Cleaner city buses

[Mosquito]

I have an idea for a cleaner type of buses for use within cities. I don't know if the idea is in production (and my googling skills have proven to be well below par), but in this city, the local buses run on diesel. And they pollute a lot.

My idea is not actually new, I just want to know if this could work, or if I'm completely off in the physics department. I might learn something if I am, which is not a waste of time, so I hope somebody here can enlighten me.

The idea is as follows:

The buses have a big, heavy engine that runs on low(?) levels of efficiency. Why not replace it with a smaller, lighter, cleaner engine? I know that the bus needs the pure strength of the big engine, but I was thinking of putting in a different source for that.

So, rather than having an inefficient, big, strong engine, I would like to put in a smaller engine with aproximately the power needed on average to run the bus, rather than peak needs. This should reduce the engine size etc. considerably, as the average need is probably rather low (acceleration is what saps much of the fuel, I suspect, and no need to run a big engine when waiting for the lights or passengers).

To make it work, the engine should be in a hybrid configuration, so that it is actually an electric motor providing force to the wheels. Since electric motors have an enormous torque(?) this should be workable even for getting uphill.

I know that the motor will need extra juice for things like acceleration (which is why the diesel is so big and powerful), this juice I would like to get from batteries (or similar).

Thus the idea is that the actual diesel/gasoline engine is small, built for average load and extra juice needed are extracted from batteries. When little or no actual power are needed for propulsion, the batteries are recharged or the engine shut off. Also they can get some of the power generated during breaking. This is existing technology, used in hybrid cars today.

Could this work? Could enough power be extracted from the batteries when needed? Could the batteries be recharged fast enough to be practical? Would they survive recharging/discharging many times a day for years? Would the setup be able to provide a cleaner bus? Cheaper?


Mosquito (trying to learn something)

 

[Brian the Snail]

You mean something like this?

 

[pauldmin]

I believe that some time ago, someone made a bus that had an enormous fly-wheel in the chassis.

The wheel would be spun in the depot and then used to power the bus during it's normal run around the city.

As an alternative, it would be possible to use a small diesel engine to power the wheel occasionally whilst in normal operation and combine this with regenerative braking to make a very efficient system.
Very quiet as well..

 

[Mosquito]

You mean something like this?

Well, sort of, yes.

So I guess it is in production, I'll check it out

From my quick 10 second glance at their web-page, their system is exactly what I was thinking about.

Now the big question is: Why are these buses not installed here? Are they expensive? (I may find out from reading their pages).


Mosquito

 

[Mosquito]

I believe that some time ago, someone made a bus that had an enormous fly-wheel in the chassis.

The wheel would be spun in the depot and then used to power the bus during it's normal run around the city.

As an alternative, it would be possible to use a small diesel engine to power the wheel occasionally whilst in normal operation and combine this with regenerative braking to make a very efficient system.
Very quiet as well..

This may be very efficient and quiet, but wouldn't the fly-wheel have to be rather heavy (and thus add a lot to the total system weight&energy needs)? Or spin faster than what is practically possible? I don't know how much of the braking energy can be restored into the wheel, but I assume there is some (a lot?) loss.

Of course, with a small engine to maintain the spin, it just becomes a very agreeable(?) "battery", similar to the hybrid idea.


Mosquito

 

[Mosquito]

Okay, I have sent some questions regarding prices and retrofitting old buses to TriMet.

It'll take a week or so to get a response, but I think it would be interesting


On a related and only slightly different note, does anybody know how good efficiency one gets from such a system in comparison with, say a normal gasoline-engine connected to the wheels-system?

Would it be possible to build this into smaller wehicu..wheic..units like small cars/motorcycles of better efficiency?

I have seen some hybrid car specifications, and they do not impress me... Seems they are still using about one litre of gasoline for each 10 kilometres, same as my father's 1981-model russian Fiat-copy. Admittedly, they are stronger, better etc. but they don't get more km/l, which is disappointing. The russian car wasn't exactly high-tech...


Mosquito, fed up with high levels of exhaust, whishing I had $100B for fixing things (donations accepted...).

 

[IllegalArgument]

Okay, I have sent some questions regarding prices and retrofitting old buses to TriMet.

It'll take a week or so to get a response, but I think it would be interesting


On a related and only slightly different note, does anybody know how good efficiency one gets from such a system in comparison with, say a normal gasoline-engine connected to the wheels-system?

Would it be possible to build this into smaller wehicu..wheic..units like small cars/motorcycles of better efficiency?

I have seen some hybrid car specifications, and they do not impress me... Seems they are still using about one litre of gasoline for each 10 kilometres, same as my father's 1981-model russian Fiat-copy. Admittedly, they are stronger, better etc. but they don't get more km/l, which is disappointing. The russian car wasn't exactly high-tech...


Mosquito, fed up with high levels of exhaust, whishing I had $100B for fixing things (donations accepted...).

