Hydrogen Vaporware VS the Big Battery Breakthrough

The compressed gaseous hydrogen & PEM FCV path is not the only route to a hydrogen economy.  

Hydrogen has many problems (e.g. very high cost for fuel cells and very poor energy density).  But ammonia (NH3) is also a carbon-free fuel, and it has an energy density a little better than that of cng (and double that of 10,000 psi H2), so it can be burned in a modified internal combustion engine (ICE) and it still produces adequate vehicle range (like diesel fuel, ammonia can be burned with a high compression ratio engine, so the efficiency will be midway between that of a fuel cell and a gasoline engine). 

The most important feature of ammonia ICE cars is that they will cost about the same as gasoline powered ICE cars, which is to say much less than fuel cell or battery electrics.  This means that they complement rather than compete with battery electrics (since batteries give lower refueling cost).  And fuel cells that run on ammonia do exist (most natural gas fuel cells can run on ammonia), so that option may play a role as costs come down.  Ammonia is also well suited to heavy duty trucks, buses, trains,  and stationary diesel generator (which would not be considered for batteries).

The ammonia path has a lower infrastructure barrier than hydrogen, since ammonia is much cheaper to transport by truck or rail than is hydrogen (due to the better energy density and much lower pressurization).  We already have a couple thousand miles of ammonia pipeline in the USA, which is used to distribute ammonia for use as fertilizer.  Ammonia is made today from fossil fuel (in some cases using carbon capture and sequestration) for a cost that is competitive with gasoline.  It is also the cheapest fuel that can be made from solar, wind, or nuclear power.  

Ammonia has the added advantage that when made from sustainable sources, it will be cheapest in developing nations with low labor costs, i.e. it is a technology that targets nations like China and India whose CO2 will soon dwarf those of the developed world. So world emissions wise, a US investment in ammonia technology would be highly leveraged.  If we mature the technology by converting a few percent of our vehicle fleet to ammonia (using Government incentives), China and India could conceivably convert a majority of their fleets to ammonia, saving money and improving their trade balances in the process.

Note also that ammonia fuel synthesis is a great way to smooth seasonal supply/demand mismatch in energy supply.  With refrigeration (to -33C), ammonia can be stored at normal atmospheric pressure.  This means that warehouse-sized insulated tanks are feasible.

Here’s a good intro to ammonia fuel:  NH3 – The Other Hydrogen

Here is a story about a Toyota sports car that has been modified by an Italian team to burn ammonia, here is a conversion done in South Korea.

Anyone who’s ever had a wiff of ammonia will not want to drive a car filled with the stuff. At one point it was used in most refrigerators and too many bad things happened, so they developed CFC’s (and then something even worse happened in the stratosphere, but that’s another story).

Hydrazine is a much better carbon-free energy carrier. It is toxic but no worse than gasoline (and much better than leaded gas was). The anhydrous form can be burned but can also explode, so that’s out; the hydrate (a 64% by weight solution in water) is however hard to ignite and even harder to make explode. Alternatively hydrazine can be stored as hydrazone that readily decomposes in water. But the best thing about hydrazine as a fuel is that it can be converted to electricity by a low-temperature fuel cell that doesn’t need a platinum catalyst and has a much higher efficiency than by burning it.

The issue here is olivine, which is a reagent in the reaction rather than a catalyst, i.e., it is used up in the process. Therefore to get hydrogen this way, you have to mine olivine. 

Here’s predicting this particular method of making H2 will never be commercialized.

I accept that ammonia is more dangerous than other refrigerants, but it does not appear that ammonia is more dangerous than other fuels.  Here is a presentation on ammonia safety, which claims that ammonia is no worse than gasoline (the higher toxicity is offset by the lower fire/explosion hazard), and better than LPG.

The material safety data sheet for hydrazine looks worse than ammonia‘s.  In particular, ammonia can be detected by smell at harmless concentrations, but hydrazine cannot; hydrazine is much more explosive and seems to be much worse when spilled into the environment.  Hydrazine is also carcinogenic and can be absorbed through the skin, but even long term exposure to low ammonia dosages is harmless (ammonia is a natural part of the metabolism of all land animals). 

On issue of special the fuel cells: reverse fuel cells have been demonstrated in the lab for ammonia.  This is a device which is fed steam, nitrogen, and electricity, which outputs ammonia.  If scaled up, this could easily reduce the cost of liquid fuel from renewable electricity by 20%.  There is probably a market for a safer fuel wherein people would pay 20% extra for a fuel like DME, but no one is going to pay extra for hydrazine, it’s not safer.

