New Tesla News

[ChrisB]

Originally Posted by Rich H

The same amount of mechanical energy is required at the wheels to move a given vehicle, regardless of the original source of that energy or the conversion process. And charging batteries incurs delivery losses from power plant to meter.

True, but the efficiency of converting the fuel to that ultimate mechanical energy is not the same. IC engines are not very efficient, though I don't know the relative efficiency of the turbines used in power generating plants versus the car engine. I suspect the turbines are more efficient.

Interesting discussion.

[tonybelding]

Originally Posted by Rich H

Electric vehicles can reduce CO2 so long as the electric utility system used to charge batteries emits less CO2 than burning gasoline in vehicles. This is not automatic, and requires regulation of utility CO2 emissions.

Well, that contradicts what I've read from most other sources.

Also, the practicalities of utility system dispatching dictate that, for the most part, natural gas will be the marginal fuel used to charge vehicle batteries.

No. Natural gas is most often used for on-demand power generation. If we assume that most electric cars are charged overnight when demand is low (as they should be), then that's when natural gas is least likely to be used. In fact, much of the grid currently has excess power generated at night which is simply wasted because demand is below the base load levels.

So CO2 impacts may boil down to deciding whether to regulate car emissions directly, or indirectly via electric utilities.

There's no question that the electrical grid needs to be cleaned up. Particularly, if you assume global warming is a problem that demands action, then the electrical grid must be cleaned up. Electric cars will benefit from that process. Gas cars won't.

And J. Salmon is correct. The same amount of mechanical energy is required at the wheels to move a given vehicle, regardless of the original source of that energy or the conversion process. And charging batteries incurs delivery losses from power plant to meter.

That is one of the most technically true but grossly misleading statements I've seen in a while.

Yes, given cars with the same mass, rolling resistance and aerodynamics, they will require the same amount of energy -- at the wheels -- to drive. However, the efficiency of delivering that energy to the wheels varies wildly with different methods. Your typical gasoline engine is about 20-25% efficient, and your typical electric motor is about 90% efficient.

Yes, it's true that there are "delivery losses" in the power grid, from the power plant to your charging station -- but not much. It's about 90% efficient on average. If you add up all the numbers and energy losses for an electric car, their efficiency works out equivalent to typically about 100-130 MPG.

[lc_09]

Originally Posted by J. Salmon

Nuclear is the way to go, in my opinion. and THEN the Tesla will be sweet!

Dude, you can't be serious.

Until somebody finds a realistic solution for nuclear waste treatment. Nuclear is far from the way to go.

Would you be willing to live with a nuclear power plant right outside your town?
i don't know anyone that would.

And in regards to the tesla. I do hope it succeeds.

It is certainly not a miracle car that's going to save the world (as so much of the hype implies.) But, i do feel that an alternative fuel success story from a little car company would go a long way towards convincing the big auto makers to get behind this green movement in ernest.

[tonybelding]

Originally Posted by lc_09

Until somebody finds a realistic solution for nuclear waste treatment. Nuclear is far from the way to go.

I think nuclear is the way to go.

There are many ways to dispose of nuclear waste, assuming you can't be bothered to reprocess it and turn it into useful fuel again. The obstacles are entirely political, not technical.

It's easy to show that today's nuclear plants are far cleaner and safer than coal-fired plants. Building new coal plants today is crazy.

There are also some promising nuclear fusion developments in the work. I've got my fingers crossed that they'll amount to something. That would resolve the last objections to nuclear power.

[ChrisB]

Originally Posted by lc_09

Dude, you can't be serious.

Until somebody finds a realistic solution for nuclear waste treatment. Nuclear is far from the way to go.

Would you be willing to live with a nuclear power plant right outside your town?
i don't know anyone that would.

I would...and did for four years. I lived in San Juan Capistrano, just a few miles up the road form the San Onofre nuclear power plant. Didn't bother me a bit. Apparently it didn't bother the other tnes of thousands of people that moved into the area either. I still live within 20 miles of it.

