Refineries May Foil IMO Aims to Cut SOx Emissions in Exhaust Gas

By George Backwell at January 31, 2011 00:31
Filed Under: General

'Refiners threaten anti-pollution efforts in shipping', blared the caption of a Reuters article by correspondents Kan and Fabi on 17, January 2011, then coincidentally, came news a couple of days later that Wärtsilä was to retrofit the Containerships Vll, 13,995 dwt,  (owned by Helsinki based Containerships Ltd. OY) with their diesel engine exhaust-gas scrubber.

Wärtsilä's first ever installation of a commercial marine scrubber (to serve their W7L64 main diesel engine) is intended to enable the ship to meet impending targets for reduced exhaust gas emissions of SOx in Emission Control Areas's while continuing to burn diesel fuel with sulfur content above the set limits.

Containerships Vll: Photo Credit, Jens Boldt

Bunkers With Minimal Sulfur to Become Scarce?

Experts in the field pronounce that SOx emissions in diesel engine exhaust gas‚ which mostly comprise sulphur dioxide with a small amount of sulphur trioxide‚ are a function of the amount of sulphur in the fuel burnt and cannot be controlled by the combustion process. The essence of the Reuters article is that a consequence of reluctance by oil refineries to invest the billions of dollars needed for tooling up plant to meet demand for cleaner-burning marine fuels is likely to set back full and timely implementation of MARPOL Annex Vl.

Shortages of low suflur-content  diesel engine fuel (concurrent with an excessive market price) might be grounds for IMO's feasibility review (scheduled for 2018) to conclude that full implementation should be delayed for the default seven years until 2025

What are the options, if refiners were indeed to  fail to step up to the plate and deliver ?

Alternative  Fuels

LNG, LPG, and bio-fuels suggest themselves. Remi Eriksen, Chief Operation Officer at classification society Det Norske Veritas told a Singapore conference last week: "LNG is the best alternative we have from an environmental and financial point of view."

Others were less optimistic about the future of LNG as a fuel: Robin Meech, MD of U.K. Company, Marine and Energy Consulting considered LNG would make up only 5% of bunker use by 2025 due to the cost of retrofitting vessels to make use of it.

LPG is out of the reckoning for low and medium speed marine diesel engines. Bio-fuels tend not to figure on the agenda, as global depletion of harvests is thought to play in to food commodity supply shortages.

SOx Cleaning by Scrubbers
Depletion of SOx exhaust gas emission by means of scrubber technology (which brings exhaust gas flow into intensive contact with an alkaline fluid) allows lower grade bunkers to continue to be burnt, and development of marine scrubbers seems set to occupy the endeavours of R & D engineers of all the major engine manufacturers.

Negatives to be overcome concern the relatively large space taken up by scrubber plant; the treatment of contaminated waste water; and disposal of the sludge residues. Waste water has to be treated prior to discharge, and sludge held on board for discharge ashore.

Wärtsilä said in a news release on 19, January 2011 that their scrubber complies with the IMO guidelines for cleaning exhaust emissions from all 2 and 4-stroke engines and oil-fired boilers, and will include a water treatment process to enable purified waste discharge at sea.  Operational performance of Containerships Vll's scrubber is going to be closely followed.


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