Gasoline vs Electricity

[The Duchess of Zeon]

Mind you, with massive submarine propulsion batteries I strongly suspect that you could create a viable battery-electric locomotive today; the problem is recharging the thing, above and beyond the charge you'd get from regenerative braking. The batteries would have to be modular components which could be quickly removed and replaced with fully charged replacements at a fueling stop. The infrastructure to do that would probably negate most of the benefits (not having to build a new overhead wire infrastructure) of the system viz. simply stringing cantenary.

[Admiral Valdemar]

This is something I've brought up a few times over on another board when trying to teach whiny teenage US drivers that what they call expensive gas, is really not so much.

I don't quite point out the argument the same way, instead I follow what the likes of Matt Savinar and Colin Campbell say with regards to "energy slaves". If you truly knew what you were accessing now, in terms of wealth, compared to any dynast king of old, you'd see how spoilt we are.

Think of it this way. A barrel of oil gets you about 25,000 man-hours of energy output, on average. Find 1,000 fit men, and then tell them to work for you under contract for 25 hours each. When it comes to payment, give them $70 to share amongst themselves evenly. Remember where your nearest exit is upon doing so.

Right now, Americans are happy to pay five bucks for a cup of coffee, yet, the far more valuable petroleum they burn which is far more useful is seen as overly pricey despite that same cup filled with gasoline being a fraction of the price.

[The Duchess of Zeon]

This is something I've brought up a few times over on another board when trying to teach whiny teenage US drivers that what they call expensive gas, is really not so much.

I don't quite point out the argument the same way, instead I follow what the likes of Matt Savinar and Colin Campbell say with regards to "energy slaves". If you truly knew what you were accessing now, in terms of wealth, compared to any dynast king of old, you'd see how spoilt we are.

Think of it this way. A barrel of oil gets you about 25,000 man-hours of energy output, on average. Find 1,000 fit men, and then tell them to work for you under contract for 25 hours each. When it comes to payment, give them $70 to share amongst themselves evenly. Remember where your nearest exit is upon doing so.

Right now, Americans are happy to pay five bucks for a cup of coffee, yet, the far more valuable petroleum they burn which is far more useful is seen as overly pricey despite that same cup filled with gasoline being a fraction of the price.

I want to declare energy equivalency month, and buy several thousand slaves.

[Darth Wong]

That's a much weaker comparison than the gas-electricity one. Human labour value is not based on simple mechanical work, even for manual labourers. Electricity, however, is poised as a direct replacement for gasoline.

[Admiral Valdemar]

Perhaps, but it serves more to illustrate the fact that oil is a highly energy dense substance, more so than any gas, and is a one off deal to boot. Without fossil fuels, you'd not have any of the industry you take for granted now, so whenever anyone questions the need for them or their high price, let them know how much manual labour they'd be doing just to replace the agri-business machinery today. Amazing how people change their opinion when they have to grow their own food or do without.

[aerius]

I've often wondered about this myself in regards to efficiency of electric vs. gasoline powered vehicles.

Mike, as an ex-automotive engineer, isn't it true that a good deal of this energy is wasted in the inefficiency of the internal combustion engine that wouldn't be wasted if you stored the power plant derived power in the form of batteries to run the car?

The average gasoline engine is about 25-30% efficient at best, and the driveline will knock another few percent off that. Figure on maybe 20-25% overall as a ballpark number. Highway driving will bump the numbers up a bit while city driving will knock a huge chunk out of them unless you're driving a hybrid.

With electric cars, the motors are around 90% efficient give or take 5% or so and it's about the same for the motor control electronics. In most cases the wheels can be directly driven by the motors so driveline losses are a lot lower. Basically, figure on an overall efficiency of 80-90% or so.

Of course if your electricity comes from fossil fuels like coal or natural gas, the overall efficiency in terms of extracting energy from the fuel isn't any better than burning gasoline in an ICE once you account for losses in the powerplant and electricity grid.

