Berkeley Engineers Have Some Bad News About Air Cars 278
cheeks5965 writes "We've argued before over compressed air vehicles, a.k.a. air cars. Air cars are an enchanting idea, providing mobility with zero fuel consumption or environmental impacts. The NYTimes' Green Inc. blog reports that the reality is less rosy. New research from UC Berkeley and ICF International puts a period at the end of the discussion, showing that compressed air is a very poor fuel, storing less than 1% of the energy in gasoline; air cars won't get you far, with a range of just 29 miles in typical city driving; and despite appearing green the vehicles are worse for the environment, with twice the carbon footprint as gasoline vehicles, from producing the electricity used to compress the air. Given these barriers, manufacturer claims should definitely be taken with a grain of salt."
"zero fuel"? (Score:2, Insightful)
At least they don't pollute the city directly (Score:5, Insightful)
Re:At least they don't pollute the city directly (Score:5, Insightful)
What benefits do these air powered cars have that aren't significantly exceeded by electric vehicles?
The range of these cars is 1/5 of electric cars *and* is less efficient.
Zero Emissions are worse?? (Score:3, Insightful)
and despite appearing green the vehicles are worse for the environment
Compressed air is just a medium in which to store energy. The energy could come from solar panels on your garage. It compresses the air. The air powers you car. Zero emitions.
This is opposed to batteries which really aren't good for the environment, but all those Prius owners don't really seem to care about Lithum strip mines while patting themselves on their backs.
Hydrogen is yet another method of storing energy.
Just compressing air from solar, wind power, etc gives Zero emissions no matter if the efficiency is only 1% or 100%
Re:Replace compressed air with compressed hydrogen (Score:1, Insightful)
I guess congratulations are in order (Score:4, Insightful)
I mean really. There's perfectly good reasons why we're not using compressed air as a 'fuel', and it's not that we hadn't thought of it. The idea (and applications) have been around since the 19th century.
Re:Zero Emissions are worse?? (Score:5, Insightful)
Those solar panels, wind turbines, penis pumps etc had to be manufactured somehow and that manufacturing process creates emissions. "Carbon offsets" is a joke, wake up people! Any emission is an emission.
Re:Zero Emissions are worse?? (Score:3, Insightful)
It said 'worse for the environment'. Using more energy is worse for the environment and will continue to be until ALL our energy comes from clean sources.
<blockquote>This is opposed to batteries which really aren't good for the environment, but all those Prius owners don't really seem to care about Lithum strip mines while patting themselves on their backs.</blockquote>
A ridiculous argument - As opposed to your air canisters which aren't made out of mined metals at all? Besides which, that's a whole different environmental issue.
<blockquote>Hydrogen is yet another method of storing energy. </blockquote>
And a vastly more efficient one, making this technology pointless.
No kidding? (Score:5, Insightful)
This is a surprise to someone? Who ever though this *could* work? Certainly not anyone with any knowledge of thermodynamics. The only compressed -gas systems that even have a chance of working are those that store the working fluid as a liquid, meaning it has to be able to be liquified at room temperature at a reasonable pressure (few hundred PSI at most). Otherwise the tanks are huge and heavy (meaning it will barely move under power) or they are small and heavy (meaning it has no range). Two excellent working fluid for this purpose are - wait for it - CO2 and Freon! Oops.
Brett
Re:"zero fuel"? (Score:3, Insightful)
Re:I guess congratulations are in order (Score:5, Insightful)
The problem of humanity is one of the capture, storage, and application of energy.
Gasoline is a fantastic medium for energy storage: it's a better battery than any battery we know how to cheaply produce and service, and that's why we use it. But the energy capture function for gasoline [getting the energy into the gasoline] sucks. And the energy dispersal/application of gasoline has some environmentalists pretty upset.
Nature gives us many ways to store energy now and release it later. The chemical combustion of gasoline is one such mechanism. The desire of a compressed gas to push forcefully against its container is another such mechanism. The strong nuclear bindig energy is a particulary potent and pervasive mechanism. The specific heat of water is yet another.
The fundamental mechanisms of energy storage have been known about for a long time. Taken as a complete system to let humanity accomplish some goal, we are concerned with how we capture the energy, how much of it we can store [and at what cost], and how easy it is to get it back out in a form condusive to the sort of work we want to do with it.
As technology changes we must continually re-evaluate the end-to-end story for a particular aqcuisition/storage/application energy cycle. We may find that we are willing to tolerate a 100 fold decrease in energy storage performance for a 200 fold increase in acquisition efficiency and a qualitative improvement in application performance.
For instance, if i live in arizona and i have a sterling-engine powered air compressor that pumps my 50G tank to 100psi after 12 hours of sunlight, and this lets me go about 10 miles with no consumption of anything other than sunlight... I'm interested. If i commute 5 miles each way, I can get to work and back using nothing but solar energy. And unlike with PV panels and electrical batteries, a guy with a pipe threading die and a welder could build refueling system in his garage, out of stuff that has zero environmental impact whatsoever.
I think that's cool. I'm obviously playing fast and loose with the numbers. Since the kJ/m^2 of solar radiation is known at gridsquares all over north america, you could actually make some ballpark efficiency guesses about peices of the process and plug in real numbers to my hypothetical example. Even if reality is 1 mile @ 30mph after 8 hrs of sunlight.. that fits _some_ usage profile.