[mopho]

Here is picture of Chris

[Rich H]

Originally Posted by ChrisB

True, but the efficiency of converting the fuel to that ultimate mechanical energy is not the same. IC engines are not very efficient, though I don't know the relative efficiency of the turbines used in power generating plants versus the car engine. I suspect the turbines are more efficient.

Interesting discussion.

Roughly speaking, you get 20 to 30 percent efficiency +/- when you burn fossil fuel to produce rotating mechanical energy across the range of engine types: IC, turbines, etc. The choice is to burn the fuel in the vehicle and use the rotating energy directly, at say 20% efficiency, vs. burning it at a power plant to produce rotating energy, at say 30% efficiency, that spins an electric generator, then transmitting the electricity over long wires to charge vehicle batteries (usually 5-10% loss), and finally discharging the batteries into electric motors that convert the electricity back into rotating energy to drive the vehicle.

So relative IC vs. electric vehicle efficiency depends upon the details of the physical equipment.

[Rich H]

Originally Posted by tonybelding

No. Natural gas is most often used for on-demand power generation. If we assume that most electric cars are charged overnight when demand is low (as they should be), then that's when natural gas is least likely to be used. In fact, much of the grid currently has excess power generated at night which is simply wasted because demand is below the base load levels.

Read the EPRI/NRDC study. You'll find detailed analyses showing that natural gas is the marginal fuel for battery charging, even assuming that most charging is done at night. Gas turbines are essential to system dispatch and reliability, at all hours. Separate from that, and unrelated, they are also used to meet peak demands, which is what I think you're trying to suggest.

And its a misperception to think that the electric system is wasting energy at night, or that there is excess power being generated. Neither is happening.

[Rich H]

Originally Posted by tonybelding

If you add up all the numbers and energy losses for an electric car, their efficiency works out equivalent to typically about 100-130 MPG.

Try playing with these numbers.

It takes about 10,000 BTUs +/- to generate one kwh at a power plant, and you lose 5-10% to deliver it to the residential meter. One gallon of gasoline contains about 125,000 BTUs. Tesla has said, I think, that its car is rated at around 30 kwh per 100 miles driving an EPA test cycle.

So how many mpg does the Tesla get if the gasoline is burned in the power plant?

[Lotus Fury]

Straight from the source, the best source.
http://www.teslamotors.com/efficiency/well_to_wheel.php

There's also a bunch of other info there too.

[tonybelding]

Originally Posted by Rich H

Try playing with these numbers.

It takes about 10,000 BTUs +/- to generate one kwh at a power plant, and you lose 5-10% to deliver it to the residential meter. One gallon of gasoline contains about 125,000 BTUs. Tesla has said, I think, that its car is rated at around 30 kwh per 100 miles driving an EPA test cycle.

So how many mpg does the Tesla get if the gasoline is burned in the power plant?

Tesla's answer found here. . .

http://www.evworld.com/library/Tesla_21centuryEV.pdf

[Lotus Fury]

It's also easier to more efficiently "scrub" the exhaust from a power plant than for cars engines. It's a matter of scale & control. It's much easier to control output & conditions at a power plant. Cars tend to be their dirtiest before the Catalytic converter is cold, the first five miles or so.

[ChrisB]

Originally Posted by mopho

Here is picture of Chris

LOL! If you only knew.

I had parathyroid surgery on Monday, but mine wasn't as big as that person's!

[Rich H]

Originally Posted by tonybelding

Tesla's answer found here. . .

http://www.evworld.com/library/Tesla_21centuryEV.pdf

Alas, that was written in 2006, before Tesla's EPA cycle test, reported in 2007 I think. The 2006 claim was 0.110 kwh per km, which translates to about 0.177 kwh per mile. Unfortunately, the later EPA test result turned out to be 0.310 kwh per mile, which equated to, I think, 245 miles on a battery charge. Of course Autoweek only managed to get 96 miles on a charge...

