Thomas Høven
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This article is about electric shore power connections in port for vessels in regular service. The main purpose is to reduce emissions from vessels while in port, and for some vessels, to include charging onboard batteries. This article does not cover the needs of vessels under repair, laid-up vessels, and permanently moored vessels.
Electric shore power connection systems have been in limited use for more than a century. Figure 1 shows an electric battery-powered vessel launched in the 1880s. Requirements for reductions of emissions from vessels while in port became a requirement in California around 2010. The Air Quality Management District in California proposed a ruling to cold iron for the Port of Los Angeles and Port of Long Beach only. But quickly, officials determined that it was premature. Around 2002, California was serious about implementing cold ironing. In 2006, the IEC/ISO/IEEE (see “Acronyms Used in This Article†for an explanation of the acronyms used throughout) started work in preparing a standard.
Figure 1. More than 100 of these electric vessels were supplied for use on lakes and canals in Germany from the 1880s onwards. Steam engine fumes were found not acceptable. No documents could be found on the shore power connection system used. (Source: Historic Siemens AG image.)
Utility connections in port are required to allow ships to stop their onboard auxiliary diesel generators while in port. This affected a larger number of ships, raising the need for developing an internationally recognized standard for utility connections in port. Large container ships and cruise ships were among the first to apply the standard for high-voltage (HV) connections that came out in 2012: the 80005-1. An updated revision came out in 2019, and Amendment 1 was issued in 2022. To meet the demands for smaller vessels using low-voltage (LV) connections, a Publicly Available Specification (PAS) was issued in 2014 as PAS 80005-3. A standard for monitoring and control communication was issued in 2016 as 80005-2.
The Joint Work Group 28 (JWG 28) is the group of experts drafting the proposals for the 80005 series of standards for utility connections in port. The expert group consists of about 80 experts from around the world, mostly from IEEE and IEC. Members come from government organizations, port authorities, ship operators, equipment suppliers, and others with an interest in utility connections in port. JWG 28 presents the drafts for IEC and IEEE for commenting and voting, including more than 170 IEC member countries, before it is issued as a standard. The 80005 series of standards for utility connections in port currently consists of the following:
PAS indicates that the document has been developed quickly to meet demands using a simpler approval process than a full standard. In this case, it is intended to be developed into a full standard.
JWG 28 is continuously working on updates and new standards related to utility connections in port. Much of this work is based on identified market needs and requests from businesses and authorities worldwide.
Ongoing work as of October 2022 includes the following:
Recently completed work as of October 2022 includes the following:
This standard was issued in 2012 and 2019, and an amendment was issued after that. HV here is 11 or 6.6 kV, mostly 60 cycles. Many utility connection systems in port are built according to this standard, and there is no work ongoing at this time to revise the existing text in this standard and the associated amendment with one exception: the annex on tankers. The standard has a section with general requirements, and annexes with requirements specific to certain ship types: roll-on/roll-off (ro-ro); cruise ships; container ships; LNG carriers; and tankers. The three first ship types are seeing the widest use. See Figures 2 and 3 for examples of these three types. Container ships are a special case where the standard specifies that the cable management system shall be on board the ship as having such systems shoreside in a container port would conflict with the container movements around the terminal. JWG 28 is not aware of any significant issues with this standard.
Figure 2. (a) An HV connection system for a cruise ship. (b) Shore power cable management on board a containership. (Source: Cavotec; used with permission.)
Figure 3. An HV shore power connection system built for passenger ro-ro (ro-pax) vessels according to 80005-1. (Source: Thomas Høven.)
Future developments planned are related to one existing and two new ship-specific annexes: vehicle carriers (a revised draft has been circulated for comments); tankers (not started); and automatic connection systems (started but in the very early stages; project not formally approved).
