Debunking Hydrogen Car Lunacy: The Truth About Pollution

[mheslep]

This paper in Science makes an interesting point on the comparative efficiencies of H2 - Fuel Cell Cars.

Hybrid Cars Now, Fuel Cell Cars Later
N. Demirdovenand and J. Deutch
13 August 2004, Vol 305.
http://www.sciencemag.org/cgi/content/abstract/sci;305/5686/974?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Hybrid+Cars+Now%2C+Fuel+Cell+Cars+Later&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT"
Subscription:
http://www.sciencemag.org/cgi/reprint/sci;305/5686/974?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=Hybrid+Cars+Now%2C+Fuel+Cell+Cars+Later&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT.pdf"

It compares Well to Wheel efficiencies of theoretical cars w/ a traditional ICE, a hybrid ICE+electric motor parallel drive train, and an H2 - Fuel Cell+battery buffer. They find the pure ICE has is 11.3% (no surprise), the H2-FC is 25.5%, but that the Hybrid is only ~1% less at 23.9%.

Assumptions:
-H-FC model: hydrocarbon fuel storage w/ a reformer (80% eff), fuel cell 50% eff., batteries 84% eff. If H2 is made available somehow without energy cost, eff jumps to 39%.
-Hybrid. Gas engine. If a diesel is used eff jumps 31.9%

The attached figure shows the relative energy flows. HICE = Hybrid ICE, AFC = Fuel Cell

 

[mheslep]

H onboard storage

The chemists are not holding out much hope for onboard H in cars in the near future.

Hydrogen storage targets out of reach
http://www.rsc.org/chemistryworld/Issues/2007/October/HydrogenStorageTargetsOutOfReach.asp

The DOE targets mentioned are 5kg of H2 (~735MJoules=204kW-hrs) in the volume of an 'average petrol tank'

I don't think there's a hope in hell of reaching the 2010 DOE targets,' said Peter Hall, a chemical engineer at the University of Strathclyde, UK. Hall, who has gradually focused his efforts away from solid hydrogen storage, spoke to Chemistry World at a special session on hydrogen storage at the ACS Fall meeting in Boston on 20 August.

'Right now we don't see how these targets can be reached, and that is also the opinion of car manufacturers,' agreed Ferdi Schüth, who works with General Motors and Opel on hydrogen storage at the Max Planck Institute for coal research, in Mülheim, Germany.

I vaguely recall the DOE storage target is intended to provide a range of ~300mi / tank. Checking: 204kW-hrs * 50% FC * 90% motor = 90kw-hrs traction. Assume 20kw required for highway level cruising 60mph = 270mi.

 

[mgb_phys]

Odd that fuel tank fires were an unforseen risk on Fords but H2 tanks are specified to something beyond nuclear waste containers. I wonder if 'vested interests' is hyphenated?

 

[mheslep]

Odd that fuel tank fires were an unforseen risk on Fords but H2 tanks are specified to something beyond nuclear waste containers. I wonder if 'vested interests' is hyphenated?

Hows that? What spec do you think is required on a 5000PSI tank sitting under your butt? A common 5000 PSI tank requires a little strength sitting safe and sound. Then put it in a vehicle and it should have some hope of not exploding in minor impacts. Since its under high pressure and highly rigid, it can not allow the deformations and even leaks that a unpressurized gas/diesel tank can often withstand without explosion. And BTW, 5000 PSI probably won't do it, you really need 10,000 PSI to make it to grandma's house.

 

[mgb_phys]

To be practical you will have to store hydrogen as a hydride or embedded in a matrix.
If you have safe, lightweight 10,000psi gas cylinders you could just use air and a turbine.

 

[mheslep]

To be practical you will have to store hydrogen as a hydride or embedded in a matrix.

Problem is per the link above hydride or solid storage (green circle) is not bad volumetrically but by weight it is worse than compressed H tanks and at least 10x worse than a tank of gas. That is, a hydride tank with the same mass as a 300 mi range tank of gas contains only 1/10 the energy. Regardless, the National Academy of Sciences report on H transpo recommended placing all research efforts in solid storage and abandoning compression or liquification.

If you have safe, lightweight 10,000psi gas cylinders you could just use air and a turbine.

10000 psi is starting to noticeably tax the energy content in compressing the gas. Then, metal tanks and piping are not lightweight. Composite tanks are made by Quantum Tech up to to 10k psi and they're much lighter, but they're also very expensive. They're being used by some of the prototype demo H cars. There's discussion that in mass productions these composite tanks can be made cheaply but I don't see how. Composite tanks have to be wound up from the carbon fiber so its got to take time and be expensive; I am not aware of any way to cast or press composites of this strength.

 

[mgb_phys]

Winding the tanks isn't necessarily a problem - I suspect it's more the cost associated with the fittings and testing.

I was being a bit cynical about the standards. There was one proposal that electric hybrids using 42V electrics should have to carry large warning signs so firefighters would be aware of the electrical shock risk in an accident.
They had nothing against hybrids but were thinking of the poor brave firefighters. Like firefighters are overjoyed at the current system of flammable gas tanks.

 

[mheslep]

From the DOE's 2007 H Storage Center:
http://www.hydrogen.energy.gov/annual_progress07_storage.html#e
E. Advanced Compressed and Cryo Tanks
http://www.hydrogen.energy.gov/pdfs/progress07/iv_e_1_aceves.pdf

...Approach
The primary focus is to meet the cost goal of the DOE hydrogen storage technical targets. Quantum’s current 10,000-psi TriShield tank technology is close to meeting many of DOE’s targets, but the cost is still a major issue. Since the carbon fiber cost is a large portion of the overall cost, the approach is to reduce the amount of carbon fiber needed to build the storage system while maintaining equivalent levels of performance and safety. This will be accomplished by improving the fiber translation using non-conventional filament winding processes and integrating sensors to actively monitor tank health...

