US tug and workboat operator Crowley Maritime has taken delivery of eWolf, a vessel hailed as the country’s first Jones Act-compliant, all-electric ship-assist harbour tug. Commencing operations at the Port of San Diego’s Tenth Avenue Marine Terminal, the 25m x 12.2m vessel, first announced in 2021, is expected to remove 178tonnes of NOx, 2.5tonnes of diesel particulate matter (PM) and 3,100tonnes of CO2 from the atmosphere over a 10-year period.
In fact, when it comes to CO2 alone, the tug’s all-electric arrangement could potentially eliminate the equivalent of more than 100 cars’ worth of CO2 pollution per year, systems supplier ABB predicts.
These anticipated results should please the San Diego County Air Pollution Control District, the California Air Resources Board, the Port of San Diego, the US Environmental Protection Agency and the US Maritime Administration, all of whom provided financial support for eWolf’s development. The electric tug was designed by Crowley and constructed by Alabama-based Master Boat Builders, and replaces an older tug which, Crowley estimates, typically consumed 13,560litres of diesel per year.
eWolf draws its propulsive power from an integrated system supplied by ABB. This includes a 6.2MWh Corvus Orca energy storage system, providing enough kick for a service speed of 12knots and an estimated bollard pull capacity of 70tonnes ahead, emissions-free. ABB estimates that the tug can trudge through a full day of work on a single charge, supplied overnight. The group adds: “The electrification concept also contributes to safety on board: because the electric drive eliminates the traditional exhaust system, the captain has a 360° panorama from the pilothouse and an uninterrupted view of deck activity.”
Schottel supplied eWolf with two electrically driven Schottel SRP 430 LE-type RudderPropellers, each rated 2,050kW. The ‘LE’ in the name refers to ‘embedded L-drive’, reflecting the unit’s low installation height, enabled by the omission of the upper gearbox. Schottel claims that this design has increased mechanical efficiency by approximately 3%.
Two gensets, rated 300kW apiece, have been included to provide back-up power for longer transits or emergency use.
eWolf has a depth of 5.46m, a draught of just over 5m and a gross tonnage of 200tonnes. Other onboard features include a deck-mounted Markey Machinery DEPC-48-50 electric recovery winch, plus tankage for 37,097litres of fuel oil and 2,839litres of fresh water. Crowley now intends to build a microgrid shoreside charging station at the Port of San Diego, which will enable the e-tug to liberally draw on power in its own backyard.
