I have read many things here where folks appear to think highly of electrical transportation. I don't think much of it because the energy needed is much higher than traditional solutions. On another thread, it was reported that only 15-20% of the input energy at an electrical power plant was used at the final destination (e.g. the fuel content at the electrical plant contained 5 to 6.7 times the energy used in the home). This is because they are unable to capture all the energy in the fuel, there are productiion losses such as friction in the generators and turbines, and there are transmission losses. I do not know what the ratio is for petroleum IC engines, but I am under the impression it is much better than this. Are there any automotive engineers here that can provide some comparisons? Thanks.
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Is electric powered transpo the answer? 2
- Thread starter Dinosaur
- Start date
civilperson
Structural
Electricity as an answer, what is the question?
I don't doubt that diesel on rails is efficient.
After looking at the Denver light rail yesterday, there seems to be a bunch of added stuff to the cantanary part.
I wonder if the electric trains are any less maintenance intenssive than the diesel?
After looking at the Denver light rail yesterday, there seems to be a bunch of added stuff to the cantanary part.
I wonder if the electric trains are any less maintenance intenssive than the diesel?
Based on recent experience in diesel-powered "heavy rail" passenger service initiated in Albuqerque (on freight lines):
Must be dedicated right of way with NO grade crossings (5 people killed so far crossing the tracks in cars/trucks).
Rules for blowing the horn at grade crossings is a real problem, typical rail practice is a very loud horn, for an extended period. Neighbors don't like.
Diesels are quite noisy near stops (acceleration).
Quite a bit of parking and support structure is needed to integrate it into the existing auto systems.
Must be dedicated right of way with NO grade crossings (5 people killed so far crossing the tracks in cars/trucks).
Rules for blowing the horn at grade crossings is a real problem, typical rail practice is a very loud horn, for an extended period. Neighbors don't like.
Diesels are quite noisy near stops (acceleration).
Quite a bit of parking and support structure is needed to integrate it into the existing auto systems.
As many other have said, it depends on how the electricity is generated.
In Australia, I believe that emmissions standards on cars are more stringent than those on coal powerstations, so switching to the electrical grid may actually cause more emmissions.
In some ways hydrogen cars may make a better environmental alternative. The hydrogen can be created where there is a good environmental source of energy(solar, hydro,tide, or geothermic) and at an off peak time and then shipped to the required location(in a hydrogen powered truck of course).
In Australia, I believe that emmissions standards on cars are more stringent than those on coal powerstations, so switching to the electrical grid may actually cause more emmissions.
In some ways hydrogen cars may make a better environmental alternative. The hydrogen can be created where there is a good environmental source of energy(solar, hydro,tide, or geothermic) and at an off peak time and then shipped to the required location(in a hydrogen powered truck of course).
Ross,
"Quite a bit of parking and support structure is needed to integrate it into the existing auto systems."
You still need to have parking, whether its at a "Park and Ride" (which is normaly free/cheap) or whether its downtown in a garage ($5-$20/hr). People have to put their car somewhere.
The major difference is the suburbs have large amounts of space to place parking, downtown space is a premium.
"Quite a bit of parking and support structure is needed to integrate it into the existing auto systems."
You still need to have parking, whether its at a "Park and Ride" (which is normaly free/cheap) or whether its downtown in a garage ($5-$20/hr). People have to put their car somewhere.
The major difference is the suburbs have large amounts of space to place parking, downtown space is a premium.
- Thread starter
- #47
It seems to me we are having three discussions.
The discussion I would like to have concerns using electric powered cars rather than IC powered cars. This is the concept that I want to evaluate. There are two hurdles. Can we generate enough electricity to add the transportation power needs to the other demands on the electric grid? Would Americans be willing to accept the electric car that could be brought to market? (e.g. How much would an electric car cost that would compare to a midsized American car?)
I accept that rail transportation is efficient. I am actually a huge railfan, except I don't think it is economically viable in the US. I also accept that we should be using nuclear technology and other technology to generate electric power. But these are side issues. I just don't think folks appreciate the scale of the problem this represents to the electric grid.
