Source: adapted from Notteboom, T. and P. Carriou (2009) "Fuel surcharge
practices of container shipping lines: Is it about cost recovery or
revenue making?". Proceedings of the 2009 International Association
of Maritime Economists (IAME) Conference, June, Copenhagen, Denmark.Fuel Consumption by Containership Size and SpeedFuel consumption by a containership is mostly a function of ship
size and cruising speed, which follows an exponential function above
14 knots. For instance, while a containership of around 8,000 TEU
would consume about 225 tons of bunker fuel per day at 24 knots, at
21 knots this consumption drops to about 150 tons per day, a 33%
decline. While
shipping lines would prefer consuming the least amount of fuel
by adopting
lower speeds, this advantage must be mitigated with longer shipping
times as well as assigning more ships on a pendulum service to
maintain the same port call frequency. The main ship speed classes
are:
Normal (20-25 knots; 37.0 - 46.3 km/hr).
Represents the optimal cruising speed a containership and its
engine have been designed to travel at. It also reflects the hydrodynamic limits
of the hull to perform within acceptable fuel consumption levels.
Most containerships are designed to travel at speeds around 24
knots.
Slow steaming (18-20 knots; 33.3 - 37.0 km/hr).
Running ship engines below capacity to save fuel consumption,
but at the expense a additional travel time, particularly over long distances
(compounding effect).
This is likely to become the dominant operational speed as more
than 50% of the global container shipping capacity was operating
under such conditions as of 2011.
Extra slow steaming (15-18 knots; 27.8 -
33.3 km/hr). Also known as super slow steaming or economical speed. A substantial
decline in speed for the purpose of achieving a minimal level of
fuel consumption while still maintaining a commercial service.
Can be applied on specific short distance routes.
Minimal cost (12-15 knots; 22.2 - 27.8 km/hr).
The lowest speed technically possible, since lower speeds do not
lead to any significant additional fuel economy. The level of service is
however commercially unacceptable, so it is unlikely that
maritime shipping companies would adopt such speeds.
The practice of slow steaming emerged during the financial crisis
of 2008-2009 as international trade and the demand for containerized
shipping plummeted at the same time as new capacity ordered during
boom years was coming
online. As a response, maritime shipping companies adopted slow
steaming and even extra slow steaming services on several of their
pendulum routes. It enabled them to accommodate additional ships
with a similar frequency of port calls. It was expected that as
growth resumed and traffic picked up maritime shipping companies
would return to normal cruising speeds. However, in
an environment of higher fossil fuel prices, maritime shipping
companies are opting for slow steaming for cost cutting purposes,
but using the environmental agenda to further justify them. Slow steaming practices
have become the new normal to which users must adapt to.Slow steaming also involves adapting engines that were designed for a specific optimal speed
of around 22-25 knots, implying that
for that speed they run at around 80% of full power capacity. Adopting slow
steaming requires the "de-rating" of the main engine to the new
speed and new power level (around 70%), which involves the timing of
fuel injection, adjusting exhaust valves, and exchanging other
mechanical components in the engine. The ongoing practice of slow
steaming is likely to have an impact on supply chain management,
maritime routes and the use of transshipment hubs.
