Hydrogen-Powered cars with Zero-Carbon-Emission?

Roland Piquepaille writes "Researchers from the Georgia Institute of Technology have a bright idea — at least at first sight. They want to create a sustainable transportation system by using hydrogen-powered cars. They would like to create an infrastructure where people could use a liquid fuel for driving while the carbon emission in their vehicles is trapped for later processing at a fueling station. 'The carbon would then be shuttled back to a processing plant where it could be transformed into liquid fuel.' Where will all this liquid carbon be stored? The researchers don't know. They suggest that it could be stored in geological formations or under the oceans."

nonsense

[ILuvRamen]

This article doesn't make any sense. Hydrogen + burning = water. Hydrogen contains hydrogen atoms and no carbon at all. And if I assume they mean how engine lubricant oil burns off a bit and that's the carbon emissions, they said they're going to trap the carbon emissions and ship it back to be made into fuel. Besides such a system having to use more energy than it generates, why would you do that when you have hydrogen powered cars? You wouldn't need to make hydrocarbon fuels from emissions if cars don't run on it anymore. And then they say they're going to dump the liquified carbon emissions somewhere under the ocean or in a mountain or whatever.
So in summary, they're going to trap non-existant carbon from cars, process it into useless fuel, and dump that fuel in a mountain...wtf?

Re:Hydrogen? Carbon?

[moderatorrater]

That's one of the worse summaries I've seen on Slashdot, and as we all know, that's saying something. Basically, there are three parts to the plan. Instead of using an internal combustion engine, you use a reactor that changes the hydrocarbon chains into hydrogen and carbon. The hydrogen is used to power the car using the already developed fuel cells while the carbon is stored. You fuel at a station, but instead of just filling up with hydrocarbon (like we do now), you also give back the carbon that your car's been storing.

In the short term, this carbon would be taken and sequestered in a variety of methods that scientists have been studying for years, either under the ocean, in old oil wells, other underground locations, or in solid carbonate form. In the long term, the carbon would go back and be remade into hydrocarbon chains to be distributed back out. As someone else pointed out, you could also use the carbon for nanotubes.

Liquid CO2 storage in your car?

[RobertB-DC]

From TFA:

The Georgia Tech team has already created a fuel processor, called CO2/H2 Active Membrane Piston (CHAMP) reactor, capable of efficiently producing hydrogen and separating and liquefying CO2 from a liquid hydrocarbon or synthetic fuel used by an internal combustion engine or fuel cell. After the carbon dioxide is separated from the hydrogen, it can then be stored in liquefied state on-board the vehicle. The liquid state provides a much more stable and dense form of carbon, which is easy to store and transport.

I don't know what planet they were planning to use these vehicles on, but on *this* one, CO2 is a GAS. You've got to have some serious refrigeration (requiring, uh oh, ENERGY) and some darned high pressure to store liquid CO2. Laws of thermodynamics aside, I'd rather not be sitting on a mobile dry ice bomb [dryiceinfo.com], thankyouverymuch.

A side note: the original tag for Roland articles was "pigpile", not "ohnoitsroland" (or any of the cruder variants). Piquepaille = Pigpile, get it? And it's usually an apt description of the science behind the "discovery".

Already is a way, and it's in development

[goombah99]

I think what they are after is a carbon source liquid that releases hydrogen and traps the carbon. THis is presumably to get around the low density of pure hydrogen storage. Perhaps some sort of fuel cell that liberates hydroggen from methane, keeps the carbon and burns the hydreogen. just a guess. low density is a problem both for the cars and for the fueling stations. to top it off liquid handling is easier than gas phase for consumers.

But there's an israeli company with an even better idea.

You use solid magnesium and water. the magnesium a spool of wire that is fed slowly into a bath of water. it reacts to produce hydrogen which bubbles out and into the engine, and also a solid magnesium oxide which sinks and is collected. THe solid magnesium waste is collected, and sent to a plant where it reproccessed back to magnesium metal electochemically, releasing oxygen in the process which itself could be collected for other uses.

ohnoitsroland

[Aaron Isotton]

Roland obviously botched the summary. It's not about hydrogen powered cars as in "cars in whose tanks you put hydrogen", but about hydrogen powered cars as in "cars with conventional fuel in the tank, which then gets split into hydrogen and carbon, and the hydrogen is used in the engine". TFA is actually interesting.