...Results
The first 10,000 psi hydrogen storage tanks developed by Quantum with DOE funding utilized high grade aerospace fiber to attain the high performance. This achievement came at a very high cost due to the premium carbon fiber used. Subsequent 10,000 psi designs were able to employ mid-grade aerospace fibers, but the costs were still too high for commercial applications...

 

[mheslep]

Plug in Cars Worry Electric Firms: WSJ

I think you are overestimating the electricity needs for the car fleet ...

We are showing about 1.4E19 joules of electrical energy produced annually...

...Electric transportation proponents often speak of using the grid off-hours to charge the batteries. ...

So the WSJ obviously has been following this PF thread and tried to catch up w/ this piece May 2:

Plug in Cars Worry Electric Firms
In general several of the car companies w/ pending plug-ins are working closely w/ the utilities to make sure there's that an ethanol type price disaster won't occur. Seems like every lab / think tank in the country has a study out on the subject: EPRI, Oak Ridge, NRDC, PNNL all have studies sighted in this article.

The

utilities view the cars with a mixture of excitement and trepidation. If drivers charge their batteries at night, when demand is low and the utilities have generating capacity to spare, utilities will increase their electricity sales and make more efficient use of their existing power plants. But if most drivers recharge their cars during the day, when demand is twice as high, utilities could have to make or buy extra electricity when it is most costly. They could even be forced to build new power plants.

The utilities are currently hedging their bets by pushing out smart meters that will heavily emphasize that night is the time to charge these cars.

the cars will need ready access to inexpensive, plentiful electricity. That means the new vehicles "will make utilities more important than the oil companies" to many drivers, says General Motors Corp. spokesman Robert Peterson. If utilities discourage the cars' proliferation by charging more for their electricity, the push toward plug-in cars could falter.

A study by the Oak Ridge National Laboratory agreed that the number of plug-in vehicles in use and when they recharge could profoundly influence power-generating costs. Under some scenarios, electricity costs would drop, but under others, they could more than double.

The plug-in car's potential to slash fuel use is dramatic. The Pacific Northwest National Laboratory found that existing U.S. power plants could meet the electricity needs of 73% of the nation's light vehicles if the vehicles were replaced by plug-ins that recharged at night. Such a huge shift could cut oil consumption by 6.2 million barrels a day, eliminating 52% of current imports.

Another study, by the Electric Power Research Institute and the Natural Resources Defense Council, concluded that electricity consumption would rise only about 8% if 60% of light vehicles in the U.S. were replaced by plug-in vehicles by 2050. That would also cut U.S. carbon-dioxide emissions by 450 million metric tons annually, equivalent to scrapping 82 million cars.

 

[vanesch]

I read about a study (don't have any internet source handy, it was cited in a book) that says that hybrid electric cars are a near-future possibility, as many car trips are relatively short distance. So relatively small batteries, charged at night, could replace the short distance displacements (commuting to work for instance), while the classical fuel engine would take over for longer trips. This limits the need for huge batteries, while nevertheless allowing most car traffic to run on electricity. An average of 2 liters / 100 km was a conservative estimate of the consumption of such a car.

 

[mheslep]

I read about a study (don't have any internet source handy, it was cited in a book) that says that hybrid electric cars are a near-future possibility, as many car trips are relatively short distance. So relatively small batteries, charged at night, could replace the short distance displacements (commuting to work for instance), while the classical fuel engine would take over for longer trips. This limits the need for huge batteries, while nevertheless allowing most car traffic to run on electricity. An average of 2 liters / 100 km was a conservative estimate of the consumption of such a car.

Yes that is certainly the plan for, say, the Chevy Volt - ~30-40mi per charge on the batteries w/ an engine for the long haul. That is the plan for numerous, high volume sales plug-ins coming out. Its not just a possibility, these plug-ins are definitely coming out in the ~2010 model year. So 100% of commute driving becomes all electric, zero emissions at the car. That is the reasoning behind the large reductions in oil imports and CO2 mentioned in the above WSJ links.

 

[mheslep]

Several new startup electric car companies in play

There are at several new/startup electric or hybrid electric plug-in car companies bringing out models between now an 2010. Many of the founders come from big car companies. These companies are going up against the competition from the models forthcoming from the large competitors Toyota, Ford, GM, Mitsubishi, Renault, and Daimler. The new car companies:

Tesla: sport all electric, 221mi range, out now

Fisker: sport hybrid 50mi electric, ICE backup, 2009

Think: all electric small commuter, 112 mi, 2008 (been around since '91 as Pivco)

Loremo: diesel hybrid 93mi electric, 600mi ICE, 2010

Mindset: hybrid, 62 mi electric, 498mi ICE, 2009

Gordon Murray Design: the McLaren UK race designer w/ experience in carbon fiber frame& body. 892 lbs lighter than other similar metal cars.

Start-Ups Race to Produce 'Green' Cars
Edward Taylor
May 6, 2008
http://online.wsj.com/article/SB121003145304669169.html

Similar US News article on the these companies:
http://usnews.rankingsandreviews.co...ild-Green-Car/?referer=sphere_related_content