Tata motors: Cars that run on compressed air?

[MarchHare]

I'm thinking inside the range of 150km or less.

Even still, that's more than enough range for most people. If you're driving to and from work and making a few stops around town for errands, 150km between refills is plenty. This could be an ideal city car; if you want to go on a road trip out of town, you can always rent a traditional gasoline-powered vehicle.

[photon]

Yup if it was really 150km it would be great.

I'm skeptical of that as well though, an actual car in production with a real range would be more interesting.

Wikipedia says Tata Motors has removed all mention of this car from their website??

[kirant]

Originally Posted by MarchHare

Even still, that's more than enough range for most people. If you're driving to and from work and making a few stops around town for errands, 150km between refills is plenty. This could be an ideal city car; if you want to go on a road trip out of town, you can always rent a traditional gasoline-powered vehicle.

Oh, no doubt. Economically, if the compressed air is cheap and affordable per km driven, it'd be a great product for the consumer. Energy efficiency wise, it may end up being worse than a gas driven car, but it could certainly end up with savings in your wallet.

[photon]

Or just get one of those Toshiba neighbourhood sized nuclear reactors and who cares how efficient it is, cheap electricity!

[Wormius]

So... what's going to heat up the car's passenger area during winter? Rely on a Costco sized box of hand warmers?

[bizaro86]

Originally Posted by Wormius

So... what's going to heat up the car's passenger area during winter? Rely on a Costco sized box of hand warmers?

They'll probably just sell it in countries that are warm all year round.

[Bill Bumface]

Originally Posted by kirant

I think a car engine is about 30% efficient

A car engine is about 20% efficient at best. Coal plants are slightly over 30% efficient, so over 1.5 times more efficient.

[kirant]

Originally Posted by hulkrogan

A car engine is about 20% efficient at best. Coal plants are slightly over 30% efficient, so over 1.5 times more efficient.

Which means in order to be just as efficient as a current car engine, the conversion process of combustion energy to electricity to compression of air to mechanical force must be 66% or better in order to be as green as the current process at a really simplistic level (which is still pretty insane). Of course, this leaves out the difference between coal and heavy gasoline (which, from a green perspective, coal is generally worse in).

At least it's more attainable than the ~100% needed with the original number.

[blankall]

Originally Posted by kirant

Which means in order to be just as efficient as a current car engine, the conversion process of combustion energy to electricity to compression of air to mechanical force must be 66% or better in order to be as green as the current process at a really simplistic level (which is still pretty insane). Of course, this leaves out the difference between coal and heavy gasoline (which, from a green perspective, coal is generally worse in).

At least it's more attainable than the ~100% needed with the original number.

You also have to take into account the fact that 20% of Earth's electricity comes from renewable sources (mostly Hydro) and another about 15% from nuclear. While these other sources aren't perfect either, they do produce a lot less carbon, which is the main worry for many right now.

[kirant]

Originally Posted by blankall

You also have to take into account the fact that 20% of Earth's electricity comes from renewable sources (mostly Hydro) and another about 15% from nuclear. While these other sources aren't perfect either, they do produce a lot less carbon, which is the main worry for many right now.

Jeez. You're making me do non-work related math that isn't simple numbers

Well, that leaves about 65% of the original energy being equal in carbon. If my mental math is right, that corrects to about 43% or greater efficiency in the changed processes (from combustion energy in plants to mechanical energy from the engine) in order to be as efficient. This could be problematic when many air compressors run inside single digit effectiveness (10-20% have been the ones I've worked with..I've heard of some 8-9% ones though). If that could be solved though, it would be approaching viability as a direct substitute.

[afc wimbledon]

Originally Posted by Wormius

So... what's going to heat up the car's passenger area during winter? Rely on a Costco sized box of hand warmers?

worked fine for my old Hyundai pony, you young punks with yer heaters and air conditioning, you don't know how good you have it.

[octothorp]

Originally Posted by photon

Good point about more efficient power plants (especially if you are trying to power your car with coal. ). I was thinking of gasoline.

But if we go with the industrial coal power plant:

Coal -> Electricity -> Compressor -> Air -> Car

I don't think is going to be more efficient than

Coal -> Electricity -> Battery -> Car

Just because of the amount of heat that'll be generated when you compress the air in the first place.

Efficiency isn't the only factor to consider, energy density per unit weight and per unit volume is important too to get a usable range in a vehicle of usable size, and compressed air might be better in those.

I'm still on the side of developing battery technology.



Hm, not sure. I googled air compressors and ones capable of 300 bar seem to to use 4kw, assuming a 4 hour charging period that's less than a dollar. Even if you double the time to compress to 8 hours or add in losses due to heat or whatever, $2 to fill a tank seems reasonable.

At least now, if you converted most of the cars on the road to compressed air, I think the price of electricity would probably change lol.

Here's something to consider about the overall efficiency model, if it were ever adopted wide-scale. One of the big problems with our power grid is that it's really crappy at storing power. Especially with hydro, solar and wind power, a significant portion of the potential energy that these systems create is simply lost because there's no way to store it.

One of the more creative (possibly crazy) ideas for storing power is to use large, underground reservoirs that have been emptied of natural gas as a sort of massive compressed air battery. Excess power on the grid during off-peak times is directed toward the compressors that build pressure during these times, that can then be released during peak times to generate power.

But let's say, rather than one massive underground reservoir, you had compressed air 'stations' scattered around a city. Each is basically a giant air compressor tank. During off-peak times, all of these tanks are filling up with compressed air using electricity that would otherwise be wasted. These become compressed air refueling stations for cars, and they'd also act a batteries that can return power to the electrical grid during peak times.

[photon]

Yeah I've read about compressed air as energy storage too, there's a few of them in use.

[freedogger]

I don't see it as a matter of choosing one technology over another. I think it is great that there is one more option to consider. It seems like world oil production has flatlined for the last six years from the stats I have read on it. It feels like we are entering a new economic paradigm where Every time the economy picks up oil rises and crushes the recovery.