Air Lubrication Saving

Air-layer or micro-bubble systems inject compressed air under the hull to reduce frictional resistance. Net saving is the frictional reduction MINUS the compressor power cost. EEDI Category C innovative-tech credit.

DesignESD

Baseline

Main-engine delivered powerkWFrictional share of total resistance%Bulk carrier 65–75, tanker 60–70, ro-ro 50–60, container 45–55.

Air lubrication

Frictional drag reduction on wetted surface covered%Typical 5–10 % on the flat-bottom region for an air-layer system; micro-bubble 3–6 %.Hull wetted-surface fraction covered%Flat bottom is usually 50–70 % of total wetted surface on a bulk carrier.Compressor power demandkWTypically 1–3 % of ME power at design speed.

Operation

ME SFOCg/kWhRunning hours / yearhFuel

Gross hull-drag saving

3.12%

Net ME power saving

112kW

Net fuel saved / year

117.6t

Net CO₂ avoided / year

366.2t

Formula, assumptions, and limits

Gross saving = main-engine power × frictional share × covered fraction × reduction rate. Subtract the compressor demand for net. Mitsubishi Air Lubrication System (MALS) reports ~5 % net on tankers; bulk carriers 4–6 % net.