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Comment by elevaet | Hacker News Reader

> The average cost of lithium-ion batteries has plummeted 89% since 2010, and is expected to reach $50 per kWh in the near future. Assuming a battery cost of $100 per kWh, the TCP for a battery-electric containership is already lower than that of an ICE equivalent, for routes less than 1,000km. And when battery prices reach $50 per kWh, which is predicted for the near future, electrified ships will be cost-effective on routes as long as 5,000km.

This was the nugget for me. Big if true, as they say.

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Cost of maintenance and expected depletion as a function of vessel lifetime is most relevant, an ICE engine itself lasts for a very long time and marine engines have special maintenance features that allow you to repair and run them simultaneously.

It's also not entirely clear if these figures consider "utility power" which is a major function of any container ship that's going to haul refrigerated or frozen cargo.

The main engine is a major source of electrical power on board, but there are also usually several large electrical generators on board to satisfy the demand of these types of containers.

it's not binary. We'll likely start seeing hybrids that follow the cost curve down while scaling up battery capacity.

> it's not binary. We'll likely start seeing hybrids that follow the cost curve down while scaling up battery capacity.

Do hybrids make any sense at all if you're mostly operating at a constant load, like I imagine container-ships do? It's not like they're stuck in stop and start traffic across the Pacific.

They (well, oil tankers at least) actually do spend a significant time lightering, idling, "in traffic" in canals, ports, some key "merge lanes" like Azores, Singapore straits, etc.

But I imagine a lot of that is more like "parking" (e.g. drop anchor an wait).

Electrical engines are far simpler than internal combustion engines, so if anything this favors EE even more.

But are they as durable in corrosive environments? They’ll be competing against 100+ years of marine diesel engine development.

Why wouldn't they be?

A lot of big ships already use electric propulsion, but deisel generators are the power source.

Lots of extremely large engines are "combust fuel to turn a generator to turn the actual engine", and have been for decades. Electric motors are great.

This is how most modern diesel (actually diesel-electric) trains work.

The issue with a big diesel engine like this actually turning the prop or wheels is the size of the transmission required. The engines are massive and the transmission would also be massive to cope with the power and torque. You also eliminate a moving part so much more reliable.

It seems so backwards to me to convert diesel into power and use that to drive an electric motor. It seems so inefficient, but I supposed it wouldn't be a thing if it was inefficient.

Like in a submarine?

Building brushless motors that work when submerged in salt water is almost trivial. The only parts that matter with respect to corrosion is the insulation on the windings and the material the bearings are made from. The rest you can just paint with whatever you'd normally use to avoid corrosion.

Lithium batteries do not stop working suddenly what people are usually talking about degradation so the capacity might be 5%-10% less. The improvements in battery tech has improved number of charge cycles as well as how badly the batteries degrade. With the way battery prices are falling if you buy batteries for $100 today after a decade of use the batteries will still have 90-95% capacity and new batteries cost less than $20. Oil and Gas prices are likely to go up in the future or at least remain the same. Solar and wind electricity price are getting cheaper by 5-10% a year. So electric vehicles will also be cheaper to run by a large margin. I think 1-2 punch of battery/electric engines and renewable electricity prices are going to change many things. And a lot of countries and their economies will be caught flat footed.

At 100 hours per cycle, current generation LiFePO4 batteries will last decades. Maintenance would consist of swapping out faulty modules.

Electric motors are far more robust than ICEs. Wear parts consist of bearings and cooling (although this last is much simpler at 90% efficiency than 50%).

The control circuitry is a potential failure point, but it's small enough that you could run two or three redundant versions and maintain the one that is off.

It sounds like you've included the solution for on board power. Keep using the same generators where they too aren't replaced with batteries (or on board solar may be viable) or in extreme edge cases, use one of the existing ships -- they're not all going to he retrofit on day one.

I guess, any cost estimations should include the cost of recycling.

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