Most Emission-Efficient Chemical Tankers
Ships ranked by AER (Annual Efficiency Ratio) — grams of CO₂ emitted per tonne of deadweight carried one nautical mile (g CO₂/dwt·nm), the IMO carbon-intensity metric behind the CII rating — from official EU MRV emissions data for reporting year 2025. Lower is greener. Pick a segment and size class to see the greenest vessels first.
| # | Vessel | Size (DWT) | Built | Carbon intensity — AER (g CO₂/dwt·nm) | Grade |
|---|---|---|---|---|---|
| 1401 |
CATHY THERESA
IMO 9478315
|
7,846 | 2011 |
20.6
|
E |
| 1402 |
ESSEX STAR
IMO 9348297
|
16,744 | 2007 |
20.6
|
E |
| 1403 |
MED TUNCER
IMO 9830599
|
8,227 | 2019 |
20.7
|
E |
| 1404 |
GENNARO IEVOLI
IMO 9268631
|
12,004 | 2004 |
20.7
|
E |
| 1405 |
GTM GERMANY
IMO 9405320
|
11,796 | 2008 |
20.8
|
E |
| 1406 |
HYDRA
IMO 9837341
|
7,870 | 2019 |
20.9
|
E |
| 1407 |
MRC MINA
IMO 9464285
|
7,718 | 2009 |
21.0
|
E |
| 1408 |
NORMA
IMO 9870666
|
7,399 | 2020 |
21.0
|
E |
| 1409 |
BLUE BIRD
IMO 9527764
|
9,938 | 2011 |
21.0
|
E |
| 1410 |
MED BALTIC
IMO 9462304
|
8,269 | 2011 |
21.0
|
E |
| 1411 |
ROLAND ESSBERGER
IMO 9504217
|
9,124 | 2013 |
21.0
|
E |
| 1412 |
DANTE A
IMO 9361029
|
12,100 | 2008 |
21.2
|
E |
| 1413 |
SONGA ATLANTIC
IMO 9447328
|
17,999 | 2010 |
21.3
|
E |
| 1414 |
LADY ELA
IMO 9511442
|
7,667 | 2009 |
21.4
|
E |
| 1415 |
BOTHNIA
IMO 9485356
|
8,985 | 2013 |
21.7
|
E |
| 1416 |
SWAN BISCAY
IMO 9466532
|
6,711 | 2021 |
21.7
|
E |
| 1417 |
MARY A
IMO 9321433
|
8,036 | 2007 |
21.7
|
E |
| 1418 |
CORAL ESSBERGER
IMO 9504205
|
9,118 | 2012 |
21.8
|
E |
| 1419 |
MED BLUE JAY
IMO 9544346
|
8,231 | 2021 |
21.8
|
E |
| 1420 |
MED ARCTIC
IMO 9410545
|
8,239 | 2009 |
21.8
|
E |
| 1421 |
MAYOURY
IMO 9777541
|
9,194 | 2017 |
22.0
|
E |
| 1422 |
MIMMO IEVOLI
IMO 9147746
|
9,554 | 1998 |
22.1
|
E |
Which engines power the greenest fleets?
The main engine is the single largest CO₂ source on board — typically well over 80% of a ship's emissions come from propulsion. We aggregated this ranking the other way around: every engine design is scored by the measured carbon intensity of the vessels carrying it, licensee-built units merged under their design brand. The verdict from the 2025 data — modern dual-fuel designs like MAN B&W's ME-GI and WinGD's X-DF families, together with EGR/SCR-abated and ultra-long-stroke G-type engines, consistently power the most emission-friendly ships in service.
AER (Annual Efficiency Ratio) = annual CO₂ emissions ÷ (deadweight × distance sailed), the IMO carbon-intensity metric used for CII ratings. It is built only from measured CO₂, distance and deadweight — not the self-reported cargo transport-work figure, which is unreliable. Implausible outliers (top 2% per segment) are excluded. Grade A–E reflects each vessel's rank within its segment. Source: EMSA THETIS-MRV.