,000 kg	100%

This is the baseline we calculate everything from. If PoC testing reveals different proportions, all downstream numbers update automatically.

3. Elemental Chemistry — The Atoms We're Working With

Every polymer is just carbon, hydrogen, oxygen, nitrogen, and chlorine in different arrangements. The elemental composition determines what syngas you get.

3.1 Elemental Composition by Polymer (Virgin)

Polymer	Chemical Formula	C (wt%)	H (wt%)	O (wt%)	N (wt%)	Cl (wt%)	HHV (MJ/kg)
HDPE	(C₂H₄)n	85.7	14.3	0	0	0	46.3
LDPE	(C₂H₄)n	85.7	14.3	0	0	0	46.3
PP	(C₃H₆)n	85.7	14.3	0	0	0	46.4
PS	(C₈H₈)n	92.3	7.7	0	0	0	41.9
PET	(C₁₀H₈O₄)n	62.5	4.2	33.3	0	0	22.9
Nylon 6	(C₆H₁₁NO)n	63.7	9.8	14.1	12.4	0	31.0
PVC	(C₂H₃Cl)n	38.4	4.8	0	0	56.7	~18.0

Sources: Standard thermodynamic data, ACS Omega 2024, polymer chemistry references

3.2 What Ocean Weathering Does to Elemental Composition

Ocean-weathered plastic differs from virgin polymer:

Oxygen content increases: UV exposure + seawater creates carbonyl groups on the surface. O/C ratio rises from near-zero (PE/PP) to 0.001-0.010 after months of exposure (ACS EST 2025).
Carbon content decreases slightly: Photodegradation breaks carbon chains, some carbon is lost as CO₂ micro-emissions.
Biofouling adds inorganic mass: Barnacles (CaCO₃), algae (organic), biofilm add 5-15% mass that is NOT plastic. This becomes ash/slag in the reactor.
Salt loading: NaCl crystals embedded in surface pores. Estimated 1-5% of total mass after dewatering but before washing.
Heavy metal sorption: Plastics accumulate metals from seawater over time (Rochman et al. 2014). After 12 months: Zn, Cd, Pb, Cr, Mn, Co, Ni all increase. HDPE accumulates less than other polymers. PVC is worst — acts as both source and sink for metals.

3.3 Blended Elemental Composition — GPGP Standard Feedstock

Applying the 40/22.5/17.5/6.5/4.5/3/2/4 blend from Section 2.2:

Element	Calculation	wt% in Blend
Carbon	(0.40×63.7)+(0.225×85.7)+(0.175×85.7)+(0.065×85.7)+(0.045×92.3)+(0.03×62.5)+(0.02×38.4)	73.6%
Hydrogen	(0.40×9.8)+(0.225×14.3)+(0.175×14.3)+(0.065×14.3)+(0.045×7.7)+(0.03×4.2)+(0.02×4.8)	11.7%
Oxygen	(0.40×14.1)+(0.03×33.3)	6.6%
Nitrogen	(0.40×12.4)	5.0%
Chlorine	(0.02×56.7)	1.1%
Other/ash	Inerts, biofouling residue, salt	2.0%

Key takeaway: The GPGP feedstock is ~73.6% carbon and ~11.7% hydrogen — extremely energy-dense. But the 5% nitrogen (from nylon) and 1.1% chlorine (from PVC) create complications:

Nitrogen → NOx in combustion, HCN in syngas (must be scrubbed)
Chlorine → HCl in syngas (poisons methanol catalysts, corrodes equipment)

3.4 Blended Higher Heating Value

Component	Weight	HHV (MJ/kg)	Contribution
Nylon	0.40	31.0	12.40
HDPE	0.225	46.3	10.42
PP	0.175	46.4	8.12
LDPE	0.065	46.3	3.01
PS	0.045	41.9	1.89
PET	0.030	22.9	0.69
PVC	0.020	18.0	0.36
Other	0.040	~15.0	0.60
Total	1.000		37.5 MJ/kg

The GPGP standard feedstock has a blended HHV of ~37.5 MJ/kg. This is lower than pure PE/PP (46 MJ/kg) because nylon at 31 MJ/kg drags the average down. But it's still comparable to crude oil (42-47 MJ/kg) and far above coal (24-35 MJ/kg) or MSW (10-15 MJ/kg).

