What is best alternative to run cars at present ?

1. Hydrogen Engine
2. Batteries (Charging done through renewable source)
3. Air engine
4. Steam engine
5. sterling engine
6. Hybrid engine (mixture of gasoline and some of other things)
7. Solar cars

None of those - there is no alternative to petrol/diesel/LPG yet.

Agreed. A steam engine running on petrol may be an attractive alternative. John

cant we use solar heated stirling engines

That would probably get you the Nobel Prize. How much solar collection panel would be needed for minimum of a 20 HP Stirling engine, i.e., very low performance car? How big is a 20 HP Sterling engine? How many HP would be required to carry that 20 HP Sterling engine, solar collection panel, and energy storage source up a 10% grade? If you eliminate the energy storage part, how will you operate in darkness?

John

The answer is 6. Hybrid technology is the best at present. But renewables are the ultimate answer. Ethonol, sun, wind, geothermal all play a role.

Get a bike or a horse.

To be honest there is no real one best answer. It all comes down to the application of the vehicle.

What would work in one application and be cost effective could very well be a dismal and expensive failure in another.

A electric powered one or two person passenger car for short trips in congested urban conditions would be a dismal failure in a wide open rural setting where driving at high speeds for long distances are considered normal.

Same with fuel based vehicles. A mechanically efficient diesel engine powered semi truck is best suited to what they do best. Haul heavy loads for long periods of time. At present no other AE based power source can serve in that application at the same operating costs and power levels required and meet similar run time between refueling.

To be honest there is no real one best answer. It all comes down to the application of the vehicle.

What would work in one application and be cost effective could very well be a dismal and expensive failure in another.

A electric powered one or two person passenger car for short trips in congested urban conditions would be a dismal failure in a wide open rural setting where driving at high speeds for long distances are considered normal.

Same with fuel based vehicles. A mechanically efficient diesel engine powered semi truck is best suited to what they do best. Haul heavy loads for long periods of time. At present no other AE based power source can serve in that application at the same operating costs and power levels required and meet similar run time between refueling.

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Your answer is more to the point. but what about solar panel , if we make photovoltaic cells 100% efficient also then would it be feasible ?
and what is the efficiency of battery and an electric motor ?

neptune said:

Your answer is more to the point. but what about solar panel , if we make photovoltaic cells 100% efficient also then would it be feasible ?
and what is the efficiency of battery and an electric motor ?

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You can't just 'make solar cells 100% efficient - in fact you can't make ANYTHING 100% efficient.

Even assuming fairly high efficiency, there's not enough surface area on a car to power it decently - not even in India!.

Electric motors are fine, it's battery technology that's the massive problem - they need to be massively smaller, massively lighter, massively higher capacity, and charge massively faster. Improve every aspect by a factor of ten, and electric cars would be viable.

Hybrid cars are just a con - it's just a petrol car that uses the engine to charge a battery - they don't give particularly better mileage, unless the performance is pathetic - and then it's better mileage because of the poor performance, not because it's hybrid.

I've driven a Lexus hybrid, a truely beautiful car, nice to drive and performance is wonderful - but it's a 3.5L petrol engine, and uses the battery to give an extra boost at high speeds. True, it does start off on battery, and it's so seamless you can't tell what it's running on - but it still uses petrol like a 3.5L high performance luxury car.

if we make photovoltaic cells 100% efficient

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That alone would earn you a dozen Nobel prizes. Unfortunately, you might not live to collect them, as vested interests such as oil companies might wish to 'suppress' you and the development.

WHATTT!! Oil companies suppressing renewable energy automobiles...Who would have thought it..... The swines...Trouble is, quite a few politicians have shares in said oil companies...We don't stand a chance.. Do we..

WHATTT!! Oil companies suppressing renewable energy automobiles...Who would have thought it..... The swines...Trouble is, quite a few politicians have shares in said oil companies...We don't stand a chance.. Do we..

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I have came to the conclusion that when oil companies and politicians widely support somthing then it probaby does not work as advertised and there is an equal chance its probably doing more harm than good.

Take emissions system requirements. Do you really think the oil companies would be backing the technology and requirements if it actually made your vehicles get better fuel economy instead of worse? Would politicians also feel so strongly about it if they didn't feel that by over regulating it they could make more tax and compliance money from less?

Hybrid cars are no hoax. The technology is based on very sound engineering principles, that a motor can by tuned for maxmum effeciency when used over a narrow power band, the electric motors making up for the balance of power required. Only hybrids are able to achieve over 40MPG combined highway/city feul economy source. No matter how poor a gas only car performs, it can't come close to hybrid's economy figures.

BrownOut said:

Hybrid cars are no hoax. The technology is based on very sound engineering principles, that a motor can by tuned for maxmum effeciency when used over a narrow power band, the electric motors making up for the balance of power required. Only hybrids are able to achieve over 40MPG combined highway/city feul economy source. No matter how poor a gas only car performs, it can't come close to hybrid's economy figures.

