How will 2024 CAFE standards impact your buying?

[supton]

Since this thread has sort of morphed into a discussion of hybrids and EVs, how come something like a diesel electric system like locomotives and cruise ships hasn’t been tried? 100% electric propulsion powered by an onboard diesel generator. There has to be some advantage to a system like this or it wouldn’t be so common.

I think, and this is just a guess, that those big ship motors can idle at really low rpm. At low rpm the prop is low(er) drag. Or maybe it has a clutch? zero idea. But a train has to to operate down to 0mph. Water has slip, trail rails don't (or shouldn't, not desirable).

The locomotive is kinda stuck with electric as it'd take a lot of gear reduction to get started, then a bunch of shifting. The cruise ship I do believe is more like an automatic transmission setup, the prop&water is like a torque convertor setup.

Maybe a train could eek out more miles per gallon (or less gallons per mile?) if it could have some top gear direct drive, but it's the transmission that is the issue.

 

[zzyzzx]

I have nothing against electric vehicles. They were some of the first vehicles made and i think they are awesome for daily activities. They just wont work for most people’s spontaneous lifestyles including mine as a primary vehicle. Its not even really a range issue but a charging speed and charger location issue. You literally cant find a tesla fast charger in the middle of nowhere and also these chargers are often full of other teslas. No one wants to wait in line to then wait some more charging.

Bring back the Chevy Volt!

 

[BMWTurboDzl]

Since this thread has sort of morphed into a discussion of hybrids and EVs, how come something like a diesel electric system like locomotives and cruise ships hasn’t been tried? 100% electric propulsion powered by an onboard diesel generator. There has to be some advantage to a system like this or it wouldn’t be so common.

Emissions. BMW flirted with this and settled on gas. The BMW i3 uses a 3 cyl gas engine as a range extender to power the electric motor.

The i3 and Chevy Volt fall under EREV (Extended Range Electric Vehicle) designation.

Ford has an idea on the shelf: https://www.motor1.com/news/446705/ford-f150-electric-patent-images/

 

[mrnkc130]

I think, and this is just a guess, that those big ship motors can idle at really low rpm. At low rpm the prop is low(er) drag. Or maybe it has a clutch? zero idea. But a train has to to operate down to 0mph. Water has slip, trail rails don't (or shouldn't, not desirable).

The locomotive is kinda stuck with electric as it'd take a lot of gear reduction to get started, then a bunch of shifting. The cruise ship I do believe is more like an automatic transmission setup, the prop&water is like a torque convertor setup.

Maybe a train could eek out more miles per gallon (or less gallons per mile?) if it could have some top gear direct drive, but it's the transmission that is the issue.

Most large ships dont have transmissions at all, motors even have to run in reverse to back up, and yes very low RPM.
Serious marine transmissions are also very low geared (3 or 5 to 1) for sub 1000 rpm prop speeds (in displacement hulls anyways)

Steam engines have mechanical drive, but yes diesel electric is just about the only option due to the reasons you mentioned as well as needing to be able to do the same speeds in reverse as in forward. So much tractive effort is needed now that class ones only want to buy AC motors instead of DC.

 

[4WD]

Most large ships dont have transmissions at all, motors even have to run in reverse to back up, and yes very low RPM.
Serious marine transmissions are also very low geared (3 or 5 to 1) for sub 1000 rpm prop speeds (in displacement hulls anyways)

Steam engines have mechanical drive, but yes diesel electric is just about the only option due to the reasons you mentioned as well as needing to be able to do the same speeds in reverse as in forward. So much tractive effort is needed now that class ones only want to buy AC motors instead of DC.

D/E migrated to AC/VFD years ago … (IGBT) …
High displacement and low RPM engines take a good deal of space + gens and associated phase modules etc. Cruise ships tend to have azimuthal propulsion - I have watched the largest park from quayside and it’s amazing. Thruster systems can be D/E to VFD and back to mechanical thrusters so that no electric motor is submerged. Tunnel thrusters in the bow. Whilst marine propulsion can be fascinating - it’s not the best analog for Route 66.

 

[4WD]

Most large ships dont have transmissions at all, motors even have to run in reverse to back up, and yes very low RPM.
Serious marine transmissions are also very low geared (3 or 5 to 1) for sub 1000 rpm prop speeds (in displacement hulls anyways)

Steam engines have mechanical drive, but yes diesel electric is just about the only option due to the reasons you mentioned as well as needing to be able to do the same speeds in reverse as in forward. So much tractive effort is needed now that class ones only want to buy AC motors instead of DC.

Yep. A surprising number of bulk freighters have one engine & screw.

 

[chris719]

How many people buy from both McD’s and Starbucks? that’s not what I tend to think of, to me thats two different groups of people. Both could be in the same debt, sure.

If Starbucks sold McD hash browns, egg McMuffin, sausage McMuffin, and the apple pie for a dollar over McD prices they would make a killing.

 

[Elkins45]

Yep. A surprising number of bulk freighters have one engine & screw.

This 14 cylinder engine is 44 feet high and 90 feet long. it powers the largest container ship in the world. It’s a two stroke and produces over 100,000 HP at 102 rpm.

There are three people standing on the upper deck.

 

[Elkins45]

There are many at 400m or close to it - Maersk built several when I was at the DSME shipyard …
Over 100k HP as well …

Emma Mærsk - Wikipedia

en.wikipedia.org

I would love to hear one of those running.

 

[JHZR2]

Since this thread has sort of morphed into a discussion of hybrids and EVs, how come something like a diesel electric system like locomotives and cruise ships hasn’t been tried? 100% electric propulsion powered by an onboard diesel generator. There has to be some advantage to a system like this or it wouldn’t be so common.

Huh? This is done routinely.

Locomotives have been diesel electric for decades. I think the only difference is that older ones just rectified the generator and had a DC motor, while newer ones flip back to variable frequency AC.

For ships, the big electric manufacturers like Siemens, ABB, and GE do indeed have hybrid and electric drive systems.

 

[Elkins45]

Huh? This is done routinely.

Locomotives have been diesel electric for decades. I think the only difference is that older ones just rectified the generator and had a DC motor, while newer ones flip back to variable frequency AC.

For ships, the big electric manufacturers like Siemens, ABB, and GE do indeed have hybrid and electric drive systems.

I meant why hasn’t it been tried for cars? All the hybrids still have a mechanical connection between the gas or diesel engine and wheels. Locomotives don’t.

 

[SC Maintenance]

I meant why hasn’t it been tried for cars? All the hybrids still have a mechanical connection between the gas or diesel engine and wheels. Locomotives don’t.

That would be less efficient for a car. When the ICE runs in a hybrid, it has enough power to both power the car and charge the battery at the same time depending on the circumstances. Additionally, the engine can kick in and provide extra power in addition to the electric motor as needed - during acceleration for example. Having an engine that was completely disconnected from the driveline would then require a much larger electric motor to provide the same amount of energy to power the car, and would hence be less efficient when not under heavy load, and cost a lot more.