Shoreside Power

Summary

• Ships at berth continue to need electrical power, so normally keep their generators running
• Emissions tend to be close to population centres, so regulators are keen to see reductions. The EU is expected to impose fuel sulphur limits of 0.2%S, reducing to 0.1%, to address this issue
• Electricity from shore is seem as a possible alternative, but presents technical and cost issues.

Detail
When at berth, ships continue to need power for many purposes. As well as keeping the ship habitable, many cargoes need refrigeration or heating and some vessels need to operate their loading and unloading gear. Tankers, in particular, have to operate pumps as well as operate the safety equipment, and all vessels need to manage their ballast to keep the ship stable and unstressed. This power is readily provided by the auxiliary generators and engines that the ship needs for safe operation at sea. However, such engines do create emissions at the ports where they berth, and these are often close to large centres of population. Regulators are thus keen to see reductions in these emissions, and are able to impose more stringent requirements than at sea. For example, the EU legislation will require that ships at berth use only low sulphur fuel (0.1%) (or clean their exhausts to very high standards). This can be difficult for ships. Such fuel is expensive, and ships often have only limited capability to store and use different fuel grades. A change of the fuel used by an engine can cause fuel feed problems, and unexpected blackouts create significant risks. An alternative approach is to feed power from shore, using electricity from the local electricity grid.

However, at present, this has significant disadvantages:

• The cost of electricity from shore is invariably greater, often by a factor of two or more. While the ship faces only the marginal cost of the fuel used for generation, shoreside electricity has to cover the costs of the transmission and distribution infrastructure, the generation capacity required for the ship, and, in most cases, profit for the utility.
• The CO2 emissions arising from shoreside power generation, including transmission and distribution losses, can be greater than those of an efficient on-board diesel generator, particularly if coal plays a significant role in the generator mix.
• The technical standards associated with on-board electricity vary widely. So both the ship and the shore have to adapt the power to match each other. This can be expensive, with no assurance that a ship adaptation for one port is of use at another, or for the port that an adaptation for one ship is of use to another.
• It is surprisingly difficult to make the ship to shore connection. The cables are bulky, safety critical, and need special handling. By their nature berths need to be kept clear of obstructions for their primary activity of moving goods, and have to cope with ships of different lengths and sizes. It is not “plug and play”.
• It is hard to make the changeover between ship and shore power supplies without power interruptions, however short. This imposes extra costs and precautions to avoid harm to a great deal of the sensitive electronic equipment upon which modern ships depend.
• The power demands are large in comparison with other port uses. For example, the base consumption of individual ferries can be 2MW, and for Dover to offer shoreside power it would need an extra 10MW of capacity, at both 50Hz and at 60Hz.

Despite these difficulties, there are special cases where the emissions benefits justify the expense, or where regular berthing by specific ships makes the connections easier. Almost invariably, this is subsidised by the port.
It is not yet clear how the balance between effective shipboard abatement and shoreside power connections will evolve as more stringent port emissions constraints are imposed. SEAaT hopes an effective market will emerge, but also recognises that there are many regulatory jurisdictions involved, and many technical options to be explored before this is likely.