The most effective method for measuring emissions is in-situ monitoring using a continuous emissions monitoring system (CEMS)
In just a matter of months, shipowners operating in emissions control areas (ECAs) will have only three choices to comply with mandatory 0.1% sulphur levels; burn marine distillates, switch to liquefied natural gas; or install abatement technology such as scrubbers, says Chris Daw, Managing Director, Procal, part of Parker Group.
With 2015 literally just around the proverbial corner, decisions must be made now. And this is – understandably – heightening debate around not only which approach to adopt, but also the efficacy of available technology and emissions measurement techniques. Owners and operators are under pressure to ensure that comprehensive analysis and planning is undertaken to ascertain which of these options is the most viable and profitable for their business.
In the near term, it is widely considered that distillate fuels are likely to be the most popular choice. This is largely because – of each of the three options – switching to burning distillates within ECAs requires the least up front operational investment, albeit at a premium of $300 to $400 over regular HSFO.
Distillates may very well be the best option for some owners and operators, particularly those who will operate only for short periods within ECAs. However, exacerbated fuel costs are not the only consideration; with the rapid increase in demand post-2015 is expected to exert extreme pressure on the supply chain. And, in addition, as greater demands are placed upon fuel oil systems, the crew must not only concentrate upon the implementation of timely fuel switching procedures, but attention must also be heightened to condition monitoring, maintenance and processes.
LNG as bunker fuel presents the second option. With almost no sulphur content, reduced NOx and lower carbon emissions, as well as offering lower fuel costs than even conventional bunkers at current prices, it represents an attractive proposition. However the youth of LNG bunkering naturally presents logistical challenges and it will take time for the infrastructure to develop sufficiently before the use of LNG as a fuel becomes widespread practice.
The third option for ECA compliance is the installation of exhaust gas cleaning systems, or scrubbers, to reduce the emission of sulphur and other particulate matter from HSFO. From an operational perspective, certain scrubbers remove SOx by up to 98% and harmful particulate matter emissions can be reduced by 85%. Ultimately though, whichever option is adopted, shipowners will be under significant pressure to prove compliance or else face significant fines they can ill-afford.
Measuring emissions during the entire journey
The Clean Shipping Coalition (CSC) has suggested to the International Maritime Organisation (IMO) that continuous monitoring technologies that measure emissions directly during the entire journey should be installed on all ships.
Exhaust gases from the combustion of residual and distillate fuels can be analysed and shown on screen or in report format, so that compliance can be confirmed in port, in Emissions Control Areas and in international waters. In its submission to the IMO, CSC said bunker delivery notes (BDNs), which have been “the primary instrument” for ships to verify compliance with sulphur limits, leave too much room for uncertainty. As regulations become increasingly stringent, the shipping industry need no longer rely upon comparing fuel consumption and route data to assess compliance.
A key concern for CSC is to ensure that there are no loopholes in efforts to enforce the provisions of MARPOL VI, which sets limits for emissions to air from ships. Several shipping companies, including DFDS, Maersk and Wallenius Wilhelmsen Logistics (WWL) have also raised concerns about inadequate monitoring of ships for compliance with the sulphur limit in ECAs from 2015, when the cost of compliance will increase dramatically.
A recent consultation by the UK’s Maritime and Coastguard Agency suggested that it could prove hard for port state control (PSC) authorities to check if a vessel with a scrubber onboard was actually using it. This prompted Meindert Vink from the Netherlands Shipping Inspectorate to state, as reported by Bunkerworld, that he had faith in scrubber technology, especially if combined with tamper-proof continuous monitoring technology. He noted that this would make it straightforward for PSC to simply check the record on paper.
The most effective method for measuring emissions is in-situ monitoring using a continuous emissions monitoring system (CEMS). In contrast to extractive sampling where a gas sample needs to be physically extracted from the system for analysis, ‘in-situ’ monitoring provides a continuous, real time measurement of the content of a vessel’s exhaust gases, with data provided instantaneously on a screen that can be installed in the engine room and on the bridge.