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40mpg is pretty pathetic, a great many diesel cars (and even high performance ones) far exceed that - and that figure in a hybrid is simply because it's performance is useless. An obvious advantage of such a hybrid is in traffic jams, where it can 'run' on electric for a good length of time, and lack of performance isn't an issue. However, a great many petrol cars do something similar, automaticlaly stopping and starting the engine.

No petrol car other than a hybrid can get near 40MPG combined city/highway, and the performance is certainly not pathetic. It's as good or better than the other, lower performing gas only cars, and better than many small diesel cars. Better performing diesel cars can't approach the fuel economy of hybrids. Diesel fuel is the most expensive fuel at all the stations I've been to, and isn't sold at ever neighborhood station, and diesel cars cannot be purchased in 5 US states. Hybrids don't have to start and stop the engine in traffic, they can run for miles on battery power only, and only need to start the engine to keep the battery from eventually running out. That saves not only fuel, but wear on the enginer and starting components. And when the hybrid does start the engine, it doesn't need to use the starter motor, only the momentum of the care as it's moving under battery power, further saving wear on maintence items. A further effeciency gain is hybrids use regenerative breaking, which uses the car's breaks during decelleration to return charge to the batteries.

In the EPA's list of best fuel economy, only two diesels make the cut, Audi A3 at 34 combined MPG and Volskwagon Jetta SportWagen at 34 combined MPG. By contrast the Toyota Prius V gets 50 combined MPG. source

No petrol car other than a hybrid can get near 40MPG combined city/highway

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Eh? My old Toyota 1.6 litre lean-burn engined petrol car gave me nearly 47mpg in combined city/highway use, averaged over ~9 years.

In 2012, the most efficient gas only car tested 37 combined MPG.

40mpg is pretty pathetic, a great many diesel cars (and even high performance ones) far exceed that - and that figure in a hybrid is simply because it's performance is useless.

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I fully agree. Back in the late 70's and into the 80's, before the emissions trolls got a hold of things, the Volkswagen Rabbit diesels where pushing mid 40's MPG numbers in the city and mid 50's MPG number on the highway in factory stock form even on the American gallon opposed the imperial gallon which is larger. http://s87762315.onlinehome.us/history.php?site=vw

Back in the mid nineties when I went to college at NDSCS a college buddy of mine even hot rodded his little 'rattling can of walnuts' engine and gained a few more HP and MPG over its original stock design. As far as driving one went I never thought his little rabbit was any less gutless than any other econo car of its day. By todays standard I would say it was rather peppy or at least his 5 speed one was!

Just going to throw my 2 cents in:

One of the biggest problems with fuel efficiency in an IC engine is the design of the engine itself; this design hasn't changed much in about a hundred years. It is still more-or-less a piston sliding up and down a cylinder, connected via a crank to a crankshaft. Along with a camshaft opening and closing valves, connected to the crankshaft via some belt/gear/chain and pulley arrangement.

In other words, a lot of parts - a lot of power (and fuel) robbing parts. Reduce the part count and/or the connections between them, and you'll gain a more efficient engine (in theory). Think about the following:

1) Why are the valves actuated by the engine? Why not have them electronically/electro-mechanically controlled?

2) The piston slides up and down - but due to side forces from the crank action, there is side-to-side rubbing and wear (causing cylinders to take on an elliptical shape over time). Eliminate that extra friction!

3) Why a crank at all?

4) Note that the piston has to be accelerated down, then brought to a "halt" and driven back up (other pistons firing, plus the flywheel to even things out); this back and forth motion, while balanced, isn't as stable as say something like a turbine, which just spins (but has its own issues - such as needing to run at a fixed speed for maximum efficiency).

5) Turbine hybrid vehicle, perhaps - where the turbine runs at a fixed speed, of course...

All of these issues and problems have been explored, and engines invented/researched to address some or all of them. The Wankel and other rotary engines attempted to solve some of these issues. I've read about one engine that had double-ended pistons, where one end of the piston drove hydraulic fluid through turbines (eliminating the crank and crankshaft). Not too many years back, there was the McMaster motor (which was a nutating disk engine).

Many of these ideas and such have had issues which may have "doomed" them in their time (but maybe today, with today's new materials - something better could be done?), but I sometimes wonder if some of them just died for lack of funding, or if they were bought by "interests" and are just being sat on, waiting for the day when they are absolutely needed - and sold to the public for $$$ as a "new invention" or something. I mean, many of these engines and ideas originally came about in the 1960's or earlier - then seemingly nothing more about them. The McMaster was one of the latest; it seemed like a workable idea, but the website went down a long while ago - I don't know what happened with it.

Speculation and conspiracy, I guess...