Ship rerouting due to narrow ECAs could increase emissions

The International Council on Clean Transportation (ICCT) issued a white paper studying Emission Control Areas in China, considering the potential for ships to route around the ECA. The paper reveals that ECAs which are too narrow may actually increase emissions if ship operators divert to save on fuel costs.

As China tackles its air quality issues, government regulators have turned their focus to shipping, which contributes a great part of global emissions.  China has already implemented domestic emission control areas (ECAs) in three port clusters along China’s coastline, although they are smaller and currently have less stringent standards than an IMO ECA.

A delineation closer to shore is politically easier to achieve because China can unilaterally regulate ships in its territorial waters, ICCT notes.

However, a narrow ECA delineation may actually increase emissions if ship operators divert around the ECA to save on fuel costs, as ECA-compliant fuel is more expensive than traditional marine fuel. Therefore, China should consider how to delineate an ECA to prevent rerouting and ensure maximum emission reductions and public health benefits.

In the paper, ICCT quantified the emissions reduction potential of four ECA delineation scenarios, considering the potential for ships to route around the ECA. The paper found that:

1. An ECA needs to be at least 100 nm from the coast to be most effective. Under a narrow ECA, ship operators may reroute some of their heavily frequented coastal voyages around the ECA to save money on fuel. The closer the ECA boundary is to the coast, the more ships will reroute. Therefore, narrower boundaries undermine the effectiveness of the ECA.
2. When ships bypass the ECA zone, they avoid environmental regulations, redistributing rather than reducing emissions. Worse, rerouting results in a modest (up to 2%) increase in fuel consumption compared to shorter, more direct voyages because rerouted voyages cover longer distances and, in some cases, require ships to speed up (and burn more fuel) to stay on schedule.
3. The more expensive ECA-compliant fuel is compared to globally compliant fuel, the more ships will reroute. Indeed, the decision to reroute is sensitive to bunker fuel prices. The larger that price differential, the wider the ECA boundary needs to be from shore to discourage rerouting.