Hybrid Propulsion Tugboats: Pioneering the Future of Maritime Sustainability

Hybrid Propulsion Tugboats: Pioneering the Future of Maritime Sustainability

Hybrid tugboat - Hybrid electric green tugboat
Photo by Mohan Nannapaneni

Hybrid Tugboat: Pioneering the Future of Maritime Sustainability


An overview of the recent developments for green hybrid tugs

Hybrid propulsion tugboats are at the forefront of transforming the maritime industry. By integrating alternative fuels and cutting-edge propulsion technologies, these tugboats offer significant environmental and operational benefits.

The Paris Agreement of 2016 has intensified global efforts to reduce GHG emissions, making it a critical issue for the shipping sector. In response, the International Maritime Organization set ambitious goals in 2018 to halve GHG emissions from international shipping by 2050, with the ultimate goal of achieving zero emissions by the end of the century.

Therefore, hybrid propulsion comes into play because of its promise of reducing emissions. Hybrid vessels can operate on electrical power combined with conventional fuel or utilize a blend of traditional and alternative sustainable fuels. Tugboats, given their near-shore operations and regular recharging needs, were among the earliest maritime vessels to adopt battery technology. The first hybrid tugboats began operations as early as 2009, with fully electric, zero-emission models following in 2019.

This article explores the innovations in the field of hybrid green tugs, focusing on both the environmental and operational benefits, as well as the challenges. To do so, industry examples and case studies will be provided.

Hybrid Tugboat models through the years

Through the years, tugboats have increasingly relied on batteries and various fuels to reduce emissions and enhance efficiency.

In 2010, the US-based company Foss Maritime’s hybrid tugboat Carolyn Dorothy, powered by diesel engines and batteries, demonstrated significant environmental benefits. It retained the power and maneuverability of conventional tugs while dramatically reducing emissions, noise, and fuel consumption. The hybrid electric tugboat achieved a 73% reduction in particulate matter, 51% in nitrogen oxide, and 27% in carbon dioxide. 

In 2015, NYK Line and IHI Power Systems Corporation developed Sakigake, the first Japanese LNG-fueled tugboat. Using LNG, Sakigake reduced sulfur oxide emissions by nearly 100%, nitrogen oxide by 80%, and carbon dioxide by 30% compared to heavy oil. Currently, IHI Corporation is working on developing a hybrid ammonia-powered tugboat. Ammonia, which emits no CO₂ when burned, shows promise as a next-generation fuel for reducing shipping’s environmental impact. 

Another example of the industry’s commitment to innovation and sustainability is offered by Seabulk’s hybrid diesel-electric tugs Spartan and Titan. These new green hybrid tugs, which started to operate in the USA in 2022, combine the benefits of diesel and electric propulsion for enhanced efficiency and reduced emissions. They offer exceptional power and maneuverability, fitting the high-powered needs of their customers while improving fuel efficiency.

Another example is the Hydrotug 1, operating in Antwerp since 2024, which features dual-fuel BeHydro engines that run on hydrogen or traditional fuel. This tug is part of the Port of Antwerp-Bruges’ plan to transition to a climate-neutral port by 2050.

The Panama Canal Authority’s new hybrid tugboats are another example of the growing adoption of this technology in high-profile operations. In October 2023, the Authority contracted for ten hybrid electric tractor tugboats, aiming to reduce emissions during ship towage through the canal and docking in Panamanian ports. Corvus Energy plays a crucial role in the performance of these 30-meter long hybrid tugboats by supplying advanced battery systems. These battery systems enable the tugboats to operate efficiently and sustainably. Corvus Energy CEO, Fredrik Witte affirmed that the battery systems significantly decrease vessel emissions, supporting the Authority’s goal of achieving net-zero GHG emissions by 2050.

