Myth busting

As we present our research at conferences, meetings and events we come across common objections and arguments against the use of green ammonia as a maritime fuel. This page outlines some of these objections and provides a fact-based response to each. We call it myth busting.

If you have a comment or an ‘objection’ you think we should include, contact us and we’ll do our best to address it.

Whilst it must be acknowledged that producing ammonia using electrolysers is an energy intensive process, there are many other factors that also contribute to the energy intensity of fuels.

Storage: ammonia has significantly lower storage costs and volumetric requirements than hydrogen as it has higher energy density and does not need to be stored at cryogenic temperatures. Methanol has a significantly higher energy density than ammonia and hydrogen, and whilst it is less energy intensive to store, bio-methanol requires greater land mass for production.

Transportation: whilst ammonia has higher volumetric demands than existing marine fuel oils, it can also be made in-situ reducing the energy requirements for recovery, storage and transportation that is incurred by fossil fuels that are only found in specific global locations. This also has implications for both energy sovereignty and security. Ammonia is more energy dense than hydrogen and it is likely that ammonia will be used as a solution to hydrogen’s energy density and transportation challenges.

In short, the main contributing factors to green ammonia’s current costs are the cost of renewable energy and the current scale of production; these will reduce with renewable energy market expansion and production economies of scale and learning. Across the TCO, there are key areas where, in the long term, green ammonia will be cost-effective.

Market economics: when well-to-wake costs are factored, ammonia is cost competitive, and these risks will continue to reduce with declining renewable energy prices. Due to the finite availability of fossil fuels, there will be ongoing price volatility within international markets, which are not only dependent on supply but political aspects also. As such, it can be evidenced that ammonia’s cost comparison will improve over time with the ability to effectively forecast – the same cannot be said for fossil fuels. Ammonia, as a highly traded chemical, has a better-established supply chain than hydrogen, indicating that economies of scale will likely be achieved faster.

Environmental legislation: another aspect of this cost and intensity measurement is whether carbon or any greenhouse gas emissions are tolerable – increasingly these emissions will be taxed due to their undesirable effects. As a result, fuels that produce emissions will be taxed heavily, increasing their cost of use.

Purchase price: ammonia as a fuel will be introduced on vessels in two ways – retrofit or purchasing an ammonia-ready engine. It is thought that initially retrofit will be the most cost-effective solution at between 250 – 650 euro per kW of engine power, newer vessels with electronically controlled engines will generally be easier to retrofit. The price of ammonia-ready engines will be initially higher before market economies, but this will be balanced by better fuel efficiency, and reduced maintenance and operational costs. The costs for retrofitting hydrogen are comparable to ammonia.

Operating costs: the ammonia supply chain is well established but will require expansion to have an operational maritime solution. There is the potential to adapt existing LPG infrastructure for ammonia storage and bunkering, which means lower initial costs and hurdles including local planning systems. Compared to hydrogen, ammonia will have lower storage costs as it requires less space and energy; further, the infrastructure for hydrogen is in the early stages of development and will likely factor ammonia as a part of the solution to storage and transportation challenges. Biofuels can be used within existing infrastructure, but sustainability of feedstock can be a concern.

Training costs: these costs are foreseen for all new fuels, due to safety concerns. However, ammonia is frequently present on vessels for functions such as cooling amongst others, meaning that there is an existing cohort of ammonia-trained crew.

Ammonia is the second-most produced chemical in the world, meaning that there are well established guidelines for its safe handling and transportation. Ammonia is present on most vessels and is frequently transported by sea, meaning that there are many ammonia-trained vessel crew.

Extensive information is available on the types of materials and processes that are safe for the storage and piping of ammonia. The novelty of the application is in combusting ammonia to use as fuel. The danger of ammonia rests in its toxicity, however, this is easily detectable at low concentrations due to its unique scent. There are extensive labour regulations that address the acceptable level of ammonia within a working environment, and legislation is now addressing what would happen in the event of an emergency situation.

The need for this legislation is not unique to ammonia and is required for all other available fuels. Indeed, some gas-based fuels have had additives introduced to allow for early scent-based detection, much like that which is inherent to ammonia.

Ammonia is the second most commercialised chemical on the planet. It is used daily and is distributed worldwide, which means that ammonia transportation is a very mature field with robust guidelines in place to ensure its safe handling. However, incidents do occur, but these mainly happen in countries where the regulations are loose and largely disregarded. In Europe, North America and Japan, the number of deaths over the last 50 years is less than 200.

Additionally, the pungent smell of ammonia at concentrations (5ppm) is much lower than exposure limits (35ppm TWA – time weighted average) and can act as a clear early warning for onboard personnel to enact the safety protocols to curtail any leaks. The worst case would be for an uncontrollable crash, where the ammonia could be suddenly released. Thus, other methods for ammonia storage (e.g. material composites based on boron or magnesium, or more robust confinement solutions) could be attempted to mitigate this problem.

While it is true that the current infrastructure for ammonia is not as extensive compared with that for conventional fuels, there are significant ammonia production, transport and storage facilities around the world.  In addition, investments are being made worldwide to adapt existing and create new facilities for the use of ammonia as a fuel.

Some examples of ammonia infrastructure development include ammonia terminal projects, such as the plans for an ammonia import terminal in Hamburg and the development of a large-scale green ammonia plant in the Salalah Free Zone in Oman. More can be read in World’s largest green ammonia projects could clean up half the market (newatlas.com). Further, there is ample expertise in creating this additional infrastructure compared to cases like hydrogen where many components are being developed for their use under new, unknown regimes.

The formation of NOx depends heavily on factors such as combustion design, fuel–air mixing and aftertreatment systems. Research from the MariNH3 project has demonstrated that with dedicated ammonia-engine designs and optimised control strategies, engine-out NOx emissions can be reduced by up to 60% compared to typical diesel engines.

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There are several fishing vessels that use ammonia-based refrigeration systems in operation today, where ammonia as a working fluid, is transferred around the vessel in addition to being compressed, heated and cooled on board the vessel.

Furthermore, fuel circuits can be made to ensure safety with solutions like double walled/jacketed pipes, leak detectors and water mist containments etc, many of which are already being employed for low flash point fuels like LNG as per the International Maritime Organisation (IMO) IGF code. The IMO has recently amended this IGF code to enable the use of ammonia as a fuel. However, further research and development are required to develop failsafe fuel handling, operation and maintenance processes which would in turn reduce the probability of a leakage due to the toxicity of ammonia.

One emerging solution to overcome slow combustion is the use of onboard ammonia cracking, which partially decomposes ammonia into hydrogen. This hydrogen-enriched fuel blend burns more readily, enhancing ignition stability without requiring a separate fuel supply (some of which can be buffered).

Work in MariNH3 has shown that only 20-30% hydrogen by energy is required, which also helps control engine emission.

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Ammonia is a DeNOxing agent in power plants and chemical processes. Recent work on the use of ammonia at high fuel/air ratios shows that unburned ammonia can mitigate all NOx emissions from the flue gases. Some remnants of ammonia remain.

These tests have been conducted for constant pressure conditions (burners, furnaces and gas turbines). However, we have not found yet the right “combination” to achieve negligible NOx in internal combustion engines due to their transient nature. Current research is mainly focused on this.

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