Cargo shipping carries the bulk of the global traffic in goods. Over 90 percent of the further growing global trade flow is transported across the world’s seas and oceans. The trend is towards larger and more especially faster ships. Even if they are the most efficient ones of all means of transportation, as a result of which fuel consumption and carbon dioxide emission in sum will continue to rise. About 1,000 million metric tons of the greenhouse gas are discharged into the atmosphere by international shipping. This means that maritime transport accounts for approximately the same proportion (2.7 percent) of global CO2 emissions as air transport. However, the exhaust fumes from a ship’s funnel are not only harmful for the climate. “Diesel fuel for ships” is the distinctly euphemistic term applied to heavy oil, the viscous, tar-like residue left behind after fractional distillation of crude oil which collects pollutants from the oil.

Klaus Jopp, freelance technical journalist, Hamburg, Germany

The smoke trails from cargo ships are consequently harmful to the environment. “A large fraction of ship emissions occur within 400 kilometers (250 miles) of coastlines causing air quality problems in coastal areas and harbors with heavy traffic,” confirmed Dr. Veronika Eyring from the Institute of Atmospheric Physics of the German Aerospace Center (DLR) in Oberpfaffenhofen. Various other studies also confirm that the proportion of various emissions attributable to shipping is increasing constantly, especially in coastal regions and ports, and that this is rising faster compared with land-based forms of traffic on a percentage basis. “Projections for Europe as a whole show that if the environmental legislation framework does not change, the sulfur and nitrogen oxide emissions caused by shipping will exceed the proportion of these emissions from on-shore sources within the foreseeable future. Since more than 50 percent of all ships are permanently within 200 nautical miles of the coast and not on the high seas, coastal regions, riverine areas and first and foremost seaports are affected,” states a policy document that was commissioned by the Bremen Senator for Economic Affairs and Ports, Rolf Nagel.

Seaports suffer particularly from pollution, not only due to ships entering and leaving, but also during their lay days. The generating sets in the engine room remain running during loading and unloading of cargo ships or during boarding and disembarking of passengers from ferries and cruise ships. In just one hour at the dockside a passenger ship discharges as much fine dust into the atmosphere as 50,000 cars traveling at 130 km/h (80 mph) on the motorway. In 2020, experts estimate that in certain port regions, 20 percent of all fine dust emissions will be caused by ships. In some places today, emissions of relevant pollutants by ships already represent a much higher proportion of total pollution, accounting for as much as 90 percent of nitrogen and sulfur oxides. For this reason, in many ports pilot projects have already been initiated with shoreside power supply systems for berthed ships. Improvements in the fuels would also be necessary in order to effectively ease the emission problem.

In 2006, the International Maritime Organization (IMO, London) decided to reduce the limit value for the sulfur content in fuels for shipping in the Baltic from originally 4.5 to 1.5 percent. But this move is little more than a drop in the ocean. The most commonly used Bunker-C oil contains on average 2.7 percent sulfur, 2700 times more than is allowed for diesel fuel for cars or trucks. With effect from January 2010, the EU is to stipulate the use of “low-sulfur” MDO (Maritime Diesel Oil) with 0.5% sulfur. This limit will then apply for all ports in the EU. According to UN figures, 16 percent of all sulfur emissions come from ships’ funnels – and by 2015 transport of goods and passengers by ship is expected to easily double. Worrying prospects, indeed.

Shoreside power – energy direct from the local utilities

Against this background, Siemens in Hamburg, Germany, has been working for years on a solution known as “Siharbor” to counter harbor smog. It is based on the medium voltage back-to-back link Siplink (Siemens Multifunctional Powerlink). While DC long-distance transmission systems and back-to-back links are already state-of-the-art in high-voltage technology, advances in power electronics now make systems of this kind interesting for the medium voltage level as well. Ships berthed in port will also be connected to the medium voltage system of the local utility and provided with electrical power in this way.

This means ships would shut down their on-board generating sets which not only produce nitrogen and sulfur dioxide emissions but also soot, fine dust and noise. Emission of pollutants is reduced by over 50 percent in this way. This is one reason why the Commission of the EU Council issued a Recommendation (2006/339/EC) in May 2006 to promote the use of shoreside power systems by ships while berthed in port. The Siharbor connection system not only follows this recommendation but also fulfils the highly disparate requirements of port operators, ship-owners, shipyards and power supply companies. The Siharbor system can also supply all types of different vessel, from cruise ships, container ships, bulk carriers and ferries to reefer vessels with power from an onshore supply. Thanks to the modular design of the system, any solution using the frequency combination of 50-Hz and 60-Hz as well as all voltage levels required in the shipping industry can be adapted and realized.