Finally, one last notable project that has yet to come to fruition is Svitzer’s methanol hybrid fuel cell tug. The company is designing the world’s first methanol hybrid fuel cell tug, aiming to combine the environmental benefits of methanol with the efficiency of fuel cells. This new hybrid electric tugboat is expected to enter operations in 2025, helping the port of Gothenburg to fulfil the ambitious target to reduce shipping emissions within the port area by 70% by 2030.

Comparing Conventional and Hybrid Propulsion Systems in Maritime Applications

Green hybrid tugboat - Comparison of a conventional system and a hybrid electric system
Comparison of a conventional system and a hybrid electric system
Insights:

The graphic illustrates a comparison between conventional propulsion systems and hybrid propulsion systems for hybrid tugboat in maritime applications. The conventional system, depicted in the top diagram, consists of a main engine connected to a shaft, Zpeller, and an auxiliary generator to manage the hotel load. The hybrid system, shown in the bottom diagram, integrates a motor/generator and a battery into the propulsion chain. This system allows for a smaller main engine, with the motor/generator and battery providing additional power as needed. The auxiliary generator remains in place to handle the hotel load, while the hybrid configuration enhances efficiency and reduces emissions by optimizing the power sources.

 

The Challenges of adopting green hybrid tugs

The promises of adopting green hybrid tugboat are many, but there are also some downsides, both when it comes to hybrid electric tugboats which rely on batteries, and when the hybrids rely on non-conventional fuels. 

The very first downside, for all hybrid tugboats, is the need to invest on two propulsion systems and their maintenance. In the case of electric hybrid systems, for example, these have higher start-up costs due to the expensive Battery Energy Storage Systems. Additionally, crew training for these highly automated systems can be costly. And the need for significant space to install batteries also adds to the vessel’s weight.

But, when it comes to relying on alternative fuels, instead, these might not be as green as expected. If Hydrotug 1 or the Japanese ammonia-fueled tugboat are taken in examination, it is arguable that their reliability on hydrogen is a downside because this is very energy-intensive to produce and difficult to transport. Despite this, hydrogen produces no emissions when burned, and it can even be produced in an entirely green way, through sustainable processes or renewable resources. This shows the importance of assessing “well-to-wake” and “tank-to-wake” emissions to understand the environmental impact of fuels when evaluating the performance of a hybrid tugboat.

But, apart from the disadvantages, the benefits of hybrid tugboats are the primary reasons why they are attracting owners and operators globally. And with thorough data analysis, research, and development, companies will be able to elevate the hybrid sector to its full potential.

Operational Profiles and Data Utilization

Hybrid propulsion technology has been deployed on tugboats to reduce emissions and enhance the efficiency of operation. The operational profile of a vessel plays a significant role in determining the efficiency and emissions of hybrid propulsion systems. By analyzing and optimizing these profiles, maritime operators can improve fuel efficiency and reduce emissions. Continuous monitoring and optimization of operational profiles are vital in achieving the full potential of hybrid tugboats. Doing this in the right way results in an improved performance of the ship in terms of fuel consumption, emission regulation, operational flexibility, and reduced noise and vibration.

Operational efficiency of hybrid electric tugboats can be improved, for example, by implementing power management strategies that are able to optimize the running hours of the engines to run them at optimum efficiency. Or also, by knowing when to change the primary source of energy for the propulsion between high and low-speed operations.

Conclusion - A Greener Future with Hybrid Propulsion

In conclusion, the potential of hybrid propulsion in reducing emissions and improving efficiency is immense. These green hybrid tugs have demonstrated benefits in lowering fuel consumption, cutting emissions, and improving operational performance. By integrating alternative fuels, advanced battery systems, and data analytics, hybrid tugboats can significantly lower their environmental impact while maintaining high operational efficiency. 

Continuous innovation and effective data utilization are essential in maintaining and enhancing their performance. As the maritime sector increasingly pursues carbon reduction initiatives, the number of hybrid tugboats worldwide is projected to grow significantly. The maritime industry is poised for a greener future, driven by the adoption of hybrid propulsion technologies.

