E-Tug Charging S.Diego

With the caveat that I’m a cynical boomer deck officer, 5 years retired, help me understand this E-tug phenomenon.
A recent article indicated “total capacity of 2,990 kW, with each container housing battery modules with a storage capacity of almost 1.5 MWh”. The charging facility includes a solar array.

  1. Realistically, what’s the “delta” in emissions between the propulsive engine on the tug when its underway vs emissions required at the fossil-fueled power plant ashore?
  2. How often does it need a recharge when working?
    3)CA already offers shore-power connections for moored vessels-so the tug, when not underway could plug in.
  3. How much energy is collected from the solar array?
  4. Where are the charging stations between AL & CA?

Remember the old saying about assumptions? Why assume the power comes from a fossil fuel plant?

San Diego claims 55 percent of their power is produced by renewables such as solar and wind.

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Since I didn’t use the word “assume”, my query stands. If SDGE is truly getting 55% renewable, that leaves 45% dead dinosaurs or nuke.

  1. no idea. I have looked at California as a whole and recall above 50% of their energy is from natural gas.
    2)Vessel is designed to work an 8 hour day. Remember harbor tugs average duty cycle is quite low. Requirement of SD was that the vessel could do bollard pull scenario (70 short tons) for 30 min. Batteries are designed to be able to complete the specified mission and the end of the useful life so there will be more margin early on. L-drive thrusters with 2100ekw e motors on each thruster, its a PM motor so you could have some ability to recharge with current at the dock or potentially while being dragged behind containership but I have no doubt the pilots would not prefer that.
    3)i asked that same question the other day, doubtful its much towards the actual usage but I guess it all adds up and that space is not being used for anything else.
    4)there are none, vessel will be shipped to SD
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I don’t know how charging will be done in California, but the many electric and hybride ferries in Norway (as of July 2023, there are 87 electric ferries and boats in operation, distributed over 56 routes) charge at each end of their crossings, using autonomous system installed at the ferry wharfs.
There are several companies supplying charging systems. Here is one of them:


PS> The power grid in Norway is supplied by hydro electric and wind turbines. (No coal, Gas or Nuclear)

Maybe this answer some of the questions raised here?: