Beginning in early 2024, a new microgrid-powered electric tugboat will be a workhorse for the Port of San Diego, pushing and pulling big container ships and tankers to help navigate them into the port.
But another important workhorse is the microgrid that will power the eWolf, an 82-foot tugboat from Crowley Maritime that draws up to 1 MW per hour until it’s fully charged at 6 MW.
Electric tug to be powered by solar and batteries
The microgrid serving the eWolf — which includes 3 MW of batteries and 74 kW of solar — will power the tug from a custom-designed, shoreside charging station that includes batteries from Corvus Energy, said Alberto Cordero, director of business development, advanced energy at Crowley Maritime.
The project is a partnership between Crowley, the San Diego County Air Pollution Control District, the California Air Resources Board, the Port of San Diego, the U.S. Environmental Protection Agency and the U.S. Maritime Administration — which all provided financial support and other resources.
Another California microgrid for electric boats planned
Crowley has additional electric tugboats in the works, along with microgrids to serve them. The company’s projects include a microgrid in California comprised of 1 MW of solar, 6 MW of batteries and 300 kW of hydrogen, Cordero said. Electrifying tugboats can displace about 30,000 gallons of diesel a year, he added.
The electric tugboat projects are part of a growing effort to provide power for transportation electrification with microgrids, reducing diesel, stress on the grid and demand charges from utilities. They’re also an alternative to utility power in areas where utilities can’t meet the needs of large electrified loads.
For example, Schneider Electric, in partnership with Miller Electric, has deployed a microgrid in Jacksonville, Florida, to power the city’s electric buses as well as educate the growing number of individuals and organizations interested in electric vehicles (EV), said Chris Evanich, program director for energy as a service at Schneider Electric.
The microgrid is part of a public facility in Jacksonville – the EV Innovation Design Center – that aims to help EV users evaluate different charging options.
A microgrid on tap for Jacksonville Transportation Authority
Schneider and Miller Electric are planning another microgrid for the Jacksonville Transportation Authority (JTA), which wants to electrify its bus fleet, said Kerri Stewart, chief strategy officer at Miller Electric.
“There is not enough energy currently coming from the utility to power the charging stations necessary to charge the fleet of buses,” Stewart said. Schneider and Miller are working with the JTA on a solar, battery and microgrid deployment to address these challenges. The microgrid will manage the energy from the utility along with the energy stored in the batteries. In addition, the microgrid will control the flow of energy from a solar array on JTA’s maintenance facility’s roof that is expected to overproduce, she said.
“Sometimes feeding electricity to electric fleets with grid power can be challenging when the local grid doesn’t have enough capacity at any given moment,” said Evanich. A microgrid that includes solar and a battery can charge big loads — and do it with clean energy, he added.
Utility limitations increase microgrid use
High utility demand charges also give electrification advocates a reason to choose microgrids.
In San Diego, if Crowley had decided to charge the eWolf with only grid power, it would have had to charge very slowly — below 500 kW per hour — or pay high demand charges, said Cordero.
Instead, Crowley is using solar and grid power to charge the microgrid. The company can decide when to charge the microgrid’s batteries — which can reduce or eliminate demand charges — or choose to charge the batteries slowly. The solar array will provide some resilience, he said.
The electric tugboat will operate at the Port of San Diego’s Tenth Avenue Marine Terminal. The charging station, which was custom designed, will be available to other electric boats.
Inductive charging for electric buses
However, the lack of standardization in charging plugs — especially for boats and buses — will make it difficult for existing boats and buses to use the charging station.
Schneider Electric and Miller Electric will address the standardization challenge with inductive charging — along with other forms of charging — at the EV Innovation Design Center.
Inductive charging, in this case for buses, is wireless charging that can provide more power.
A number of other microgrids are now deployed to provide charging for EVs, including Duke Energy’s depot near its Mount Holly microgrid in North Carolina. It demonstrates how to charge EV fleets from both a microgrid and the grid.
The project is designed to help speed the electrification of commercial fleets, a growth market for both utilities and microgrids.
Helping fleet owners get unstuck
But not all utilities are as proactive about meeting the needs of electric fleets.
Microgrids can help fleet owners get “unstuck” from utility limitations and accelerate electrification efforts, Evanich said.
“The microgrid makes a really great solution when a utility can’t or won’t take capacity or doesn’t have capacity. They’re for customers that are stuck right now,” he said.
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