Sustainable fuels gather momentum

While the adoption of alternative fuels has been slower than many people would like, in the last few years progress has been made on all fronts and a number of significant milestones have been reached. This has been at all levels; technological, perceptual and financial. As of 2023, the rollout of sustainable propulsion and power generation across a wide range of vessel types is now within reach as the technology has advanced and a number of bottlenecks have been eased or removed altogether.

It's when, not if

One major advance is that almost all vessel owners and operators looking to buy new vessels are bringing up sustainable fuels early on in the conversation. With new assets having a lifetime of around 30 years, they fully appreciate that they need to prepare now for the combination of regulatory activity, changes in social attitudes and advances in technology that will make alternative fuels the logical choice. It is also now widely accepted that there will not be just one solution that suits everyone. Different operational profiles will suit different vessel types, based on the twin criteria of range and performance.

“Everyone that we speak to about newbuilds asks about sustainable fuels,” says Mijndert Wiesenekker, Sales Director Benelux at Damen Shipyards Group. “It is accepted that over the long term they will be the most economical option. This is supported by much better availability of finance for sustainable investments and a reluctance to invest in carbon intensive solutions that may end up being more expensive to operate and so rapidly lose their value.”

Gathering momentum

The increase in the momentum for change has come from various quarters, not least from the availability of finance and the progressive tightening of EU and IMO directives, but also from technological advances and the prospect of smaller vessels being included in the European emissions trading system. The current cut-off for vessels is no less than 5000 GT, but discussions are already underway about taking it down to 500 GT, and possibly 400 GT thereafter. Not all vessel types are included in the programme, however initiatives like these will ensure that carbon intensive solutions will no longer be attractive.

Government-ownership has been another positive factor, with local and national bodies often able to consider wider criteria in their purchase decisions than just profit. The harbour tug sector has benefited from this with a number of hybrid models now demonstrating their capabilities around Europe and Damen’s allelectric RSD-E Tug 2513 at work in Auckland, New Zealand.

This assistance and the subsequent demand has brought the price of sustainable harbour tugs down to near their conventional equivalents over their projected 30-year lifetime.

The alternatives

• METHANOL is seen as a good, all-round fuel for a wide range of vessels. Among other advantages it can be burned in internal combustion engines, its main by-products being heat and water, and as it is a liquid it is easier to store than some of the alternatives. Although methanol itself is energy-intensive to produce, it does have momentum behind it with methanol engines already in advanced stages of development. Orders for more than 100 methanolpowered container ships have been placed.

• BIO-DIESEL is increasingly seen as the sustainable, low-emission fuel of the future for very energy intensive vessels, with its high energy density and engines that are already in their third generation. At present it is generally blended with conventional diesel in varying proportions. However, Damen is already working on an order for a Combi Freighter 3800 that will run on 100% biodiesel (FAME).

• AMMONIA is another ongoing contender for powering long distance vessels via combustion engines, with its only byproducts being water and nitrogen. However its production is energy intensive and so to be truly green its producers will require access to large amounts of surplus sustainable energy. For the types of vessels that Damen builds, its toxicity is also a challenge.

• BATTERIES that are charged from shoreside facilities or other sources that draw on renewable energy, are now a reality for harbour tugs, ferries and other inshore vessel types including luxury yachts. For battery powered vessels, getting the right battery technology is very important. Presently, while they can deliver high performance for short periods, the race is on to perfect batteries that can enable extended periods of operations and also have lifetimes equal to the vessels in which they are fitted.

• HYDROGEN has had much publicity as a potential fuel for all sorts of applications with the only by-product of its conversion into energy being water. However production, storage and safe combustion at scale plus its low energy density continues to present challenges as does its production, which also requires large amounts of energy. A number of hydrogen-powered vessels are already operational in niche applications such as ferries and inland waterway vessels.

• LNG, once seen as the fuel of the future, is now regarded as more of a transitional solution Not only is it a hydrocarbon with harmful byproducts, it also has to be stored at high pressure and at -163 degrees centigrade, which introduces additional costs as well as safety and technical issues. Together these factors mean that in the long term it does not have a future as a mainstream source of energy for typical Damen ships.

Concordia Damen is currently building a 135-metre, 3,700 tonne inland waterway barge for Lenten Scheepvaart that will be powered by a 320 kW hydrogen fuel cell supplying 36 Ebusco batteries with a total capacity of 1100 kWh. These batteries will power twin 600 kW PMM E-motors. The vessel is being built under the WEVA project which is intended to demonstrate the feasibility of hydrogenpowered, zero emission vessels in the near future.

Future fuels roadmap

For all alternative fuels the benchmark is the liquid hydrocarbons currently in use, which have an exceptional energy density along with being easy to store and transport. To replace hydrocarbons, trade-offs will need to be made and this will be best done with a range of potentially viable choices available. For example, methanol has many of the same properties, but ammonia will likely be cheaper. Having a number of fuels being developed and optimised over time extends the odds that solutions will be available to all, depending on their operational and financial goals.

Making the transition

While enthusiasm for making the transition to low-emission propulsion is growing, with clients lining up to be early adopters, the engines required are still under development and costs of the fuels are not yet commercially viable.

Meanwhile the development of methanol engines is proceeding but they are not yet available in commercial quantities, and green methanol has yet to achieve large-scale production. Damen maintains close contact with the OEMs with information flowing freely both ways. For electrical propulsion, the lack of availability of the necessary expertise to design, install and commission the systems that will control and monitor the new technology; software developers, automation experts and others, is a constraint for the shipbuilders.

“There’s a long way to go, but given recent progress in closing the performance gap between fossil fuels and advances in battery technology we feel optimistic about the road ahead,” says Mijndert. “The challenges of each fuel type still need to be fully explained and acceptance won over, but the trend is in the right direction. We feel that it is better to have a good solution rather than to compete to be the first. And at Damen our focus on standardised vessels enables us to justify investing in finding the right solutions for everyone as we know that we will be building them in series. Our policy is to take the time to get it right, and then act fast. One thing is for sure. It will end up being a mix of solutions. There will be no one-size-fits all, and that’s as it should be.”