Emissions & CII

CO₂ to commercial consequence.

Five regulatory regimes now turn the same exhaust stream into financial obligation. The question isn’t which one to track — it’s whether your data is good enough to see where each regime stands before the year-end number locks in.

CII ratingEU ETS allowancesFuelEU intensityEEOIIMO DCSyear-end forecast

Three stages

Read noon reports + BDN  →  Compute all five regimes  →  Forecast + escalate

Read — daily noon reports (distance, fuel by grade, cargo on board) plus Bunker Delivery Notes (quantity, grade, sulphur).
Compute — each regime independently: CII attained, EEOI per voyage, EU ETS allowance demand, FuelEU GHG intensity, IMO DCS fuel totals.
Forecast — project every metric to year-end using linear trend or planned-voyage profile, then escalate when a rating or obligation is heading outside acceptable range.

The five regimes

Regime	Enforced by	What’s measured	Consequence
CII	IMO	Annual CO₂ per transport work	A–E rating; D×3 or E×1 triggers SEEMP III
EEOI	IMO	CO₂ per cargo-tonne-mile, per voyage	Operational benchmark
EU ETS	European Commission	CO₂ on EU-touching voyages	Allowance purchase obligation
FuelEU Maritime	European Commission	GHG intensity well-to-wake	Penalty per gram above target
IMO DCS	IMO	Annual fuel consumption report	Compliance reporting

The five regimes share the same source data but slice it differently. A vessel can be A-rated on CII while failing FuelEU on its fuel mix; it can be EU ETS-compliant while its DCS data has integrity gaps. The pipeline computes all five every refresh — they don’t reduce to a single number.

CII — the centerpiece

The IMO Carbon Intensity Indicator is the most operationally consequential regime. Two calculations drive the result:

CII_attained = total_CO2 (g) / (Capacity × total_Distance_nm)

CO2_i = mass_fuel_i × CF_fuel

Carbon factors by fuel grade:

Fuel	CF (gCO₂/g fuel)
HSFO	3.114
VLSFO	3.151
MGO	3.206
LNG (combustion)	2.750

Rating bands (ratio = CII_attained / CII_required):

Rating	Ratio
A	≤ 0.86
B	0.86 – 0.94
C	0.94 – 1.06
D	1.06 – 1.18
E	> 1.18

Worked example — MV OCEAN

82,000 DWT container vessel, end-of-April review (4 months into operating year):

Metric	Value
YTD CO₂	14,820 t
YTD distance	38,400 nm
CII attained (YTD)	ratio 1.12 → D-band
Linear year-end forecast	ratio 1.16 → D-band, close to E
Operational forecast (planned voyages)	ratio 1.18 → E-band threshold
EU ETS YTD obligation	4,180 EUAs (~€352k at €84/EUA)
EU ETS year-end forecast	~~12,500 EUAs (~~€1.05M)
FuelEU GHG intensity YTD	86.8 gCO₂eq/MJ vs target 89.3 — currently compliant

Verdict: HIGH-CRITICAL on CII trajectory. Three action candidates:

Slow-steaming — reducing average speed by 1 knot reduces CO₂ per nm meaningfully.
Bunker mix shift — LNG dual-fuel if available; VLSFO-to-MGO net carbon impact is marginal.
Engineering efficiency — hull cleaning and propeller polishing reduce required power for the same speed.

Under the hood

CII implementation — attained calculation and rating lookup

def cii_attained(voyages, vessel_type, dwt):
    """CII attained = total CO2 / (capacity * total distance)."""
    total_co2 = 0.0
    total_distance_nm = 0.0

    for v in voyages:
        for fuel_type, mass_t in v["fuel_consumed"].items():
            cf = CARBON_FACTORS[fuel_type]            # gCO2 / g fuel
            total_co2 += mass_t * 1_000_000 * cf      # to grams
        total_distance_nm += v["distance_nm"]

    capacity = dwt if vessel_type != "passenger" else gt
    return total_co2 / (capacity * total_distance_nm)


def cii_rating(attained, required):
    ratio = attained / required
    if ratio <= 0.86: return "A"
    if ratio <= 0.94: return "B"
    if ratio <= 1.06: return "C"
    if ratio <= 1.18: return "D"
    return "E"

Year-end forecast — two methods

Method 1 — Linear projection

CII_forecast = CII_attained(t) + trend_recent × (T − t)

where trend_recent is the rate of change over the last 3 months and T is year-end.

Method 2 — Operational profile

When the voyage plan for the rest of the year is known, the analyzer projects emissions using planned distance and fuel consumption per leg. More accurate when the operational pattern is stable.

The forecast is reported as a confidence range — a vessel currently at C-band with a forecast trending toward D has time to act if surfaced at mid-year.

EEOI and EU ETS formulas

EEOI (Energy Efficiency Operational Indicator):

EEOI = sum(CO2_i) / sum(cargo_i × Distance_i)

EEOI uses cargo-tonne-miles rather than capacity-miles — a vessel running below capacity on backhauls shows high EEOI relative to CII, useful signal that the operational pattern is the issue rather than the engineering.

EU ETS scope:

Voyage type	CO₂ scope
Intra-EU	100%
EU ↔ non-EU (one end EU)	50%
Extra-EU (both ends non-EU)	0%

Phase-in: 40% obligation in 2024, 70% in 2025, 100% from 2026.

FuelEU Maritime:

GHG_intensity = sum(GHG_i_wtw) / sum(Energy_i)

Compared against a reducing annual target. Non-compliance penalised per gram of GHG above target multiplied by total energy consumed. ISCC-certified biofuels reduce GHG intensity proportionally to their share of energy mix.

Fleet rating dashboard — sample output

Vessel    Type        DWT      CII attained   Required   Ratio   Rating
POSUN     Bulker      52,000   5.18           5.34       0.97    C
AQUILA    Tanker     115,000   3.65           3.74       0.98    C
OCEAN     Container   82,000   8.42           7.95       1.06    D
NEXUS     Tanker      58,000   4.21           4.45       0.95    C

The reviewer scans for vessels approaching D / E — those need active management for the rest of the year. Vessels of the same type consistently above CII required points to a fleet-wide operational issue, not a vessel-by-vessel problem.

Escalation triggers

Trigger	Severity
CII rating projecting E with ≥ 6 months remaining	CRITICAL
CII rating projecting D for third consecutive year	CRITICAL
FuelEU intensity above target by mid-year	HIGH
EU ETS obligation forecast variance > 25% from plan	HIGH
IMO DCS data integrity gaps in submitted reports	HIGH

What the senior review contains

The reviewer reads nine sections in order: headline ratings (CII and forecast, EU ETS YTD and forecast, FuelEU margin) → CII trajectory with band projections → per-voyage EEOI → EU ETS obligation and financial impact → FuelEU intensity vs target → IMO DCS data quality → operational change candidates (slow-steaming, bunker shift, hull cleaning) → recommendations → escalation decision.