Although shipping is generally seen as a fuel efficient, and hence ‘carbon friendly’, mode of transportation, the shipping industry is facing increasing pressure from regulators to improve its environmental performance.
Currently, the levels of sulphur oxide (SOx) emissions from the use of normal high sulphur heavy fuel are significant, and feasible solutions should be adopted to reduce them. That said, it remains to be seen whether this will be achieved through abatement technology or a switch to low sulphur fuels.
Nitrogen oxide (NOx) emissions are also likely to attract more regulatory focus. These gaseous emissions will probably be regarded more as a global pollution issue rather than a local problem due to their slow depletion rates, which in turn links them to long distance transportation.
NOx emissions from burning heavy fuel oil in diesel engines are mainly the result of high combustion temperatures in such engines and the relatively long reaction period during the combustion process.
While the SOx issue can possibly be resolved through improved production technology for marine fuels at the refinery, NOx emissions will have to be addressed on board the vessel unless new fuel types such as LNG are introduced.
In addition to NOx-reducing modifications to the engine, various NOx abatement technologies have been developed and tested; for example, SCR, HAM, SAM, DWI, FWE and EGR(*). Whichever solution is chosen for the onboard reduction of NOx (and SOx) emissions, one concern is the added operational complexity and the need for skilled personnel to maintain the equipment. The crew will also have to provide continuous documentation to the authorities to prove that the equipment’s efficiency is maintained. This is a challenge.
When it comes to CO2 emissions, these are directly proportional to the amount of fossil fuel being consumed. Since liquid petroleum fuel – whether with a low sulphur content or otherwise – is likely to remain the dominant energy source for marine propulsion in the foreseeable future, effective energy management and optimisation will be the only practical way to reduce CO2 emissions. This can be achieved by introducing improved technologies such as new hull shapes and designs for less resistance, building bigger ships, better hull and propeller surface treatment and coating, improved propulsion and engine designs, and heat recovery systems that optimise energy utilisation.
Apart from technological improvements, significant gains can be achieved through more efficient operational patterns that reduce fuel consumption. Recent studies have suggested that the application of available tools for voyage planning, weather routing, adjustment of auto-pilot systems and optimised use of onboard energy consumers may contribute to fuel savings in the range of 5–12 per cent without the need for any design or structural modifications.
Further, substantial savings can be achieved by reducing speed. The potential for savings through slow steaming is dramatic for certain ship types, particularly ships like container vessels that normally operate at high speeds. However, various consequences must be taken into account, including logistical implications, time charter contract terms, port infrastructures, the impact on the overall transportation capacity, and financial considerations such as capital ‘bonding’.
On account of the factors mentioned above, slow steaming was until recently regarded as a non-topic, but we now see that ship operators are increasingly implementing this option and are able to overcome the obstacles, with significant fuel savings as a result.
In addition to improving their environmental performance, the recent steep increase in marine fuel prices is a strong incentive for ship operators to reduce their fuel consumption and overall operational costs. Irrespective of the main driver, the fact remains that more environmentally friendly operations in most cases go hand-in-hand with a positive impact on the financial bottom line. In this respect, both ship operator and cargo owner should have a common interest.
Land-based industries are under pressure to significantly reduce their emission levels in order to comply with new regulations and the Kyoto Protocol obligations.
Within shipping, the trend is towards an increased need for goods transportation due to global economic growth. The number of ships on order for the coming decades and the corresponding engine power to be installed will lead to an increase in the relative proportion of CO2 emissions from ships compared to land-based industries. Hence, shipping will be pushed to adopt effective means for reducing fuel consumption in order to maintain its image as an environmentally acceptable and sustainable mode of transportation.
In this respect, it will be important to identify the most viable alternatives and preferably establish incentive schemes to catalyze this process. One critical success factor for such schemes is to ensure that a level playing field is maintained within the shipping industry.
It will also be necessary to use proper and commonly understood benchmarking tools to establish the baselines and define industry best practices. Without widely accepted baselines, an environmental performance rating for ships and their emissions will be difficult to achieve.
Likewise, a reliable benchmark will be a fundamental requirement for individual ships and fleets to demonstrate improvements in their environmental performance over time.
*) SCR = Selective Catalytic Reactor
HAM = Humid Air Motor
SAM = Scavenge Air Moisturizing
EGR = Exhaust Gas Recirculation
DWI = Direct Water Injection
FEW = Fuel Water Emulsification