Is diesel-electric or all-electric the future?

[Corvidae]

Originally Posted by Statistical

Thanks for the real world example. Just curious what is the size of your battery bank and how large is your generator?

It's a 12kw generator pushing two 5kw chargers into two 48v 200ah battery banks that powers a pair of 10kw motors. The 12kw inverter runs off one of the motor banks, for now. I'm working on the wiring to install a selector switch.

I really wanted to use two smaller inverters but it'd take a lot more rewiring. At some point I may do it anyway, but there's a list that has to be taken care of first.

[Brian Pokosh]

Originally Posted by Corvidae

It's a 12kw generator pushing two 5kw chargers into two 48v 200ah battery banks that powers a pair of 10kw motors. The 12kw inverter runs off one of the motor banks, for now. I'm working on the wiring to install a selector switch.

Is this an AC generator then? Around on the boat or installed for this purpose?

[Corvidae]

It's a permanently installed diesel generator. The boat originally had two 65hp Volvo Penta's and an 8kw generator. Being 40 years old, they were all pretty much toast. The genset was dead when we bought it, the starboard motor leaked like Exxon Valdez, the port motor seemed weak, but ran. So we expected to be repowering the boat from the start.

For a more typical electric sailboat project our friend has a 38foot boat running the Electric Yacht Quitetorque 5.0. He really should have the 10, but it was there when he bought it. Two banks of 48v 100ah gold cart batteries gets him almost 20 miles of range if he's not fighting a current. It's a bit on the slow side, but he can hold 3.5 knots running off a 1kw charger on a portable 2200 watt generator.

[seandepagnier]

Originally Posted by valhalla360

Who told you this?

Go down to the ICW some time. You will find 90%+ motoring along.

I have sailed hundreds of miles on the ICW and I am 100% sailing the ICW all the time. I did not find what you did.

Cars and boats have wildly different power needs and electric is much more favorable to cars vs displacement boats.

They have different needs, but boats are more favorable to fully electric than cars which is the opposite of what you just said. Since boats have sails, they do not need the same battery capacity of cars for electric propulsion.


Keep in mind a typical marine inboard drive is only about 20% efficient at the propeller due to being extremely undersized on almost all cruising boats. The diesel engine and gears it is optimistic to say 30% efficient, and the refinery to produce the diesel 40%. Then consider all the infrastructure required to extract and transport the oil and transport the diesel. Then also the energy required to produce the engine.


In the end if you care about efficiency, or if you care about not being glutinous of energy use out of the other 7.8 billion people if you just take your share, it is completely impossible to use a marine diesel engine in good conscience. The overall efficiency of less than 2% is really unacceptable.


All these "debates" are really ridiculous as you don't need any kind of mechanical propulsion anyway. sails are enough, but people also afraid of running out of toilet paper when you don't need that either.

[Brian Pokosh]

Originally Posted by Corvidae

It's a permanently installed diesel generator. The boat originally had two 65hp Volvo Penta's and an 8kw generator. Being 40 years old, they were all pretty much toast. The genset was dead when we bought it, the starboard motor leaked like Exxon Valdez, the port motor seemed weak, but ran. So we expected to be repowering the boat from the start.

For a more typical electric sailboat project our friend has a 38foot boat running the Electric Yacht Quitetorque 5.0. He really should have the 10, but it was there when he bought it. Two banks of 48v 100ah gold cart batteries gets him almost 20 miles of range if he's not fighting a current. It's a bit on the slow side, but he can hold 3.5 knots running off a 1kw charger on a portable 2200 watt generator.

It’s a 220V AC generator, though, not 48V DC? The 5kW chargers convert the AC output to 48V to charge the batteries?

[Corvidae]

Yeah, the generator puts out 52amps 240/120 to an auto transfer switch with the 50 amp shore power. That feeds a second transfer switch with the inverter. I was using the pass through on the inverter, but I've since found that's really bad juju. Pass-through doesn't mean contactor switch, it means line conditioner. Keeping the full circuitry of the inverter in the loop. On the up side it means I had an excuse to get a 12kw inverter instead of 10kw. The down side is I now have to ship an AIMS inverter to Reno NV to be repaired, and freight shipping is expensive.

Something to beware of when buying larger inverters, they're very heavy, and many have to be shipped to the manufacturer if you burn them out. This time I went with a model of Growatt that will ship me a replacement board anywhere I happen to need one. We'll see if I manage to burn it up or not.

[SteveSadler]

A small generator, electric motor, and battery bank is far cheaper than a diesel auxilary engine. It could also use an outboard style motor to eliminate the drive train for less weight and drag. For a day sailor this has big advantages, plug in at days end and rarely start the genset. Big horsepower available cheap with electric, but most of the time cruising speed only uses 1/3 of a main engines hp. A small motor is more efficient and extra power available when needed.
For a long distance cruiser, I think it would also be beneficial as it generates lots of power to charge when you have no sun or wind, the prop would also generate power, and the engine would run at an efficient load to not build carbon deposits so common in big engines running slow to reduce fuel consumption.