The LV standard, 80005-3 PAS:2014, is based very much on the 80005-1 and is not considered a fully developed standard, and it is in urgent need of a significant update. Voltages covered are in the 400–690-V range, 50 or 60 cycles. The current PAS has annexes for certain ship types. The direction it is currently moving in (as well as the current status) is a move away from ship-specific annexes in LV. As this work is in progress, final decisions have not been made, but currently, the main concept discussed is to make the system described in 80005-3 Annex C become the proposal for all ship types, even for container ships. Figure 4 shows an installation made according to this standard. Small container ships (using LV utility connections) more often visit ports that are not dedicated container terminals and also have less space on board for a cable management system. Smaller ships calling at different types of ports make it more beneficial to have the same shore power connection system everywhere.
Figure 4. A typical LV utility connection system built according to 80005-3. (Source: Thomas Høven.)
There is a challenge with the national code in some countries not permitting the same plug to be used for different voltages. JWG 28 is still discussing how to address this. One option is to specify the system for 690 V, and if permitted by local code, allow the use of lower voltages. A smaller and lighter system for the smallest vessels limited to 400 V/50 cycles and 440 V/60 cycles has been discussed, but no consensus has been made. If included, it will be an addition to what is currently being discussed and may mitigate the issue of different voltages in the same plug. As for the HV standard, an annex for automatic connections will also be considered for 80005-3, but it will most likely come as an amendment after the revised 80005-3 has been published.
Very early discussions have been started on electrical shore connection systems primarily targeting the charging of large onboard battery banks for energy storage used as part of the (or the only) source of energy for propulsion. The published 80005 series of standards has not been written with this use in mind, and the current opinion of JWG 28 is that these requirements are best described in a new standard. This may become a new 80005-4, but this project has not yet been formally approved by the involved standardization bodies. However, the need for such a standard is now requested in certain markets. In lack of a standard, there are currently many different shore-power connection systems in use for battery-equipped vessels. These include differences in the physical connection systems; different voltages used; and how the voltage is controlled. For systems with higher power needs (>2–5 MW), 11-kV ac is sometimes used with a step-down transformer and rectified on board. Smaller vessels may use LV ac or dc.
For weight-critical vessels, like high-speed passenger ferries, this solution is not desirable, and a direct dc connection to charge the batteries will be preferred. We are looking at systems developed and used for electrical vehicles (CCS and MCS, see www.charin.global), which may suit certain power demands for some types of vessels and will have the benefit of being large-volume products, bringing unit costs down. We must also consider other systems depending on the needs of this segment of marine shore power connections.
For local ferry services using electric energy storage and propulsion, quick connection times are essential as longer charging times allow a reduction in the installed battery capacity. Many such vessels stay in port for fewer than 10 min, and some may call at ports more than 20 times daily. For one such service in Norway, it was calculated that a 15-s-longer charging time in port allowed a $US50,000 reduction in the investments for the required onboard battery system per vessel.
Ships come in many types and sizes, making it impossible to identify a “one-type-fits-all†solution. Larger ships often call at ports built to receive only one type of ship. This makes it easier to specify a connection system specifically designed for each ship type as it is specified in 80005-1. For smaller ship types, this is more of a challenge as both ships and ports are more diverse. Smaller ports more often receive vessels of different types at the same berth. Battery charging often requires very quick connections to allow sufficient time for charging, particularly for short-distance vessels in regular service. This calls for a different connection solution where speed and automatic operation are essential.
This challenge has been found where electric ferries are servicing more remote areas; have a short stay in port for charging; and need high power during that short stay—up to 10 MW, like the example shown in Figure 5. One solution already in use is to install another battery onshore that charges at a much lower power level and then discharge into the vessel at high power during its short stay in port. Another solution would be to have swappable battery systems.
Figure 5. Bastø Electric operating on a 20-min crossing of the Oslo Fjord. Nine MW of power is needed for charging while in port. Norway has about 60 electric and hybrid ferries in operation as of September 2022, with about 20 more coming into service. (Source: Thomas Høven.)