And regarding the observation that a trains dynamic blows off energy as heat, I always wished the railroad could find a reliable rechargable battery that they could put in a "slug" when they travel downhill on a long division. Then these charged slugs could be used to pull the next train uphill. I'm sure there is an economic reason they do not do this. And it could be that diesel fuel is just that cheap.
The discussion I would like to have concerns using electric powered cars rather than IC powered cars. This is the concept that I want to evaluate. There are two hurdles. Can we generate enough electricity to add the transportation power needs to the other demands on the electric grid? Would Americans be willing to accept the electric car that could be brought to market? (e.g. How much would an electric car cost that would compare to a midsized American car?)
I accept that rail transportation is efficient. I am actually a huge railfan, except I don't think it is economically viable in the US. I also accept that we should be using nuclear technology and other technology to generate electric power. But these are side issues. I just don't think folks appreciate the scale of the problem this represents to the electric grid.
And regarding the observation that a trains dynamic blows off energy as heat, I always wished the railroad could find a reliable rechargable battery that they could put in a "slug" when they travel downhill on a long division. Then these charged slugs could be used to pull the next train uphill. I'm sure there is an economic reason they do not do this. And it could be that diesel fuel is just that cheap.
btrueblood
Mechanical
I'll switch my daily driver in a heartbeat. Needs to be reasonably comfortable, 40 mph, 60 miles per charge. 2 seater would be okay, 4/5 seats better. Cost not too much more than a hybrid, and battery life > 10 years. It's those last two that aren't here yet.
But...if we assume distributed power, and put a grid of conductors all over town...everybody could drive bumper cars, like at the amusement park. There wouldn't be much difference in actual commute-hours driving speeds (at least in THIS town), and then all the cars would just bounce off each other instead of crunching and blocking traffic whilst the drivers stand in the middle of the road staring at the damage and talking on their @$$^$# cell phones...
But...if we assume distributed power, and put a grid of conductors all over town...everybody could drive bumper cars, like at the amusement park. There wouldn't be much difference in actual commute-hours driving speeds (at least in THIS town), and then all the cars would just bounce off each other instead of crunching and blocking traffic whilst the drivers stand in the middle of the road staring at the damage and talking on their @$$^$# cell phones...
I'd go for an electric car that was the size of the old King Midgets (2-pass, 1200 lbs tops, 10" wheels), using deep-cycle lead acid batteries that last 2 yrs, and only cost $50 apiece. 40 mph/40 mile range is acceptable. No A/C, RIM body panels, a radio and crank windows. Cost must be under $10k.
It wouldn't replace my gas car, it would be solely for daily commute and errands, 90% of my driving.
It wouldn't replace my gas car, it would be solely for daily commute and errands, 90% of my driving.
There are two problems with electric cars.
The first has been talked about a fair bit here. That is the need for expanded generation and transmission. It is possible to expand the current generation capacity using "green" technology, mainly through solar farms and expanded hydro-power. Some areas may extend that to tidal power as well.
The main issue is the size of the investment required. Longterm it may pay off, but the size of the projects required means that they will not be done without government participation. And governments tend to think in the shortterm, as longterm successes don't help at the ballot box.
The second issue is battery disposal. The most efficient batteries are laden with some of the most toxic materials around. Treatment and disposal will also require large costs.
IMO the electric car is more realistic than the hydrogen one. Hydrogen has the current hurdles of finding an effective storage system, developping and entirely new transmission system, consumes huge gobs of water and still needs as much added electric generation, if not more. Unless someone come up with a catalyst for electrolysis, hydrogen is likely less efficient.
As a side note, the comments about charging at off peak hours having less impact are somewhat false. It has less economic impact on the utilities as power is cheaper during off peak hours, but it has roughly the same overall impact on the grid. Many hydro-electric plants only operate at peak capacity during peak hours in order to maintain reservoir levels and maximise profits. For example, BC Hydro operates at full capacity during peak hours and sells power to the US. During off-peak hours they import power. Due to price differences this results in large profits.
The first has been talked about a fair bit here. That is the need for expanded generation and transmission. It is possible to expand the current generation capacity using "green" technology, mainly through solar farms and expanded hydro-power. Some areas may extend that to tidal power as well.
The main issue is the size of the investment required. Longterm it may pay off, but the size of the projects required means that they will not be done without government participation. And governments tend to think in the shortterm, as longterm successes don't help at the ballot box.