[Darth Wong]

Perhaps, but it serves more to illustrate the fact that oil is a highly energy dense substance, more so than any gas, and is a one off deal to boot. Without fossil fuels, you'd not have any of the industry you take for granted now, so whenever anyone questions the need for them or their high price, let them know how much manual labour they'd be doing just to replace the agri-business machinery today. Amazing how people change their opinion when they have to grow their own food or do without.

If you want to impress people with the energy storage of gasoline, just point out that 1 litre of gasoline is worth the energy yield of 7.6 kg of TNT. Or for Americans, 1 gallon of gasoline has the energy output of 67 pounds of TNT.

[Darth Wong]

The average gasoline engine is about 25-30% efficient at best, and the driveline will knock another few percent off that. Figure on maybe 20-25% overall as a ballpark number. Highway driving will bump the numbers up a bit while city driving will knock a huge chunk out of them unless you're driving a hybrid.

With electric cars, the motors are around 90% efficient give or take 5% or so and it's about the same for the motor control electronics. In most cases the wheels can be directly driven by the motors so driveline losses are a lot lower. Basically, figure on an overall efficiency of 80-90% or so.

Turns out the DOE has a page on this subject.

http://www.fueleconomy.gov/feg/evtech.shtml

75% for electrics vs 20% for gasoline. But the spectacular energy density of gasoline vs batteries makes that look considerably less favourable when you look at it in terms of power output relative to the weight of the stored fuel.

[Sea Skimmer]

All modern diesels are diesel-electric, yes. Geared diesels were a failure of the 1930s.

No they aren’t, the Germans still produce and use diesel-hydraulic locomotives with torque converters. These locomotives are significantly lighter then diesel-electrics of the same power, and apparently cheaper to build too. However maintenance issues have kept them from ever catching on that widely, US railroads did import some hundreds of them back in the 1960s. If we could build a CTV that could handle the power, and work reliably, then geared locomotives could become the world standard. Might happen in the next 30 years.

[Arthur_Tuxedo]

Battery weight is definitely a problem, but advances in battery tech should continue to yield cells with higher energy density, and the Tesla Roadster manages to cram a battery that powers an engine capable of propelling the car to 60 MPH in 3.9 seconds with a range of 250 miles into a two-seater with today's technology.

The 4 to 8 hour charge time may be true for many existing EV designs, but newer ones can, IIRC, be charged from empty to full in about one hour.

The replacement cost of the battery is a valid point, but an EV probably saves as much or more in reduced maintenance and repairs as the battery replacement costs, and if the government subsidized EV's as much as they do large SUV's, it would more than pay for the cost of a new battery.

[Drewcifer]

...US railroads did import some hundreds of them back in the 1960s. ....

Ah, the infamous Krauss-Maffei locomotives.

From here:

After much research, SP [Southern Pacific RR] decided to go offshore and get Krauss-Maffei of Germany to build three 4000hp diesel-hydraulic locomotives. DRGW also ordered three, to make the first order a total of six. A number of modifications were required once operating experience on mountain lines was had, and the three DRGW units fairly quickly found themselves in SP ownership.

The first order was successful enough, for SP to go back to Krauss- Maffei and ordered another 15. These were different enough for the first order to be called 'cab units' and the second to be called 'hood units'. 9001 is an example of the 'cab units' and 9014 an example of the 'hood units'.

As mountain operating experiences were less than desirable, these units soon found themselves as 'flatlanders'. Eventually the usual practice was to operate one KM and a GP9 or F7 [regular diesel-electrics] on a train.

US locomotive technology finally caught up with these units, and all were scrapped between 1967 and 1968, except for #9113 which was rebuilt to a Camera Car.

[Drewcifer]

edit: I was going to say something on topic, too. Someone (smarter and more eloquent than me) should write one of those annoying emails that everybody forwards about all of this. Most would get deleted, but a few might get through. It still works for spam.

[Darth Wong]

The fact that 1 gallon of gasoline has the energy output of 67 pounds of TNT is pretty damned impressive if you know how much damage 67 pounds of TNT can do. If you detonated that much TNT in a car, you wouldn't just blow it up. You would obliterate it.

