Hybrid electric drive

[Keysdisease]

As I said in post # 2 there is a narrow range where existing technology works. European canals sound just like one of those exceptions. Another place where the current technology works in a narrow range is a Ferry in Alabama. This project was part of a panel discussion at the last Hybrid/Electric Propulsion Show.

Alabama’s Gee’s Bend Ferry to go all-electric - Alabama NewsCenter

The flip side of a Greenline for a European Canal boat would be a conventional drive with a conventional generator. Given a top shelf isolation / insulation / driveline treatment you would not hear it at canal speed, it would be less complex than a Greenline system, and cheaper up front and to operate, with all the same creature comforts.

I don't have a visceral hatred of electric boats, I see them as emerging technology, but as a boat operator with some little experience I have a preference for simplicity = reliability and I have no hatred of saving a few boat dollars when I can.

I had a customer that was very sold on hybrid propulsion. He was like a 3 am tele-evangelist about it. His engineer was an engineer, in other words grounded in reality. They were both committed to hybrid, but one had "religion" and the other an engineering degree.

There are 8,000 km of canals in France, and thousands more in Belgium, Netherlands, Germany, etc. A typical speed limit in a French canal is 10km/h. You can spend the rest of your life going from one quaint, history-filled town to the next. So, motor a little while, some solar, and quiet propulsion the rest of the day. The boat comes with a household fridge, dishwasher, washer/dryer, A/C, etc. What's not to like? Horses for courses.


I just don't get the visceral hatred of electric cars or boats.

 

[Cottontop]

As I said in post # 2 there is a narrow range where existing technology works. European canals sound just like one of those exceptions. Another place where the current technology works in a narrow range is a Ferry in Alabama. This project was part of a panel discussion at the last Hybrid/Electric Propulsion Show.

Alabama’s Gee’s Bend Ferry to go all-electric - Alabama NewsCenter

The flip side of a Greenline for a European Canal boat would be a conventional drive with a conventional generator. Given a top shelf isolation / insulation / driveline treatment you would not hear it at canal speed, it would be less complex than a Greenline system, and cheaper up front and to operate, with all the same creature comforts.

I don't have a visceral hatred of electric boats, I see them as emerging technology, but as a boat operator with some little experience I have a preference for simplicity = reliability and I have no hatred of saving a few boat dollars when I can.

I had a customer that was very sold on hybrid propulsion. He was like a 3 am tele-evangelist about it. His engineer was an engineer, in other words grounded in reality. They were both committed to hybrid, but one had "religion" and the other an engineering degree.

Perhaps I'm biased by my Volt experience. In 5-1/2 years and more than 100,000 miles, I have spent 0 (zero) on repairs. It has been in the shop once, warranty. I've changed the oil four times, and some tires. That's it. As far as I know, a Prius is dependable, and there are loads of them about. So hybrid technology can be dependable.

Assuming that the hybrid technology on a boat works, which is better? Slogging along at 5 knots with your 150hp engine(s) at about idle, and a generator running most of the time? With the fumes wafting gently over the boat? Or running the diesels only occasionally, when speed is permitted, or to charge the batteries at a decent load factor, and electric the rest of the time. Being able to maneuver in locks at low rpm and no shifting in and out of gear is very handy.

When I cut through the knee-jerk skepticism about hybrids, I don't find the traditional approach to be a slam dunk.

 

[ranger58sb]

Assuming that the hybrid technology on a boat works, which is better? Slogging along at 5 knots with your 150hp engine(s) at about idle, and a generator running most of the time? With the fumes wafting gently over the boat? Or running the diesels only occasionally, when speed is permitted, or to charge the batteries at a decent load factor, and electric the rest of the time. Being able to maneuver in locks at low rpm and no shifting in and out of gear is very handy.

When I cut through the knee-jerk skepticism about hybrids, I don't find the traditional approach to be a slam dunk.

I don't think you're seeing any hate, here... just that your canal example is different from many. Sounds like a good example where electric or hybrid can work fine. Another often cited is the the short get-out/get-in runs sailors make to/from their marinas before hosting sails.

