Star Bulk Carriers’ carbon intensity has increased as charterers asked its bulkers to speed up.
The US-listed Greek bulker owner said the fleet’s annual efficiency ratio (AER) rose to 3.43 last year from 3.25 in 2020.
AER is defined as the ratio of the annual CO2 emissions of a ship divided by the product of the distance sailed and the deadweight, expressed in grams of CO2/dwt-mile.
The 2021 figure was up 5.4% compared with 2020 “due to the increase in the operating speed as per charterers’ instructions”, the owner said.
The company’s aim is to reduce the fleet’s carbon intensity ratio by 12% by 2026, using 2019 as a baseline year.
The total fleet and office energy consumption spiked to 36.9m gigajoules from 33.4m gigajoules in 2020, as the fleet grew and speeds increased.
Scope 1 emissions rose 10.2% to 2.9m tonnes of CO2 equivalent, from 2.6m tonnes the year before, following the increase in fleet size from 116 vessels to 128.
Fuel consumption increased to 910,000 tonnes, from 824,000 tonnes, the company revealed in its latest environmental, social and governance report.
The owner uses low-friction paints and energy-saving devices, as well as voyage optimisation techniques, to improve energy efficiency.
Zero-emission fuels in focus
“We actively research the feasibility and application of zero-emission fuels,” Star Bulk said.
During 2021, the ships travelled 7.2m nautical miles (13.3m kilometres) and the average fuel consumption per day per vessel was 20.11 tonnes — a 3.2% increase on 2020 levels as speeds increased.
Star Bulk had 94% of its ships fitted with scrubbers last year, down from 98% in 2020.
The vessels used 777,572 tonnes of heavy fuel oil, 36,625 tonnes of low-sulphur bunkers and 95,873 tonnes of gasoil.
The average SOx emission per vessel was 63.64 tonnes, up 0.5% in comparison with 2020.
But NOx emissions fell to an average of 494.61 tonnes, down 5.5% as Star Bulk added 12 ships with Tier II engines that emit much fewer NOx emissions per vessel.
