Energy storage, cheap and low tech.

[KennyG]

The 86% may be overall. Optimized high voltage motors and generators should be close to 95%. That would give you about 90% on the motor/generator cycles.

 

[SPYDERLK]

I think the way to look at it is getting 74% OF your money back, not 74% Interest ON your money.

Then theres startup and overhead.

The 86% may be overall. Optimized high voltage motors and generators should be close to 95%. That would give you about 90% on the motor/generator cycles.

Yes, possible for the barebones. But the losses from transmission gearing, rolling, air resistance all add up too. With all the money to set up and run and maintain it will have to be very efficient to be viable. ... And making it more efficient just costs more.

 

[Redneck in training]

Then theres startup and overhead.

Yes, possible for the barebones. But the losses from transmission gearing, rolling, air resistance all add up too. With all the money to set up and run and maintain it will have to be very efficient to be viable. ... And making it more efficient just costs more.

Gear loses are generally low. Less than 4% on high speed and way less on slow turning machines. (In example AWD cars have about 3-4% greater fuel consumption.) Air drag is not significant at the speeds the cars are moving and since it rides on metal wheels the rolling resistance is also low. I also think that maintenance expenses will be low. Less than railroad cars and tracks because of low speed. Therefore I think that the 87% efficiency is about right.

 

[MossRoad]

I don't know if I'll ever own one, but did you know that a Prius or any other hybrid can be used as a standby generator for your house with a simple kit?

Prius has a 30kW generator.

The better ones start and stop the engine as needed to maintain the charge. Quiet too!

I respect your opinion and many informative posts, but several things need to be corrected.

First - I never mentioned a "kit" in my posts. You must be confusing me with other posts.

Second - I don't know where you got your information that the Prius needed to run at 5,000 RPM to produce it's maximum output. Here is a chart for the early version of the Prius (30kW) that clearly indicates that the maximum output occurs between 940 and 2,000 RPM, significantly lower RPM than a typical generator. In fact at 5,000 RPM the output drops off.

Well, your first post mentions a simple kit and implies that you can make a 30,000W generator to run a house with a simple kit.

That graphic you show for the 30,000w Prius is the 2000 RPMs of the generator to produce 30,000W. How many RPMs does the gas engine have to turn to produce that much power??? 5000 RPMS. Here's the source.
Prius Specifications

 

[buickanddeere]

The 86% may be overall. Optimized high voltage motors and generators should be close to 95%. That would give you about 90% on the motor/generator cycles.

There is no way possible to achieve that kind of electrical and mechanical efficiency. 75% overall would be real world.
Have the proponents of this loaded rail storage system provided actual numbers of the Kw/hr storage and the cost per KW/hr ? How many thousands of these trains per state would be required.How many US mountain sides are available ? What about all the screaming environmentalists ?
A sodium battery system would be more viable.

 

[KennyG]

There is no way possible to achieve that kind of electrical and mechanical efficiency. 75% overall would be real world.

When we specify motors, we require over 92% for even small motors. If I recall correctly, the current US standard for large motors is either 95% or 96%. As was noted earlier, slow moving trains could be low friction loss. Again, I think the efficiency is achievable, I just wonder how the capital and operating cost would net out compared to other options.

 

[orezok]

That graphic you show for the 30,000w Prius is the 2000 RPMs of the generator to produce 30,000W. How many RPMs does the gas engine have to turn to produce that much power??? 5000 RPMS. Here's the source.
Prius Specifications

Let me enlighten you as to how a hybrid vehicle works. The electrical motor/generator provides virtually all of the torque up to a speed of about 45 MPH. With typical driving that would be at less than the 2,000 RPM where the peak electrical energy is produced. Above 45 MPH the gas engine increasingly takes over and the electrical side starts to drop off as the graph indicates. Yes, the gas engine will reach 5,000 RPM eventually as you accelerate to a speed above 45, but it is not necessary for the engine to run at that speed to produce it's maximum electrical output.

 

[SPYDERLK]

Let me enlighten you as to how a hybrid vehicle works. The electrical motor/generator provides virtually all of the torque up to a speed of about 45 MPH. With typical driving that would be at less than the 2,000 RPM where the peak electrical energy is produced. Above 45 MPH the gas engine increasingly takes over and the electrical side starts to drop off as the graph indicates. Yes, the gas engine will reach 5,000 RPM eventually as you accelerate to a speed above 45, but it is not necessary for the engine to run at that speed to produce it's maximum electrical output.

The unavoidable question is how more power can be derived at a given rpm than the engine can produce. Leave stored power out to avoid confusion.

 

[SPYDERLK]

Gear loses are generally low. Less than 4% on high speed and way less on slow turning machines. (In example AWD cars have about 3-4% greater fuel consumption.) Air drag is not significant at the speeds the cars are moving and since it rides on metal wheels the rolling resistance is also low. I also think that maintenance expenses will be low. Less than railroad cars and tracks because of low speed. Therefore I think that the 87% efficiency is about right.

If it is 86% overall
,,,,,I believe it is a theoretical maximum using conventional technology. This would be using ALL optimization short of; superconducting power components and non contact bearings and totally rigid track support with tracks and wheels made of tungsten carbide or harder to minimize hysteresis.

 

[orezok]

The unavoidable question is how more power can be derived at a given rpm than the engine can produce. Leave stored power out to avoid confusion.

Thats EXACTLY why they have batteries. The batteries provide additional power above the output capacity of the motor/generator at any given RPM. The motor/generator then replenishes the batteries when possible. When the vehicle reaches the maximum COMBINED output of the motor/generator and batteries, the gas motor directly provides the additional horsepower.

There is no confusion about the combination of motor/generator and batteries in a hybrid. They HAVE to work together unless you are talking about something like diesel/electric locomotives which relies only on the generator.