IMO 2020 – A Strikeout for Sulfur, but Black Carbon Is Still on Base

Posted on November 7, 2019 by Susan Cooke

Greenhouse gas (GHG) emissions from international shipping supposedly represent 2% to 3% of the world total, about on par with those emitted by Germany.  However, there are no GHG emission restrictions covering ships on the high seas.  Moreover, even the current limits on sulfur and NOx are far less stringent than those imposed in many developed countries, although things are about to change on the SO2 front.

That is about to change.  The International Maritime Organization (IMO), which is part of the United Nations, recently announced a new and more stringent standard, set forth in Annex VI  of the International Convention on the Prevention of Pollution from Ships (MARPOL).  On January 1, 2020, marine vessels must meet a 0.5% (by weight) sulfur-in-fuel standard or install scrubbers to meet that standard.  In addition, starting March 1, 2020, such vessels without scrubbers may no longer carry heavy fuel oil on board.  Even more stringent standards are already in place within so-called Emission Control Areas.  For example, there is a 0.1% sulfur-in-fuel limit for vessels operating within the territorial waters of Canada, the continental U.S., Alaska, Hawaii, Puerto Rico, and the U.S. Virgin Islands. 

Annex VI also contains provisions for lowering NOx emissions.  Marine diesel engines above 130 kW installed on a ship constructed on or after January 1, 2011 must meet so-called Tier II standards, and such diesel engines installed on vessels constructed on or after January 1, 2016 and operating in the U.S. and Canadian waters described above must meet the more stringent Tier III standards. 

It is expected that most vessels will utilize lower sulfur fuel rather than employ scrubbers.  This move away from residual fuel oil (known as heavy fuel oil or HFO) toward low sulfur blended intermediate fuels and lighter, more refined grades will have another salutary effect – a reduction in the emission of black carbon, the sooty material resulting from incomplete combustion of fossil fuel, which comprises a significant portion of particulate matter, an air pollutant.  And while black carbon has a lifetime of only days to weeks after its release into the atmosphere, its warming impact on climate, per unit of mass, is 460-1,500 times stronger than CO2.

In 2018 the IMO adopted an initial climate strategy targeting a 50% reduction in GHG emissions by 2050 from 2008 levels through a mix of proposed measures ranging from efficiency improvements to existing vessels, speed reductions, use of lower carbon fuels, methane and VOC emission controls, national action plans, and GHG reduction initiatives implemented at ports.  While black carbon is estimated to account for 7%-21% of the overall climate impact of international shipping, this initial strategy does not include any specific measures for reducing black carbon emissions.  However, an IMO subcommittee is now considering what action might be undertaken to address this pollutant beyond the ancillary effect of the new sulfur standard. 

One particular concern is the increased shipping anticipated in Arctic waters as ice recedes, and the deleterious impact of black carbon emissions from an increased number of vessels plying those waters.  Indeed, the impact of black carbon emissions is specifically noted in Par. 70, ANNEX 2, of the IMO Note regarding adoption of its Initial Strategy.   

A new ball game – or at least the warm-up for that game – is about to commence where various measures to control black carbon emissions will be tossed out for consideration.  While the winning strategy is expected to be several years in the making, one proposal garnering interest is the mandated use of distillate fuel in lieu of HFO, which can be paired with mandated use of diesel particulate filters to remove most of the black carbon.  But this strategy will be costly and may not make it to first base.  Consequently, in the inimitable words of Yogi Berra: “It’s tough to make predictions, especially about the future”.



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