With new international standards forthcoming from the IMO, and a number of regional and national regulators in the process of imposing others, ship emissions are set to face increasingly tougher control in the coming years.

The industry is in an era that is witnessing a proliferation of environmental regulations, ever-tighter emission limits and the looming prospect of new regimes for tackling global greenhouse-gas (GHG) emissions from shipping.

Legislation such as the IMO’s ‘MARPOL Annexe VI’ air-pollution prevention regulations have made monitoring an essential data tool in order to demonstrate that requirements are fulfilled – particularly in light of the EU’s plans to ensure ships using European waters monitor their emissions. Getting it right will be crucial for compliance, but it can also lead to substantial commercial and operational benefits.

The emergence of emissions benchmarking and vessel-efficiency tools show that shipping has taken a huge step forward in becoming more sustainable. However, emissions need to be accurately assessed. While the regulations are being put in place, little is being done about how these regulations will be met.

It seems there is some uncertainty too, about exactly when these requirements will come into force. ‘Annexe VI’ established a time frame for more stringent limits on sulphur and nitrogen oxides (SOx and NOx), but those plans have suffered some setbacks.

With the arguments surrounding SOx – particularly the implementation of 2015 IMO regulations requiring low sulphur fuel or SOx scrubbers – rumbling on, the NOx timetable also took a knock at May 2013’s Marine Environment Protection Committee (MEPC) meeting.

"It was anticipated that the committee would agree on a 2016 implementation date for IMO Tier III NOx limits, which would require some sort of after-treatment technology to reduce NOx emissions, such as selective catalytic reduction" (SCR), says Dr Johnny Briggs, of the International Association for Catalytic Control of Ship Emissions to Air (IACCSEA).

However, though the IMO committee, which looked at the availability, efficacy and cost of NOx reduction, recommended that the 2016 date be upheld, Russia’s delegation raised questions regarding the technology, asking for the deadline to be postponed to 2021.

"As an association, we strongly disagree with the Russian arguments, and we are working with many others to argue the case for 2016," Briggs says.

It all now hangs on the next MEPC meeting in April 2014.

Whichever date – 2016 or 2021 – is finally chosen for NOx, invariably, as emission limits across the board become tighter, achieving them inevitably becomes more challenging, and more costly. It also means that demonstrating compliance assumes ever greater importance – and that has brought the spotlight to rest firmly on continuous emissions monitoring (CEM).

A new approach

In-situ exhaust monitoring is an area of particular focus. In contrast with extractive sampling, where an exhaust gas sample needs to be physically extracted from the system and then analysed, in-situ emissions monitoring provides a continuous, real-time measurement of the content of exhaust gases. These systems can be accurate to a few parts per million [ppm] with gas species-specific ranges from 100 to more than 1,000ppm, depending on what requires measuring. The technology is there to provide instant, accurate CO2 measurement.

The Procal 2000 uses the reflective beam principle to measure process gas directly as it enters the sample cell. Mid-IR pulses, at two specific wavelengths for each monitored gas, are transmitted through the cell. The ‘reference’ pulse passes through unaffected, while the ‘measure’ pulse is partially absorbed, thus giving a reading of the gas concentration.

"Environmental organisations are fighting for stricter regulations, and emissions monitoring is not something that the industry can afford to ignore."

Unlike extractive systems, this sintered metal technology removes the need for filtering, allowing the analysis of an unmodified and truly representative gas sample, where multiple concentrations can be monitored simultaneously.

Lasers are another optical approach being applied to in-situ emissions monitoring, with developments in quantum cascade lasers (QCL) helping to make CEM an increasingly realistic proposition for shipowners.

Emsys is one solution that has made steady inroads into the market in the last two years – WR Systems’ unique second-generation solid-state, QCL-based approach, is specifically designed for use on scrubber and SCR-type applications. Offering gas emissions and particulate matter (PM) measurement, and boasting comprehensive approvals, it covers all current maritime standards.

According to the company, it has the lowest operating costs in the industry, is virtually maintenance free and retrofitting can be completed in just three days. Installed within the funnel space, the system can monitor up to ten exhaust stacks – with each requiring only one penetration for gas and PM sampling – and measure up to eight gases simultaneously.

It is designed to integrate into the vessel’s systems and become another supplier of data to allow optimisation of efficiency and ensure compliance. Having NOx, SOx, CO2, CO, CH4 and PM as measured gases, it can provide operational efficiency for engines and boilers operating on all fuel types.

The system has been ordered for a number of new builds, as well as featuring significantly in various retrofit applications.

The aptly named Cascade Technologies offers another laser-based solution, with novel patented methods developed to expand the scope of gas detection achievable by QCLs to include simultaneous multiple gas measurement and hundred-thousand-counts-per-second capability.

The system uses direct absorption spectroscopy to detect NO, NO2, SO2, CO2 with other gases such as CO, NH3, CH4 also available, if required. Using a narrow-band, low-noise, coherent QCL source brings significant improvements in sensitivity and selectivity to this established gas-sensing technique, as well as making the system immune to cross interference and providing a swift response time.

The introduction of emission control areas (ECAs), where stricter limits apply, forms another part of the global drive towards stricter environmental controls, and lends added importance to tying emission monitoring with global positioning. CEM solutions are, accordingly, increasingly featuring electronic charting GPS interfaces.

Environmental organisations are fighting for stricter regulations and emissions monitoring is not something that the industry can afford to ignore. If fuel switching is the chosen option, monitoring provides assurance that fuels have been changed in a timely manner before entry into an ECA, and that compliance is ongoing.

The good news is that the industry has grasped the commercial importance of this issue, and is not simply sitting back and waiting for regulators to tell them what to do. That is certainly a measure of success.