Achieve Sustainability with LionRock’s Waste Free Shipping Service

LionRock offers advanced solutions for maritime operations. The “Waste Free Shipping” service is designed to achieve lower emissions and eliminate waste. This service ensures that the tugboats operate sustainably, adhering to the highest environmental standards, by keeping their operational profile in check. LionRock’s Waste Free Shipping leverages cutting-edge technologies and comprehensive waste management strategies to minimize the environmental footprint of maritime operations.

Partnering with LionRock for Waste Free Shipping can help companies achieve sustainability and operational excellence. By leveraging LionRock’s expertise and innovative solutions, maritime operators can lead the way in creating a greener future.

Join us in transforming the maritime industry and making a positive impact on the environment. For more information on how LionRock can help you achieve waste-free and efficient maritime operations, visit LionRock Maritime’s Waste Free Shipping.

Frequently Asked Questions

What are the main benefits of using hybrid tugboats in the maritime industry?

Hybrid tugboats offer several benefits, primarily driven by their integration of advanced battery systems and alternative fuels. The alternative fuels significantly reduce emissions, contributing to a greener maritime industry. These vessels also improve operational efficiency at different loads, enhance ship handling, reduce maintenance and reduce noise and vibration levels, making them a preferred choice for sustainable maritime operations.

What challenges are associated with adopting green hybrid tugs?

Despite their advantages, green hybrid tugs require, foremost, the capability to invest on and maintain two propulsion systems. In the case of hybrid electric tugboats, this also means higher start-up costs due to expensive Battery Energy Storage Systems and the need for specialized crew training. Additionally, space requirements for battery installations increase the vessel's weight. There are also concerns about the environmental impact and production complexities of alternative fuels used in green hybrid tugboats, such as hydrogen, which is energy-intensive to produce and difficult to transport.

How do operational profiles and data utilization enhance the efficiency of hybrid electric tugboats?

The efficiency of hybrid electric tugboats can be significantly enhanced by analyzing and optimizing their operational profiles. By continuously monitoring these profiles, maritime operators can implement power management strategies that optimize engine running hours and switch energy sources based on operational demands. This approach helps in reducing fuel consumption and emissions, thus improving the overall performance of green hybrid tugs.

What is the future outlook for hybrid tugboats in the maritime sector?

The future outlook for hybrid tugboats in the maritime sector is promising. As the industry increasingly adopts carbon reduction initiatives, the number of hybrid electric tugboats is expected to grow. Continuous innovation, integration of alternative fuels, and advanced data analytics will drive the development and deployment of green hybrid tugs, paving the way for a more sustainable and environmentally friendly maritime industry.

Related Topics

IMO Decarbonization on Maritime Emissions: Tugboat Compliance & Solutions

New Tugboat Software: A Fuel Consumption Monitoring Alternative | 2024

Efficient Tugboat Fleet Management Analytics: Implementing a Tugboat Tracker System

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Green Ports: Decarbonizing Ports through Data and make Ports more efficient

Author: Albert Moritz

Port decarbonization - Green ports - Shipping carbon footprint | LionRock Maritime
Image by 12019 from Pixabay

Green Ports: Decarbonizing Ports through Data


A look into the maritime shipping industry, the environmental effect of inefficient ports, and how maritime companies use technology to combat this issue.

The International Maritime Organization (IMO) aims to have net-zero shipping emissions in under three decades. Yet, the global shipping industry produces over a gigaton of greenhouse gasses every year. While barriers to advancements for this goal are in no short supply, companies such as Techbinder and LionRock Maritime are already using data to reduce carbon waste.

