Shoreside Power: To Plug or Not to Plug

The Port of San Diego’s ‘bonnet’ system of emissions control and capture. Photo: Port of San Diego.

In 2008, the California Air Resources Board (CARB) laid out new regulations that mandated strict reductions in air pollutants produced by container, cruise and refrigerated cargo ships docked at the busiest ports in the state.

Scaled upward over the following years, the key requirements of the regulation called for a minimum cut of 80% in emissions starting in 2020.

The directive—the strictest such pollution control guidelines in the country—has sped the implementation of so-called “cold ironing,” in which ships damp their main and auxiliary engines while at berth and “plug-in” to power onboard generators and other equipment with high-voltage electrical power provided by a shore-side grid.   

According to CARB, providing shoreside power to a cargo vessel for one day provides air quality improvement equaling the removal of 33,000 cars from the road for that day. 

In September, officials seeking to meet California’s emissions- control directive faced a major challenge as the state sweltered in a record-breaking heat wave.


Record high temperatures prompted Gov. Gavin Newsom to issue an official State of Emergency proclamation that included a weekend-long moratorium on ships at the states’ seaports plugging in to shoreside power. The directive marked the third summer in a row in which outage fears prompted an emergency proclamation from the governor that restricted the ability of the state’s ports to offer shore side power.

“We are prepared for those moratoriums to continue into the near future as our members transition more towards an electrical infrastructure and zero-emissions equipment at the state’s ports,” said Mike Jacob, vice president and general counsel at the Oakland-headquartered Pacific Merchant Shipping Association (PMSA).

Despite the State of Emergency, the Port of Los Angeles proved an exception to the rule as it was little affected by the directive. 

Shore power at the port is linked to the city of Los Angeles’ independent power grid, which, at the height of the September heat wave, was actually selling excess electric power to neighboring agencies. 

The port—ranked as the No. 1 container port in North America by annual volume—was at the forefront of employing plug-in technology over the past two decades. The agency supplied power through 25 shore-side power hook-ups at its seven container terminals.

Christopher Cannon, the Port of L.A.’s chief sustainability officer and director of environmental management, though, is quick to offer a caveat, stating “that’s not to say that we couldn’t be impacted in the future,” adding that the port is working with the city energy agency to gear up for the anticipated strain on its electricity capacity—a strain caused by the gradual shift to electric vehicles and cargo handling equipment at its terminals, as well as shore-side power for vessels calling at the port.  

“We’re working with the (L.A.) Department of Water and Power to make sure that there is enough electrical generation capability in the future, not only to meet the anticipated surge in the need for shoreside power, but the transition to electric vehicles and cargo-handling equipment fueled with energy produced without causing dirty emissions,” Cannon said.


Adjacent to the Port of L.A. is the Port of Long Beach. Together, they form a massive shipping hub with more than 40% of the nation’s containerized cargo imports passing over their docks every year.

Unlike its neighbor, which is governed by the City of Los Angeles, the Port of Long Beach is an independent entity from the City of Long Beach.

The first ship to plug-in at the port was the tanker Alaskan Navigator. The 941-foot vessel berthed at the BP Terminal on Pier T in June 2009 and was connected to what the port billed as the world’s first onshore power supply (OPS) grid, built at a cost of more than $23 million. 

Within five years, the port had installed dockside power capability at its Pier C, Pier F and Pier J facilities.

Since then, the Long Beach port has installed more than $185-million worth of dockside power hookups and other infrastructure to facilitate shore power.

“In the interest of cleaner air and reduced greenhouse gas emissions, the Port of Long Beach pioneered the use of shore power for container ships and has made major infrastructure investments to deliver shore power to our terminals,” POLB Managing Director of Planning and Environmental Affairs Heather Tomley said.

The port, she said, “remains committed, and we are pushing forward to achieve a zero-emissions future. We are collaborating with our energy partners on plans to meet future demand and increase resiliency of the supply.”

The Port of Oakland has a decade-long commitment to providing shore-side electric power. The port first plugged in a containership—Hapag-Lloyd’s Dallas Express—in December 2012, and over the past decade has made improvements to help secure its power needs making it, in a sense, energy independent.

In March 2017, the port, which operates its own electrical utility, inked an $8.9-million deal to purchase solar power for 20 years and resell the electricity to port tenants.