This challenge has also been identified for ports planning to receive several vessels with onboard battery systems at the same time. One example is a fleet of fishing vessels arriving during the fishing season. Here, the challenge is not the quick connection time but the total load on the utility power grid. In this case, a system to control the power used for charging must be managed by the port limiting the power consumption to prevent grid overload. This will often be acceptable, particularly where vessels are hybrid vessels (having both a diesel engine and an electric system for propulsion). Such a system has, to my knowledge, not been installed yet but is being planned. There are no suitable standards describing such systems today for marine use, but it shares many similarities with charging stations for vehicles. The CCS system designed for vehicles is being deployed in some areas for marine use for smaller craft.
Introducing electric connections between shore and ship also introduces the risk of electric current finding a return path through the hull and sea. The result will be galvanic corrosion, which may severely damage the hull, propellers, and rudder. This has been observed in some cases, and the most common recommended mitigation is to make sure the electric supply to the vessel is galvanically isolated from the shore supply. This method is also described in the standards for utility connection in ports.
In some cases, the utility shore power uses the same voltage and frequency needed by the vessel, and it is of commercial interest to try to avoid the transformer, which in this case is used only to provide galvanic isolation. One method applied is to disconnect the grounding between ship and shore to break the return current path. This involves certain risks and the need for careful monitoring of differences in the electric potential between parts expected to be bonded. A deviation from national codes will usually be required.
Plug and connection systems have fault ratings, which may be exceeded unless the utility connection system is properly designed. A particular risk is where parallel connections are used, and a fault in one of the connections results in all the others feeding fault current into that connection. The separate protection of each of the connections is required. Another risk where vessels with batteries are connected is the high fault level contributions from the batteries. This is particularly important to consider where a dc connection is used for the shore power supply directly connected to the batteries for charging. This solution will often be preferred for fast vessels where limiting onboard weight is essential.
Modern ships typically have a lot of power electronics on board. If such equipment is in operation while connected to shore power, there will be electric disturbances, including harmonics, introduced into the onshore utility power grid. Whether this is acceptable or not will depend on several factors. A ship with a certain number of harmonics generated may be acceptable in a port where the power grid is strong (low network impedance), but the same ship connected to a weaker grid or a grid already having harmonic content may raise the level of harmonic content on that grid to unacceptable levels. Work is still needed to better define the requirements for ships and ports to make sure a ship can safely connect in any port.
System neutral and what to do with it has caused several discussions in the expert group drafting the 80005 series of standards. There are different practices in different businesses and countries, some following the division between those primarily using ANSI standards and those primarily using IEC standards. This has resulted in a consensus on what to include in the standards, which do not always include all the details but leave some for the design engineer in each project to decide on, also considering the applicable national code for the project location. Some shipping industries wanted to be more specific on certain details to ensure a more uniform design practice. For example, the container industry specifies a single voltage (6.6 kV) and a value for the neutral grounding resistor (NGR) (200 Ω), while the cruise industry allows both 6.6 kV and 11 kV and a 540-Ω value for the NGR and a described standard system grounding arrangement. This allows the designer of ship power systems to identify the ground-fault current that can be experienced when connected to shore power to make sure the onboard system will work with that ground-fault current.
Utility connections in port will often involve major investments to be made, both on board and shoreside. Operation and maintenance are other costs to be covered. Most shore power connection systems are being driven by regulations introduced to reduce emissions while not being commercially attractive without such regulations. Subsidies and/or increased contributions from end customers will be required to make this work, or alternatively, imposing taxes on those who do not connect.
Some ports receive only ships of certain types during a short season every year. A good example is the cruise industry, which visits certain areas only during a short season every year. Figure 6 shows three large cruise ships in the port of the Norwegian town of Stavanger, popular with cruise ships during summer. Investments in utility connection systems will be very high compared to the actual electric energy delivered. Financing this by increasing the cost of shore power electricity alone will quickly become prohibitive. Subsidies will likely be required, or one may consider the money better spent on other environmental programs that give more emission reductions per dollar spent.
Figure 6. Developing expensive shore power connection systems for several large cruise ships with high power demands is a commercial challenge where the cruise season is short, and the investments do not generate revenue most of the year. (Source: Thomas Høven.)
