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reprinted with permission from www.bunkerworld.com
24th October 2011 10:05 GMT
A technology firm says its emissions sensor, which can measure particulate
matter (PM) as well as other pollutants, may also help operators who want to
identify and mitigate emissions of black carbon (BC).
The recent revisions of MARPOL Annex VI "were primarily based around
switching to cleaner, lower sulphur fuels, and were seen as the solution to many
of the maritime industries' air pollution issues," Simon Brown, Director of
International Marine Business at WRSystems told Bunkerworld and
Sustainable Shipping.
These cleaner fuels may have the effect of reducing sulphur dioxide (SO2)
emissions but "their effect on increased PM has not been fully understood,"
Brown observed.
He noted that the recently introduced Emission Control Area (ECA) in North America was different from previous
ECAs, where only SO2 emissions have been limited, as it also mentions restrictions of PM emissions, as well as
nitrogen oxides (NOx).
"Currently no IMO regulations are in force to control PM emissions, thus the enforcement of this particular
regulation remains a major concern to the wider shipping community," Brown noted.
WRSystems has developed Emsys®, a calibration-free laser-based emissions sensor with the ability to monitor
PM emission outside the stack, Brown explained.
The system was developed in response to the ever-expanding range of emissions regulations, which are set to
challenge the maritime community over the next 5-10 years. Brown said Emsys® is fully Type Approved for the
measurement of PM, plus all the traditional emissions species such as NOx, sulphur oxides and carbon dioxide
(CO2).
The system can additionally provide mass inventory of each pollutant in kilograms and tonnes to allow full
environmental impact assessments to be carried out.
There has been been increasing attention surrounding emissions of BC, or soot, because of its global warming
potential, with the International Maritime Organization (IMO) now looking into regulating shipping emissions of
BC affecting the Arctic.
Brown mentioned recently published research by Mark Z. Jacobson of Stanford University in the United States
claiming that soot's effect on climate change has not been adequately addressed in national and international
global warming legislation.
BC is a constituent part of PM formed by incomplete combustion. Because it is dark, it absorbs heat and this can
cause climate effects, especially if deposited on snow and ice in the polar regions.
But BC emissions from shipping are not clearly defined, a problem highlighted at the most recent meeting of the
IMO's Marine Environment Protection Committee (MEPC 62).
A submission to MEPC 60 regarding the impact of BC from shipping cited a report in the 'Journal of Geophysical
Research' by Daniel Lack which estimated BC to be 5 - 15% of the total PM produced, Brown said.
This would suggest that lower sulphur distillate fuels, which produce much less PM by mass than heavy fuel oil
(HFO) that has a higher sulphur content, also lead to less BC emissions.
National Oceanic and Atmospheric Administration (NOAA) scientist Daniel Lack told the recent Sustainable
Shipping conference that evidence is accumulating that fuel sulphur has an impact on BC emissions, although
he said engine load was also big factor.
Other recent studies cited in the MEPC 60 submission says BC is dependent on engine type and combustion
efficiency, and that medium speed marine engines typically used on tugboats, fishing vessels and ferries emit
BC at more than twice the rate of slow speed engines used on large ocean-going ships (excepting container
ships) and high speed engines used on passenger ships.
According to the paper submitted to MEPC 60, the incomplete combustion that leads to BC emissions is less
influenced by fuel grade than the air fuel ratio, fuel injection quality and the temperature and pressure of the air
charge.
"Because there is not a huge amount of operational PM emissions data from commercial shipping, it is currently
difficult to have an accurate perspective on the means to tackle this problem," Brown observed.
"Ships are all different, they operate on differing fuels and have widely varying operational profiles, therefore
there may have to be many solutions. It is understood that BC is most prevalent on start-up and during transient
load conditions where it is usual to produce black smoke and soot, so optimisation of the engine and fuel system
is the first step in this process."
The Emsys® PM sensor can measure opacity (%), volumetric PM (mg/m3), and specific PM in g/kWh, which
Brown said will allow vessel operators to benchmark their engines and boilers for each differing fuel type and
evaluate the environmental impact of each.
"Although we can't specifically apportion the BC content of the PM, using the above ratios and 'fingerprinting' the
vessels engines over their usual operating profile will provide operators the best available data to decide on
mitigation strategies," he concluded.
BC is under scrutiny not just because of its climate impacts, but also impacts on human health associated with
fine and ultra-fine PM. Reduction of shipping PM emissions can therefore provide benefits to human health as
well as the climate.
Research is also being undertaken by the Norwegian Marine Technology Research Institute (Marintek) to
improve understanding of the nature of PM emissions that result from burning typical marine fuel qualities in
marine engines, especially relating to the fuel sulphur content.
Unni Einemo, London News Desk, 24th October 2011 10:05 GMT
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