Leapfrog Tier III and go straight to electric

Port authorities and operators are beginning to request, or even demand, emissions-reduction technology in towage concession tenders. And IMO rules coming into force within four months will change tug enginerooms for the better.

In this rising environmental wave, owners need to react sooner rather than later, and electric power should be considered the long-term goal.

Other options could be adopted initially, but why wait when owners can pioneer this technology. The most obvious and timely option is to ensure tug newbuildings comply with IMO’s Tier III regulations, which covers minimising NOx and particulate matter emissions from new vessels with diesel engines of over 130 kW with the keel laid after 1 January 2021.

US tug owners are ahead of the curve with more vessels built in their shipyards to IMO Tier III equivalent, US Environmental Protection Agency (EPA)’s Tier 4.

Shipyards install emissions abatement technology such as selective catalytic reduction equipment and urea tanks for compliance. Another option comes from Wabtec subsidiary GE Transportation, which has developed exhaust gas recirculation and two-stage turbochargers for its medium-speed engines to reduce NOx for IMO Tier III and EPA Tier 4 compliance.

In readiness for the rule enforcement, designers and shipyards are producing tugs with main diesel engines ready for retrofitting to IMO Tier III. Some owners have ordered tugs now that are IMO Tier III-compliant following new towage concession awards, such as Boluda Towage Europe after gaining a concession renewal from the Port of Zeebrugge, Belgium. Eight IMO Tier III-compliant tugboats will be put into action to support ships in the port for five years.

This shows a commitment to meet emissions requirements prior to the deadline. But, the cynics among us may anticipate owners ordering newbuildings with their keel laid prior to January 2021 to circumnavigate these rules.

Another option is installing LNG, or compressed natural gas, and dual-fuel engines on tugs. As an idea, using gas instead of diesel to exceed compliance is a good one. However, the capital costs versus a conventional tug are millions of dollars higher. Plus, there are operating costs and challenges during the tug’s life due to the additional safety management needed when bunkering and maintaining LNG systems.

In the long term, owners will be expected to cut greenhouse gas emissions. This could be achieved by using non-carbon fuels such as ammonia and hydrogen fuel cells. But these are currently only at the test stage.

Or there is electric propulsion. As we have heard during Riviera Maritime Media’s Maritime Hybrid, Electric and Fuel Cell webinar weeks, hybrid propulsion incorporating shaft generators and batteries, or all-electric tugs are the most viable way forward.

Navtek Naval Technologies general manager Ferhat Acuner introduced the world’s first all-electric tug in operation, Zeetug. Navtek has other electric-driven tug designs ready for construction if owners want to invest in batteries and shore power.

If they need the extra power from diesel, then hybrid propulsion with Tier III-compliant engines and batteries would be the best option.

With IMO’s plans to cut carbon and ports under pressure to cut emissions, tugboat owners should consider leapfrogging over diesel and LNG alternatives and going straight for all-electric tugs.

Alternative fuels, hybrid and electric options for powering tugs will be discussed in depth during Riviera Maritime Media’s Tug Technology Webinar Week, from 1 September 2020