It used to be that every farm in North Dakota [where I live] had a windmill powering the farm. Then they disappeared and became an anachronism paying homage to a bygone era. Now windmills are dotting the countryside again. It didn't get windier here.
What changed?
The physics of energy capture, storage, and dispersion have always been the same; our efficiency and the context of the problem space continue to change. As such we must constantly re-evaluate what we did in the past against the realities of today.
Re:At least they don't pollute the city directly (Score:3, Insightful)
Yeah but how many people actually need a car that is specifically designed for those kind of environments? They fill a very limited niche that doesn't seem to overlap all that much with most peoples' driving needs. The range is far too short.
Re:Zero Emissions are worse?? (Score:3, Insightful)
Compressed air is just a medium in which to store energy. The energy could come from solar panels on your garage. It compresses the air. The air powers you car. Zero emitions.
Okay, smart guy. Explain to us the zero-emissions process for manufacturing those solar panels, your air compressor, and your air car.
We're waiting.
Re:There are other ways to compress the air. (Score:3, Insightful)
Sounds like a tech geek's way of looking at it.
Most people would say -- having a sizable amount of compressed air storage in one's house is great all around -- for your pneumatic power tools.
Re:Burning wood is not zero emission (Score:4, Insightful)
As said in great grandparent post, compressed air and hydrogen are energy storage mediums. Wood is the same thing. Trees use solar energy to convert CO2 into carbon. When you burn the wood, you put the CO2 back into the air and get the energy back as heat.
It doesn't matter if we burn the wood for something useful, the trees dies and rots, or the tree is burned in a forest fire: at some point the carbon is coming back out of that tree.
Re:At least they don't pollute the city directly (Score:3, Insightful)
To power the air compressors, you'd need more power plants. Many more, since compressed air isn't efficient. Moreover, the compressors themselves would be dirty, so "free A/C" would be unhealthy.
Re:There are other ways to compress the air. (Score:5, Insightful)
But you could just as easily have that windmill power a turbine to generate electricity to charge the battery in your electric car and get a far higher energy density leading to more mileage per charge and per each day's wind. I think that's the point that's being made. There's lots of clean ways that can generate energy -- any of which can be used to compress air, but why add that extra unnecessary step in the middle when it's just an added inefficiency?
Wow, they said it... (Score:2, Insightful)
Actually admitting that a "green" energy source may not be as green as they thought. Wish more hybrid owners understood that... that battery must be disposed of eventually. As I understand it, hybrids aren't as green as people think. So much of the "green movement" is a total sham b/c it focuses narrowly on supposed benefits while ignoring reality & even data that contradicts the claims made.
Re:"zero fuel"? (Score:3, Insightful)
Ugh? I suppose if I connected the bottom of a tank, to the top of itself -- it'd explode (from infinite pressure?).
(What ever pressure you gain from going down, you'll lose by going back up (with your connecting tube)
Re:At least they don't pollute the city directly (Score:3, Insightful)
Blows... (Score:3, Insightful)
Using a mechanical air pump driven by the wind makes massive sense to me, it is patently obvious. This method alone makes air power a win.
How we generate energy now for air cars now makes no sense, is patently stupid. Fossil fuel -> heat energy -> mechanical energy -> electricity over a lossy inefficient grid -> pumping compressed air -> filling up your car.
bad news about bad news (Score:3, Insightful)
Since when does a conclusive study demonstrating what you already knew was true constitute "bad news"?
Bad news: perpetual motion doesn't exist. Would it be good news if it did exist? With such a toy, an enterprising galaxy could tip the universe toward heat death. Maybe a supernova is just perpetual motion gone Sorcerer's Apprentice.
If you're in a troubled relationship and you finally have a big blow out argument, and one of you storms off into the night, is that bad news, or good news? If you defined keeping the peace as good news, isn't that how you got yourself into that situation in the first place?
Life consists of nested narratives. What's good at an inner level of narrative might be a complete disaster for a containing narrative. Is the discovery of a big new oil field good news or bad news? Good for Exxon, bad for Bangladesh? Good for me, bad for my children?
The one case where I really understand good luck / bad luck was an episode of the Sopranos where Corrado says "these things come in threes". Corrado suffers from a narcissistic sampling bias, and thinks the outcome of his own cancer might complete the trinity of two other deaths. There's half a dozen deaths in every episode, but since Corrado has a deep insight into bad luck that I personally lack, he's able to frame his fear in specific terms.
Bobby's inquiry, "With all due respect Junior, what do you care about the details?" is one of my favourite lines of the whole series. That's not the sentiment of a man dumb enough to marry Tony's psychopathic sister Janice, which is where I started to lose interest in the series. "Hey, let's shack up and double our screen time." Bad news: Bobby just married Janice, and now the show sucks. Actually, I didn't regard that as bad news so much as an unpleasant insight into the law of least redemption in David Chase's fictional hell.
What does "bad news" really mean? How about "I'm about to tell you something you won't like, so please take three deep breaths before pulling out your gun and shooting me"? I think it's a hereditary conversation tick we use to give the recipient's hominid brain an extra moment to distinguish message from messenger, or to give an air-car believer a moment of hesitation before prematurely ending it all.
I thought if you first converted it into ethanol, one pint could power days and days of hard pedalling.
It's all about heat (Score:2, Insightful)