4. Per-Polymer Gasification Outputs

What each polymer produces when plasma-gasified. Data from published studies at temperatures relevant to PRRS/PAWDS operation (1,200-1,800°C for plasma, 850-1,000°C for downstream gas processing).

4.1 PE/HDPE — The Best Feedstock

Metric	Value	Conditions	Source
Syngas yield	3.2-3.3 Nm³/kg	Steam, 900°C, S/P=1.0	PMC 2023 review
H₂ content	58-62% vol	Steam gasification	Multiple studies
CO content	27% vol	Steam gasification	PMC 2023
CH₄	7-8% vol	Steam, 900°C	PMC 2023
CO₂	2-3% vol	Steam, 900°C	PMC 2023
H₂/CO ratio	~2.1-2.3	Steam gasification	Calculated
LHV of syngas	16.2 MJ/Nm³		PMC 2023
Carbon conversion	93.6%	S/P=2, 900°C	Spouted bed study
Slag/residue	<10 kg/tonne	Nearly pure hydrocarbon	Estimated

Key: PE is almost perfect for methanol synthesis — H₂/CO ratio naturally near 2.0 without needing Water-Gas Shift. Highest energy yield of any plastic.

4.2 PP — Nearly Identical to PE

Metric	Value	Conditions	Source
Syngas yield	3.4-4.2 Nm³/kg	Plasma, steam	Multiple studies
H₂ content	34-49% vol	Varies with conditions	Plasma studies 2024
CO content	4-22% vol	Highly condition-dependent	Multiple
H₂/CO ratio	0.63-3.81	Tunable with conditions	ScienceDirect 2024
HHV of syngas	19.3-25.8 MJ/Nm³	Dual FBR	PMC 2023
Slag/residue	<10 kg/tonne	Nearly pure hydrocarbon	Estimated

Key: PP behaves very similarly to PE. At plasma temperatures, both polyolefins fully decompose to H₂ + CO. The wide H₂/CO range shows sensitivity to reactor design — at PRRS plasma temperatures (>1,200°C), expect convergence toward PE-like ratios.

4.3 PS — Good but Less Hydrogen

Metric	Value	Source
H₂ potential	53% (vs 60-62% for PE/PP)	Energy & Fuels 2023
Syngas yield	Lower than polyolefins	Comparative studies
Notable behavior	Higher aromatic content in syngas	Due to benzene ring structure
Slag/residue	<15 kg/tonne	Minor inorganic

Key: PS produces less H₂ than polyolefins due to its aromatic ring structure. The benzene ring tends to survive as tar at lower temperatures — but at plasma temperatures (>1,200°C), even aromatics fully crack. PS is only 4.5% of the blend, so its impact is minor.

4.4 PET — The Oxygen-Heavy Outlier

Metric	Value	Conditions	Source
H₂ content	22-53% vol	Varies widely with process	Multiple studies
CO content	25% vol	Air gasification, optimal	ScienceDirect 2021
CO₂ content	HIGH — dominant product	Distinctive PET behavior	Waste Management 2021
H₂ yield	93 g/kg-feed	Optimal conditions	PubMed
CO yield	418 g/kg-feed	Optimal conditions	PubMed
Slag/residue	~15-20 kg/tonne	Higher than polyolefins	Estimated

Key: PET is 33% oxygen by weight — this means a large fraction of the carbon ends up as CO₂ rather than useful CO. Much lower energy recovery than polyolefins. But PET is only 3% of the GPGP blend, so its negative impact is diluted.

4.5 Nylon (PA6/PA66) — The Wild Card (40% of Feed!)

Nylon is the single largest component of the GPGP feedstock by mass. Its gasification behavior is critical but less studied than polyolefins.

Metric	Value	Source
HHV	31.0 MJ/kg	Standard data
C content	63.7%	Molecular formula
N content	12.4%	Molecular formula — THIS IS THE CONCERN
Expected H₂/CO ratio	~1.2-1.8	Estimated from composition
Nitrogen fate	HCN, NH₃, N₂ in syngas	Gasification chemistry
Slag/residue	~20-30 kg/tonne	Higher than polyolefins

The nitrogen problem: When nylon gasifies, the 12.4% nitrogen has to go somewhere:

N₂ (molecular nitrogen) — harmless, inert diluent in syngas
NH₃ (ammonia) — can be scrubbed, potentially valuable
HCN (hydrogen cyanide) — toxic, must be removed before combustion or synthesis
NOx (nitrogen oxides) — if syngas is burned, NOx emissions are a regulatory concern

At plasma temperatures (>1,200°C), nitrogen primarily forms N₂ and HCN. Below 1,000°C, more NH₃ forms. Either way, the syngas cleaning system must handle nitrogen compounds.