Under the agreement, the port committed to buy approximately 11,000-megawatt hours of electricity, or about 35% of the renewable energy it needs by 2030, to meet California renewable energy mandates. 

In 2021, the port had an overall ship plug-in rate of 70%. As of August 2022, 333 of the 552 vessels calling at the port’s four terminals successfully drew shore power, a rate of 60%.  

During that eight-month period, vessels operated by MSC (eight calls), Yang Ming (two calls), One (12 calls) and Hyundai (one call) drew 100% of their power shore side while berthed at the port. Matson (12 calls) drew 92%, followed by Evergreen Marine (eight calls, 75%), CMA-CGM (six calls, 67%) and Maersk (nine calls, 33%).

Oakland operates its utility with an infrastructure that runs from its main substations to on-terminal substations.

“We didn’t have any rolling blackouts at the seaport during the heat wave and have performed multiple reliability projects that increased efficiency to the power grid at our harbor and airport in just the past few years,” Jared Carpenter, the Port of Oakland’s utilities administration manager said. “We’ve modified our entire energy metering system over the past three years to increase data to better optimize the distribution system.”

“In 2020, our power content label was 70% renewable and another 13% carbon free, making us 83% green,” he said.


The American West Coast’s southernmost seaport, the Port of San Diego, self-identifies as a ‘specialty port’ handling refrigerated containers, breakbulk, dry bulk cargoes and one out of every ten automobiles shipped to the U.S. from overseas.

San Diego currently has one shore power outlet at its 96-acre Tenth Avenue Marine Terminal and one shore power outlet at its cruise terminals. A second shore power outlet is currently being installed at its cruise terminals and is expected to be online by the end of 2022.

The port is also planning to activate a new shore power system with at least two outlets by 2025 at its National City Marine Terminal and an additional shore power outlet at the Tenth Avenue terminal by 2031.

In May 2022, the agency’s Board of Port Commissioners approved a public-private partnership agreement with Clean Air Engineering – Maritime, Inc. to design, build and operate a barge-based Marine Exhaust Treatment System (METS) to both control and capture stack emissions.  

Called a ‘bonnet,’ METS involves positioning a cap over a vessel’s stack to capture and treat exhaust while the ship is at berth. When deployed the device will reduce stack emissions from non-shore powered ocean-going vessels while they are at berth.

It is expected to be operational by 2025 and will be available for use by cargo vessels that aren’t yet equipped to connect to shore power and/or for use when shore power isn’t available.

The system “will give some of our cargo carriers a great option in reducing their air quality impacts while they work to transition their vessels to being shore-power compatible,” Port board Chairman Dan Malcolm said.

California’s other boutique deep-water seaport, the Port of Hueneme—located about 65 miles north of the Los Angeles/Long Beach harbor complex—in Mid-October announced that it received a $5 million grant from the Volkswagen Environmental Mitigation Fund. The grant allows officials to purchase shoreside power hardware for the North Terminal Ro-Ro facilty, and enhance the existing “cold ironing” capabilities at its South Terminal, which berths both container ships and reefer vessels.

On average, 210 vessels per year are expected to use the North Terminal shore power facility “resulting in a 94% reduction in particulate matter and a 99% reduction in nitrogen oxides over the lifetime of the entire shore power infrastructure project,” the port said.

The Port of Hueneme, which utilized shoreside power for the first time in 2014, plans to have the North Terminal Shore Power System operational sometime in 2024. 


Despite the progress, the state’s ports are making toward a more emissions-free future, the real issue, the PMSA’s Jacob said, is the problem of “the reliability and scale of the California electrical grid, which is somewhat compromised during the summer, when you’re relying on renewable energy sources that have peaks and valleys.”

The problem, he said, “during these heat events is that there are massive amounts of demand. It’s unfortunate that we’re anticipating finding ourselves in these situations for many years to come. This will continue until there’s some massive new investment in California’s infrastructure to deliver power in the hot summer months, especially when there are potential compromises from wildfires and high-wind events that make it even harder to import power from neighboring states and jurisdictions.”

Part of that new infrastructure, focuses on two components, the Port of LA’s Cannon said.