[Na Mara]

Originally Posted by Corvidae

It's a 12kw generator pushing two 5kw chargers into two 48v 200ah battery banks that powers a pair of 10kw motors. The 12kw inverter runs off one of the motor banks, for now. I'm working on the wiring to install a selector switch.

I really wanted to use two smaller inverters but it'd take a lot more rewiring. At some point I may do it anyway, but there's a list that has to be taken care of first.

Great to have real life experience of someone who has gone diesel electric. By my calculations you have 19.2kWh of batteries, which implies an embodied emissions in your bank alone of about 4 tons of CO2, which is the same amount of CO2 that is released burning 1500l of diesel.

How often do you think you will need to replace your batteries?

Do you know the difference in diesel usage before the upgrade and after? It would be great to know what the real word fuel savings for your system.

By my calculations your generator should be more or less redundant, so long as you stay within the motoring range of your banks, once you fit the 1kw of solar. Is your goal to go full electric or will you keep the generator onboard as a backup?

[Na Mara]

Originally Posted by seandepagnier

I have sailed hundreds of miles on the ICW and I am 100% sailing the ICW all the time. I did not find what you did.


They have different needs, but boats are more favorable to fully electric than cars which is the opposite of what you just said. Since boats have sails, they do not need the same battery capacity of cars for electric propulsion.


Keep in mind a typical marine inboard drive is only about 20% efficient at the propeller due to being extremely undersized on almost all cruising boats. The diesel engine and gears it is optimistic to say 30% efficient, and the refinery to produce the diesel 40%. Then consider all the infrastructure required to extract and transport the oil and transport the diesel. Then also the energy required to produce the engine.


In the end if you care about efficiency, or if you care about not being glutinous of energy use out of the other 7.8 billion people if you just take your share, it is completely impossible to use a marine diesel engine in good conscience. The overall efficiency of less than 2% is really unacceptable.


All these "debates" are really ridiculous as you don't need any kind of mechanical propulsion anyway. sails are enough, but people also afraid of running out of toilet paper when you don't need that either.

But you are not comparing like with like here. The "green" alternative to to the diesel/propane boat is the all electric. To make that work for long term cruising you will need about 20kWh of battery storage, which has an embodied emissions of 4tons CO2. Those batteries will need replaced after maybe 2000 discharge cycles. If you are a liveaboard cruiser that entails replacing them every 7 years or so (being really generous here and only assuming one discharge cycle a day). So the all electric boat is churning through nearly 600kg of CO2 a year.

Now compare that to the frugal diesel/propane sailing boat that uses shore power for everything when it can, has renewable charging for its 1kwh of battery capacity, uses its engine only getting into and out of harbours, and only uses propane away from marinas. That boat will emit maybe 400kg of CO2 from its engine, 100kg from cooking, and about 30 from the embodied emissions of its battery bank. Total of 550kg say. I.e. the frugal diesel/propane boat can beat the all electric boat on emissions for live aboard cruising.

Now admittedly many sailboats are used like slow motorboats with lightning rods, but then all electric wont work for those owners anyway and diesel electric will be way worse on emissions than straight diesel, as these boats would be mostly operating in diesel electric mode which at best is 75% of the efficiency of straight diesel, and then add the tons of embodied emissions in the battery bank that aren't being properly utilised. The optimal thing for these sailors to do would be to buy a displacement motorboat and be done with it a la Dashew.

So whilst I too am captivated by the wonders of the all electric sailboat and have this feeling that the diesel engine under my pilothouse floor is evil, the numbers just don't support those feelings. Basically, I and the environment am far better off if I spend less money on making my boat as efficient as possible in its energy use, as competent as possible at using shore power when available, and AS EASY AND JOYFUL TO SAIL as possible whilst keeping the smelly diesel, than we would be by me spending a small fortune converting to all electric.

[Simon.Sails]

I don't think you're doing a fair comparison here Na Mara:

1. You use a single discharge cycle per day for electric, but only frugal motoring for diesel. Consumption has to be factored in seriously with a given distance (per day/year)

2. Your discharge cycles estimate of 2'000 before replacement is way off. Battleborn for example says "Conversely LIFEPO4 (lithium iron phosphate) batteries can be continually discharged to 100% DOD and there is no long term effect. You can expect to get 3'000 cycles or more at this depth of discharge."

3. But not only do they last longer than 3'000 discharge cycles which - at moderate use - should last 10 year or more, you're unlikely to just dump them at <90% capacity. Either you keep them or they get reused in other applications, thus lowering the initial environmental co2-equivalent impact.