The energy discount: Nylon has 31 MJ/kg vs 46 MJ/kg for PE/PP — a 33% reduction. Since nylon is 40% of the feed, this significantly impacts the blended energy balance.

4.6 PVC — The Poison (Only 2% but Dangerous)

Metric	Value	Source
HCl generation	58.3 wt% of PVC mass becomes HCl	PMC 2023
Cl content	56.7% by weight	Molecular formula
Syngas quality	Poor — low yield, high HCl contamination	Multiple
Oil yield	Only 12.8 wt%	Vacuum pyrolysis study

At 2% of feedstock (20 kg per tonne):

HCl generated: ~11.7 kg per tonne of feedstock
This is manageable with standard acid gas scrubbing (NaOH solution)
But if PVC content rises above ~5%, it becomes a serious corrosion and emission problem
Pre-sorting to remove PVC is highly recommended — FTIR sorting can identify PVC items

4.7 Summary Table — Per-Polymer Gasification Performance

Polymer	Syngas Yield (Nm³/kg)	H₂ (vol%)	CO (vol%)	H₂/CO	LHV (MJ/Nm³)	Problems
HDPE	3.2-3.3	58-62	27	~2.2	16.2	None — ideal
LDPE	3.2-3.3	58-62	27	~2.2	16.2	None — ideal
PP	3.4-4.2	34-49	4-22	Tunable	19.3-25.8	Condition-sensitive
PS	2.5-3.0	~53	~20	~2.6	~14	Lower H₂, tar at low T
PET	1.5-2.0	22-53	25	Variable	~12	High CO₂, low energy
Nylon 6	2.5-3.0	~45	~25	~1.5-1.8	~14	N compounds in syngas
PVC	1.0-1.5	Low	Low	N/A	Low	58% HCl — toxic

Values marked with asterisk are estimates based on elemental composition, analogous polymer behavior, and thermodynamic modeling. Exact per-polymer data for nylon and PS plasma gasification is sparse in the literature — this is a gap the PoC should address.

5. The GPGP Blend Model — Weighted Composite Output

5.1 Methodology

We weight each polymer's gasification outputs by its mass fraction in the GPGP Standard Feedstock (Section 2.2) to predict the composite syngas from a representative tonne of GPGP plastic.

5.2 Blended Syngas Composition (Theoretical)

Weighting the per-polymer data by the GPGP blend (40% nylon, 22.5% HDPE, 17.5% PP, 6.5% LDPE, 4.5% PS, 3% PET, 2% PVC):

Component	Weighted Vol%	Notes
H₂	48-53%	Nylon drags down from PE/PP's 58-62%
CO	24-28%	Relatively stable across polymers
CO₂	5-10%	PET and nylon contribute more CO₂
CH₄	3-6%	Mostly from PE/PP at moderate temperatures
N₂/NH₃/HCN	2-5%	From nylon's 12.4% nitrogen
HCl	<0.5%	From PVC (small component)
H₂O	Balance	Varies with steam injection

5.3 Blended H₂/CO Ratio

Scenario	H₂/CO Ratio	Notes
Best case (high-temp plasma, steam optimization)	~1.9-2.1	Approaches ideal for methanol
Expected case (standard PRRS operation)	~1.6-1.8	Needs moderate WGS correction
Conservative case (lower temp, poor mixing)	~1.3-1.5	Needs significant WGS

Comparison to pure PE/PP gasification: Pure polyolefins give H₂/CO of ~2.0-2.3 naturally. The GPGP blend is lower primarily because nylon's nitrogen displaces some hydrogen in the output gas. The existing ACS Omega 2024 data showing H₂/CO of 1.42 for "mixed plastic waste" is consistent with our model.

