Bio-ammonia as a hydrogen source for fuel cells

Here's a slightly edited version of a previous post.  It is an alternative to using bio-methanol as a source of hydrogen for fuel cells.  That is to say, produce ammonia instead of methanol by using biomass.  The costs could be a bit higher, though.  The advantage is the efficiency of fuel cells.

Monday, March 14, 2011


Why fuel cells?

 It seems that hydrogen fuel cells are more efficient in terms of energy use. A fuel cell powered auto can get 60 miles to a kilogram of hydrogen. If the cost of a kilogram of hydrogen is twice that of a gallon of gas, it can still be economically competitive. Most cars get less than 30 miles a gallon for gas, thus the comparison.

It turns out that a kilogram of hydrogen produced from ammonia is less than a dollar per kilogram. Now, if ammonia can be synthesized from hydrocarbon feedstocks, the end cost of a kilogram of hydrogen could be competitive with traditional fuels such as gasoline. Let's say that refineries can shift production from gasoline to ammonia. The crude oil would go further economically if the price of a kilogram of hydrogen can be held under twice that of a gallon of gasoline. The cheaper the production, the greater the benefit.

 It also came to mind that natural gas is cheaper than oil these days. One could use the hydrogen in natural gas to synthesize ammonia. The chances that one could come up with a liquid fuel that is cheaper than gasoline and will go twice as far should not be too difficult to imagine.

As for the price of fuel cells, which are not cheap, these can also come down if the economies of scale can be applied. This will occur if popular acceptance reaches a sufficient number to begin large scale manufacturing. In addition, if an extraterrestrial source of platinum group metals is found, the price of could be further reduced.

 I bought a pdf on the subject. The cost of hydrogen from this method is about 2 dollars per kg. That was a few years ago, but it was in a time of high fuel prices, so the comparison may still be good. If so, that would mean about 1 dollar per gallon equivalent assuming the 60 mp kg holds up for this configuration. The analysis shows a considerable expense in setting up an electrolyzer. One would presume that if these were mass produced along with the fuel cells, the costs could be brought down to economic viability. This is my guesstimate at the moment. If there are other factors that aren't being considered here, I am unaware of them.

So, why not do this? It was done in the case of the Tesla Roadster, where a battery powered car was produced. Perhaps it would take a similar effort by someone who could pull off the same feat with hydrogen fuel cells. If you used the same approach, with a high end vehicle, such as a luxury car, you could get a foot in the door, so to speak.

Wednesday, March 16, 2011

Electrolyzing Ammonia for Hydrogen Fuels Continued


As I mentioned earlier, I purchased a pdf file which studies the concept in detail. Here is the money quote from the study:

According to scale-up calculations, using an in situ ammonia
electrolyzer on board will allow a HFCV to travel 483 km between
refueling by storing 203 L of aqueous ammonia. At 0.36 US$ kg−1
of ammonia, the cost of producing hydrogen on board is 2.02 US$
kg−1.

The price is right for the hydrogen, but there's a problem.

The sticking point in my opinion, is the cost of the electrolyzer itself. It is estimated from the paper that an appropriate sized electrolyzer will cost over 32000 dollars at then platinum prices that were half of today's price. It is quite clear to me that the price of platinum and platinum group metals will have to come down somehow, or some other way must be found. One way to lower the price of platinum is to mine a lot more of it. Thus a source of abundant platinum must be found. That source can come from outer space.

There may be a way to reduce these numbers, but it is clear that the numbers don't work without more platinum. That is my opinion.

Wednesday, March 16, 2011

In situ hydrogen production from ammonia


Further reflection on this idea seems to rule it out unless a plentiful source of platinum becomes available. An alternative to this would be to produce the hydrogen at the refueling station. This increases the costs per kilogram because the need to put it into a form that it can be stored, such as high pressure or cryogenics.

The estimate for in situ hydrogen from ammonia was about 2 dollars per kg. Now if you were to compress it or cryogenically store it, that would at least double the price, I guesstimate. Even then, it would still be relatively cheap because of the high efficiency of hydrogen fuel cells.

The final hurdle would be to get the price of fuel cells down. This would be accomplished by the economies of scale that would come from mass acceptance of this mode of energy production. That hurdle could be overcome by having organizations with large fleets agree to purchase fuel cell vehicles of this type. That could be a problem. As in many cases, if enough people in leadership stepped up to the plate and committed to this, it just might be doable.

Update:

Here's a pdf file, but not the same one I mentioned above.  It describes a set up for an ammonia electrolytic cell.  The output is hydrogen.  Now, the idea of time share could be applied to this device as well.  Even though it is expensive, it can spread out over many users and make its usefulness more financially accessible.

Let's say $140, 000 for an entire system.  It has a useful life of 5 years.  That 260 weeks.  Average cost per week $538.46. A week per year would yield a cost of $2692.31.  Tacked on the price of a Nissan Leaf, and that puts an entire system at your use for less than 30k.  This would only be available for 1 week per year, but how often do you drive a lot?  Once a year during vacations?

Think about it. Wouldn't a range extender's availability be a selling point for a battery electric car with only a range of 70 miles or so?