Tug designers and owners need to ensure their tugs meet tightening environmental requirements, including underwater noise reduction, says ABS vice president of technology Gareth Burton
“Tug operators need to consider and understand how new fuel and propulsion technologies in the future can be applied.”
This includes being familiar with alternative fuel options and dealing with the challenge of installing energy storage. “Hybrid integrated systems using diesel-electric with battery storage systems are increasingly of interest to owners seeking to reduce their carbon footprint,” says Mr Burton.
ABS has produced guidance and rules for implementing battery storage, fuel cells and hybrid integrations, Guide for Hybrid Electric Power Systems for Marine and Offshore Installations.
“Also of importance to tug operators is the issue of underwater noise,” says Mr Burton. “Both IMO and the European Union have made efforts to reduce the impact of underwater noise pollution on marine life and habitats.”
The guidelines contained in IMO MEPC.1/Circ.833 are technical advice for designers, shipbuilders, and ship operators for reducing underwater noise from commercial shipping.
“There is a need to develop optional notations to establish the baseline underwater noise levels for vessels and quantify the relationship between individual ship noise levels and the regional ambient noise level reductions,” says Mr Burton. “It is anticipated there will be future development work by IMO’s marine environment protection committee on this issue.”
Options for alternative fuels have so far been LNG, with trials using ammonia, hydrogen and methanol coming.
“Regulatory and classification requirements are in place for using LNG fuel in marine applications,” says Mr Burton. “The specific gas-fuelled ship arrangements depend on the fuel containment, the fuel gas supply system, and selected prime mover technologies.” The link between fuel storage, fuel preparation, and gas consumer is much more interdependent as compared to conventional fuels. “Critical equipment and system design decisions cannot be made in isolation,” he says.
Ammonia is identified as a zero-carbon fuel that can enter the global market relatively quickly and help meet greenhouse gas reduction targets for 2050. “Ammonia offers shipowners and operators a zero-carbon tank-to-wake emissions profile, regardless of the source of the fuel,” says Mr Burton.
Use of ammonia as a fuel is expected to grow due to its zero-carbon content, easier distribution, storage and bunkering compared to hydrogen, and its suitability with existing and emerging technologies for propulsion and power generation.
ABS has worked with tug builders such as Sanmar to review and approve designs and collaborate on ideas.
It ensures builders meet the International Association of Classification Societies and international rule requirements.
Port and towage requirements will be discussed in depth during Riviera’s series of virtual conferences and webinars during 2021 - use this link to access more details and register for these events