But even using Tesla's own EPA figures, and its calcs in the 2006 writing, the Tesla efficiency looks to be about the same as a Prius, driving in EPA style that is...

And not to bore, but Tesla's 2006 assumption of the world's single most efficient combined cycle turbine as the electricity source is simply not realistic, or even practical.

[Rich H]

Originally Posted by Lotus Fury

It's also easier to more efficiently "scrub" the exhaust from a power plant than for cars engines. It's a matter of scale & control. It's much easier to control output & conditions at a power plant.

Interesting thought perhaps, but EPRI/NRDC studies did not cite this as a potential air quality benefit.

[rob13572468]

Originally Posted by tonybelding

I think nuclear is the way to go.

There are many ways to dispose of nuclear waste, assuming you can't be bothered to reprocess it and turn it into useful fuel again. The obstacles are entirely political, not technical.

It's easy to show that today's nuclear plants are far cleaner and safer than coal-fired plants. Building new coal plants today is crazy.

There are also some promising nuclear fusion developments in the work. I've got my fingers crossed that they'll amount to something. That would resolve the last objections to nuclear power.

This is correct. Nuclear has been and still is our best bet for long term environment friendly power generation. The amount of nuclear waste generated in a typical power plant is miniscule compared to coal or gas. (a nuclear reactor produces 100-200kg of waste per year compared to *millions* of metric tons that a coal plant does. The average citizen really has no concept of the immense waste we have been dumping into the atmosphere and rivers around our coal plants.

Nuclear waste disposal is safe, So safe in fact that the storage sites (salt deposits surrounded by granite have been shown to be stable over geologic time scales (100,000 years) due to the plastic ability of the salts to flow. Nuclear plants are safe, far safer than *any* other power generation, even wind power (apparently guys get hurt alot putting the turbines up). We tend toexxagerate the dangers of nuclear power because nuclear mishaps are sensationalized in the news. What we dont see of hear about are the thousands of deaths and injuries every year caused by coal. If you dont believe me check out the OSHA report on job safety for any given year since the advent on nuclear power.


Coal *sucks*. But the real reason for switching to electric cars is not to save the environment or reduce emissions, at leats not in the near term. The reason has everything to do with reducing our dependence on oil which is a *huge* cause for instability in the world today.

[rob13572468]

Originally Posted by ChrisB

True, but the efficiency of converting the fuel to that ultimate mechanical energy is not the same. IC engines are not very efficient, though I don't know the relative efficiency of the turbines used in power generating plants versus the car engine. I suspect the turbines are more efficient.

Interesting discussion.

Power plant turbines *are* quite a bit more efficient than IC engines. The reason has to do with how they are operated. All IC engines have a narrow range near full power where they operate with the highest efficiency. for example our elise hit peak efficiency at 5-6K and under constant load. The problem of course is that to drive we must use our engines within a much larger range because of the transmission and the fact that we have to slow down sometimes (as much as we hate to..)

You can take your elise engine out of the car and remap it to work as a generator, running at one speed at peak efficiency and have the engine drive a generator which charges your (now electric elise) batteries. The same 8 gallons of gasoline will now give you 2-3 times the energy that you would have with the engine in the car. Some of this gain will be lost back to charging losses in the batteries themselves but otherwise it is a huge net gain. This is why hybrid vehicles can have similar performance using a much smaller engine. Another way to look at it is to think of the HP rating. The elise is 190HP but you only use the full 190HP a small percentage of the time. When crusing on the hwy in 6th gear you may be using 40 hp. Hybrids leverage this by playing the law of averages; as long as the drive motor can output enough power to produce the same acceleration you can keep a much smaller IC engine as a power supply knowing that at 60HP it can charge the batteries to provide those instaneous bursts of power for the big acceleration.

