NOAA: “low sulphur fuel is cleaner”

The study, published online in Environmental Science & Technology examined a container ship operating under the 2009 California regulation requiring that ships switch to low-sulphur fuels as they approach the California coast, and also adhering to a voluntary state slowdown policy, intended to reduce pollution. The research team found that emissions of several health-damaging pollutants, including sulphur dioxide and particulate matter, dropped by as much as 90%.

The findings of this study are expected to have some significance, with the US Coastal ECA regulations due to enter force in 2012. The research team found reductions in emissions even where none were expected, meaning even greater reductions in air pollution, and associated respiratory health effects in humans, than regulators originally estimated.

“This study gives us a sense of what to expect in the future, for the people of California, the nation, and even the globe,” said Daniel Lack, chemist with NOAA’s Earth System Research Laboratory and the Cooperative Institute for Research in Environmental Sciences. “This really is where science gets fun – a study with first-rate institutions, equipment and people, probing the effects of policy. It’s important to know that the imposed regulations have the expected impacts. The regulators want to know, the shipping companies want to know, and so do the people.”

In May 2010, a NOAA research aircraft flew over a commercial container ship, Maersk Line’s Margrethe Maersk, about 40 miles off the coast of California. Researchers on the aircraft used sophisticated instruments to ‘sniff’ the ship’s emissions before the ship switched to lower-sulphur fuels (by law, within 24 miles of the California coast) and slowed down voluntarily.

A few days later, scientists aboard the NOAA-sponsored Woods Hole Oceanographic Institute’s research vessel Atlantis sampled emissions of the same ship as it cruised slowly within the low-sulphur regulated zone. Sulphur dioxide levels, which were expected to drop, did do so, plummeting 91% from 49g/kg of fuel to 4.3g. Sulphur dioxide is best known as a precursor to acid rain, but can degrade air quality in other ways, directly and indirectly through chemical reactions in the atmosphere. In particular, emissions of sulphur dioxide lead to formation of particulate matter in the atmosphere which poses serious public health concerns.

Particulate matter pollution, regulated because it can damage lungs and hearts, dropped 90% 3.77g/kg of fuel to 0.39g. Unexpectedly, black carbon levels also dropped, cut by 41%, the team reported. Black carbon comprises dark-coloured particles that can warm the atmosphere and degrade air quality.

In 2009, the US Environmental Protection Agency and its Canadian equivalent, Environment Canada, estimated that shifting to low-sulphur fuels near coasts could save as many as 8,300 lives per year in those two countries, and ease the acute respiratory symptoms faced by another 3 million. But that 2009 assessment did not include the observed drops in several pollutant categories that Lack and his colleagues found, so the authors suggest the impacts could be greater.

Finally, the new paper discusses the net radiative (warming vs. cooling) effect of the ship’s fuel switch. Changes in the emissions of various air pollutants – some which have a warming effect, others which have cooling effects – likely mean net warming.

The project was funded by NOAA and the California Air Resources Board and conducted in close collaboration with Maersk Line.

“These scientific findings clearly demonstrate that ships off our coast now emit significantly less sulphur pollution than in the past,” said California Air Resources Board chairman Mary D. Nichols. “This is good news for California and for the nation. When the federal regulations kick in for ships to use low-sulphur fuel, communities throughout America that live near shipping lanes and next to ports will see clean air benefits.”

The new paper, Impact of Fuel Quality Regulation and Speed Reductions on Shipping Emissions: Implications for Climate and Air Quality, is available at the Environmental Science & Technology website. Lack’s 28 co-authors are from 10 research institutions from the US and Canada.

NOAA says its mission is to understand and predict changes in the Earth’s environment, from the depths of the ocean to the surface of the sun, and to conserve and manage our coastal and marine resources.