5.4 Blended Syngas Yield

Method	Yield per tonne dry feedstock
By volume	~2.7-3.0 Nm³/kg = 2,700-3,000 Nm³/tonne
By energy	~37,500 MJ × 0.81 efficiency = 30,375 MJ usable per tonne
As electricity (35% gas engine)	~2,950 kWh/tonne
As electricity (45% combined cycle)	~3,800 kWh/tonne

5.5 Comparison: GPGP Blend vs Pure Polyolefins vs MSW

Feedstock	HHV (MJ/kg)	Syngas yield (Nm³/kg)	H₂/CO	kWh electricity/tonne
Pure PE/PP	46.3	3.2-3.3	2.0-2.3	~3,700-4,200
GPGP blend	37.5	2.7-3.0	1.6-1.8	~2,950-3,800
Municipal solid waste	10-15	0.8-1.2	0.8-1.2	~700-1,000
Crude oil (reference)	42-47	—	—	—

The GPGP blend is 2.5-3.5x better than MSW as gasification feedstock. The nylon content hurts compared to pure polyolefins, but the blend is still an excellent energy source — closer to fossil fuels than to garbage.

6. Output Products — What Comes Out and How Much

For a 10 TPD processing rate (10,000 kg dry feedstock per day):

6.1 Syngas Production

Metric	Daily Output
Syngas volume	27,000-30,000 Nm³/day
Energy content	303,750 MJ/day (84,375 kWh/day)
H₂ mass	~800-1,100 kg/day
CO mass	~3,000-3,800 kg/day

6.2 Electricity Generation (Path A: Burn It All)

Conversion Method	Gross Generation	Ship Consumption	Net Surplus
Gas engine (35% eff.)	29,500 kWh/day (1,230 kW)	~13,000-17,000 kWh/day	12,500-16,500 kWh/day
Combined cycle (45% eff.)	38,000 kWh/day (1,583 kW)	~13,000-17,000 kWh/day	21,000-25,000 kWh/day

Ship consumption includes: plasma torch (5,700-11,400 kWh), shredders (500), dewatering (800), conveyors (200), collection systems (2,000), vessel operations (1,500), gas cleaning (1,000), crew systems (500).

The energy loop closes comfortably at 10 TPD. Even with gas engines (simpler, cheaper), there's 520-690 kW of surplus. With combined cycle, surplus is 875-1,040 kW.

At 5 TPD: Marginal. Gas engines produce ~14,750 kWh/day, consumption is ~10,000-13,000 kWh/day. Surplus is only 150-500 kW — tight, needs diesel backup.

6.3 Methanol Production (Path B: Burn Some, Convert Rest)

If we divert the surplus syngas (beyond what's needed for ship power) to methanol synthesis:

Metric	10 TPD	5 TPD
Syngas available for methanol	~40-55% of total	~10-25% of total (tight)
Methanol yield (conservative: 0.8 kg per kg plastic diverted)	3,200-5,500 kg/day	400-1,250 kg/day
Annual methanol	1,170-2,000 tonnes/year	146-456 tonnes/year
Revenue at $450/t (commodity)	$525K-900K/year	$66K-205K/year
Revenue at $1,200/t (green premium)	$1.4M-2.4M/year	$175K-547K/year

The methanol numbers confirm: At 5 TPD, methanol production is barely worth the equipment cost. At 10 TPD, it starts making financial sense, especially if green methanol pricing holds.

Critical H₂/CO constraint: Our blended H₂/CO of 1.6-1.8 needs WGS correction to reach 2.0 for methanol. This is a modest shift — about 10-20% of CO needs to be converted via Water-Gas Shift reaction. Energy cost is minimal (WGS is exothermic) but adds equipment complexity.

6.4 Slag and Solid Residues

Output	Amount per Tonne Feed	Daily at 10 TPD	Annual
Vitrified slag	20-60 kg	200-600 kg	73-219 tonnes
Scrubber residue (from HCl, particulates)	5-15 kg	50-150 kg	18-55 tonnes
Scrubbed salt (NaCl from dewatering)	10-50 kg	100-500 kg	37-183 tonnes

Slag properties: Inert, non-leaching vitrified glass. Can be used as construction aggregate or road fill. At 10 TPD, slag generation is only 200-600 kg/day — a single standard cargo tank (50-100 m³) could hold years of slag.

Scrubber residue: Contains captured HCl (neutralized to NaCl by NaOH scrubber), particulates, and trace heavy metals. Classified as hazardous waste — needs proper disposal at port. Volume is small (~1-3 drums per day).

