* Singapore to enforce ban on open-loop scrubbers from Jan 2020
* Ban aimed at protecting environment in top world bunkering hub
* Possible setback for shippers who installed open-loop scrubbers (Recasts, adds MPA comment and detail)
SINGAPORE, Nov 30 (Reuters) - Singapore's Maritime Port Authority (MPA) said on Friday that it is banning with effect from Jan. 1, 2020, the discharge of "wash water" used in ships to scrub engine exhaust.
The ban on so-called open-loop scrubbers in Singapore, home to the world's top ship refueling or bunkering hub, is a potential setback to shippers that have invested millions in the exhaust gas cleaning systems.
The move is to help prepare one of the world's busiest ports for new International Maritime Organization (IMO) rules that come into force in 2020 and oblige ships to use cleaner fuels.
"To protect the marine environment and ensure that the port waters are clean, the discharge of wash water from open-loop exhaust gas scrubbers in Singapore port waters will be prohibited," said Andrew Tan, Chief Executive Officer of the MPA during an event in Singapore.
"Ships fitted with hybrid scrubbers will be required to switch to the closed-loop mode of operation," Tan said, adding that Singapore will be providing facilities for the collection of residue generated from the operation of scrubbers.
The MPA told Reuters separately that the ban "is already part of our current legislation" but that its enforcement would start from Jan. 1, 2020.
The IMO, the United Nations shipping agency, shook the fuels and maritime industries in 2016, when it said it would ban ships from using fuels with sulfur content above 0.5 percent from Jan. 1, 2020, compared with 3.5 percent now.
To comply with the new rules, shippers can switch to burning costlier but cleaner fuels like marine gasoil or low-sulfur fuel oil, shift to alternative fuels like liquefied natural gas, or invest in exhaust gas cleaning systems, known as scrubbers.
Open-loop scrubbers use seawater as a scrubbing liquid and the waste stream is treated before being discharged back into the sea. In closed-loop systems, scrubbing is performed using water treated with additives and the liquid is recycled back into the scrubber. Hybrid scrubbers are a combination of both.
A spate of scrubber installation orders this year has led energy researchers to raise their demand forecasts for high-sulfur fuel oil (HSFO) bunkers as the scrubbers will let the ships continue to burn HSFO once the IMO's sulfur regulations go into effect.
A switch to low-sulfur fuels is still widely seen by industry observers and participants as the most practical form of compliance, however, given the high investment and operational costs associated with scrubbers and uncertainty around future emissions regulations. (Reporting by Roslan Khasawneh; Editing by Tom Hogue)