[Sea Skimmer]

Yes and this is all because the liquid fuel is actually being combined with about 14.7 times its own weight in sea level air. That works out to about 92lb of oxidizer to make that gallon of gasoline actually do anything without being boiled (causing a boiling liquid vapor explosion) by a vast amount of heat. This is why a fuel air explosive bomb is potentially far more powerful then the same weight of conventional explosives. It’s just very difficult to get the fuel to disperse purely to explode. Newer ‘Thermobaric’ FAE designs use a solid fuel for increased reliability, but this only seems to work for modest sized warheads.

TNT will always work given a detonator, say when underwater or inside a shell flying through the air. The stuff is also engineered to be relatively stable, and gets mixed with more powerful, less stable chemical explosives in military munition fillings.

67lbs of TNT is easily tank smashing territory.

[Sea Skimmer]

Ah, the infamous Krauss-Maffei locomotives.

Hmm, I’d thought it turned into a larger order, guess not.

Still regardless of how the locomotives work, diesel powered ones are too flexible to go away completely; even a totally electrified system would still realistically need them for heavy work trains. Diesels are quite efficient users of oil, and some oil will be available for a long time to come. It’s also not very difficult to adapt big diesel engines to run on a wide range of alternative fuels if it was necessary. You could even turn old tree stumps into methanol, if it was some utter national disaster, and fuel the things off that

[Winston Blake]

The fact that 1 gallon of gasoline has the energy output of 67 pounds of TNT is pretty damned impressive if you know how much damage 67 pounds of TNT can do. If you detonated that much TNT in a car, you wouldn't just blow it up. You would obliterate it.

Sugars and fats are other materials with surprisingly high energy density. Fat has 38 MJ/kg, so one kg has the energy of 9.1 kg of TNT.

That gives 68 lb of TNT for one gallon of fat (with fat density 0.9g/mL). The average person probably has enough energy in their body fat to obliterate their house. Clearly we must weaponise obese people before the Soviets do.

[NeoGoomba]

Damn, I guess General Ripper wasn't kidding about preserving bodily fluids.

[Admiral Valdemar]

Sugars and fats are other materials with surprisingly high energy density. Fat has 38 MJ/kg, so one kg has the energy of 9.1 kg of TNT.

That gives 68 lb of TNT for one gallon of fat (with fat density 0.9g/mL). The average person probably has enough energy in their body fat to obliterate their house. Clearly we must weaponise obese people before the Soviets do.

I remember on ASVS years ago, when someone argued about phaser output and bollocksed up their numbers to the point that a Big Mac had more energy content than a phaser beam on high setting. Throwing Big Mac burgers at Federation ships would, therefore, obliterate the ship.

[Zixinus]

Now the cost of 1 gallon of gasoline in America is around $3 right now, which most people think is exorbitant and outrageous. 1 US gallon is 4 litres (...)

Holy... people in the USA are outraged for, what? Roughly 1.3$ for litre (I'm pretty sure that's not it)? In my country fuel is heavily taxed, about 1.6$ per liter.

While I'm tempted to assume that an electric car must be more efficient than a gasoline car, I'm not sufficiently familiar with the current state of technology in that field to say.

My father, who is an electric engineer, tells me that an electric motor converts electric energy to mechanical energy with very high efficiency, about 90%.

He also tells me that the motors could be built within the wheels, and that you could tap power when braking, saving you some energy and the weight of several mechanical parts responsible for braking in a traditional car. I read somewhere that charging a battery losses about 20% of the energy given in.

I once saw a movie done by a futurist talking about paradigms. There, as an example, he shown a car built by a bunch of "energists" that only needed IC to maintain speed, and converted the wasted energy either as stored air pressure or electric energy. You didn't even need to start the motor to get the car rolling, and it had amazing performance.

Also, does anybody know anything about EEStor? They claimed that they produced a capacitator that was competitive with batteries.

[Sea Skimmer]

He also tells me that the motors could be built within the wheels, and that you could tap power when braking, saving you some energy and the weight of several mechanical parts responsible for braking in a traditional car. I read somewhere that charging a battery losses about 20% of the energy given in.

Even the best electric car still needs normal brakes. Regenerative braking can only do so much before you need friction contact to slow down faster; it also doesn’t work at all at very low speeds.