Any real comparison has to use current technology, equal usage and a realistic renewable/shore power mix. I am confident that many fully electric boats will fare much better in such a comparison in most usage patterns, the exception being of course an already installed diesel engine that's rarely used.

Personally I would only install EE on a reasonably light, fast sail boat that's primarily used as such and that doesn't have solid inboard diesels installed.

[valhalla360]

Originally Posted by Adelie

I was addressing the world of cruising sailboats not the world as a whole. I was very specific in my second paragraph. Did you miss that or were you intentionally trying to expand the issue?

And the world of cruising sailboats burning fossil fuels is irrelevant to the big picture.

Even if you modify it to an individual sailboat owner, once you figure in their fossil fuel use commuting to work, it's irrelevant.

Not missing anything just pointing out a big flaw in the logic of a lot of the eco-faithful. If you want to cut down on fossil fuel use, this is a silly, expensive and ultimately not effective way to do it.

[valhalla360]

Originally Posted by kirklkjb

It optimizes diesel engine efficiency

If we were talking automotive engines, this would be a big deal. In stop and go traffic, they spend a lot of time idling, then hard acceleration, then cruising at speed, then braking....repeatedly. The engines are way oversized to provide for that hard acceleration and a ton of time is spent way outside of ideal operating speeds. A hybrid system that smooths out the load on the ICE has great potential to improve efficiency.

A cruising sailboat on the other hand, once you get out of the harbor, throttles up to cruise speed and stays there. Since the engines are largely sized for this load, they are up at near ideal output for efficiency. The potential benefits are much smaller and will typically be lost when you consider energy conversion losses.

[valhalla360]

Originally Posted by seandepagnier

I have sailed hundreds of miles on the ICW and I am 100% sailing the ICW all the time. I did not find what you did.


They have different needs, but boats are more favorable to fully electric than cars which is the opposite of what you just said. Since boats have sails, they do not need the same battery capacity of cars for electric propulsion.


Keep in mind a typical marine inboard drive is only about 20% efficient at the propeller due to being extremely undersized on almost all cruising boats. The diesel engine and gears it is optimistic to say 30% efficient, and the refinery to produce the diesel 40%. Then consider all the infrastructure required to extract and transport the oil and transport the diesel. Then also the energy required to produce the engine.


In the end if you care about efficiency, or if you care about not being glutinous of energy use out of the other 7.8 billion people if you just take your share, it is completely impossible to use a marine diesel engine in good conscience. The overall efficiency of less than 2% is really unacceptable.


All these "debates" are really ridiculous as you don't need any kind of mechanical propulsion anyway. sails are enough, but people also afraid of running out of toilet paper when you don't need that either.

Very odd that you didn't see most motoring on the ICW. We've run from Mobile to NYC along with most of the Great Lakes and the Spanish coast of the Med...pretty much the same everywhere, folks going from A to B almost always are motoring.

If you just go out for day sails, sure electric is viable. Prop efficiency is irrelevant to the motor type. The prop doesn't care what is turning it.

PS: If you want to make this a moral discussion, logic goes out the window. If you really feel that strongly, I suggest you do your part and not buy a boat but live in the smallest one room apartment you can find and short of life threatening situations, do not use heat or air/con. Eat only a locally sourced plant based diet but in near starvation quantities....once you do that you can come back we can have the moral argument over your thousands of pounds of petrochemical based boat.

[valhalla360]

Originally Posted by SteveSadler

A small generator, electric motor, and battery bank is far cheaper than a diesel auxilary engine. It could also use an outboard style motor to eliminate the drive train for less weight and drag. For a day sailor this has big advantages, plug in at days end and rarely start the genset. Big horsepower available cheap with electric, but most of the time cruising speed only uses 1/3 of a main engines hp. A small motor is more efficient and extra power available when needed.
For a long distance cruiser, I think it would also be beneficial as it generates lots of power to charge when you have no sun or wind, the prop would also generate power, and the engine would run at an efficient load to not build carbon deposits so common in big engines running slow to reduce fuel consumption.

Run the numbers for us on cost please.

I think on something like this is viable but not cheaper. See the below thread I started to try and come up with some specs for a viable system.

https://www.cruisersforum.com/forums...ghlight=hybrid

[GordMay]

Originally Posted by valhalla360

If we were talking automotive engines, this would be a big deal. In stop and go traffic, they spend a lot of time idling ...

Automatic shut-down/start-up, and idle limiting systems are becoming increasingly available in road vehicles.
AUTOMATIC SHUT-DOWN/START-UP SYSTEMS
Electric-powered start-stop systems automatically turn off a vehicle’s engine, when the vehicle is stopped, and immediately restart it when the driver presses the accelerator or lifts off the brake/clutch.
IDLE LIMITERS
Idle limiting systems work by automatically shutting the engine off, after the vehicle has been idling, for a predetermined amount of time.