Maritime Shipping as a Greenhouse Gas Contributor

According to the IMO, maritime shipping accounts for nearly 3% of all global greenhouse gas emissions. This is about 1.2 gigatons of human produced gasses, of which approximately 800–850 tons are carbon dioxide. Left the way it is, without policy or technological intervention, all shipping emissions are predicted to increase by 16% before 2030. The sheer volume of greenhouse gasses that comprise the shipping carbon footprint is a aggravating the climate problem and in need of solutions.  Ports are a primary cause of maritime shipping emissions, contributing to 2% of all greenhouse gas emissions, worldwide. Ports play a large, and essential, role in the shipping industry. This is why port decarbonization is a key component of lowering maritime emissions and creating a greener industry.
LionRock Tugboat Fuel Calculator - Port decarbonization
LionRock Tugboat Fuel Calculator - Port decarbonization

Port Decarbonization: a Closer Look

Port decarbonization is the process of eliminating environmental impact associated with activities in port, such as tugboat operations, and cargo handling. A key part of this is reducing carbon emissions. The goal is to transition ports to more sustainable and eco-friendly practices, for both local and global communities.

Workboats form a critical part in port decarbonization: A 2002 study in British Colombia and Washington State showed that 28% of port CO2 emissions were from harbor craft and tugboats, making them the second-largest port CO2 contributor, behind container ships.

Each step towards port decarbonization is a step towards a shared environmental goal. There are several strategies to achieve this. They include the use of renewable energy sources, more efficient technologies, and improved logistics to minimize emissions and environmental harm. Each solution comes with its own limitations, making some advancements easier to adopt than others. However, one major tactic to reduce emissions, optimizing operations through the use of data, is already in use.

 


You can schedule a meeting with our representatives and get a consultation on how you can achieve a better operational efficiency: Schedule a Call now.

Technology for the Environment

New technology helps ships pollute less. By using data, shipping companies can learn important things about how their ship’s operation. From granular data about ship’s maneuvering to the utilization and performance of its machinery. The insights gained can help see blind spots and areas for improvement.

While there are similarities between ship types, each of those also has unique characters that requires a tailored optimization approach. While route optimization is (still) considered a major source of fuel optimization and emission reduction for long haul ships to decrease emissions, it is probably less relevant for harbor tugboats. Harbor Tugboats typically operate over relatively short distances within ports, meaning they have less extensive routes to optimize.

Reducing the Carbon Footprint of Tugboats

Today, it is difficult to accurately measure and thereby help decrease the fuel consumption of tugboats. Tugs are designed for a wide range of operations and similarly have a wide spread in their consumption range. Fuel consumption meters, widely used in other shipping segments, have found low adoption in the tugboat sector. The high investment cost as well as the installation from a barrier. Not only are these units expensive, they are also time-consuming to install.

We wanted to address the challenges and promises of accurately measuring fuel consumption without having to rely on expensive fuel consumption meters. In doing so, trying to make data more accessible to tugboat owners, thereby contributing to the goals of port decarbonization and the creation of green ports. LionRock Maritime’s expertise is tug operations data. Applying machine learning and contextual data analysis, LionRock explored correlations between tugboat speeds, power variations, and the unique characteristics of the vessels they assisted, aiming to reduce the shipping carbon footprint. While the direct correlation between tugboat speed and power during light sailing is strong, large variances occur during vessel assistance. LionRock’s innovative models using contextual and engine data separately showed promising results. However, the fusion of these models provided strong predictions of fuel consumption per job, marking a significant breakthrough in accurately estimating tugboat fuel usage, thus contributing to port decarbonization efforts and the reduction of the shipping carbon footprint.

An obstacle to obtaining RPM data lies in its collection from the tug’s engine, necessitating an installation process. To streamline this installation process and ensure the tug remains in operation, LionRock partnered with Techbinder. A tech scale-up from the Netherlands with backing from Schneider Electric that produces and installs industrial grade and cyber-secure data-loggers. LionRock has built a set of software that decodes the data and understands the tugboat operations, helping to turn data into actionable advice. By combining hardware and software, this joint endeavor promises a low-cost solution for assessing tugboat fuel consumption without disrupting tugboat operations, thus advancing the vision of green ports.