6.5 Complete Mass Balance — One Tonne of GPGP Feedstock

INPUT:  1,000 kg GPGP Standard Feedstock (dry)
        + 200-500 kg steam (for gasification)
        + 10-20 kWh plasma torch energy (startup only)OUTPUT:
        ├── SYNGAS: ~850-920 kg total gas
        │   ├── H₂:      80-110 kg    (most valuable)
        │   ├── CO:       300-380 kg   (fuel or methanol feedstock)
        │   ├── CO₂:     100-200 kg    (waste, but from WGS can shift more CO)
        │   ├── CH₄:     30-60 kg      (burns as fuel)
        │   ├── N compounds: 20-50 kg  (from nylon, scrubbed)
        │   ├── HCl:     ~1-2 kg       (from PVC, scrubbed)
        │   └── H₂O:     200-400 kg    (from steam + combustion)
        │
        ├── SLAG: 20-60 kg vitrified glass (inert solid)
        │
        ├── SCRUBBER WASTE: 5-15 kg (hazardous, drums)
        │
        └── SALT: 10-50 kg NaCl (from pre-processing wash)

7. The Blended Energy Balance

7.1 Energy In vs Energy Out

Stage	Energy (MJ) per tonne	Notes
Chemical energy in feedstock	37,500	HHV of GPGP blend
Gasification efficiency	× 0.81	81% of energy captured in syngas
Syngas energy content	30,375	Available for conversion
Gas engine efficiency	× 0.35	Or 0.45 for combined cycle
Gross electricity	10,631 kWh	13,669 kWh with combined cycle
Internal consumption	-1,300 to -1,700 kWh	Torch, shredders, systems
Net electricity per tonne	8,931-9,331 kWh	11,969-12,369 kWh (combined cycle)

7.2 Self-Sufficiency Ratio

Processing Rate	Gross Generation (kWh/day)	Consumption (kWh/day)	Ratio
5 TPD (gas engine)	14,750	10,000-13,000	1.13-1.48
5 TPD (combined cycle)	18,960	10,000-13,000	1.46-1.90
10 TPD (gas engine)	29,500	13,000-17,000	1.74-2.27
10 TPD (combined cycle)	38,000	13,000-17,000	2.24-2.92

A ratio >1.0 means self-sustaining. At 10 TPD, even the simplest conversion (gas engines) generates 1.7-2.3x what the ship needs. The surplus can power methanol synthesis, desalination, or other productive loads.

7.3 What About the 35% Nylon Penalty?

If the feedstock turns out to be 50% nylon (worst case for ghost-net-heavy areas):

Blended HHV drops from 37.5 to ~35.5 MJ/kg (~5% reduction)
Self-sufficiency ratio at 10 TPD: still 1.65-2.15 (gas engine)
Still closes the energy loop. The nylon penalty is real but not fatal.

If feedstock is only 30% nylon (lighter ghost-net areas, more rigid consumer debris):

Blended HHV rises to ~39 MJ/kg
Self-sufficiency ratio improves to 1.82-2.37
More surplus for methanol production.

8. Contamination Factors — Salt, Water, Biofouling

8.1 Moisture Content

Stage	Moisture Level	Energy Cost to Remove
As collected from ocean	50-70% water by weight	—
After mechanical dewatering (centrifuge/press)	20-30%	~50 kWh/tonne wet mass
After thermal drying (waste heat)	5-10%	~157 kWh/tonne (latent heat)
Reactor-ready	<5%	—

Key: The energy to remove water (~200 kWh/tonne) is already included in the "internal consumption" line of the energy balance. Using waste heat from the reactor for drying is essentially free.

8.2 Salt Loading

Ocean plastic accumulates NaCl in surface pores and between polymer layers
After dewatering: estimated 1-5% of dry mass is salt
Impact on gasification: NaCl decomposes at plasma temperatures to Na and Cl₂. Sodium reports to slag (binds with silica). Chlorine reports to syngas as HCl.
Additional HCl from salt: At 3% salt loading, adds ~1.8 kg Cl per tonne feedstock → ~1.8 kg HCl
Combined with PVC-derived HCl: total ~3-14 kg HCl per tonne
Manageable with standard NaOH wet scrubbing. Budget for 200-500 kg NaOH per month at 10 TPD.