Or diamonds....

[EmbeddedJanitor]

With all that surplus carbon you should be able to give your Valentine a diamond the size of a brick.

Folks, we have no shortage of C, that's why there's a disposal problem.

Hint to moderators: parent was hoping for funnies, not insightfuls.

Re:Already is a way, and it's in development

[goombah99]

Link [physorg.com]. also google for magnesium hydrogen car and you'll also find other companies.

Re:I thought

[ciggieposeur]

There were already some pretty good ways of storing hydrogen for cars and the issue was just creating the hydrogen in the first place.

Not really. The Department of Energy has estimated that one would need at least a device capable of storing up to 0.6 kg of hydrogen per kg (e.g. a 100kg storage tank has 6kg of raw hydrogen in it) before hydrogen is just barely usable as a transportation fuel source. Ideally, 12% wt/wt storage is necessary to achieve the 300 miles per tank that most cars get today on gasoline. The best storage systems (circa 2004 when the report came out) topped out around 8% for liquified hydrogen tanks, but those are very difficult to use in practice because the hydrogen leaks out quickly. All other systems topped out around 4% and required either high temperature (metal hybrides) or very high pressures (700bar, approximately 10000 psi), again making them not yet ready for widespread use.

Hydrogen production is still an issue too though. Most of what we get now is a byproduct from natural gas processing, so it's still not carbon-neutral.

(Disclaimer: This topic is actually part of my master's thesis.)

What else could 'they' use it for?

[florewacks]

A commenter on Greentech Media points out that this research is mostly NASA and DOD funded [greentechmedia.com].

Re:Hydrogen? Carbon?

[timmarhy]

your comment is typical of all global warming idiots, you don't even understand your own imaginary problem.

water vapour is THE green house gas. the majority of the greenhouse effect comes from water vapour. hence why everyone is trying to tell you people CO2 doesn't drive climate change.

Re:Hydrogen? Carbon?

[Rostin]

You were doing more or less ok until you got to the energy density part.

According to Wikipedia, liquid hydrogen has a density of 70.8 kg/m^3. That sets a generous upper bound on the density we could hope to achieve in pure hydrogen storage.

Let's assume a density of 700 kg/m^3 for our liquid hydrocarbon. According to Wikipedia (again), gasoline is around 737 kg/m^3. Let's further assume that hydrogen makes up about 15.8% of the weight of our fuel. I arrived at that number by doing a straight average of the percentages for C5 to C12 linear alkanes. That means the part of the density we can attribute to usable hydrogen is around 111 kg/m^3.

So, in terms of effective hydrogen density, liquid hydrocarbons beat the pants off of even pure liquid hydrogen.

Re:Here's are two brighter ideas!

[letxa2000]

Real public transit. In the majority of the USA, public transit is so bad your really have no choice except to drive if you want to get to work in a reasonable time.

Won't happen. Our sprawl won't allow efficient public transit except in concentrated downtown areas. And malign sprawl as much as you'd like, but I lived in another country where there wasn't as much sprawl. No thank you. I'll take the sprawl any day of the week. Not everyone wants to live in a crowded city.

For what it's worth, I'm self-employed and work from my home 99% of the time so my contribution to the "problem" is less than that of most tree-huggers, including those that take the bus or train.

Re:What, nobody's thought of the obvious?

[Rei]

and focus on Electric Cars powered by Hydrogen cells and NOT Hydrocarbons and not Hydrogen combustion engines... they are too inefficient.