The second issue is battery disposal. The most efficient batteries are laden with some of the most toxic materials around. Treatment and disposal will also require large costs.
IMO the electric car is more realistic than the hydrogen one. Hydrogen has the current hurdles of finding an effective storage system, developping and entirely new transmission system, consumes huge gobs of water and still needs as much added electric generation, if not more. Unless someone come up with a catalyst for electrolysis, hydrogen is likely less efficient.
As a side note, the comments about charging at off peak hours having less impact are somewhat false. It has less economic impact on the utilities as power is cheaper during off peak hours, but it has roughly the same overall impact on the grid. Many hydro-electric plants only operate at peak capacity during peak hours in order to maintain reservoir levels and maximise profits. For example, BC Hydro operates at full capacity during peak hours and sells power to the US. During off-peak hours they import power. Due to price differences this results in large profits.
In 1980 my senior design project was a review of the lead-acid battery industry's ability to meet a demand ramping up to 10 million electric cars by 1995 (the whole senior class in IE got a piece of the Professor's DOT project, but he got the whole pay). My group's conclusion after a semester of danged hard work was that the major bottleneck was a couple of elements that were added to the battery (I don't remember what they were). These elements were mined in some pretty unstable economies, and the demand projections indicated a need for several hundred times as much of this stuff as was currently being mined.
Our conclusion was that a major breakthrough would be required in battery technology to make widespread electric cars viable. The electric-grid team came to a similar conclusion.
I know there have indeed been some major improvements in battery technology over the last 28 years, but I'm confident that every one of them will have some choke point that will make significant production increases difficult or impossible. There are A LOT of cars on the road, and as long as fuel is cheep, there will still be a lot of IC engines on the road.
David
Our conclusion was that a major breakthrough would be required in battery technology to make widespread electric cars viable. The electric-grid team came to a similar conclusion.
I know there have indeed been some major improvements in battery technology over the last 28 years, but I'm confident that every one of them will have some choke point that will make significant production increases difficult or impossible. There are A LOT of cars on the road, and as long as fuel is cheep, there will still be a lot of IC engines on the road.
David
Fossil fuel use won't end with a bang but with a whimper. epending on the location and application other sources will become more viable. First short commutes plugged in overnight, then longer and longer. The caveat to investing is the fact that convection in the troposphere invalidates the simplified concept of "global warming" so the opposing forces are reality and the propaganda of carbon traders like Al Gore. Coal to oil conversion is pretty efficient, but it's not free, so somewhat higher prices will result - but there is enough coal to last for centuries.
owg,
I think mad max was called 'road warrior' in the US. Beats me why hollywood insists on 'dumbing down' the titles here in the us.
Anyway, I can see it happening in London. If the London Borough allows electric cars to avoid paying the central london access fee then I can see them taking off.
I think mad max was called 'road warrior' in the US. Beats me why hollywood insists on 'dumbing down' the titles here in the us.
Anyway, I can see it happening in London. If the London Borough allows electric cars to avoid paying the central london access fee then I can see them taking off.
Dinosaur, sorry for taking this off track, on the bright side it hasn't yet decended into another 'global warming exists, not it doesn't, yes it does but it isn't linked to fossil fuel use...' debates.
Now as to all the implied questions: Can we generate it 'cleanly', well it will depend on your definition of clean but I think there are big hurdles. Can we distribute it, probably not without significant upgrades to current distribution system but I'm no expert. Will environmentalist & nimbys etc allow all the power plants to be built, probably not. Will anyone want to spend all that money in anywhere near the short term, I doubt it.
I think in the shorter term plug in hybrids will be more attractive than battery power alone. You still get to regenerate energy (not sure that makes sense as written, I mean capture energy othewise lost in breaking) and potentially make short/slow journeys on electricity alone. The total electrical demand will be less and may fit in better with off peak charging (as you can always travel on the IC even if the power company wont let you charge the vehicle due to demand). I'd be interested how series rather than parallel hybrids compare once you have the plug in element.
I propose we all buy old British Milk floats, stick a pallet of batteries & diesal generator on the back & see what happens!
KENAT, probably the least qualified checker you'll ever meet...
