Could bubbles be the missing piece to unlock maritime decarbonisation?

What are Air Lubrication Systems (ALS)?

Air lubrication is the process of injecting micro air bubbles close to the surface of a ship as it sails. Much like the humble Post-it Note and the cardiac pacemaker, air lubrication began life as a right engineering solution to the wrong problem. Historically, air lubrication was a naval invention adopted to dampen engine room noise signatures from enemy subsurface sonar detection. Little did the inventors appreciate that those tiny bubbles blanketing the external surface of the ship’s hull, were also profoundly impacting the hydrodynamic frictional resistance of the vessel as it moved through the water. Fast forward a few decades; whilst the concept has survived, its intended application has shifted. Ship owners are now realising the measurable fuel and emission saving benefits from the application of air lubrication systems (ALS). Additionally, as there is no dominant design for ALS it continues to be a prime target for innovative disruption. Like much of the best engineering innovations, the beauty is in its simplicity. With ever developing innovations in the industry, there are ever more advanced breakthroughs in ALS solutions, promising greater fuel savings, lower total cost of ownership and easier installation and ongoing system maintenance.

With ALS, air is injected through the bottom of the ship to be captured within the ship’s boundary layer (a thin layer of water that interacts with the vessel due to surface friction). This serves two purposes; the first is to reduce the average viscosity of the fluid in contact with the ship, and the second is to modify the turbulence of the fluid within the boundary layer. Together this significantly reduces the overall friction the vessel experiences and therefore reduces the required engine power to push the ship forward at the desired speed. This is great for the owner, but even more so for the environment.

As it stands, shipping has an enormous environmental footprint. Whilst on a tonne per mile basis shipping is by far the most efficient method of transporting the close to 90% of world trade, ships annually emit a high level of carbon on par with Germany. To put this into context, the energy required to power shipping for one year, would power New York City for over 60 years. Looking forward, with population growth and the economic prosperity of developing economies, our global buying habits are set to exponentially increase the demand for shipping – and its environmental emissions as an unfortunate by-product.

Luckily, there is a hive of activity in place to decarbonise shipping, both on the regulatory and innovation fronts. Aside from air lubrication, specialist energy saving devices such as flow modifiers, propeller boss cap fins, wind assisted technologies and rotor sails, are also in development or available on the market. Fiscal pressures driven by excessive fuel prices, twinned with the regulatory incentives to maintain compliance, has boosted interest in what was previously considered a purely ‘novel’ technology category.

Understanding the "maritime puzzle"

If there is increased interest in energy saving technology, why are we not seeing mass implementation across the world shipping fleet? And why is energy efficiency not the shipping industries key tool of choice to drive the maritime agenda both further and faster?

The answers to these questions are nuanced and many. However, in short, shipping as an industry is highly attuned to mitigating risk. This approach has proven very successful over the years in mitigating accidents and injury on ships, however we must ask ourselves, is this generalised risk adversity serving our planet as we enter an ever-escalating climate crisis that warrants quick, entrepreneurial, and sometimes risky investment decisions? Can shipping adapt quickly enough to realise true maritime decarbonisation in time?

To answer these questions, we must consider shipping’s ‘rules of the game.’ Owners like quick pay back on proven technologies, making innovation leaps for a next generation technology extremely difficult and time consuming. Many industry leaders fail to recognise the true value and importance of energy saving technologies as a key piece of the maritime decarbonisation puzzle and instead dismiss them as not solving the issue in its totality – so, why bother? Whilst it is true that any one energy efficiency technology cannot completely decarbonise the total emission of a ship, a suite of solutions working in harmony will go a long way to achieving this objective. Many are conflicted with contradictory ideas; knowing that viable carbon abating solutions are ready but choose to focus solely on the future implementation of zero carbon fuels such as Hydrogen and Ammonia – an area of work that is extremely well funded and way over subscribed in terms of resource allocation. This blinkered view does not consider the ‘time value of maritime decarbonisation’ and is akin to burying one’s head in the sand as progress towards maritime decarbonisation slows - with every passing year another close to one billion tonnes of CO2 is emitted into our environment.

Fortunately, certain maritime leaders such as Rio Tinto (through their maritime pioneer portal) and Maersk (through their foundations start up donation to the centre for zero carbon shipping) are taking a two-pronged approach. Effecting change now with the demonstration and implementation of both proven and next generation energy efficiency technologies, whilst supporting actions for tomorrow by expediting the widespread roll out of zero carbon fuelled vessels and providing shipping test beds for demonstrations. They do this as they appreciate that energy efficiency and carbon abatement are intrinsically linked and cannot be defined by an and – or mindset. They fundamentally appreciate that the widespread implementation of energy saving technologies will not only enable, but also expedite the mass roll out of the zero carbon fuels given their inherent challenges of energy density and onboard storage constraints. This sort of environmental leadership is crucial as it enables next generation, blue sky, maritime solutions to see the light of day, whilst also sending a strong signal to the rest of the market to act rapidly with a significantly diminished risk on investment.