You talk about efficiency and advocate hydrogen fuel cells in the same sentence? You do realize that hydrogen fuel cell vehicles are extremely inefficient, right? At low loads, fuel cell vehicles are typically 46% efficient at turning hydrogen in the tank into wheel torque and 36% in the NEDC driving cycle [doi.org]. On top of that, you have generation losses (modern power plants are 40-50%, older ~30%, and possibly up to 60% in the future), transmission losses (7.2% average in the US), electrolysis losses (80-85% efficiency if done in the most efficient manner possible, regeneratively on hot steam). Which makes hydrogen worse than gasoline in terms of a carbon footprint. You can also make it from methane reforming, but that's no better. You can grow it from bacteria, but that costs an utter fortune. There are direct sunlight to hydrogen cells, but they are expensive, very inefficient, and break down quickly.

The hydrogen economy [daughtersoftiresias.org] is simply unrealistic. On the other hand, there is an awful lot of promise in electric vehicles [daughtersoftiresias.org].

Re:Hydrogen? Carbon?

[sectionboy]

I might be one of "global warming idiots" - for not knowing too much about it, but I failed to see how water is as bad as CO2 in this issue. Earth, as we know, has 3/4 of its surface covered by water, thus the atmosphere is basically saturated for water vapour, i.e., no matter how much water (liquid, vapour, ice, all forms combined) exists on this planet, the amount of water vapour in atmosphere as a whole system is almost constant as long as the climate (temperature, pressure) doesn't change dramtically.

Re:What, nobody's thought of the obvious?

[Rei]

Do realize that those batteries don't provide a 10x increase in energy density. After the first charge, the capacity drops to only 8x. Furthermore, it's only an anode advancement, so it would only provide a 2-3x increase in battery density. Of course, in pure electric vehicles, that's good enough to put them on range-parity with gasoline. Other techs that have the potential to do the same are lithium vanadium oxide and barium titaniate ultracapacitors.

Also, two neat things happen as you increase the energy density. Unless they cost a lot more to manufacture, you lower the cost per stored watt at the same time. Also, you reduce the number of charge/discharge cycles they need to be able to tolerate, since a single charge/discharge cycle takes you further. Then factor in mass production on top of that all...

Yeah, the future for EVs looks pretty good right now.

Re:Hydrogen? Carbon?

[Anonymous Coward]

Water vapor is A greenhouse gas. Any gaseous molecule with an IR/microwave spectrum will trap heat and act as a greenhouse gas if it's present in a large enough quantity. The nice thing about water is that it reaches an equilibrium vapor pressure when all else in the atmosphere is equal. So at our current temperatures on earth, it's hard to saturate the atmosphere with more than just a little bit of water (a few percent). However, pumping CO2 into the atmosphere adds another greenhouse gas and upsets this equilibrium. And yes, I know there are plenty of CO2 sinks (one earlier poster correctly pointed out the oceans as a major CO2 sink), but with the amount of CO2 we're pumping into the atmosphere (about 10% or so of total CO2 generated on earth), the sinks can't soak up the carbon emissions as effectively or completely. You can think of it this way: if you have a bathtub where the spigot empties water into it as quickly as the drain takes it away, then you're in equilibrium. But if you turn the flow of water on the spigot up, even just a little bit, the bathtub will begin to fill. That's the situation we're in right now with CO2 emissions. The big problem comes when the carbon sinks are full and the atmosphere begins to accumulate CO2 in appreciable quantities. Since you have more greenhouse gases in the air, the temperature rises. It's at this point when your water problem comes in. If you raise the temperature, then the vapor pressure of water in the atmosphere rises. This means more water evaporates, exacerbating the warming, which leads to more water evaporating, further exacerbating the warming, etc. Classic positive feedback (until another equilibrium is reached). So yes, the majority of the greenhouse effect comes from the water vapor in the air (right now). It keeps our planet comfortably between about 0 and 100 deg F (about -20 to 40 deg C for all you purists). But this doesn't mean that the science behind global warming is flawed.

By the way, if I said I loved Windows and Linux, would you mod me up or down? I'm kind of new here, so I don't know how it works.

Re:Hydrogen? Carbon?

[Mspangler]

My version, which is only slightly modified;

Step 1: Generate pure hydrogen in highly efficient processing plant
Step 1A: Remove CO2 from air and reduce it to carbon in a highly efficient processing plant.
Step 2: Merge with carbon to create lower density hydrocarbon based fuel called methanol.
Step 3: Use existing liquid fuel transport system to ship methanol.
Step 4: Use methanol fuel cell to the power the car, producing CO2 and H2O
Step 5: $$$, at least compared to hydrogen fuel cycles.