An in-situ continuous monitoring system will immediately flag up any problems. By contrast, a six stack extractive system will monitor any stack for only 12 minutes in any hour, causing potential delay in relaying failure. In-situ systems are also more reliable, as they do not require any filtration or drying of the exhaust gas, and are the only real monitoring option for low maintenance seawater scrubbing operations. Although it is recommended that extractive solutions should be checked every three months, the guaranteed reliability of an in-situ analyser requires only an annual check.
The unique nature of infra-red in-situ systems make them sensitive enough to confirm compliance, even when emission limits are very low. Emissions that are the equivalent of 0.1% sulphur fuel are around 22ppm of SOx in the exhaust gas. Any instrument with a range over 0-100 ppm will not be accurate enough to measure this and an inappropriate choice for operational scrubber monitoring. For example, the Procal 2000 – an infra-red (IR), duct or stack-mounted system, designed to provide in-stack analysis – has an SO2 monitoring range of 0-100 ppm but can automatically switch ranges to 0-500/1000 ppm for monitoring operations outside of an ECA on high sulphur fuels.
An instrument such as this can measure up to six exhaust gases and a typical system could comprise of up to six stack-mounted analysers to measure gases such as SO2, CO2 and NOx. The analysers are connected to a data acquisition system, which displays, data logs and retransmits the monitored concentrations and SO2 and CO2 ratio – in accordance with IMO regulations – without any manual intervention.
Scheme A or B?
Continuous monitoring of sulphur emissions is one of two methods that can be used to certify scrubbers, according to IMO guidelines; Scheme A and Scheme B. Scheme A demands initial certification of performance followed by periodic survey with continuous operating parameters and daily emission checks to confirm performance in service. Scheme B requires performance confirmation by continuous monitoring of emissions with daily operating parameter checks.
Many in the industry believe that Scheme B should be the single allowable method. Firstly, Scheme B gives complete and ongoing assurance of emissions at exit from ship, whereas Scheme A does not. In addition, if a CEMS is not fitted there is a potential risk that the indirect Scheme A method of monitoring system parameters could result in non-compliant emissions being undetected between daily emission spot checks – particularly undesirable in port and ECAs. Continuous monitoring of exhaust gas emissions is the only way to provide complete reassurance, no matter the type of scrubber system installed. Furthermore, any port state control inspection will be able to readily confirm emissions are compliant under Scheme B using MEPC 184(59) Table 1, whereas under Scheme A, cross reference of unfamiliar operating parameters will need to be made with those in the EGCS technical manual (ETM-A).
With regard to applicability of analysers, whilst CEMS for Scheme B must be approved according to MEPC 184(59), the daily spot checks required under Scheme A risk use of unapproved portable analysers that are neither ranged appropriately for a very low level of SO2 emissions (less than 20ppm) nor meet the performance specifications appropriate for the application. Due to the manual method of obtaining an emissions reading using a portable analyser, there is risk of an inconsistent and non-representative result, not to mention the associated safety risks if an access point to a hot flowing exhaust needs to be opened and a hand held probe inserted.
Reliable and mature technology
Unlike portable analysers, CEMS for SO2 and CO2 are a reliable and mature technology, with a number of commercially available marine systems approved according to MEPC 184 (59). To ensure ongoing emissions compliance it is vital to take into account 2015 ECA requirements and that there is already a need to meet a limit equivalent to using 0.1% sulphur fuel in European ports. CEMS must therefore be ranged appropriately to measure the low levels of SO2 that will be found in the exhaust stream i.e. less than 20ppm. The measured concentration should also fall between 15% and 100% of the measurement range used. This will ensure future proofed accurate monitoring and simplifies matters for ship operators (same analyser requirements regardless of where vessel is located). Simplicity really is key. At a time when crew members are being asked to undertake increasing responsibility to meet changing legislation; only robust, reliable tools and technology that need minimal maintenance and resourcing are viable.
Finally, the compliance argument centres around the provision of accurate and reliable measurement that provides a simple means of determining compliance, and the adoption of the same methodology regardless of vessel location, providing reassurance and clarity. The clock is ticking and whether shipowners and operators choose to switch between high and low sulphur fuel or install a scrubber, CEMS has a central role to play.