Tackling the alternative fuels conundrum

Port authorities and operators are under pressure from regulators and non-governmental organisations to reduce emissions of harmful gases and compounds to improve human health.

This pressure will intensify as IMO considers strategies to reduce greenhouse gas emissions over the next 10 years. It aims to reduce carbon intensity from shipping by 40% from 2008 levels by 2030 and cut CO₂ emissions by 50% in 2050.

This will be an industrywide initiative requiring all stakeholders to collaborate, including shipowners, ports, charterers, shipyards, designers and the marine service vessel operators. Tugs are in the firing line as one of the most visible aspects of the shipping industry.

Upcoming regulations will require NOx and particulate matter to be cut from tug operations. IMO Tier III is coming into force at the beginning of 2021, driving tug builders to install abatement technologies on newbuildings. These requirements are to national rules already in place, such as US Environmental Protection Agency (EPS)’s Tier 4 emissions requirements and legislation coming in China.

Some owners have acted ahead to ensure their tugs are IMO Tier III-compliant. Boluda Towage Europe has promised to update its fleet through newbuildings and retrofits to Tier III in Belgium port of Zeebrugge. There are growing examples in the US where newbuildings comply with EPA Tier 4.

But this is just the start of a trend, where tug owners will also be expected to cut their carbon emissions. Some owners have taken the initiative, with hybrid propulsion installed on new tugs. There are also a handful of electric-powered tugs. However, as one tug owner tells Tug Technology & Business, batteries are expensive and complicated to install and integrate, putting them off this investment.

Tug owners could explore using alternative fuels to diesel. There are more than a dozen tugs powered by LNG, with the latest deployed in Singapore and China, although there can be challenges with bunkering, storage and operations. LNG may be a temporary fix.

A less carbon-intense fuel in the frame is methanol, which is already readily available in 150 ports. This has less handling issues, but still produces CO₂.

Ammonia is gaining ground as another alternative owners could consider. Hydrogen fuel cells is another potential alternative being tested over the next five years.

It is a conundrum for owners to find the right solution for long-term operations, with tugs able to work for at least 20-30 years. My money would be on batteries complementing another solution – sustainably sourced biofuels.

Retrofitting tugs with energy storage systems and abatement technology will remove NOx and particulates, while running generators on biofuel as backup to batteries.

Owners could then invest a small percentage of operating costs into planting trees to offset the biomass in fuel. This would bring public perception and environmental benefits.

In addition, batteries could be recharged quayside using renewable energy for a green and sustainable tug and maritime industry.