Wightlink Shore Power & Emissions Model

Vessel emissions — CI and propulsion kept separate

CI = cold-ironing / berth auxiliary demand. Propulsion = sailing energy. Direct exhaust pollutants, GHG Protocol scopes and net electrification impact are calculated independently for each stream.

Accounting boundary used here: vessel/operator perspective for the displaced vessel energy. Fuel combustion is Scope 1; purchased shore/charging electricity is Scope 2; upstream marine fuel and electricity generation/T&D are Scope 3. If the port generates, owns or resells electricity, its organisational scope classification can differ.

Total direct CO₂

—

tCO₂/yr, CI + propulsion

Scope 1

—

tCO₂e/yr, fuel combustion

Scope 2

—

tCO₂e/yr, purchased electricity

Scope 3 — fuel

—

tCO₂e/yr, marine fuel WTT

Scope 3 — electricity

—

tCO₂e/yr, upstream + T&D

Baseline total

—

tCO₂e/yr, Scope 1 + fuel Scope 3

Electrified total

—

tCO₂e/yr, Scope 2 + electric Scope 3

Net GHG avoided

—

tCO₂e/yr, baseline minus electrified

Direct vessel exhaust displaced

Baseline emissions associated with the energy displaced by electrification; CI (auxiliary) and propulsion (main engine) remain separate.

Pollutant	CI factor g/kWh	CI annual	Propulsion factor g/kWh	Propulsion annual	Total annual	Unit

CO₂, CH₄ and N₂O feed the Scope 1 CO₂e calculation. NOx, SOx, PM₁₀, PM₂.₅, CO and HC/NMVOC are air-quality outputs and are not added to CO₂e.

Scope 1 / 2 / 3 GHG accounting

Annual tCO₂e for the displaced CI and propulsion energy.

GHG line	CI	Propulsion	Total

Positive “net avoided” means the electrified scenario has lower operational supply-chain GHG than the fuel baseline. Battery manufacture, vessel construction and infrastructure embodied carbon are outside this screen.

Route GHG comparison

Baseline fuel (Scope 1 + fuel WTT Scope 3) versus electrified energy (Scope 2 + electricity Scope 3).

Route	CI baseline	Propulsion baseline	Baseline total	Electrified total	Net avoided

Editable direct-emission screening factors

g pollutant/kWh of engine output. These are generic screening defaults, not vessel certificates. CO₂ is linked to the retained Diesel avoided / kWh assumption above; the other pollutant factors remain editable. Replace with EIAPP/engine/fuel-specific values when available.

Pollutant	CI auxiliary g/kWh	Propulsion main g/kWh	Use

SOx and particulate defaults are deliberately low-sulphur/distillate screening assumptions. Actual fuel sulphur, engine tier, load, after-treatment and vessel-specific certificates should supersede them for an inventory or compliance submission.

Cold-ironing

Propulsion

Electricity GHG

Total MWh demand, by route

Annual, cold-ironing + propulsion

Net GHG impact, by route

Baseline fuel Scope 1+3 vs. electrified Scope 2+3, annual

UK ETS savings, by route

Route	MWh /yr	Net avoided tCO₂e /yr	ETS-scoped share	Saving £ /yr
Fleet total

How the numbers are built

1
Sailings — real departure counts pulled from Wightlink's live timetable API for all 6 route/direction legs, 2026–03–01 to 2027–01–03 (309 days, 34,125 sailings), scaled ×365/309 to an annual run rate per location.
2
Every vessel serving a route carries its own share of that route's annual calls, and its own shore-power draw (kW) and propulsion energy intensity (kWh/nm) — not a single route-wide average.
3
Cold-ironing MWh, per vessel per port = calls at that port × vessel's share of route calls × (shore power enabled?) × charge rate (kW) × that port's docking time (hr) ÷ 1000. Docking time is a port property, not a vessel one — car-ferry berths default to 20 min, the foot-passenger FastCat berths to 8 min.
4
Propulsion MWh, per vessel per location = calls at that location × vessel's share of route calls × (electrify?) × route distance (nm) × energy intensity (kWh/nm) ÷ 1000.
5
Direct vessel emissions are calculated separately for CI auxiliary load and propulsion main-engine load: displaced MWh × pollutant EF (g/kWh). Outputs include CO₂, NOx, SOx, CH₄, N₂O, PM₁₀, PM₂.₅, CO and HC/NMVOC.
6
Scope accounting uses a vessel/operator boundary: baseline fuel combustion is Scope 1; marine-fuel WTT is Scope 3; purchased electricity is Scope 2; electricity upstream generation and T&D are Scope 3. CI and propulsion are calculated independently before being summed.
7
Net GHG avoided = [baseline Scope 1 CO₂e + fuel-WTT Scope 3] − [electricity Scope 2 + electricity Scope 3]. CH₄ and N₂O are converted to CO₂e with editable model GWP constants; air pollutants remain separate physical outputs.
8
ETS saving = direct vessel CO₂ avoided × carbon price for vessels inside the model's GT filter. Grid emissions are not subtracted from the vessel's direct CO₂ avoidance in this line.

Sources & caveats

Route distances (nm) are publicly-cited approximations, not Wightlink-published figures — treat as editable.
Shore-power/electrify flags and their kW/kWh defaults are scenario assumptions seeded from today's real fleet, not a confirmed rostering or engineering spec.
Each vessel's share of its route's calls is an even-split assumption (no public rostering data exists) — edit it if you know the real split.
Wightlink fleet overview
Victoria of Wight — hybrid, 816kWh battery
MV St Clare — 5,359 GT
HSC Wight Ryder I — 520 GT, 2×Cat C32
UK ETS maritime extension, 1 Jul 2026, ≥5,000 GT
UK ETS Authority 2026 civil penalty carbon price: £49.41/tCO₂e
DESNZ 2026 UK grid-average electricity Scope 2 default in this model: 0.13096 kgCO₂e/kWh; electricity upstream + T&D Scope 3 is modelled separately and remains editable.
Marine fuel WTT Scope 3 and direct pollutant factors are screening defaults. Use vessel EIAPP / engine family, actual fuel sulphur and fuel-specific factors for an auditable vessel inventory.
IMO Port Emissions Toolkit — bottom-up engine/load/emission-factor approach

Built for Wightlink by NatPower Marine · scenario tool, not a compliance filing.