I sometimes can't maintain steerage at 4-5 kts here where we are, and its not uncommon that even at "faster" slow speeds (7-9 kts) in beam seas, roll here can be too uncomfortable. IOW, electric/solar wouldn't work for us... even though I think there would be some nifty advantages.

One of the members here converted an Eclo diesel to an Elco electric drive (a search will turn up the threads) but then found she didn't have the range she wanted to get from her home port to a specific destination, approx 25 nm. Didn't mean the electric drive was at fault; just didn't work out perfectly for her intended mission (last I heard).

-Chris

 

[Cottontop]

I don't think you're seeing any hate, here... just that your canal example is different from many. Sounds like a good example where electric or hybrid can work fine. Another often cited is the the short get-out/get-in runs sailors make to/from their marinas before hosting sails.

I sometimes can't maintain steerage at 4-5 kts here where we are, and its not uncommon that even at "faster" slow speeds (7-9 kts) in beam seas, roll here can be too uncomfortable. IOW, electric/solar wouldn't work for us... even though I think there would be some nifty advantages.

One of the members here converted an Eclo diesel to an Elco electric drive (a search will turn up the threads) but then found she didn't have the range she wanted to get from her home port to a specific destination, approx 25 nm. Didn't mean the electric drive was at fault; just didn't work out perfectly for her intended mission (last I heard).

-Chris

To do the European canals, there are some feisty rivers that must be dealt with, and some coastal cruising, and I have the US great loop in mind, as well, so traditional diesel power is essential.

 

[RT Firefly]

Greetings,
Mr. C. As mentioned, a hybrid vessel does have it's place in certain circumstances. Outside of those specific circumstances current technology is not sufficient to provide a viable alternative to fossil fuel YET. 50 lb of battery simply does not have the energy "density" of 50 lb of gasoline.

Using an electric car as an example, until "refueling" on a cross country trip becomes as quick and convenient as pulling into a service station to top up a gasoline/diesel fuel tank, fully electric vehicles will not replace what's presently on the road. For running around town within the range limitations of battery power electric is indeed far superior to anything else thus far.

 

[Cottontop]

Using an electric car as an example, until "refueling" on a cross country trip becomes as quick and convenient as pulling into a service station to top up a gasoline/diesel fuel tank, fully electric vehicles will not replace what's presently on the road. For running around town within the range limitations of battery power electric is indeed far superior to anything else thus far.

See Chevy Volt. Day-to-day around town, fully electric (Gen 2 of the Volt will go 50+ miles on battery). But need to go on a road trip, no problem, gas engine (I get 37 mpg on the gas engine).

 

[Benthic2]

I think it depends on what your goal is. Do you want to go boating, or do you want to be an electro-mechanical hobbyist ?

 

[Jeff F]

I'm skeptical, but it's certainly not a knee-jerk reaction. I'm a big fan of electrification and drive a Prius and a Leaf. Haven't had a non-electric car for years and don't expect to have one ever again.

Twistedtree said most of what I was thinking. Any use case has to start with energy requirements, and the energy requirements to maintain anything but a very low speed on our boats is huge when put up against current battery storage capabilities. Fossil fuels are hard to beat when it comes to stored energy.

If you can live with traveling at low speeds and short distances then electric starts to make sense. But that's not our use case.

I've thought about optimal power for canal cruising, as that's my current boating passion. Do you add electric to give the opportunity for occasional motor-free operation? That seems like a lot of extra gear and complexity. How much can solar contribute? The upper bound of solar charging is pretty well established, so the only way to make solar a major part of the energy mix is to reduce overall energy consumption. It's really hard to get down to a consumption pattern where the solar contribution becomes meaningful. And given the losses in going from diesel to electric it's hard to see a case where overall diesel consumption goes down.

So if you are willing to go down that path of committing to low energy operation why not just put a small quiet efficient diesel in and be done with it? A 10 km/hr boat could run on a very small motor. I could replace my 250 HP with a 30 hp and run at those speeds forever.

Now if I had an unlimited budget I could imagine some pretty cool arrangements, but really I'd just be playing, and I wouldn't expect to reduce my fuel usage.

 

[Jeff F]

See Chevy Volt. Day-to-day around town, fully electric (Gen 2 of the Volt will go 50+ miles on battery). But need to go on a road trip, no problem, gas engine (I get 37 mpg on the gas engine).

