Scrub-less in Seattle, but not yet in Tacoma

Last month, we celebrated the news that Canada’s largest port, the Port of Vancouver, had implemented a scrubber washwater ban for all ships at anchor and at berth. It’s a very encouraging and progressive development, and broader restrictions will come in future phases. Now the proverbial scrubber-ban ball is passed back to Vancouver’s U.S. neighbors to the south, Seattle and Tacoma.

Since July 2021, when the Port of Seattle released Terminals Tariff No. 5, passenger cruise ships have been restricted from discharging scrubber washwater while at berth. However, after fierce negotiations between port authorities, environmental organizations, and the cruise industry, the ban is only guaranteed to be in place until the completion of an independent study commissioned by the port on washwater content. The ban might be lifted after that, but it’s unlikely the study will find much different from the many independent studies that have already been done, and they show that washwater content is polluting and damaging to marine organisms. Just 50 kilometers away from Seattle, though, the Port of Tacoma doesn’t currently restrict any scrubber discharges.

Both ports should follow Vancouver’s lead and ban scrubbers permanently, but there’s also an opportunity to do more. Indeed, the Northwest Seaport Alliance, which covers the Seattle and Tacoma ports, could become a leader in the transition to zero-emission technologies by combining progressive environmental policy and its ambitious greenhouse gas (GHG) emissions reduction goals—to cut total port GHG emissions by 80% by 2050 compared to 2005—with its already established supply of low-carbon electricity. About 86% of the region’s grid is hydroelectric powered, and less than 10% of electricity currently comes from fossil fuels. Moreover, last year, Tacoma Power adopted a one-of-a-kind electro-fuel tariff to support low-cost production of electrolytic hydrogen. The goal is to promote fuel cell technology by incentivizing the production of “green” hydrogen that can replace fossil fuels, and one of the possible applications is providing shore power to docking ships through floating, barge-mounted hydrogen-fueled proton exchange membrane (PEM) fuel cells.

The potential is exciting. In 2013, the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy published a study that considered the feasibility of implementing this technology at major West Coast ports. It showed that using PEM fuel cell barges is more technically feasible in Tacoma and Seattle’s ports, especially for container ships. This is due to the ports’ already existing in-port electrical power demand, environmental regulations, safety and operational rules, and the frequency and logistics of port visits.

Note, too, that this would not require building infrastructure at either port, because the fuel cells are capable of providing electric power directly to vessels at berth if the receiving ship has a shore power connection. A fuel cell barge typically includes hydrogen storage, a PEM fuel cell, and power conditioning and cable equipment. The equipment is placed on the flat top of a barge that can approach a berthing ship and plug in. The barge size can vary depending on the hydrogen volume and number of batteries stored onboard. An additional advantage of this system is its service flexibility, as it can carry equipment of different voltages, frequencies, and plug-in configurations.

Importantly, this hydrogen fuel can be deployed in a way that’s complementary to solving the issue of scrubber pollution. We’ve written extensively about what scrubber washwater discharges mean for the marine animals that traverse the Georgia Basin-Puget Sound area, unaware they will be in contact with pollutants from washwater including nitrates, polycyclic aromatic hydrocarbons, and heavy metals. Imposing a scrubber washwater ban would also bring significant health benefits to the people living near the ports. Further, if a ship could plug into shore power instead of continuously running its engines and burning heavy fuel oil (HFO) or another fossil fuel while in the port, that would reduce the risk of both water pollution and air pollution.

To get a sense of how much washwater discharge Seattle and Tacoma would avoid if they were to follow Vancouver’s lead and permanently ban scrubber discharges, we utilize the methodology from our global scrubber washwater discharges report from last year. That study used 2019 ship traffic data and estimated discharges within a 1 nautical mile radius of ports. To refine those results, we re-calculate washwater discharges from the ships operating within both ports’ legal boundaries, as provided by the U.S. National Oceanic and Atmospheric Administration. We estimate that 56 ships in the Port of Seattle and 68 ships in the Port of Tacoma operating in 2019 had scrubbers installed by the end of 2020. Without the current ban in Seattle, these 56 ships are estimated to discharge 1.5 million tonnes (Mt) of scrubber washwater each year, 81% of it from just 14 cruise ships. Cruises at berth would have been responsible for nearly 1 Mt (66%) of washwater discharges in Seattle, but again, that is avoided due to the ban. In contrast, the ships equipped with scrubbers in the Port of Tacoma are mainly container ships; these were 47 out of 68 ships sailing within the port’s boundaries and were responsible for 97% of the total 0.8 Mt of scrubber washwater discharge. The distribution of the discharges is illustrated in Figure 1.

Map illustrates the spatial distribution of discharges in the two ports

Figure 1. Washwater discharges distribution in the official port boundaries of Port of Seattle and Port of Tacoma. Data sources: NOAA port boundaries, exactEarth (AIS data); IHS (ship characteristics data); Clarkson Research Services (scrubber characteristics data); and QGIS (map layer: Stamen Terrain – USA/OSM).

We also see that ships with scrubbers are already taking advantage of shore power where it’s available. One cruise terminal at the Port of Seattle currently has shore power installed, and two more terminals are expected to have new capacities by 2023. Tacoma will add shore power soon; the Northwest Seaport Alliance raised $2 million for electrical infrastructure construction in the port by the end of this year. We estimate that about 32% of banned washwater discharges in Seattle could have been avoided because of the existing shore power supply, as 40% of the cruise ships that operated there were able to plug in and the average berthing cruise ship in Seattle emits 68,000 tonnes of washwater annually. In Tacoma, half of the container ships that called on the port had compatible plug-in equipment. Assuming enough shore power to supply all of these ships, approximately 38% of washwater from berthing containers could have been avoided (Figure 2).

charts show number of ships and washwater discharges, including those that could be avoided with shore power

Figure 2. Number of ships with scrubbers and corresponding washwater discharges in thousand tonnes (kt) by ship type.

Shore power could be doing much more if ports authorities provide enough shore plug-ins to serve all ships, and if all docking ships were equipped with compatible plug-ins. So, why not let a scrubber ban also serve as a catalyst for shipowners to install compatible plug-ins and for ports to increase shore power supply?

First, the Northwest Seaport Alliance can follow the Port of Vancouver’s example and ban scrubbers permanently. It will be an important step by itself, and also help incentivize ships to install compatible plug-ins to access shore power. With that done, the ports can be more confident in expanding shore power, either in ports or by setting up PEM fuel cell barges. As we’ve shown here, demand already exists, as a number of ships with scrubbers are using shore power when they can. And with an abundance of renewable electricity already available, it’s crucial that shore power use expand soon. All three ports made the joint commitment to phase out emissions from seaport-related activities throughout the Georgia Basin-Puget Sound airshed by 2050, and it’s important to keep promises.

Alternative fuels Electrification
Emissions control