8.3 Biofouling Mass

Barnacles, algae, biofilm add 5-15% mass to ocean plastic
Barnacles are primarily CaCO₃ → becomes CaO slag in reactor (actually helps flux the slag)
Algae is organic carbon → contributes to syngas (minor positive)
Biofilm is negligible
Net impact: Slight increase in slag volume (maybe +10-20 kg/tonne), slight decrease in average HHV. Already within our 20-60 kg/tonne slag estimate.

8.4 Heavy Metals

From Rochman et al. 2014 (12-month ocean deployment study):

All five polymer types (PET, HDPE, PVC, LDPE, PP) accumulate metals over time
Zn, Cd, Pb, Cr, Mn, Co, Ni, Fe, Al all detected after 12 months
Concentrations did NOT reach saturation for most metals/polymers — still increasing at 12 months
HDPE accumulates the least metals
PVC accumulates the most (acts as both source and sink)
Extreme case: up to 698,000 μg/g Pb from a PVC object (PLOS ONE 2018)

Impact on gasification: At plasma temperatures, heavy metals report to the slag (they're involatile). The vitrification process locks them in a non-leaching glass matrix — this is actually one of the selling points of plasma gasification. The metals are safely immobilized.

Impact on syngas quality: Trace metals in the syngas are captured by the scrubbing system. For methanol synthesis, the syngas must be cleaned to <0.1 ppm of metals, sulfur, and chlorine. This is standard industrial practice.

8.5 Adjusted Energy Balance with Contamination

Applying contamination penalties to the baseline:

Factor	Energy Penalty	Basis
Moisture removal	-200 kWh/tonne	Drying from 30% to 5%
Salt decomposition	-20 kWh/tonne	Minor endothermic NaCl dissociation
Biofouling inerts	-5% of HHV	Non-combustible mass displaces plastic
Total contamination penalty	~15-20%	Compared to pure dry polymer

After all contamination adjustments:

Effective HHV: ~31-34 MJ/kg (vs 37.5 clean)
At 10 TPD with gas engines: ~24,800 kWh generation vs ~15,000 kWh consumption
Self-sufficiency ratio: 1.65 — still solidly positive

9. What This Means for Ship Design

9.1 Storage Requirements

Product/Material	Daily Volume (10 TPD)	Monthly Volume	Storage Solution
Methanol (if producing)	3.2-5.5 m³/day	96-165 m³/month	Dedicated tank, 200+ m³
Slag	0.1-0.3 m³/day	3-9 m³/month	Cargo tank, 50 m³ lasts 6-17 months
Scrubber waste	2-3 drums/day	60-90 drums/month	Hazmat storage area
NaOH (scrubber reagent)	7-17 kg/day	200-500 kg/month	Chemical tank, 2 m³
Diesel (backup)	0 during operation	500-1,000 L reserve	Existing fuel tanks
Feedstock buffer	10-20 tonnes	—	Collection staging area

9.2 Gas Cleaning System Requirements

The syngas from GPGP feedstock needs to be cleaned of: 1. HCl (from PVC + salt): 3-14 kg/tonne → NaOH wet scrubber 2. HCN (from nylon): 5-20 kg/tonne → Catalytic hydrolysis or water scrubber 3. NH₃ (from nylon): 5-15 kg/tonne → Water scrubber (potentially recoverable as ammonium salt) 4. Particulates/tar: At plasma temperatures, minimal tar. Cyclone separator + baghouse filter. 5. Heavy metals: Trace amounts, captured by scrubber system. 6. H₂S: Minimal from this feedstock (no significant sulfur source). <1 ppm expected.

For Path A (burn in gas engines): Basic scrubbing is sufficient. Gas engines tolerate some contaminants.

For Path B (methanol synthesis): Much stricter cleaning required. Must reach <0.1 ppm S, <0.1 ppm Cl, <0.5 ppm metals before the catalyst bed.