Not dissing the Volt here - I'd be happy driving one - but for sustained highway operation a comparable diesel powered car is significantly more efficient. And that's the analog for the boating use case.

 

[Cottontop]

Not dissing the Volt here - I'd be happy driving one - but for sustained highway operation a comparable diesel powered car is significantly more efficient. And that's the analog for the boating use case.

Most people don't do sustained highway operation in their cars, and some (many) don't do sustained highway operation in their boats. I have no idea how many boats there are cruising on the European canals, but it is not a small number.

Electric would be great on the Trent-Severn, but diesel is needed at each end.

 

[BobH]

One reason diesel/electric works for cruise ships and locomotives is that the diesel engine generators can be placed anywhere, the diesel is not tied directly to the drive train/propeller. Also by using multiple generators they can run just the numbers needed at the time. Can you imagine trying to connect a diesel engine directly to the drive wheels of a locomotive?

 

[diver dave]

These conversations should start with this page: https://xtronics.com/wiki/Energy_density.html

Assuming you realize what the data says, the results are quite clear.
Rechargeable batteries are now about 1.5 to 2 orders of magnitude too low in energy density to replace diesel. But look how good U235 is!

 

[RT Firefly]

Greetings,
Mr. BH. Direct drive diesels are used in lower power locomotives, shunting engines, for example. The limiting factor is the transmission. Diesel-electrics don't use any transmission.

 

[twistedtree]

Lifestyle features, that's right. But then you went back to the usual strawman arguments. Nobody serious is suggesting cruising at 20 knots with electric propulsion. And while solar is nice, and relatively cheap, it's not key. A Greenline 40', for instance, can be equipped with two 7kw motor/generators which will charge the 23 kwh of LiPO batteries in two hours. That's plenty for house loads, or to power the boat for 20 km at 4 kn.

There are 8,000 km of canals in France, and thousands more in Belgium, Netherlands, Germany, etc. A typical speed limit in a French canal is 10km/h. You can spend the rest of your life going from one quaint, history-filled town to the next. So, motor a little while, some solar, and quiet propulsion the rest of the day. The boat comes with a household fridge, dishwasher, washer/dryer, A/C, etc. What's not to like? Horses for courses.

If it's not already obvious, I'm considering a Greenline. But not because I'm trying to save money, and not because I'm trying to be green, and not because I'm trying to be holier than thou. It's strictly about the creature comforts.

I drive a Volt. I've had it more than 5 years, 100,000 miles plus. People say, "Let me explain how you're not really saving money." Yes, I know that. Don't care. "Well, let me explain how you're not really being green." Not sure I agree, but don't care one way or the other. "Well, let me explain how fast my Corvette can go." Don't care; the last time I drove 150 was never. Then why, you might ask? I'm tired of sending money to people who hate me.

I just don't get the visceral hatred of electric cars or boats.

It's not visceral hatred. I just don't see any benefit from it. And BTW, I have an electric car, so it's really not that I have an axe to grind. And I don't mean to judge anyone who is happy with the performance and tradeoffs of a hybrid boat. What I do want to do is be sure the realistic performance of such a boat is understood, since most people don't.

As for the Greenline, I don't see how that 7kw generator can charge 23kw of batteries in 2 hrs. 3 hrs sounds more realistic, assuming they are down to 10%. And that would match the discharge using the same 7kw motor, running for 3 hrs to cover 20km @ 4kts.

As an example of where I don't see the benefit, it takes 3 hrs of engine run time to charge the batteries to get 3 hrs of electric motor run time. So you are still running the motor for the same amount of time as you are underway. If running the motor at a different time that when you are cruising is important to you, then by all means.

And if you want to do your charging from shore power after each 3hrs underway, by all means, knock yourself out.

I'll start a separate thread to see how many people who be accepting of a boat that can only do 4 kts for 3 hrs, then needs to stop for 3-8 hrs, depending on the shore power capacity and other house loads, or run the motor for 3-5 hrs time to recharge the batteries and power house loads. My guess is that it will be very few. But for those where that is acceptable, knock yourself out.

