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Nuclear Hydrogen?
Jamais Cascio, 30 Nov 04

Here's one for the Green Dilemma bin: researchers at the Idaho National Engineering and Environmental Laboratory have shown that they can crack hydrogen from at a conversion rate of 45-50% (compared to ~30% for conventional electrolysis) by adding heat to the process, 1000°C worth -- the kind of heat one gets from a so-called "Generation IV" nuclear reactor. Green Car Congress has a terrifically-detailed write-up of the research, including this provocative line: "According to INEEL, a single next-generation nuclear plant will be able to produce in hydrogen the equivalent of 200,000 gallons of gasoline each day."

The two big hurdles for the advent of the Hydrogen Economy are the price of fuel cells and the availability of hydrogen. While research continues on improving solar->hydrogen technology, the reality is that hydrogen fuel is expensive to make in quantity. What if the most cost-effective way to make enough hydrogen for fuel cell vehicles required nuclear reactors?

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Comments

Why make H2 when you can just make Electricity?

Many environmentalists know that the "best" way to make electricity now is Nuclear; it creates no greenhouse gasses (beating out Natural Gas and oil), no carbon particles, and the waste it creates is a tiny fraction of Coal (which actually creates MORE radioactive waste per MW, but disperses it over the countyside instead of in a nice, portable, concentrated chunk you can keep out of the water supply). Nuclear also has the potential to meet a significant percentage of demand (sorry, solar, wind, and biomass can only be niche solutions with current technology). The only "gotchya" is what to do with the high level radioactive waste, and geologic depository (i.e. Yucca Mountain) is a good solution...except for the NIMBY problem.

Safety you say? Nuclear Reactors built in the 50s are being relicensed for another 40 years - this is because they were so overengineered and then so carefully monitored and maintained that they are quite capable of operating safely for that much longer and more. The next generation designs referred to above are made to be safe *with all the active cooling turned off*, and are extremely stable, sturdy, and secure. Safety is really now a PR issue, not a design problem.

Economics? That's the rub. Amortizing a reactor and operating it at the same time tends to break the bank when competing against oil, gas, and coal, none of which have to pay the premium to dispose of their waste properly that they ought to, and none of which face the (justifiable) safety and security scrutiny (which raises operating costs, naturally).

Now, if only there were a tax on carbon emissions that led coal, oil and gas plants to either pay "Extra" to a cleanup fund or, better yet, recapture the carbon on the way out (increasing costs also), then maybe we'd be talking about building more Nukes.


Posted by: Peter Brenton on 1 Dec 04

To answer the first question, H2 seems to be a better "fuel" for individual transportation than electricity. Hydrogen fuel cell cars, expensive though they may be, already have a better range and faster "refuel" time than battery cars. A conversion to hydrogen cars (assuming the fuel cell cost can be brought down, as it almost certainly will) will require ready access to abundant H2, which this proposal could provide.

You won't be surprised to learn that I'm not as sanguine as you about the waste and safety issues with reactors, even the so-called "inherently safe" pebble-bed reactors (e.g., the problem where imperfections in the graphite "pebbles" can lead to leaks, and the reactor designs don't have the added layers of shielding to deal with accidental leaks, in order to keep the costs down). As for wind/solar/etc., "current technology" is improving rapidly, and in many places wind and tidal are quite competitive with old-style power sources. Still, the "nuclear vs. global warming" dilemma may be one of the difficult choices for us all in the next couple of decades.


Posted by: Jamais Cascio on 1 Dec 04

The problem with nuclear power is that you are creating a 100,000 year lethal storage problem to gain an energy solution that will only be relevant for at most 50-100 years. Talk about a selfish perspective: our generation is 1000 times more important than any future generation? (Future civilizations will undoubtedly call us the Radiation Peoples, because that's our unfortunate legacy to them.)

It also seems to me the Hydrogen Economy is misnamed. Hydrogen is just an energy storage medium competing with many others. It may win, it may lose. It doesn't matter. What we need most is a way to generate electricity sustainably. How that energy is stored is secondary. Let's call it the Renewables Economy, and stop talking about hydrogen cars, and start admitting they are simply electric cars that swapped out their batteries for fuel cells, and might swap them out again for the latest battery technology someday.

I'm for us all driving less, becoming efficient, and letting solar, wind and wave come of age. You can build a wind plant a lot faster than any nuclear plant design out there, however advanced. They are popping up monthly in the UK.


Posted by: Jeff Rusch on 1 Dec 04

Life on earth produces all of its infinitely-recycled materials at ambient temperatures and pressures. Requiring high temperatures to produce more hydrogen may indicate a lack of investigation into more elegant alternatives, such as microbial fermentation. It's also not completely clear that the total nuclear fuel cycle is actually a net producer of energy - to date, the nuclear industry relies on financial subsidies and subsidies of concentrated fossil energy to exist. Without those subsidies, it may very well not be viable.


