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Old 05-11-2021, 12:43   #751
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by kiwin View Post
Hydrogen as energy storage is always going to be massively innefficient compared with batteries. That alone will limit it's use to applications where battery electric will not work. A cruising yacht may be one of those applications. A passenger car will never be.
Hydrogen drives rockets into space for decades, but it is not safe for the average Joe.

Hydrocarbons are safer to handle, as they are liquid, the longer the carbon chains, the fire / ignition safer the fuel (crude oil vs diesel vs gas/benzin vs butane vs propane vs ethene vs methane) and the higher the energy density.

I read always combustion engines are inefficient, you get only 1/3 after the prop. Well electric engines don't work without a prop either, so efficiency is comparable after the prop, I don't think you will see linear magnetic hoovering drives on vessels in the water any soon.
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Old 05-11-2021, 13:36   #752
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by BigBeakie View Post
But what about LPG? You won't get in a taxi running on LPG?


LPG is compressed to about 150psi, that’s 10 atmospheres.
H2 is compressed to 6,000-10,000psi, 400-667 atmospheres of pressure. That is a big change in safety regardless of flammability.
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Old 05-11-2021, 14:00   #753
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Re: Jimmy Cornell goes Electric, with a Cat

The differences in safety between the various fuels has a lot more to it than just pressures. The energy required to ignite the fuel, the upper and lower explosive limits and the speed of the flame propagation are what makes hydrogen an extremely dangerous gas.

Diesel is pretty hard to ignite. Propane has a very narrow air fuel ratio range in which it will ignite and a very wide explosive AFR range, the energy required to ignite it is very very small and the speed of a the flame propagation borders on what you'd class as a detonation. This means that a very small leak can do a massive amount of damage. The violence of hydrogen explosions is frankly quite shocking (sorry ).

As a young engineer I worked in a gas plant where I worked on and designed equipment for an acetylene generator. Acetylene and hydrogen behave quite similarly. As part of my training we went through many many case studies of industrial acetylene explosions. The extreme destruction from what was often tiny leaks of very small quantities of gas will forever be burned into my mind.
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Old 05-11-2021, 17:20   #754
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Re: Jimmy Cornell goes Electric, with a Cat

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Inefficient in what sense? Hydrogen would solve the range issue at higher power levels, compared to battery.
Inefficient in the only sense. That is energy out/energy in. If you have to turn electricity into hydrogen by electrolysis, compress it, cool it, pump it through pipes, store it, decompress it, heat it, process it into electricity via a fuel cell, and finally use it to drive the boat via electric motor, then you lose a little - or a lot - at every step. In the end you are only going to be seeing about 20% of the electrons you originally generated at the prop. With battery electric this is at worst about 80%, and could easily be 90%.
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Old 06-11-2021, 03:42   #755
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Re: Jimmy Cornell goes Electric, with a Cat

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Certainly it is hard to make a valid economic argument to replace your diesel with an electric engine, however the world is full of such tough decisions and I cannot for the life of me understand the vitriolic way we criticize people trying to do the 'right' thing!
It's not only economically hard but imo in some situations also ecologically. Example: if I replace my old rather small and sparingly used diesel engine with electric propulsion then a) a lot of grey energy is needed for the lithium batteries (and the motor), b) afaik lithium production is not exactly environmental friendly and c) in germany almost 30 % of the electricity is generated by coal, this likely makes it worse than diesel. [comment posted before, but in the wrong thread].

I wouldn't criticize people for trying/installing electric propulsion; it's rather cool, especially in cats where there is plenty of space for solar panels. However I'd criticize if "they" look down on "diesel sailors" and propagate switching as a way to "save the world".
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Old 06-11-2021, 04:07   #756
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Re: Jimmy Cornell goes Electric, with a Cat

The embodied energy & CO2 of a full battery electric installation is a little more than a diesel. But only a little. And if you use the electric drive for a season, even with coal fired electricity, you are ahead of the diesel in energy use and carbon emitted. This stuff has been litigated so many times......oil company propaganda is effective, apparently.
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Old 06-11-2021, 05:10   #757
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Re: Jimmy Cornell goes Electric, with a Cat

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The point people miss is that electric drive has many advantages, not just on the emissions front. It is silent, doesn't stink, fantastic torque curve, doesn't need oil changes, it is lightweight (very important in a cat) with very flexible weight distribution. It is expensive to install but cheap to run.

The only real sacrifice is range. Of course, you can increase range by putting in more batteries but then that erodes the lightweight advantage.
More batteries does not necessarily mean eroding the lightweight advantage. There are 2 big fuel tanks no longer required which is about a tonne of weight.
Also electric motors weigh a lot less than diesel engines thus saving more weight.
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Old 06-11-2021, 05:33   #758
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by Rjstutch View Post
More batteries does not necessarily mean eroding the lightweight advantage. There are 2 big fuel tanks no longer required which is about a tonne of weight.
Also electric motors weigh a lot less than diesel engines thus saving more weight.


