Comment by nwah1
3 days ago
Energy density of batteries is much lower than that of fossil fuels. Which means that the weight of the ships would increase. In addition to the high price of the batteries, potential risks of electrocution, etc.
There are intermediate options. Moving away from diesel towards natural gas would dramatically reduce emissions (including sulfur emissions), while retaining high energy density.
LNG and LPG marine engines do exist, and are gaining popularity. The main issues are the price of gas fuel compared to marine diesel - which is the fraction too soft for roads and too viscous for other engines so is often really cheap - and safety considerations when retrofitting in to existing ships.
Unlike diesel fuel, gas fuels are readily ignitable and present a suffocation hazard in enclosed spaces. This is solvable with installation of a proper gas detection system, but if you've ever dealt with the shipping industry you'll know that maintenance is not top of their list.
Also gas fuels require new port-side storage and handling equipment, and in the case of liquified gas this might require a refrigeration system.
Electricity on the other hand is already port-side, and most ports will have a significant supply available.
As for weight, that's not really a problem for ships, especially tugboats. In the case of tugs the near instant peek power of electric propulsion is a huge advantage.
> and safety considerations when retrofitting in to existing ships.
So, we're keeping the fire hazard, but adding a stored energy hazard in the form of compressed gas? All in a retrofit? This doesn't sound like a good idea for international ships.
> and most ports will have a significant supply available.
Are you sure about that?
> So, we're keeping the fire hazard, but adding a stored energy hazard in the form of compressed gas? All in a retrofit? This doesn't sound like a good idea for international ships.
Indeed not, I haven't heard of any large cargo ship using gas fuel at sea other than gas carriers. I know that there are some dual-fuel ships, which use gas fuel in costal waters for emissions reasons, but they carry much less gas than would be required for a full voyage.
> > and most ports will have a significant supply available.
> Are you sure about that?
Ports have electric cranes (the big ones, not the straddle cranes), shore power supply for ships, bulk goods handling facilities, etc. They often have a high voltage (110kV+) supply. This won't be true everywhere, but it is common.
Of course it's not just a drop in process and it will be expensive to get all the new equipment in place.
My nearest port got their first electric tug two years ago and they documented what they needed to do. They did have to install a new substation, but their existing 110kV feeder lines have plenty of capacity, they already consume over 13GWh per year so the increase needed to charge the tug wasn't high.
I am ignoring the issues with charging battery-electric large cargo ships because the article did not consider those either.
Electric is an immediate option. Norway has 80 electric ferries in service. https://businessnorway.com/articles/norway-showcases-award-w...
It may be an immediate option for places that have a very strong desire to reduce carbon emissions, but for profit-driven entities the push towards natural gas ends up as both more economical and more ecological.
https://www.lngindustry.com/special-reports/21112023/the-ris...
It seems like the profit-driven attitude put us in the ecological situation and maybe it's time to put the environmental impact first.
Not going to work in the EU.
Fossil fuels like natural gas are assumed to be the baseline in the Fuel EU directive entering into force in 2025.
All required reductions will have to come on top.
https://transport.ec.europa.eu/transport-modes/maritime/deca...
Looks like another intermediate option is bio-methanol. But, both options are very rare, with diesel being the overwhelming majority of international shipping.
Shifting to either would be a very significant improvement over the status quo. Whether that meets EU requirements is another matter.
https://www.reuters.com/markets/commodities/maersk-buy-bio-m...
Yep, everything is on the table. All done through complete lifecycle well to wake calculations to prevent hiding emissions in intermediate steps.
Works by forcing say 2% green fuel in 2028 and then a market for shipping companies to buy and sell rights. The requirement will increase every couple of years.
Which means old ships will continue to operate but will have to pay for their emission to greener vessels. Thus we have a very direct gain from going all the way rather than half hearted attempts, allowing modern green vessels to make a business case on selling their credits by being over performers.