If methanol is good enough for 5000 hp tractor pullers, it should do just fine to get me work, even if the fuel cells don't work out.

Re:What, nobody's thought of the obvious?

[Rei]

Eh, while electric engines are somewhat more efficient than internal combustion or hydrogen fuel cell

Huh? What planet are you from?

* ICE: 30-35% efficiency for the engine, but due to internal losses, only about 20% efficient to the wheel well
* Fuel cell: 40-60% efficient *before* the power goes to the electric motor.
* Electric motor: 85-90% efficient in typical driving conditions (in optimal conditions, with an optimal engine, you can near 95% efficiency).

They have the same power generation inefficiency and higher transmission losses than hydrogen.

Huh? In the US, there's only an average 7.2% efficiency loss in electricity transmission. That doesn't even compare to the energy costs of making and pressurizing/pumping hydrogen.

[quote]Then toss in the considerably lower energy density of electricity storage[/quote]

Once again, huh? Hydrogen not in a storage medium will get you 250 miles, perhaps 300 at best. Li-ion present-day typically gets 200-250, but there are three different techs being worked on which each individually can 2x-3x that range (lithium vanadium oxide, silicon nanowires, and barium titanate caps). To get the range on hydrogen up, you need to either increase the pressure (which nobody wants to do), use liquid hydrogen (whole host of major, major problems that nobody wants to deal with), or use a storage medium. With a storage medium, you can get up to 300-350x (the reported range of the upcoming all-electric ZAP-X is 350mi, might I add -- and 300-350x is still way below the upcoming battery techs), but you lose even more efficiency in the process. The more hydrogen dense a storage medium, in general, the more inefficient it becomes. So, you take something that's already less efficient than an ICE, and you're making it *even worse*.

and even though you might get more wheel torque from the original source, the vehicle is going to be heavier than a fuel cell driven vehicle (even though the latter will probably have some sort of electricity storage as well).

Since when are fuel cell vehicles any lighter than electrics? The FCX weighs in at almost two tons. The Tesla Roadster's not even 1 1/2 tons.

Re:Hydrogen? Carbon?

[The Great Pretender]

Personally I think guys are on the right track, even if they aren't there yet. http://www.asemblon.com/hydrnol [asemblon.com]. I've talked a little to a couple of them and they have a liquid organic carrier that can release H2 under reasonable conditions using a catalyst. The carrier can then be rehydrogenated for reuse. The carriers supposedly easily produced and the net energy is pretty good.

Re:What, nobody's thought of the obvious?

[khallow]

Let's try this again. First, in the vehicle, electric motors are maybe twice as efficient as a fuel cell. Second, as mentioned early, making hydrogen from electolysis is around 85% efficient with minor losses from pressurizing and pumping hydrogen. That's because most of the energy of pressurization can be recycled by the time it gets used in the vehicle. I figure 90-95% is reasonable depending on how much of the energy of pressurization can be recovered (if it's in the car, it's ptobably going to be far lower). Meanwhile we have at least a 7% hit from electricity transmission for electric engines plus losses from rectification (2-5%). I don't see the electric motor being a factor of two better in efficiency. It sounds like a lot, but energy cost is a surprisingly small part of the total cost of the vehicle especially with the efficiencies we're discussing here.

And again hydrogen has much higher energy density than any electricity storage. Googling around, I'm seeing at least a factor of 5 better just for pressurized hydrogen (over supercaps). And the FCX versus Tesla comparison is flawed. The FCX is a somewhat light but standard 4 passenger car while the Tesla is a 2 person convertible. The Tesla is also in excess of $80,000 while the FCX will be competing with mundane gas powered cars and has to be a lot cheaper.

Ultimately, electric engines do have an efficiency edge. But they are severely hindered by energy storage. Neither of the above options has the infrastructure in place for mass use. It's not clear to me which would be cheaper to put up though hydrogen is notoriously explosive. That risk might tip things in favor of electric engines.