Current batteries at 20 times heavier then diesel per energy stored. It’s not a good situation.
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Old 06-11-2021, 07:01   #759
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Re: Jimmy Cornell goes Electric, with a Cat

How is that good or bad? It’s a fact of life.

By the same token I can’t recharge my diesel tank from onboard energy sources. I don’t see that as bad, just a fact of life to be dealt with.
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Old 06-11-2021, 07:32   #760
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Re: Jimmy Cornell goes Electric, with a Cat

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The embodied energy & CO2 of a full battery electric installation is a little more than a diesel. But only a little. And if you use the electric drive for a season, even with coal fired electricity, you are ahead of the diesel in energy use and carbon emitted. This stuff has been litigated so many times......oil company propaganda is effective, apparently.
Can you provide numbers (links)? Severly doubt that coal is ahead of diesel. Thanks, and btw, no need for ad hominem attacks.

- in the example it's an existing diesel motor vs. a new electric installation
- with a small consumption of let's say 50 l diesel per year for motoring it will (likely) take decades to reach the grey energy of a new electric motor/battery. With Tesla I once read of about 70'000 km (but I'm not sure/convinced that this is accurate).

- if your diesel engine is not EOL and your "electric-aim" is to make a positive individual "contribution" towards a "greener future", it might make sense to first analyse what other options you have, e.g.
- - use the motor less, it's a sailboat after all
- - do you fly (far/often) to your vessel? Could you improve this?
- - what about your home heating? Oil? Is your home well insulated?
- - do you commute to work? Could you move nearer?
- - ...
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Old 06-11-2021, 09:46   #761
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by blu3534 View Post
Can you provide numbers (links)? Severly doubt that coal is ahead of diesel. ...


https://www.epa.gov/greenvehicles/el...-vehicle-myths

https://www.reuters.com/business/aut...rs-2021-06-29/

https://theicct.org/publications/glo...r-cars-jul2021

https://www.forbes.com/sites/energyi...n-america/amp/
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Old 06-11-2021, 12:06   #762
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Re: Jimmy Cornell goes Electric, with a Cat

Thank you, interesting. Will try out the GREET model later to see what happens with different inputs.

From a quick glance I saw "Tesla Model 3 in the United States .. would need to be driven for 13,500 miles (21,725 km) before it does less harm to the environment than a Toyota Corolla. ".

Don't think this can be carried over to boats. But anyways, with an assumption of 6 l/100 km this is 1300 l ~Diesel. And I suppose quite some (smaller) sailboat could sail with this amount for 13 years... Lithium batteries are also dead at this point.
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Old 06-11-2021, 15:03   #763
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Re: Jimmy Cornell goes Electric, with a Cat

Here's another thread with some interesting tests being done in relation to smaller boats:

Using 6kW electric outboard for added propulsion on 39' catamaran
https://www.cruisersforum.com/forums...ml#post3515591
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Old 06-11-2021, 16:37   #764
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Re: Jimmy Cornell goes Electric, with a Cat

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Originally Posted by blu3534 View Post
It's not only economically hard but imo in some situations also ecologically. Example: if I replace my old rather small and sparingly used diesel engine with electric propulsion then a) a lot of grey energy is needed for the lithium batteries (and the motor), b) afaik lithium production is not exactly environmental friendly and c) in germany almost 30 % of the electricity is generated by coal, this likely makes it worse than diesel. [comment posted before, but in the wrong thread].



I wouldn't criticize people for trying/installing electric propulsion; it's rather cool, especially in cats where there is plenty of space for solar panels. However I'd criticize if "they" look down on "diesel sailors" and propagate switching as a way to "save the world".
This. I'm all in favor of those hobbyists who want to explore the fringes. But don't think or insist that the mass market future is electric, or "real sailors" don't need to motor for hours on end.
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Old 06-11-2021, 17:28   #765
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Re: Jimmy Cornell goes Electric, with a Cat

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yeah cos theres no emissions expelled in building the boat is there???

sorry but this is just yet more hypocritical virtue signalling

the least emissions path by far would be to NOT BUILD ANOTHER NEW BOAT and make do with an existing one.


I’m a bit surprised he just doesn’t take an existing Outremer 45 or, for that matter, any other cruising cat, and do what he can to show how they can be converted fairly easily and inexpensively to giving the boat the occasional power you want/need from an electric engine without scrapping the existing diesels. Doing that would reduce the use of the Diesel engines by 90% for the vast majority of cruisers (along with reducing the hassle of maintenance). The conversion can also greatly reduce—or, if done right, eliminate—the burning of diesel by running a generator, which for many cruisers, is what burns the most diesel on their boats. Stories on “pretty darn good” solar and electric motor conversions of cats may not be as sexy a story as eliminating the need for diesels altogether, but it will do a lot more practical good for a lot more cruisers (not to mention the planet). Getting rid of the diesels (or buying a brand new Outremer 45) just isn’t a practical solution for 99% of cruisers and, as such, is of little interest to me.
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