What is Alternative Marine Power (AMP) or Cold Ironing?
Alternative Marine Power (AMP) is a pollution control measure that helps reduce air pollution generated by diesel generators by using shore power as an alternative energy source.
When ships are docked in port, AMP is used to avoid unnecessary diesel engine use. This, in turn, helps significantly reduce ship emissions. This process is also known as cold ironing.
Alternative Marine Power
The chilling process can be explained in a few simple steps:
While ships are loading or unloading cargo in port or at berth, they are powered by Alternative Marine Power. Power is supplied via a cable that connects one side to a switchboard in the port and the other side to the ship’s switchboard. This process is called “chilling” because, in the past, when a ship’s main engines were stationary, they were cooled during the power transmission process.
This process not only protects marine ecosystems but also helps reduce the use of diesel and other petroleum-based energy sources. Alternative Marine Power (AMP) provides the power needed for lighting, refrigeration, air conditioning, and other equipment on board. Power can be drawn from independent generators on shore or from power plants that supply power to coastal towns.
Currently, there are four different types of alternative marine power (AMP) systems used to power ships or tankers in port. They are as follows:
- 11,000 V AC (alternating current)
- 6,600 V AC
- 660 V AC
- 440 V AC
With growing awareness of the importance of a clean environment, some ports, such as Los Angeles, have taken steps to protect the environment by reducing air pollution.
For example, ships docked at the Port of Los Angeles or other California ports are required to shut down their engines (operate at reduced load) and transfer power to a land-based base. This allows the ship to shut down its generators, significantly reducing noise and air pollution.
An AMP system consists of key components such as a cable drum, drum control center, pendant wire, AMP junction box, 6600 V grounding plate, transformer, main switchboard, and AMP control panel.
We will explain each of these components below:
Cable Drum
A cable drum is a drum installed on a ship that manages the cables connecting the ship to the mainland power source while the ship is docked in port. These cables serve as conduits for power and fiber-optic communications.
Once the cable is connected, the drum rotates for a few seconds every few minutes (as designed) to compensate for slack caused by vessel motion and wind, then switches to automatic mode. The cable drum is grounded to the ship’s hull via a grounding bolt.
Drum Control Center and Pendant Control Cable
The drum control center is an IP box that contains the switchboard required to control the drum’s operation. A four-function pendant control console serves as the operator’s interface, and indicators mounted on the door provide information.
AMP Junction Box
The AMP junction box connects the grounding cable from the other end of the cable drum. There are two cables, one on the left and one on the right. The junction box connects the plug to the dockside. Normally, the plug remains connected, except during maintenance.
6600V Grounding Box
This junction box is a conversion unit that receives power from shore power. It contains a vacuum circuit breaker (VCB), a high-voltage earthing switch (ES), and a high-voltage protective relay.
Converter
When using the AMP system, shore power is converted from high voltage to low voltage and supplied to the main switchboard (MSB).
Main Switchboard
The AMP switchboard in the main switchboard (MSB) can be operated automatically or manually to synchronize with shore power without causing a power outage.
AMP Control Panel
The AMP system is controlled by this panel, which also features status monitoring.
Fiber Optic Communications
In some AMP systems, fiber optic communications are used between the shore and ship. Fiber optic cables are used for communication. Clean fiber optic components are essential for high-quality communication between fiber optic devices. Any contamination in the fiber optic connection can cause communication failures.
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Even tiny dust particles can cause various problems with fiber optic connections. By comparison, the diameter of a human hair is typically between 50 and 75 microns, about eight times the size of a dust particle. Therefore, even dust particles invisible to the naked eye are present in the air and can settle on connectors. In addition to dust, other types of contaminants must be removed from terminal interfaces.
AMP Junction Boxes
Cable Reel Overview
Cables: Cables serve as conduits for power and fiber optic communications. They are designed for reeling and offer excellent flexibility and high tensile strength. Special coating compounds effectively withstand the harsh marine environment.
Reels: Reels are used for cable storage. The inner diameter of the reel should be selected to meet the minimum cable bend radius requirements and ensure the optimal relationship between torque and cable tension. The outer diameter of the reel should be selected to accommodate the entire cable.
Guide: The guide provides a relatively frictionless path for the cable between the drum and the ship’s side. It consists of multiple rollers arranged with a radius greater than the cable’s minimum allowable bend radius.
Assembly: The assembly is used to transmit power and data between the rotating, reeled cable and the fixed mechanical cable.