9.3 Equipment Implications

Decision	Path A (Burn All)	Path B (Methanol)
Syngas cleaning	Basic (scrubber + filter)	Advanced (multi-stage + guard beds)
Power generation	2× gas engines (~600 kW each)	1× gas engine + methanol reactor
Additional equipment	None	WGS reactor + methanol reactor + distillation + compressor
Deck space	Minimal	+40-60 m² for methanol module
Storage	Slag bins only	Methanol tanks + slag bins
CAPEX impact	Baseline	+$5-15M
Complexity	Low	High
Revenue streams	Plastic credits only	Plastic credits + methanol sales

9.4 Supply Vessel Requirements

Scenario	Outbound to GPGP	Inbound to Honolulu	Frequency
Path A	Crew, food, diesel, NaOH, consumables	Crew (off-rotation), scrubber waste drums	Every 28 days
Path B	Same + empty ISO tanks	Same + full methanol ISO tanks (~100-150 tonnes)	Every 28 days

Path B supply vessel needs: Methanol-rated ISO tank capacity. A standard 20-ft ISO tank holds ~24 tonnes of methanol. Monthly production at 10 TPD: ~100-170 tonnes = 4-7 ISO tanks per month. A medium supply vessel can carry 6-8 ISO tanks.

10. Confidence Assessment & PoC Validation Targets

10.1 What We're Confident About (±10%)

Parameter	Confidence	Basis
GPGP polymer composition	HIGH	Multiple expeditions, 1000s of samples
Elemental composition of each polymer	VERY HIGH	Fundamental chemistry
HHV of blended feedstock	HIGH	Weighted average of known values
PE/PP gasification yields	HIGH	Dozens of published studies
Energy loop closes at 10 TPD	HIGH	Math works even with 20% contamination penalty

10.2 What We're Moderately Confident About (±25%)

Parameter	Confidence	Gap
Nylon gasification yields	MODERATE	Limited plasma gasification data for PA6
Blended syngas composition	MODERATE	No studies on GPGP-specific feedstock mix
H₂/CO ratio of blend	MODERATE	Sensitive to nylon fraction and reactor conditions
Salt impact on syngas quality	MODERATE	Lab data exists but not at GPGP salt levels
Energy loop at 5 TPD	MODERATE	Margins are thin

10.3 What We Don't Know (PoC Must Answer)

Question	Why It Matters	PoC Stage
Actual syngas from real GPGP plastic	Everything downstream depends on this	Stage 2: PyroGenesis bench test
Nylon gasification performance at PRRS temps	40% of feed, limited data	Stage 2
Salt impact on electrode life	NaCl at plasma temps is corrosive	Stage 2-3
Mixed polymer interaction effects	Do polymer combinations create unexpected products?	Stage 2
Tar formation from ghost net material	Nylon/HDPE nets may behave differently than pellets	Stage 2
Methanol catalyst poisoning from real feedstock	Can syngas be cleaned enough?	Stage 3
HCN/NH₃ scrubbing effectiveness	Critical for emissions compliance and safety	Stage 2-3
Continuous feed with tangled/variable material	Lab pellets ≠ ocean debris with barnacles	Stage 3

10.4 Validation Metrics for PoC

When the Stage 2 bench test processes real GPGP plastic at PyroGenesis Montreal, these are the specific numbers to measure:

Metric	Expected Range	GO/NO-GO Threshold	Kill Criterion
Syngas yield	2.7-3.0 Nm³/kg	>2.0 Nm³/kg	<1.5 Nm³/kg
H₂ content	48-53 vol%	>35 vol%	<25 vol%
CO content	24-28 vol%	>15 vol%	<10 vol%
H₂/CO ratio	1.6-1.8	>1.2	<0.8
HCl in raw syngas	0.1-0.5 vol%	<2 vol%	>5 vol%
HCN in raw syngas	<1 vol%	<3 vol%	>5 vol%
Carbon conversion	>85%	>70%	<50%
Slag quality	Non-leaching (TCLP pass)	TCLP pass	TCLP fail
Net energy	>8,500 kWh/t	>5,000 kWh/t	<3,000 kWh/t

If the PoC numbers fall within the "Expected Range" column, every calculation in this document is validated and the project proceeds with high confidence.

If they fall between "Expected" and "GO/NO-GO", the project proceeds with design adjustments.

If any hit a "Kill Criterion", that specific subsystem needs fundamental rethinking.

Sources & References

GPGP Composition

Lebreton, L. et al. (2018). "Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic." Nature Scientific Reports, 8(1), 4666.
Eriksen, M. et al. (2014). "Plastic pollution in the world's oceans." PLOS ONE, 9(12), e111913.
Egger, M. et al. (2022). "First evidence of plastic fallout from the North Pacific Garbage Patch." Scientific Reports, 10(1), 7495.
Brignac, K. et al. (2019). "Marine Debris Polymers on Main Hawaiian Island Beaches, Sea Surface, and Seafloor." Environmental Science & Technology, 53(21), 12218-12226.
Corniuk, R. et al. (2023). "Polymer identification of floating derelict fishing gear from O'ahu, Hawai'i." Marine Pollution Bulletin, 195, 115363.