Posted by: David Foley on 2 Dec 04

from the INEEL report:
If you take the nuclear-specific element out of it for a
moment, however, what the INEEL-led team is
discovering and developing is not inextricably bound
to nuclear energy; all HTE requires is a high heat
energy source.

Accordingly, another DOE initiative is exploring the
solar-hydrogen potential, and is coordinating with
the experimental work at INEEL.


You lost me with the NIMBY comment. Made me realize that everything else you were saying was too clever and likely suspect...and on investigation, it is all suspect. This is a technique that can make solar and geo-thermal resourses even more viable, and nucluar won't be needed in the mix.

Besides the other excellent points above, the nuke industry relies upon public financing of the insurance, and can't get along without heat polution of its surrounding waters. There are not a viable long or short-term option.


Posted by: C J Flynn on 5 Dec 04

Sorry to be so late to this discussion, but I have to comment on this:

To answer the first question, H2 seems to be a better "fuel" for individual transportation than electricity. Hydrogen fuel cell cars, expensive though they may be, already have a better range and faster "refuel" time than battery cars.

So far as I know, H2 fuel-cell cars are vastly INFERIOR to battery vehicles in both their range and end-to-end efficiency when electrolytic hydrogen is the fuel; range of the current fuel-cell prototype cars is around 60 miles, while range of the lithium-ion tzero is nearly 300 miles.  On top of this, there are battery technologies which are quite a bit cheaper than Li-ion (like Zn-air) which eliminate all the worries of compressed gases, thermal runaway in the batteries and range limitations.

The one bugaboo of secondary cells is recharging time, but waiting an hour to recharge a Li-ion pack after 4 hours of 70-MPH cruising is going to beat refuelling every 40 miles no matter how fast the pump fills the tank.  If you go to a primary cell and just replace the reactants instead of regenerating them on-board (remove ZnO, add Zn) even that problem goes away.

The real problem with hydrogen is that it's horribly cumbersome to transport unless it's bound to carbon.  I suggest a change in paradigm:  the ZEV will not carry a tank of elemental hydrogen under high pressure, but a two-compartment tank of methanol fuel and carbon dioxide fuel cell effluent.  At the fuelling station the CO2 is removed, the methanol is refilled, and the CO2 is regenerated to CH3OH off-line.  This closes the loop on the carbon cycle.


Posted by: Engineer-Poet on 6 Dec 04

range of the current fuel-cell prototype cars is around 60 miles

That information seems a few years out of date, E-P. See, for example: http://www.iags.org/n081304t1.htm -- the 2005 model Honda FCX (fuel cell sedan) has a 190 mile range, 20% better than the 2004's 160 mile range. A quick Google shows a few other examples of fuel cell vehicles with greater than 100 mile ranges, and at least one with a 300 mile range (the Chrysler "Natrium" minivan).

That said, you're correct that current technology fuel cells don't have the necessary range. That's one of the myriad reasons we don't see too many fuel cell vehicles yet. The potential energy density of pressurized hydrogen is significantly greater than for batteries, however (see the graphs in the Physics Today article linked in the "Hydrogen 101" post), so 300+ mile ranges are fairly likely.

The two-tank concept is interesting. Has anyone worked out plans for that? What kind of range would you see with methane, especially given you'll have less fuel storage space? And how readily could CO2 waste be compressed onboard the vehicle?



Posted by: Jamais Cascio on 6 Dec 04

Not methane, methanol.  There are fuel cells which can use methanol directly, and methanol can also be reformed to hydrogen (CH30H + Δ -> CO + 2H2; CO + H2O -> CO2 + H2).  The density of liquid methanol is 0.79, and after reforming it is 3/16 available hydrogen by weight; to supply the 3.75 kg of hydrogen carried by the FCX, you'd need 16/3 * 3.75 / .79 = 25.3 liters of methanol, which can be stored at room temperature and atmospheric pressure.

After "burning" the hydrogen produced from the methanol, you'd get CO2 + 2 H2O (plus one molecule of water to be recycled to the reformer).  I know of no difficulty in principle of operating fuel cells at high pressure, so compressing the effluent may not be required (use an oxygen-permeable membrane to get O2 into it without letting CO2 leak out).  Such effluent would be highly-charged soda water at a pressure of a few hundred PSI.  Each kg of hydrogen would produce 6 kg of water (including the water recycled to the reformer) plus 7.33 kg of CO2.  If it has a bulk density of 0.95, this comes to 14 liters per kg of hydrogen or 52.6 liters of tank (about 14 gallons).

You'd have conversion losses but I think the convenience and safety of storage would be more than worth it.

(I was getting my range figures from commentary about vehicles like the HyWire, and I could not help but notice that such numbers have been very hard to find.  Why would a company hide them unless they were embarrassing?  It seems that they are finally getting that fixed, sort of... I notice that the Honda FCV page does not mention cargo capacity!)


Posted by: Engineer-Poet on 7 Dec 04



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