Invoicing the supplied electric energy includes the following options:
The choice of payment model must be considered for each port. If a berth receives only ships from a single operator, which is often the case with ferries, direct invoicing from the utility company to the ship operator will often be the most efficient solution. If berths are used by different ship operators, it is the port that knows which customer is connected to what shore power connection point at any time. The utility company will often not have the means to keep track of this, and invoicing via the port may be more feasible.
Having all financial costs of the investment on shore power systems paid by a markup on the supplied electric energy will in many cases result in unacceptable high energy costs. This may call for subsidies or other sales models for energy. Some areas have an abundant availability of energy during certain periods. This energy is often sold at very low prices, like from a wind turbine farm on windy days. It should be considered to let ships buy this energy at reasonable prices and allow the ships to run internal diesel-powered generators when reasonably priced shore power energy is not available.
The positive effect on the environment locally and globally is the main driver for utility connections in port, eliminating the local impact of exhaust fumes in populated areas or tourist destinations and reducing greenhouse gas emissions. Other Health Environment and Safety (HES) benefits include a quiet ship while in port, to the benefit of both the nearby surroundings and those staying on board while in port. Shore power is in many cases also a more reliable and safer source of energy than an unattended diesel engine running.
Reference is made to this in the “How to Invoice the Supplied Electric Energy†section. In some countries, it is not allowable to (or it is a legal challenge to) resell electric energy supplied by utility companies.
Different legislation in different countries sometimes limits what can be standardized. There may also be cases where the majority of member countries vote in favor of a solution even if it is not permitted in some countries. One such example is that some countries do not allow a certain plug to be used with different voltage levels, while others do, particularly if the system is required to be used by instructed personnel only.
Agreements will need to be in place to handle denial of service, which is particularly a problem for vessels using batteries as the main source of energy storage for propulsion. Ships with auxiliary diesel power generators must be allowed to use these in case of a denial of shore power service or power outages. The agreement should state how a denial of service shall be communicated. It should also advise on responsibilities in case of unexpected power outages, including any power supply guarantees.
Requirements for shore power will quickly become more widespread as more countries “go greener.†It is expected that more countries and businesses will take an interest in utility connections in port.
We see a clear trend that the power demands while in port are increasing for the same types of ships and services every year. This also results in the introduction of higher voltages for many services. It is important to design and standardize systems that take this into account to prevent solutions and standards from becoming outdated in the near future.
We will see more electric and hybrid vessels using electric-powered propulsion systems. Large batteries will be more common, as will the use of power electronics in more applications. This will raise the need for a number of new or updated solutions to be developed. This includes direct dc connections from shore to ship to charge batteries directly, eliminating the need for transformers and rectifiers on board. CCS or MCS may be the answer for some categories of vessels, while others will need solutions not yet identified.
Utility Connections in Port – Part 1: High Voltage Shore Connection (HVSC) Systems - General Requirements, Edition 2.0, IEC/IEEE Standard 80005-1, Mar. 2019.
Amendment 1 - Utility Connections in Port - Part 1: High Voltage Shore Connection (HVSC) Systems - General Requirements, Edition 2.0, IEC/IEEE Standard 80005-1, Feb. 2022.
Utility Connections in Port – Part 2: High and Low Voltage Shore Connection Systems Data Communication for Monitoring and Control, Edition 1.0, IEC/IEEE Standard 80005-2, Jun. 2016.
Utility Connections in Port – Part 3: Low Voltage Shore Connection (LVSC) Systems – General Requirements, Edition 1.0, IEC PAS 80005-3, Aug. 2014.
Thomas Høven (thomas.hoven@siemens-energy.com) is an engineering supervisor at Siemens Energy AS, 0596 Oslo, Norway, and is the convener for the IEC/IEEE/ISO Joint Work Group developing the proposals for the 80005 series of standards.
Digital Object Identifier 10.1109/MELE.2022.3232953
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