So yes, hybrids and all electric vehicles both run more efficiently and get better overall mileage. Hybrids still use oil but use less of it whereas all electric vehicles use no oil but use coal instead (but still use less power overall).

[Rich H]

Originally Posted by rob13572468

Power plant turbines *are* quite a bit more efficient than IC engines. The reason has to do with how they are operated...

So yes, hybrids and all electric vehicles both run more efficiently and get better overall mileage. Hybrids still use oil but use less of it whereas all electric vehicles use no oil but use coal instead (but still use less power overall).

If only it were true...

Look at the US Energy Information Agency electricity data compilations. In 2006 in the US, for example, it took an average of 9,919 BTUs to produce one kwh from fossil-fueled plants, 10,434 BTU/kwh from nuclear, and 21,017 BTU/kwh from geothermal. And those figures do not include transmission and distribution losses.

Since one kwh delivered to the electric meter provides the heat equivalent of 3,412 BTU to the user, the overall electricity conversion and delivery efficiency equates to something under 30%, which is in the same ballpark as an internal combustion engine powering a car directly. Plus, some losses are incurred inside of the electric vehicle itself.

[lc_09]

Originally Posted by rob13572468

This is correct. Nuclear has been and still is our best bet for long term environment friendly power generation. The amount of nuclear waste generated in a typical power plant is miniscule compared to coal or gas. (a nuclear reactor produces 100-200kg of waste per year compared to *millions* of metric tons that a coal plant does. The average citizen really has no concept of the immense waste we have been dumping into the atmosphere and rivers around our coal plants.

Nuclear waste disposal is safe, So safe in fact that the storage sites (salt deposits surrounded by granite have been shown to be stable over geologic time scales (100,000 years) due to the plastic ability of the salts to flow. Nuclear plants are safe, far safer than *any* other power generation, even wind power (apparently guys get hurt alot putting the turbines up). We tend toexxagerate the dangers of nuclear power because nuclear mishaps are sensationalized in the news. What we dont see of hear about are the thousands of deaths and injuries every year caused by coal. If you dont believe me check out the OSHA report on job safety for any given year since the advent on nuclear power.


Coal *sucks*. But the real reason for switching to electric cars is not to save the environment or reduce emissions, at leats not in the near term. The reason has everything to do with reducing our dependence on oil which is a *huge* cause for instability in the world today.

hey Rob,

these are all good points, but i, like most people remain very skeptical. The nuclear industy and "environmentally friendly" don't have a history of being mentioned in the same breath.

I didn't want to hijack this tesla thread with a discussion of the benefits or dangers of nuclear power. But, i think as you pinted out that most people are not aware of how bad coal power plants really are for the environment.
But, in a discussion i had recently with some people from work. The fear and skeptisism relating to nuclear power can be illustated in this simple equation. (rational or not, this is how most people still feel about this issue)

Coal power plants + earthquakes = regional disaster
Nuclear power plants + earthquakes = global disaster

coal power plants + terrorist attack = regional disaster
Nuclear power plants + terrorist attack = global disaster

coal power plant accident = thousands of lives lost
nuclear power plant accident = millions of lives lost

i know its a major over simplification, but for people old enough to remember Chernobyl and 3 Mile Island, the concept of nuclear power as an environment friendly solution is hard to swallow.

[ChrisB]

Originally Posted by lc_09

coal power plant accident = thousands of lives lost
nuclear power plant accident = millions of lives lost

i know its a major over simplification, but for people old enough to remember Chernobyl and 3 Mile Island, the concept of nuclear power as an environment friendly solution is hard to swallow.

Interesting, but there was not a single death as a result of the 3 Mile Island accident. Also there was no radiation sickness among the nearby population. The maximum radiation one would have received in the area was about one-third that which you receive with a normal chest X-ray.

Chernobyl was quite a bit different, but that plant was of a very substandard design that could not have been built in the US.