Cold Iron:Receipt of shore power, along with other utilities such as potable water and steam, is part of the process of placing the engineering plant in a status known as “cold iron.” The term originates from the steamship era, when ship boilers and engines would go relatively cold after being secured. To bring a steam plant back online, supplying its own power after a “cold iron” period, would involve a substantial light-off, warm-up, and transition period compared to modern, fully automated plants.

Onshore power supply (OPS, sometimes referred to as “cold ironing”) is a system of procedures and equipment that provides ships with a source of electrical power as an alternative to the ship’s service electrical power system. The primary benefit is that, since the ship no longer has main or auxiliary engines operating, the engine emissions are virtually eliminated in the port area. Many ports around the world are located near large populations, and engine emissions from ships unfortunately contribute to unwanted levels of nitrogen oxides, sulphur oxides, particulate matter, and even the “greenhouse gas” carbon dioxide. Onshore power supply achieves a better total emissions reduction result than ship-installed emissions equipment, because the engines are off-line. On the other hand, there are difficulties associated with high voltage, varying frequencies, safety and infrastructure costs that must be addressed in order to justify an onshore power supply installation.

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