Must chime in with a question. What hybirds did you look or are you talking about bus hybrids? I'm getting 40+ MPG easy using US measurements.

 

[Mosquito]

Must chime in with a question. What hybirds did you look or are you talking about bus hybrids? I'm getting 40+ MPG easy using US measurements.

This would translate into 16-17km/l, which is not bad. But I remember seeing ads for small cars some 15-20 years ago that could do close to 25-30. Of course this would be small cars, but still. They had nothing hybrid about them, pure gasoline. (Don't ask for links or references, this is from memory.)

I got my info from "Popular Mechanics en español", which recently did a hybrid vs. diesel test. And the Diesels came out pretty good, with similar km/l. Don't remember details, and the magazine is at home, but the Prius was there.

I realize that getting a lot extra from driving down the highway isn't going to be easy, but from driving around in the city, which is most driving a lot of people do, something should have gotten better, I feel. My father's new car does about 15km/l or better when driving down the highway, and it is a regular gasoline car... I don't know how it does in the city, though, but I think it does somewhere around 10, unless heavy rushhour.


Mosquito, I may not be totally up to date, but being married my dating days are over anyhow.

 

[RichardR]

We already have zero emission buses in San Francisco

With more than 700 clean air vehicles (compressed natural gas, hybrid, electric, biofuel and propane) in its transportation fleet, San Francisco is an established leader in low emission vehicles. More than half of city’s Municipal Railway (Muni) fleet is comprised of zero-emission vehicles and the City sponsors programs to promote low-emission taxicabs and liquid natural gas, long-haul garbage trucks. Muni will be the first California transit agency to buy buses with the latest hybrid technology, and its 2004 Zero Emissions 2020 Plan calls for Muni to establish an all-electric drive fleet that includes hybrid buses, battery buses, and fuel-cell buses by 2020. “Muni aims to be emissions free by 2020,” according San Francisco Municipal Transportation Agency Executive Director Michael Burns.

Is that what you mean?

 

[Mosquito]

We already have zero emission buses in San Francisco


Is that what you mean?

Not exactly what I was thinking of, but certainly interesting

My idea is not just to reduce exhaust (though that is a good goal in itself), but to reduce dependency on fossil fuel (and costs). Something this SF project seems to include, though my idea was not as grand scale.

I understand that this SF project will do a lot of good for the city, hopefully something like this will spread throughout, so that I can enjoy it too.

Does somebody know if plant-oils are good for fuel? This would seem to me to be a way of getting the "best of both worlds" as the fuel would pack close to gasoline levels of energy, and effectively be zero CO2. Maybe even providing some food...


Mosquito (not in SF, but learning something here today)

 

[IllegalArgument]

This would translate into 16-17km/l, which is not bad. But I remember seeing ads for small cars some 15-20 years ago that could do close to 25-30. Of course this would be small cars, but still. They had nothing hybrid about them, pure gasoline. (Don't ask for links or references, this is from memory.)

I got my info from "Popular Mechanics en español", which recently did a hybrid vs. diesel test. And the Diesels came out pretty good, with similar km/l. Don't remember details, and the magazine is at home, but the Prius was there.

I realize that getting a lot extra from driving down the highway isn't going to be easy, but from driving around in the city, which is most driving a lot of people do, something should have gotten better, I feel. My father's new car does about 15km/l or better when driving down the highway, and it is a regular gasoline car... I don't know how it does in the city, though, but I think it does somewhere around 10, unless heavy rushhour.


Mosquito, I may not be totally up to date, but being married my dating days are over anyhow.

The hybrids do have one thing over diesels, zero or low emissions. Priuses do better in the city actually, they use the energy of coasting or braking to charge the battery.

I'm the forum Prius fanatic by the way.

 

[RichardR]

Does somebody know if plant-oils are good for fuel? This would seem to me to be a way of getting the "best of both worlds" as the fuel would pack close to gasoline levels of energy, and effectively be zero CO2. Maybe even providing some food...

Trouble is, the plants have to be grown, which means more land for farming. Farming (monocultures / fertilizer / herbicides etc) are also bad for the environment.

No free lunch yet.

 

[Mosquito]

The hybrids do have one thing over diesels, zero or low emissions. Priuses do better in the city actually, they use the energy of coasting or braking to charge the battery.

I'm the forum Prius fanatic by the way.

My memory (still don't have the article at hand) seems to suggest that the prius did not do substantially better than the comparative diesel (brand x) in the city either, though I buy your emissions argument. Diesels are well known for their emissions, though I believe they ave been cleaned up a bit during the last 20 years?

Still, the Prius is a big&heavy car, no? Not really built for city use, but probably excellent down the highway.

I guess the US does not really want small and efficient cars, though. What with all the SUVs running around. Not the most efficient use of fuel...


Mosquito, thinking the hybrid idea is excellent, but that the cars are too big and heavy to get really GOOD km/l ratios.

 

[Mosquito]

Trouble is, the plants have to be grown, which means more land for farming. Farming (monocultures / fertilizer / herbicides etc) are also bad for the environment.