 

[twistedtree]

Greetings,
Mr. BH. Direct drive diesels are used in lower power locomotives, shunting engines, for example. The limiting factor is the transmission. Diesel-electrics don't use any transmission.

Right. Diesel Electric is a really good variable speed, high power transmission. When that's important, it can be worth the fuel efficiency hit.

 

[Insequent]

Where a diesel electric setup makes sense to me for recreational boating is a sailing catamaran. The largish diesel sits in one hull and the other hull has the same weight in batteries, mostly for house use but for minor propulsion demands if desired.

 

[Cottontop]

As for the Greenline, I don't see how that 7kw generator can charge 23kw of batteries in 2 hrs. 3 hrs sounds more realistic, assuming they are down to 10%. And that would match the discharge using the same 7kw motor, running for 3 hrs to cover 20km @ 4kts.

As an example of where I don't see the benefit, it takes 3 hrs of engine run time to charge the batteries to get 3 hrs of electric motor run time. So you are still running the motor for the same amount of time as you are underway. If running the motor at a different time that when you are cruising is important to you, then by all means.

I'll start a separate thread to see how many people who be accepting of a boat that can only do 4 kts for 3 hrs, then needs to stop for 3-8 hrs, depending on the shore power capacity and other house loads, or run the motor for 3-5 hrs time to recharge the batteries and power house loads. My guess is that it will be very few. But for those where that is acceptable, knock yourself out.

Not sure I understand what you're saying. Greenline boat has twin diesels, so there are two 7 kw chargers.

Example: Start in morning on diesels. Batteries discharged. Cruise for two hours on diesel. Batteries now fully charged. Cruise four hours on batteries. Batteries now discharged. Cruise two hours on diesel. Batteries fully charged. Stop for the night. Use batteries for house loads. Next day, repeat. If shore power is available along the way, reduce diesel usage. If the sun shines, reduce diesel usage.

If you answer, please try to not use the word "efficiency." Nobody buying a boat for cruising cares about that.

 

[ksanders]

I would argue that if you had to buy or generate electricity for a electric drive system that it is extremely inefficient compared to your direct drive diesel engine.

Here's how the math works out.

My boat uses Cummins 6BTA5.9 engines, so we'll use those as a basis for comparison

The manufacturers fuel curve shows that at 1400 RPM (a typical cruise RPM) that the engine produces 96KW of energy and uses 2.8 gallons of fuel per hour.

Now lets take generator power.

The Northern Lights model M944W3 marine generator produces 30KW of energy at full load. To do this it burns 2.8GPH of diesel

Right off the bat it's easy to see that the direct drive diesel engine at 96KW and the generator at 30KW, both burning the exact same amount of fuel, means that the direct drive engine produces over 3X the amount of energy as the generator.

I think I'll stick with my diesel engine thank you

Guys this whole electric drive, electric car thing being "great for the planet" is a complete sham unless you are powering using renewable energy. Yes, you feel good about it, but unless you are using renewable energy you are burning more fossil fuels to run your electric driven car or boat than if you just used a regular engine.

 

[Insequent]

The manufacturers fuel curve shows that at 1400 RPM (a typical cruise RPM) that the engine produces 96KW of energy and uses 2.8 gallons of fuel per hour.

Nope! If it did it would be delivering 46 HP/gal ! As good as your 6BTA is, its not that good. Just not possible - 20 is pretty much the upper limit.

You are not reading the curves correctly. You are using the max power curve to read off your kW, but the prop curve for fuel use. Apples and oranges. You need to use the prop power curve with the prop fuel consumption.

I agree with your conclusion, but your math/analysis is seriously flawed!

 

[ksanders]

Nope! If it did it would be delivering 46 HP/gal ! As good as your 6BTA is, its not that good. Just not possible - 20 is pretty much the upper limit.

You are not reading the curves correctly. You are using the max power curve to read off your kW, but the prop curve for fuel use. Apples and oranges. You need to use the prop power curve with the prop fuel consumption.

I agree with your conclusion, but your math/analysis is seriously flawed!

Here's a link to the fuel curve for the Cummins 330 HP marine engine

https://www.sbmar.com/docs/performance-curves/6BTA [330,2800,1975,HO,Nov 00,M-90208].pdf

You are correct, I was reading from the tables, and upon closer analysis the fuel table is based on prop curve, and the KW output table is based on the max output of the engine.