The Future of Maritime Shipping

The future of the shipping industry is a low carbon footprint. Port decarbonization is an essential part of this process. As awareness and prevalence of environmental issues continues to grow, ports will have to level up to reduce their environmental impact. The International Maritime Organization has already set net-zero emission goals by 2050, for the entirety of international shipping. This is in alignment with the Paris Agreement, which calls for immediate emission reductions as well as net-zero greenhouse gas waste no later than 2050. In some countries, emissions cost the environment and businesses. The European Union has already instrumented fees for excessive CO2 emissions, adding financial pressure to reduce waste. 

 

Read here more about the IMO Decarbonization on Maritime Emissions

 

Existing services, such as LionRock’s “Waste Free Shipping” offer a way for companies to save money while contributing to more sustainable maritime shipping. By tracking port traffic and reducing fuel waste, organizations save time and money alongside carbon dioxide waste that would have entered the atmosphere. Recent innovations, such as Techbinder and LionRock Maritime’s Smart Vessel Optimizer, aim to streamline the measurement of carbon emissions, making it accessible and actionable. As more companies use data and technological advancements, the shipping industry has the potential to become greener. Technology offers the solution to decarbonize ports in a smart way, by saving resources and lowering emissions. This trend will benefit everyone, but is especially good for the planet.

Book a consultation to accelerate your business’s decarbonization objectives.

As the maritime shipping industry strives to achieve net-zero emissions, the importance of port decarbonization cannot be overstated. Companies like Techbinder and LionRock Maritime are leading the charge, leveraging data and technology to reduce fuel inefficiencies. With innovative solutions, we save money and contribute to a cleaner, greener future for all. Join us in the journey towards more sustainable maritime shipping. Schedule a demo now to make your shipping or towage business more eco-friendly.

Frequently Asked Questions

What is the environmental impact of maritime shipping?

According to the IMO, maritime shipping accounts for nearly 3% of all global greenhouse gas emissions. This is approximately 1.2 gigatons of human produced gasses, such as carbon dioxide. Left the way it is, without policy or technological intervention, all shipping emissions are predicted to increase by 16% before 2030. The sheer volume of greenhouse gasses that comprise the shipping carbon footprint is a climate problem, but also an area in need of climate solutions.

How can the shipping industry lower emissions?

Technological advancements can help lower shipping industry emissions. However, some of these advances are more accessible than others. Most shipping vessels currently require fossil fuels to operate. While developing fossil-free alternatives is necessary, it is a slow work in process. Another method of carbon-saving that is more readily implemented is through operational improvements. A key factor in that are taken by ports. Adopting methods that use market insights and data to make shipping as efficient as possible can significantly reduce carbon waste.

What is port decarbonization, and why is it important for the maritime shipping industry?

Port decarbonization refers to the process of reducing environmental impact associated with port activities, such as tugboat operations and cargo handling, by minimizing (and eliminating) carbon emissions. It is crucial for the maritime shipping industry because ports are significant contributors to greenhouse gas emissions, accounting for 2% of global emissions. Decarbonizing ports not only helps in lowering maritime emissions but also fosters sustainability and eco-friendly practices, benefiting both local communities and the planet at large.

What challenges are associated with implementing data-driven solutions for port decarbonization and the creation of green ports?

One challenge lies in obtaining accurate data, particularly about the efficient use of port assets, but also the exchange of information between stakeholders in the port call. However, collaborations between companies like LionRock Maritime and Techbinder aim to streamline data collection processes while minimizing disruptions. Additionally, there's a need to tailor solutions to fit the diverse needs of different types of ships, as technology that works for cargo ships might not be suitable for tugboats or carriers. Ensuring that these data-driven solutions contribute not only to port decarbonization but also to the creation of green ports involves overcoming technical, operational, and logistical challenges to implement sustainable practices effectively.