“One is that the only proven and mature technology for reducing vessel emissions at birth is electrification and allowing us to plug in,” he commented. “And we’ve been doing that … the industry has embraced the electrification standard for vessels at birth, regardless of what the glide path is to alternative fuels for what happens when you’re at sea and what kind of technology you’re going to be using in the future to power your main engines.”  

When a ship is alongside a berth at a California port, it is increasingly subject to compliance with the state’s commitment to shore-based power—a reality, he said, that “in the short term is not going to change.”

The second piece of the puzzle, Cannon remarked, involves a serious look at alternative power for vessels, not only while berthed, but at sea, as well.

What’s needed in the long term, he said, “is developing a clear pathway to what will be the fuel of the future. Is it natural gas or hydrogen fuel cells? We’re seeing all of that now with some new U.S.-flag vessels that are being equipped with alternative-fuel systems, and in Europe, we’re seeing the development of fully autonomous, battery-powered electric ferry and feeder vessels.”  

New technologies, both ashore and afloat, are promising heralds of things to come, but the PMSA’s Jacob said there continues to be a chronic disconnect between policymakers in Sacramento and Washington, who are committed to reducing vessel emissions, and the terminal operators and ocean carriers that handle the trade so critical to the nation’s economy.  

In July, Rep. Alan Lowenthal (D-CA) upped the ante when he introduced the Clean Shipping Act of 2022 in Congress. The legislation contains a provision that specifically mandates a total shift to shoreside power by 2030 for all vessels of all types—container carriers, tankers, bulkers, Ro-Ro, cruise ships—“either at berth or at anchor” at U.S. ports.  

“We no longer have the luxury if waiting to act. We must face the fact that we are at a tipping point in the climate crisis. No emissions sources can be overlooked,” he said in a statement announcing the legislation. 

“This is a long-term policy issue and a dilemma that our member companies have to deal with on a case-by-case basis,” said Jacob, of PMSA. “This obviously comes up when these heat waves are brewing. The question is how much time you have in terms of advance warning when these situations occur.”

For example, a vessel at a port, particularly in Southern California, “can involve multi-day calls with some of the larger vessels taking three or four days at a berth. And in fact, during the pandemic, they were taking even longer because we were loading and unloading at terminals that were congested. What you don’t want to do is have those operations stopped or slowed even further, because you are having to suspend your dockside operations.”  

What’s preferable, he said, “is to have more lead time from the state, so when a new vessel comes in, instead of asking them to plug in, assuming that they’re plugging in consistent with the regulations and then turn(ing) around and ask(ing) for them to try to coordinate with the crew to unplug the vessel. That’s very problematic from a cargo operations perspective.”

Without sufficient lead time, “you’ll have some vessels that are plugged in and other vessels that need to be, and that can be a little haphazard, which means that we’re not delivering the total reduction and electrical load that the state’s asking us for,” Jacob said.

Adding another layer to the energy generation vs. regulatory conundrum is factoring in the staggering amount of energy that will be needed to electrify of cargo-handling equipment, the trucks serving the ports and rail equipment.

Estimates of the total amount of energy it would take to electrify California’s ports reaches the neighborhood of a staggering 600 megawatts, or a little more than 10% of the total energy produced annually by Washington state’s Grand Coulee Dam, the largest hydro-electric power generator in the U.S.

“We need to make sure that we have enough power not just during heat events, but as we transition toward zero-emission technology. We need to address all of our energy-supply challenges and make sure that we have adequate energy supply in the state’s grid,” Jacob said. 

“We need to support a 24/7 operating environment; we need to be able to handle surges in demand, and we need the capacity that will allow us to enhance our cargo-handling capabilities.” 

The core problem for West Coast seaports, particularly those in California?

“We have increasing power demands, but we simply don’t have a clear path towards creating the critical power infrastructure necessary to accommodate those increasing demands,” stated Jacob, underscoring comments made by PMSA President John McLaurin in 2019.

“Regulatory burdens will continue for all parties in the supply chain that do business on the West Coast,” McLaurin remarked at the time.

Typically, he stated, such state directives “raise costs and may limit operations, but do not come with any corresponding mitigation program to offset the burdens that are created.”

The supply chain, McLaurin concluded, “has been innovative in reducing environmental impacts, but, unfortunately, policy makers have not been equally innovative, nor have some recognized the cumulative impacts these regulations have on competitiveness and jobs.”