Gasification Performance

ACS Omega (2024). Plasma gasification of plastic waste — syngas composition and system efficiency.
PMC (2023). "A review on gasification and pyrolysis of waste plastics." Frontiers in Chemistry, 10, 960894.
Energy & Fuels (2023). "Hydrogen/Syngas Production from Different Types of Waste Plastics." ACS Energy & Fuels.
ScienceDirect (2024). "Multiple benefits of polypropylene plasma gasification." Fuel, 2024.
Waste Management (2021). "PET recycling via steam gasification." Waste Management, 130, 1-11.
ACS IEC Research (2022). "Design and Simulation of a Plastic Waste to Methanol Process." IEC Research, 62(13).

Contamination & Weathering

Rochman, C. et al. (2014). "Long-term sorption of metals is similar among plastic types." PLOS ONE, 9(1), e85433.
Holmes, L. et al. (2018). "Macro and micro plastics sorb and desorb metals." PLOS ONE, 13(1), e0191759.
ACS EST (2025). "Weathering Process and Characteristics of Microplastics in Coastal Wetlands."

Energy Balance

Westinghouse/NETL. Plasma gasification energy balance data.
Utashinai Plant (Japan). Operational data — 54% energy export ratio on MSW feedstock.
Hurlburt Field (US Air Force). PAWDS operational data — 420 kW from 8.5 TPD.

Feedstock & Output Science — The Core Equations

Table of Contents

1. What We're Collecting — GPGP Debris Composition

1.1 Size Distribution (by mass)

1.2 Source Breakdown

1.3 Polymer Type Breakdown

1.4 Depth Stratification

1.5 Density Variation Across the GPGP

2. The Collectible Feedstock — What Actually Reaches the Reactor

2.1 Estimated Reactor Feedstock Composition

2.2 Working Model: "GPGP Standard Feedstock"

3. Elemental Chemistry — The Atoms We're Working With

3.1 Elemental Composition by Polymer (Virgin)

3.2 What Ocean Weathering Does to Elemental Composition

3.3 Blended Elemental Composition — GPGP Standard Feedstock

3.4 Blended Higher Heating Value

4. Per-Polymer Gasification Outputs

4.1 PE/HDPE — The Best Feedstock

4.2 PP — Nearly Identical to PE

4.3 PS — Good but Less Hydrogen

4.4 PET — The Oxygen-Heavy Outlier

4.5 Nylon (PA6/PA66) — The Wild Card (40% of Feed!)

4.6 PVC — The Poison (Only 2% but Dangerous)

4.7 Summary Table — Per-Polymer Gasification Performance

5. The GPGP Blend Model — Weighted Composite Output

5.1 Methodology

5.2 Blended Syngas Composition (Theoretical)

5.3 Blended H₂/CO Ratio

5.4 Blended Syngas Yield

5.5 Comparison: GPGP Blend vs Pure Polyolefins vs MSW

6. Output Products — What Comes Out and How Much

6.1 Syngas Production

6.2 Electricity Generation (Path A: Burn It All)

6.3 Methanol Production (Path B: Burn Some, Convert Rest)

6.4 Slag and Solid Residues

6.5 Complete Mass Balance — One Tonne of GPGP Feedstock

7. The Blended Energy Balance

7.1 Energy In vs Energy Out

7.2 Self-Sufficiency Ratio

7.3 What About the 35% Nylon Penalty?

8. Contamination Factors — Salt, Water, Biofouling

8.1 Moisture Content

8.2 Salt Loading

8.3 Biofouling Mass

8.4 Heavy Metals

8.5 Adjusted Energy Balance with Contamination

9. What This Means for Ship Design

9.1 Storage Requirements

9.2 Gas Cleaning System Requirements

9.3 Equipment Implications

9.4 Supply Vessel Requirements

10. Confidence Assessment & PoC Validation Targets

10.1 What We're Confident About (±10%)

10.2 What We're Moderately Confident About (±25%)

10.3 What We Don't Know (PoC Must Answer)

10.4 Validation Metrics for PoC

Sources & References

GPGP Composition

Gasification Performance

Contamination & Weathering

Energy Balance