Related Topics

Tugboat Industry Growth and Strategies: Navigating Emerging Markets with Data Insights

IMO Decarbonization on Maritime Emissions: Tugboat Compliance & Solutions

References

  1. Maritime Shipping- The International Council on Clean Transportation (2021)

  2. A review of the port carbon emission sources and related emission reduction technical measures- Science Direct (2023)

  3. Classifying maritime port emissions – Science Direct (2023)

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Value of tugboat speed optimization when using alternative fuels

Is tugboat speed optimization still relevant when using alternative marine fuels?

Tugboat operators are (gradually) transitioning to using alternative marine fuels than traditional diesel. Propelled by a call for urgent action to avoid climate change, the maritime industry as a whole is evaluating various options as a source of marine fuel. At LionRock we often get the question whether speed reduction to ECO speed for tugboats is still relevant once this transition to alternative fuels has been made in full. We asked 4 students (Arend Bijleveld, Benthe Kleinbekman, Daniel Mertens en Ante Simic) from the Rotterdam Mainport Institute to help us evaluate this question for a few of the main alternative fuels. We asked them to look at it from the view of cost, GHG emissions and practical considerations such as energy storage constraints. Here their conclusions for Hydrogen tugs, full electric tugs, Methanol based propulsion and finally LNG powered tugs.

Value of tugboat speed optimization when using alternative fuels

Hydrogen

When looking purely at a Mega Joule per kilogram value, hydrogen comes out on top. With an energy density almost three times that of diesel, this would mean that much less hydrogen would be needed to do the same work. In addition, the carbon emissions of hydrogen, provided it is so-called “green hydrogen”, are zero. Theoretically, the emission of nitrogen oxides should also be zero, but in practice a certain amount is a certain amount is emitted anyway. The downside, however, is that storing hydrogen presents many challenges; in order to store it compactly in liquid form it must be stored under high pressure or extremely low temperatures. Furthermore, the cost of hydrogen is currently about two to six times the price of diesel. When the costs of hydrogen and diesel are compared with their energy densities, it can be concluded that saving is still relevant from a financial point of view. A major additional driver for speed optimization is the storage constraint.

Full electric

Sailing electrically means that the electric motors are powered by a battery pack that is charged from the shore when the tug is alongside. When using the energy from the battery packs, no emissions are released and an electric ship can easily sail within the future regulations. How sustainable it ultimately is, however, remains to be seen as it depends on how the electricity was previously generated. The cost will be somewhat lower than running on diesel, and therefore there the financial need will be low. However, again, a major driver for speed optimization is the limited energy storage capacity in batteries.

Methanol

Methanol has an energy density value about half that of diesel. In addition to the fact that the energy density of methanol is lower, the volumetric density is also lower compared to diesel. The combustion of methanol releases a similar amount of carbon dioxide as with diesel. However, the emission of nitrogen and sulfur oxides is drastically lower. As a result, methanol-fueled ships will meet future emissions regulations. One disadvantage of methanol is that it requires a larger fuel tank for the same endurance of the ship. Hence taking up more space on board. With the expected prices for methanol in the future, it is possible that sailing on methanol will become cheaper than sailing on diesel.

LNG

LNG possesses the highest energy density of the fuels discussed after hydrogen. In comparison with diesel, LNG has a higher energy density but a lower volumetric density. Storage of LNG must also take place at low temperatures because otherwise it would evaporate. LNG requires a number of modifications to the ship, the main ones being larger fuel tanks and a new fuel tanks and a new or rebuilt engine. The cost of one kilo of LNG is comparable to that of a kilo of diesel. Because the energy density is somewhat higher, the cost of LNG are slightly lower, the margins on fuel savings are smaller compared to diesel. However burning LNG also emits N20 which is a greenhouse gas 265 times more potent than CO2 so operators do well by keeping speeds as ECO efficient as possible.

Slowsteaming remains relevant. Contact us

From this review that the need for speed optimization remains relevant. Depending on the type of fuel used, the driver for speed optimization becomes different. It might be cost, the emissions or simply the energy storage space constraint.

References

RMIPIP01 – ADVIESRAPPORT by Arend Bijleveld, Benthe Kleinbekman, Daniel Mertens en Ante Simic