Yes, I'm sure the US could build lots of coal power stations if it wanted.
Now as to all the implied questions: Can we generate it 'cleanly', well it will depend on your definition of clean but I think there are big hurdles. Can we distribute it, probably not without significant upgrades to current distribution system but I'm no expert. Will environmentalist & nimbys etc allow all the power plants to be built, probably not. Will anyone want to spend all that money in anywhere near the short term, I doubt it.
In the short or probably medium term I doubt the American public will accept likely offerings on a large scale. America more so than where I used to live is addicted not just to the car but to large cars (& trucks). Even of those who would be willing to drive smaller vehicles many of them seem scared to because they think they'll be run off the road by all the trucks & SUVs. If you want to get an idea of cost take a look at Tesla. OK at the moment they only have the sports care but I believe they're working on sedan.
I think in the shorter term plug in hybrids will be more attractive than battery power alone. You still get to regenerate energy (not sure that makes sense as written, I mean capture energy othewise lost in breaking) and potentially make short/slow journeys on electricity alone. The total electrical demand will be less and may fit in better with off peak charging (as you can always travel on the IC even if the power company wont let you charge the vehicle due to demand). I'd be interested how series rather than parallel hybrids compare once you have the plug in element.
I propose we all buy old British Milk floats, stick a pallet of batteries & diesal generator on the back & see what happens!
KENAT, probably the least qualified checker you'll ever meet...
electricpete
Electrical
The efficiency gains of hybrids come in large part from capturing the energy used for braking, as stated.
Is there any significant benefit in being able to adjust the loading on the gas engine (by adjusting generator) so that the gas engine operates near some kind of "best efficient point"?
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Is there any significant benefit in being able to adjust the loading on the gas engine (by adjusting generator) so that the gas engine operates near some kind of "best efficient point"?
=====================================
Eng-tips forums: The best place on the web for engineering discussions.
moltenmetal
Chemical
The energy captured from regenerative braking is stored and used to supplement the IC engine's peak demand. Hence a good portion of the efficiency comes from not having to lug around a larger, more powerful (and less efficient at idle)IC engine merely to satisfy the horsepower requirements the driver has 10% of the time.
If the hybrid powerplant is large enough, you could imagine running the engine at a max efficiency or lowest emissions point and then modulating gently around that point based on power demand. But in reality most of the hybrid systems for sale at the moment are really just performance enhancement for modestly smaller IC engines- some of them so tiny to be basically "green-washing" rather than of any real use.
If the hybrid powerplant is large enough, you could imagine running the engine at a max efficiency or lowest emissions point and then modulating gently around that point based on power demand. But in reality most of the hybrid systems for sale at the moment are really just performance enhancement for modestly smaller IC engines- some of them so tiny to be basically "green-washing" rather than of any real use.
Hence my comment on series rather than parallel Hybrids.
At present as far as I know the hybrids on the market are all more or less parallel. i.e. at higher power they use both the electric motor & IC engine. At lower power they may use just elecrical, if enough charge etc. At times they'll use just IC.
In a series hybrid there would only be the electric motors. They'd need to be bigger but you would have a simpler gear box/powertrain, at least potentially. The IC would run just to keep the batteries topped up. As such it could always be run at optimal efficiency.
However depending how you look at it for some of the time the IC is effectively dead weight - especially for a plug in series hybrid.
I believe their may be series hybrid busses on the market.
KENAT, probably the least qualified checker you'll ever meet...
At present as far as I know the hybrids on the market are all more or less parallel. i.e. at higher power they use both the electric motor & IC engine. At lower power they may use just elecrical, if enough charge etc. At times they'll use just IC.
In a series hybrid there would only be the electric motors. They'd need to be bigger but you would have a simpler gear box/powertrain, at least potentially. The IC would run just to keep the batteries topped up. As such it could always be run at optimal efficiency.
However depending how you look at it for some of the time the IC is effectively dead weight - especially for a plug in series hybrid.
I believe their may be series hybrid busses on the market.
KENAT, probably the least qualified checker you'll ever meet...
electricpete
Electrical
Thanks moltenmetal and Kenat. I hadn't digested the whole thread... missed the part about discussion of mass of the engine. Makes sense that is another very important part of the equation.
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