Hydraulic Transmission: The hydrodynamic transmission is a specially designed reduction gearbox containing an oil-immersed, torque-regulated clutch. Torque is generated by shearing oil between two rotating metal discs. The pressure applied to the interface, and the resulting torque, can be easily adjusted over a wide range.
The AMP concept has come a long way. Initially, cold ironing was used solely as an auxiliary device for tanker refueling. However, given its widespread use and significant growth in recent years, it can be assumed, even hoped, that alternative marine energy sources will become even more important and necessary than they are today.
Ship-to-Shore Transfer Procedure
There are two transfer methods: automatic and manual.
In automatic transfer, synchronization and load transfer occur automatically. Manual transfer allows for manual synchronization and load transfer. Both automatic and manual synchronization transfers can be accomplished by operating a single generator. The load needs to be lowered and switching needs to be achieved at the lowest load.
Cold Ironing Circuit
Ampere Connection Procedure
First, ensure the generator is running at the lowest possible load and that the voltage is approximately 440 volts. To lower the cable guide, first connect the remote control to the drum. The drum is then ready for operation. The operating indicator light on the drum control center will illuminate.
Push the cable upward and lift it from its position. When it reaches its maximum limit, the drum will automatically stop rotating.
Guide the cable to the cable drum guide and press the lower button to prepare for lowering. Press the unload button and unload the cable, ensuring there are no obstructions, twists, or tangles. Continue unloading the cable until it reaches the port staff on the pier.
Port staff should pull the cable toward the terminal box while it is still loose, then remove the protective cap at the end of the cable and connect it to the shore station. The cable plugs must be connected according to the color code and connected correctly.
After the cable is connected, switch the selector switch to the automatic position. The drum will automatically operate to recover any slack caused by vessel movement and wind.
You will need to confirm with the port staff if you are using a fiber optic connection. If so, you need to place the fiber optic switch in the master position. If not, you can connect via VHF or telephone.
Execute an emergency stop on the AMP control panel. The pilot standby light should go out to confirm that the emergency stop has been activated.
Execute an emergency stop on the cable drum control panel. The light should go out to confirm that the emergency stop has been activated. Reset from the panel.
After all tests are complete, activate the vacuum circuit breaker (VCB) and close the breaker. Verify with shore personnel that the VCB can be closed. Once confirmed, close the VCB.
Once the voltage circuit breaker (VCB) is closed, the vessel can be synchronized. Synchronization can be done automatically or manually. First, you must check the shore power reception parameters to ensure they are correct and within the valid range. For automatic synchronization, press the “SYNC” button on the AMP control panel. The shore power will synchronize with the vessel’s generators. For manual synchronization, you can use the synchronization method or the three-light method.
After the shore power and the vessel’s generators are synchronized, you can discharge the generators, allowing the shore power to absorb the full load. Once the generators are discharged and the voltage circuit breaker is opened, the vessel can operate on marine AC power.
Ports charge for the electricity they provide (in kilowatt-hours). Therefore, when using marine AC power, it is always recommended to use the lowest possible load to avoid significant cost increases.
AMP Disconnection Procedure
The disconnection procedure is the reverse of the connection procedure. The following steps must be followed to discharge shore power and charge the vessel’s generators:
Start the vessel’s diesel generators and synchronize them with the shore power, either automatically or manually. After the generators are properly charged, open the voltage discharge circuit breaker (VCB) to discharge the shore power. Do not disconnect the AMP VCB until confirmed with shore personnel.
Once the AMP VCB is disconnected, the vessel will operate on the ship’s generator, and the connection is complete. The cable must be ready for disconnection.
Switch the selector to the manual position and press the “Down” button to disconnect the cable.
Dock personnel must disconnect the plug and socket and replace the cover.
Press the “Up” button to restore the cable. Avoid pulling the protective plug cover along the dock; this is best done manually to reduce wear.
Continue to press the “Up” button until it reaches its maximum limit. With the help of another person, press the “Down” button and guide the plug to the stop area. Close the reel control center. However, while cold ironing has many advantages, it also has some disadvantages. The most important of these can be summarized as follows:
Cost. Due to the large size of ships and tankers, electricity consumption can be very significant. This is a major disadvantage of cold ironing.
Any port where these ships call to load or unload cargo, and thus perform cold ironing, requires significant investment to install the necessary cold ironing equipment.
Some ships are incompatible with or unsuitable for alternative marine energy sources. Furthermore, equipping these tankers with appropriate cold ironing equipment would require significant investment.
Pollution reduction can only be achieved when the ship is stationary. When the ship is in the water, pollutants are released into the marine atmosphere due to the use of conventional engines.
