World Bunkering > News > Summer 2011 > To scrub or not to scrub?

As the 2015 deadline for ships to use fuel with less than 0.1% sulphur content within Emission Control Areas (ECAs) draws closer, shipoperators need good information on which to base their decisions. One option is to install one of the several exhaust gas cleaning systems, or ‘scrubbers’, now on the market or under development.

A new US publication, written by Glosten Associates for the government-funded Ship Operations Cooperative Program (SOCP), goes a long way towards explaining the considerations operators need to bear in mind. The Exhaust Gas Cleaning Systems Selection Guide notes that, after the 2015 deadline, a shipoperator may meet RCA requirements by burning high-sulphur fuel at sea, and then switch to low-sulphur fuel within the ECA. Or they can change to always burning lowsulphur diesel fuel oil or use natural gas that has almost no sulphur content.

Alternatively, the guide notes, international convention MARPOL Annex VI allows a shipoperator to burn high-sulphur fuel if using an exhaust gas cleaning system (EGCS) that can reach an equivalent level of emission reductions. The guide has been developed to assist shipoperators who are members of the SOCP to determine their emissions requirements, calculate potential cost savings, and understand the integration and operational challenges of various EGCS technologies.

The author of the guide, Kevin Reynolds, stresses that each shipoperator will need to consider the discussions for and against each EGCS in the light of their own specific situation. The guide says that “shipoperators considering this option should conduct an individual analysis, and consider a prototype installation in the near future”. The guide notes cost of 0.1% distillate fuel oil has historically been 50% higher than high-sulphur marine grade residual fuel oils.

An analysis of fitting scrubbers on three ship types, each of which operated at least partially within an ECA, predicts net present values between $5m and $20m, and internal rates of return between 20% and 53%. This assumes operations from 2015 through 2025, and an 8% fuel escalation rate. If fuel prices were to escalate at a rate of 11% annually, the net present value would increase by almost 50%. The guide concludes: “These cost savings are so significant that some shipoperators may find installing an EGCS a competitive necessity.” The guide does also flag counter arguments and also the numerous uncertainties surrounding the various new technologies.

It notes: “Most systems are still in their prototype development phase, and therefore carry with them technical risks. Even assuming early technical issues are overcome, the ongoing impact of these large and complex devices may include: heavy fuel oil heating, purifying, and waste stream management; treatment and waste chemical handling and storage; approximate doubling of the engine stack size to accommodate scrubber units; weight and stability issues; and additional engineering staff to run the machinery and monitoring equipment.”

The guide also notes that it is not yet clear if wet scrubbers can remove fine particulates to an equivalent level of reduction as is achieved by switching to low-sulphur fuel oil. That could be an issue under future legislation. It puts the dilemma like this: “The shipoperator considering an EGCS faces a conflicting pair of recommendations. On the one hand, the fuel cost savings for those operating within an ECA is so substantial that an EGCS may be a competitive necessity. On the other hand, installations are discouraged because the technology is not yet fully mature, places a significant burden on ship arrangements and operations, and raises some environmental impact concerns.”

The guide makes clear fitting EGCS is no small matter, cautioning: “The impact of an EGCS on ship arrangements, operations, and logistics is both broad and pervasive. The machinery is very large, impacts key mechanical, electrical, and control systems, and in the case of chemical-based systems requires impacts logistics for bunkering and safety response.”

Nevertheless, the conclusion is: “In spite of these challenges, the cost savings potential remains significantly high.”