No free lunch yet.

I was hoping to get paid for this lunch, but I see your point. Any optionals? Like using the sea? Or "non-farmable" land and some tough/GM plants?

Mosquito, going for his $0.40 lunch now

 

[bPer]

Still, the Prius is a big&heavy car, no? Not really built for city use, but probably excellent down the highway.

I don't think so. I've never driven a Prius, but I've followed one in city driving several times, and it seems like a zippy little performer. And it isn't big, at least compared to my VW Golf.

I did bit of Googling, and it weights about the same as a Golf (1300 kg), which is more than its stable-mate the Echo (975 kg) admittedly, but hardly what I'd call heavy.

As far as fuel economy is concerned, the Prius apparently gets 4.0/4.2 l/100km, or 71/67 mpg (Cdn measurements).

Sounds like an excellent city and road performer.

βPer

 

[IllegalArgument]

My memory (still don't have the article at hand) seems to suggest that the prius did not do substantially better than the comparative diesel (brand x) in the city either, though I buy your emissions argument. Diesels are well known for their emissions, though I believe they ave been cleaned up a bit during the last 20 years?

Still, the Prius is a big&heavy car, no? Not really built for city use, but probably excellent down the highway.

I guess the US does not really want small and efficient cars, though. What with all the SUVs running around. Not the most efficient use of fuel...


Mosquito, thinking the hybrid idea is excellent, but that the cars are too big and heavy to get really GOOD km/l ratios.

Actually, my Prius is quite nimble. It's not a what we would call a sub-compact in the US, but it's on the small side for a sedan. It's well designed so that it has plenty of room inside, but is short and thinner than most of the cars I park next to.

 

[Mosquito]

I don't think so. I've never driven a Prius, but I've followed one in city driving several times, and it seems like a zippy little performer. And it isn't big, at least compared to my VW Golf.

I did bit of Googling, and it weights about the same as a Golf (1300 kg), which is more than its stable-mate the Echo (975 kg) admittedly, but hardly what I'd call heavy.

As far as fuel economy is concerned, the Prius apparently gets 4.0/4.2 l/100km, or 71/67 mpg (Cdn measurements).

Sounds like an excellent city and road performer.

βPer

That's interesting. I didn't think it was that good, but about 4l/100km isn't so bad This is city? (Cdn means zip to me) If so, I'd agree that it is more excellent than I thought.

On the weight issue... I thing 1300 is quite (but not very) heavy, though I am aware that modern cars are much heavier than older cars. I suppose there is some research being done on reducing the weight? I'd like to see the weight down in the 7-900kg, but I suppose that is a bit optimistic with modern demands on luxury and safety.


Mosquito, learning more and more today, a good day.

 

[Mosquito]

Actually, my Prius is quite nimble. It's not a what we would call a sub-compact in the US, but it's on the small side for a sedan. It's well designed so that it has plenty of room inside, but is short and thinner than most of the cars I park next to.

This doesn't really tell me much, as US cars are HUGE...

I've seen a picture of the Prius (in the aforementioned article) and it seems like a decent sized sedan to me, but I always thought Mercedes, Volvo and (good old) Ford Scorpio were big cars.

And I do not envy you the car, mostly because I have seen the local population here drive...

When will miniaturization hit the car-market? Where is my 250kg 80KW microvan (with decent space for a family and some groceries)?


Mosquito

 

[bPer]

That's interesting. I didn't think it was that good, but about 4l/100km isn't so bad This is city? (Cdn means zip to me)

{sigh} Mosquito, Google is your friend. A little more use of it might mean less need for questions here.

'Cdn' - Canadian

I was warning you that the mpg calculations may be using Imperial gallons. I really don't care for the old measurements, since we've started expressing fuel economy here in litres per 100 kilometres, and that's how my car expresses it, so I will leave it to you as an exercise to figure out what 4.0 l/100km translates into in your (unspecified) location.

The Prius gets 4.0 l/100km in the city. 4.2 on the highway.

βPer

 

[Mosquito]

{sigh} Mosquito, Google is your friend. A little more use of it might mean less need for questions here.

'Cdn' - Canadian

I was warning you that the mpg calculations may be using Imperial gallons. I really don't care for the old measurements, since we've started expressing fuel economy here in litres per 100 kilometres, and that's how my car expresses it, so I will leave it to you as an exercise to figure out what 4.0 l/100km translates into in your (unspecified) location.

The Prius gets 4.0 l/100km in the city. 4.2 on the highway.

βPer

No, Google, as I have explained in my thread on how to use my laptop for showing movies from a settop DVD-player, is NOT my friend. I seem to be completely useless with it. Sad, really, as it would have been a great tool.

I am quite happy about litres and kilometres, and 4.0l/100km is good in the city

Maybe I should try googling for a website that gives information on how to google, previous experience tells me it would probably be a waste of time though


Mosquito, no friend of search engines, and not proud of it.