A major fuel shift is taking place in the maritime industry as shipowners attempt to find solutions to comply with the 2020 global sulfur cap. This new limit on sulfur (SOx) emissions will provide great benefits for human health and the environment. But with the deadline for compliance approaching fast, the pressure is rising—and there are still numerous questions left unanswered. The IMO and other organizations are hard at work to provide support where it is needed and have been reviewing guidelines on numerous areas, including fuel oil availability and exhaust gas cleaning systems (ECGSs).
Fuel safety and availability need to be addressed
Switching to clean, compliant fuels is a major challenge for practically everyone involved in the industry. Firstly, there are numerous safety concerns that come with the introduction of new fuel types. With so many different options available, shipowners are worried that their ships’ engines could be damaged as a result of accidentally mixing incompatible products. And, the fuels themselves will need to be tested to check for harmful impurities. Demands for stricter quality controls have risen since 2018, when hundreds of tankers were damaged by tainted fuel. The impure fuel clogged pipelines and filters, leading to significant costs and delays.
According to the IMO, most ships are expected to utilize new blends of fuel oil to achieve compliance. However, it is very likely that these will initially face compatibility issues, and availability is still uncertain at present. The International Chamber of Shipping (ICS) therefore recommends storing fuels in segregated tanks to prevent comingling in the fuel system and using an appropriate test kit on board to check compatibility.
Due to their usability in most engine configurations, distillate fuels are an attractive option for compliance. However, many issues remain. Firstly, fuel tanks that have previously used heavy fuel oils will have to be cleaned thoroughly to prevent contamination. Moreover, there are concerns about the price and availability of distillates and marine gas oil. Last but not least, residual and distillate fuels have different cold flow properties. To avoid loss of propulsion from thermal shock, ABS recommends that owners and operators should prepare detailed a fuel switching procedure in consultation with engine/machinery makers. This should be placed on board and the crew trained accordingly.
Scrubbers: Still an ‘open’ issue
One way to avoid the uncertainty of alternative fuels is to install an EGCS, commonly known as a ‘scrubber’. These cleaning systems allow ships to continue sailing with high-sulfur fuel oil, while complying with the sulfur cap. There are several different types of scrubber, including open-loop and closed-loop systems. Open-loop scrubbers are the simpler option, neutralizing the sulfur in exhaust gasses by utilizing the natural alkalinity of seawater. The advantage is that they have fewer components and do not require any hazardous chemicals. However, they are not suitable for brackish and freshwater operation, and more and more countries are banning their use in ports and other areas due to concerns about washwater discharges.
Closed-loop systems offer greater flexibility as they can be used in all areas. However, they are more complex and rely on a constant supply of an alkaline medium, which requires special handling. These systems are therefore much more expensive to purchase and operate . There are numerous other factors that need to be considered for all scrubber types. Scrubbers increase the weight and wind profile of vessels, and therefore influence vessel stability. They may also cause excessive exhaust system backpressure, which could have an impact on the operation of engines and boilers. To prevent this risk, it is crucial to check that backpressure limits will not be exceeded. Pressure may be reduced by installing a fan on the scrubber outlet to the exhaust pipe.
As of February 2019, more than 2,700 ships had either installed or ordered scrubbers to be installed by 2020. This will correspond to approx. 10–15% of marine fuel consumption.
“Global Sulphur Cap 2020, 2019 Update”, DNV GL
In addition to the sulfur cap, the IMO is committed to reducing greenhouse gas emissions in general. The organization has set reduction targets of 40% by 2030 and 70% by 2050 compared to 2008 emissions levels. While that may sound ambitious, a recent study by the European Commission found that specific policies would make it possible to achieve these targets.
In response, the IMO and the government of Norway are collaborating on the GreenVoyage-2050 project to “demonstrate and test technical solutions for reducing [greenhouse gas] emissions” throughout the maritime sector and provide technical assistance to Member States. A number of additional reduction measures have also been proposed, including speed reduction and higher operational efficiency standards. 107 shipowners sent an open letter to the IMO in support of mandatory speed limits. Even simply capping average speed at the 2012 level would be enough to reduce annual CO2 emissions by 13%, according to the European Commission’s projections. However, the speed limit proposal was met with opposition at MEPC 74 in May 2019. Click here to see the full detailed report of the study’s findings.