Cold ironing for seagoing vessels and barges implies that a ship at berth uses shore power for the auxiliary engines instead of bunker fuel. This reduces emissions from the ships by a substantial margin, although the reduction in pollution occurs only when the ship is stationary at berth.
Power cables are plugged into an electricity supply board at the terminal on one end and to the ship’s power supply board on the other. The power is used for lights, refrigerators, air-conditioners, and other equipment on a ship. The power coming from the shore can be from a separate power generation unit or the power plant supplying power to the port city or town.
At present, cold ironing is most widespread in the cruise shipping market and ferry business as the pressure on cruise and ferry terminals to reduce emissions is high, particularly when they are located close to (historical) city centers:
- Due to strict local and state environmental regulations for idling ships, early adopters of cold ironing practices are found along the west coast of North America (i.e. Vancouver, Seattle, Los Angeles, San Diego, San Francisco, and Oakland). Cold ironing for commercial vessels was launched in Los Angeles in 2004 when China Shipping’s container ships were plugged into a dedicated port barge floating close to the berth.
- In Northern Europe, Scandinavian countries, Germany, Belgium, and the Netherlands have already developed cold ironing solutions. Since 2010, vessels berthing for more than two hours have switched to a 0.1% sulfur fuel or use alternative technologies, such as shore-side electricity. The EU approved Directive 2014/94/EU on the deployment of alternative fuel infrastructure in 2014. This directive obliges member states to implement alternative infrastructure networks such as shoreside power technology by December 2025. The EU’s TEN-T program has indicated that shore power is an area where funding is available to help with up to 50% of the costs of research and 20% of its implementation costs.
- Cold ironing technologies are also being implemented in several Asian ports. China has included cold ironing in its 12th five-year plan and links it to the existing domestic emission control areas.
Despite its potential contribution to promoting green shipping, the cold ironing solution faces some major challenges:
- There are challenges related to the investment cost (terminal and ship), the division of these costs between different stakeholders (shipping line, terminal operator, and port authority), and the break-even cost compared to bunker fuel.
- There are still some issues with the standardization of on-shore power systems in terms of on-board and terminal equipment and voltages.
- Shipping lines are not always eager to invest in the retrofitting of ships as long as cold ironing possibilities are limited to only a few ports of call (a ‘chicken and egg’ problem). Certain ships are not even compatible and suitable for the process of on-shore power. Most new-build ships are pre-equipped.
- The large-scale application of cold ironing in a port might require extensive capacity upgrading of the local or regional power grid. For example, a large container ship typically requires approximately 1,600 kilowatts (kW) of power. In contrast, at berth, the power requirements can differ substantially (cruise ships need a lot more power), depending on the size of the vessel and the number of refrigerated containers on board.
- Environmental advantages of cold ironing depend on how clean the shore-based electricity production process is. If shifting the power production from ship to shore increases the load on fossil-fuel power plants and increases the air emissions, then the overall impact on emissions might be marginal.