Now looking at the data the direct engine output is still higher than the generator output, for the same fuel used, but by how much it's difficult to tell since without the table it comes down to plotting the same point on two graphs.

Thanks much for pointing that out

 

[Jeff F]

Not sure I understand what you're saying. Greenline boat has twin diesels, so there are two 7 kw chargers.

Example: Start in morning on diesels. Batteries discharged. Cruise for two hours on diesel. Batteries now fully charged. Cruise four hours on batteries. Batteries now discharged. Cruise two hours on diesel. Batteries fully charged. Stop for the night. Use batteries for house loads. Next day, repeat. If shore power is available along the way, reduce diesel usage. If the sun shines, reduce diesel usage.

If you answer, please try to not use the word "efficiency." Nobody buying a boat for cruising cares about that.

Hmm. 14kw * 2 hours = 28 kwh. Running six hours on that allows a 4.5 kw/hr steady draw. So if you dedicate that entirely to propulsion, turning off instruments and other house loads that allows about 6 HP to be sent to the shaft for six hours. Going to be pretty relaxed cruising

 

[twistedtree]

Not sure I understand what you're saying. Greenline boat has twin diesels, so there are two 7 kw chargers.

Example: Start in morning on diesels. Batteries discharged. Cruise for two hours on diesel. Batteries now fully charged. Cruise four hours on batteries. Batteries now discharged. Cruise two hours on diesel. Batteries fully charged. Stop for the night. Use batteries for house loads. Next day, repeat. If shore power is available along the way, reduce diesel usage. If the sun shines, reduce diesel usage.

If you answer, please try to not use the word "efficiency." Nobody buying a boat for cruising cares about that.

Thanks for the correction. I missed that it has twins. But make not mistake about it, if you cruise that same speed/distance pattern on diesel alone, you will consume less fuel to cover the distance than operating in hybrid mode.

As for efficiency (sorry, I used the word), I think it does matter. It's not the only consideration, but why would I want to do something that reduces the efficiency of my boat? Answer, I would do it because I got some lifestyle benefit from it. So if it makes you happy to run with the pattern above, and that's worth burning more fuel to get where you are going, knock yourself out. You understand the trade-offs and have made a decision that fits your needs/desires. I wouldn't do it, and don't think most trawler owners would either simply because they don't want to travel at 4 kts.

 

[Cottontop]

Thanks for the correction. I missed that it has twins. But make not mistake about it, if you cruise that same speed/distance pattern on diesel alone, you will consume less fuel to cover the distance than operating in hybrid mode.

As for efficiency (sorry, I used the word), I think it does matter. It's not the only consideration, but why would I want to do something that reduces the efficiency of my boat? Answer, I would do it because I got some lifestyle benefit from it. So if it makes you happy to run with the pattern above, and that's worth burning more fuel to get where you are going, knock yourself out. You understand the trade-offs and have made a decision that fits your needs/desires. I wouldn't do it, and don't think most trawler owners would either simply because they don't want to travel at 4 kts.

Sigh. The speed limit in thousands of miles of canals is dead slow. People riding their bikes on the tow paths are moving faster than the boats. Some joggers are.

I understand the dollars and cents. Having air conditioning on the boat reduces efficiency, but I won't be without it. I understand that burning diesel to produce electricity to cruise on is inefficient. I understand that a battery has less energy density than diesel. I'm willing to pay for less noise, vibration and fumes. And easier slow speed maneuvering.

The important question is reliability. I do care about that. A lot. And people correctly point out that a hybrid system is more complex. But so is my Volt, and it has been problem free.

So, I wonder, is there some reason a hybrid system on a boat will be unreliable? "Yes!", everyone shouts. "Why," I wonder. "It's less efficient," everyone shouts.

 

[sdowney717]

Electric boats will work great, some day in future time, if you can completely get rid of internal combustion engines and power from liquid fuels to a fuel cell, as in direct conversion of liquid fuel to electric, which will have a much greater efficiency.

I say in a hundred years maybe... piston engines will be obsoleted.
https://www.technologyreview.com/s/421277/cheap-diesel-powered-fuel-cells/

 

[Gabe n Em]

I know a really good boat for diesel electric!

 

[Cottontop]

Indeed it will, for a few weeks..... This motor was designed and optimized for intermittent duty: momentary moderate power when acellerating and then very low power all the rest of the time at cruise on the highway. When asked to provide 50 to 80 % power for hours on end, which is typical marine usage, it will fail prematurely.

Why? The enemy of electric motors is heat, not load (recognizing that greater load = greater heat). The Volt motors are water cooled. Is the cooling adequate for higher sustained loads? I don't know, but I would bet it is.

 

[lpedleur]

See Chevy Volt. Day-to-day around town, fully electric (Gen 2 of the Volt will go 50+ miles on battery). But need to go on a road trip, no problem, gas engine (I get 37 mpg on the gas engine).

Yep, this is why i had the volt power train in mind. I own a '17 volt myself 42000 km and 0 issues yet.

 

[Keysdisease]

A properly designed and installed driveline with low noise and vibration as a priority, a properly designed and installed insulation system and a top shelf exhaust system can be had for a lot less complexity and a lot less energy management fussing than what you describe. You will need that for your generator too, if you want less "noise, vibration and fumes"

At canal speeds I would bet a properly engineered conventional drive boat with noise and vibration reduction as a priority would be just as quite as a Greenline, or whatever was cobbled together, with no fumes either. Your "noise, vibration and fumes" issues are inflated when a proper system is the standard.

I've been watching this emerging technology for years. I have been party to several hybrid projects, supplied components and advice, and except for a narrow range of missions there are added complexity issues, reliability questions due to the additional complexity, and cost / benefit concerns.

At the last Hybrid / propulsion show there was a case study of a harbor tug, comparison of conventional vs hybrid. Mission was close to being in the current hybrid technology envelope to be viable, until the batteries needed to be replaced. Then the cost benefit went way out the window.

There's religion, and then there engineering, IMHO, not ready for prime time, but by all means have at it and move the learning curve forward

I'm willing to pay for less noise, vibration and fumes.

 

[Woodland Hills]

Lifestyle features, that's right. But then you went back to the usual strawman arguments. Nobody serious is suggesting cruising at 20 knots with electric propulsion. And while solar is nice, and relatively cheap, it's not key. A Greenline 40', for instance, can be equipped with two 7kw motor/generators which will charge the 23 kwh of LiPO batteries in two hours. That's plenty for house loads, or to power the boat for 20 km at 4 kn.

There are 8,000 km of canals in France, and thousands more in Belgium, Netherlands, Germany, etc. A typical speed limit in a French canal is 10km/h. You can spend the rest of your life going from one quaint, history-filled town to the next. So, motor a little while, some solar, and quiet propulsion the rest of the day. The boat comes with a household fridge, dishwasher, washer/dryer, A/C, etc. What's not to like? Horses for courses.

If it's not already obvious, I'm considering a Greenline. But not because I'm trying to save money, and not because I'm trying to be green, and not because I'm trying to be holier than thou. It's strictly about the creature comforts.

I drive a Volt. I've had it more than 5 years, 100,000 miles plus. People say, "Let me explain how you're not really saving money." Yes, I know that. Don't care. "Well, let me explain how you're not really being green." Not sure I agree, but don't care one way or the other. "Well, let me explain how fast my Corvette can go." Don't care; the last time I drove 150 was never. Then why, you might ask? I'm tired of sending money to people who hate me.

I just don't get the visceral hatred of electric cars or boats.

I've had an i3 for nearly three years and have built and ride two fat tire eMTBs and an electric recumbent bicycle: I like electric vehicles, but only where they are better than an ICE.......

As far sending money to people who hate me, as a Californian and given how they seem to hate my home state, I would rather not buy fuel sourced in places like Texas or Oklahoma, but there is not much I can do about it. So I can understand where you are coming from.

 

[FF]

The major advantage to electric drive for cruising boats is the engine can be operated at its best BMEP range..

With only a 2 or 3% loss a shaft and mechanical tranny is far more efficient.

To get in the proper BMEP range , its"cruising prop" time.