Nice debunking, thanks. I’m not as optimistic as you about the BBB coming any time soon, simply because the economic benefits has been huge since a very long time, and despite of that the latest real breakthough to hit the stores is still LiIon, which are commercialized since the start of 90’s, and the technology was known long before.

Well there has been one significant real industrial breakthough since a few years, LiFePo4 batteries, but while being on the whole a very significant progress, it’s not enough of a breakthough to make people really excited. Still, except on the fact the density is lower, it’s a very useful progress on many point, the higher number of cycles make it significantly cheaper when considering lifecycle cost.

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The thing makes ammonia worse than gasoline is that it’s a caustic gas (vapor) under ambient conditions, while gasoline is merely a volatile liquid. That means a tank of liquid ammonia is necessarily under considerable pressure, and if it leaks it all comes out at once and mixes with the surrounding air. If you’re in the garage or even the vicinity of an automobile accident outdoor when a tank ruptures, you’re going to get caustic burns all over, including your eyes and lungs. And if that mixture with air just happens to be roughly four parts ammonia to three parts oxygen, you’ve got a fuel-air bomb ready to explode at the slightest spark.

Like gasoline, hydrazine hydrate is a volatile liquid, and it does have a weak ammonia-like oder which could easily be made a whole lot stronger by adding an oderant, possibly even a bit of ammonia. I believe the same sort of alkaline fuel cell could be used with both ammonia and hydrazine, so it’s possible that a suitable mixture of water, ammonia and hydrazine would actually be the best such energy carrier. In which case we’d both be right!

By the way, hydrazine flunks the Ames test but like many such substances it’s a very weak carcinogen, probably not much worse than meat treated with sodium nitrite. That is to say it would be bad to get a bit inside you every day but is otherwise nothing to panic about. Toxicity is another matter. The LD50 of hydrazine is around 100 mg / kg orally or twice that if adminstered dermally, so you’d need to get about 10 grams of the hydrate on your skin to be in a panic situation (run for the shower!). The tetraethyl lead they used to put in gasoline is much worse than that, and it’s capable of causing chronic poisoning which as far as I can tell hydrazine is not. Choose your poison?

Here‘s a 2007 article about the hydrazine fuel cell. It is interesting, so it’ll be interesting to see if this technology goes anywhere.  Note that the fuel cell stack has to be cost competitive with an ICE (after correcting for fuel cost) to be a win.  The solid fuel idea is novel, but it sounds like the vehicle must also be tanked up with water, which would be a hassel for consumers.

Note that the explosive range of fuel/air mixtures is much narrower for ammonia than for gasoline or cng, and hydrogen (and anhydrous hydrazine) are much worse; plus ammonia has a much higher ignition temp compared to gasoline or hydrogen, so it requires a bigger spark.  Also note that ammonia will be at under 200 psi, compared to 5,000-10,000 psi for hydrogen, so it will come out more slowly for a given leak.

The safety reports on ammonia for car fuel I’ve read basically said that major fuel leaks only occur in a tiny fractions of accidents, i.e. the accident must be so severe that the passengers are all screwed anyway.

One aspect of the economics missed out in the discussion is the relative cycle efficiency of hydrogen fuel cell and battery electric vehicles. If you take losses in the hydrolysis / fuel cell generation cycle into account, you need about twice as much primary energy for a hydrogen fuel cell vehicle as for a BEV. 

Regarding the new Silicon based batteries, if weight and volume reduction of the battery pack including BMS and containment were to be of the order of 60% this could help to make electric vehicles significantly lighter and a little smaller for a given useful capacity (passenger and luggage space).

Weight reduction would be both direct and indirect with reduced volume and weight allowing other smaller lighter components. 

For a similar battery capacity, it therefore seems to me that range might be increased by 5 to 10%.

Cliff

Does this mean, at the wheel we get about 17% of the 12 KWH in the litre of petrol as mechanical energy.

2.7 KWH

As for the 3.5 KWH of battery, we get about 2.9 Kwh of mechanical energy at the wheel.

You dont have to be overly optimistic to realise with a few simple calculations that electric cars provide mechanical energy at the wheel at about 10% of the cost of petrol.

The second of the challenges for hydrogen are why the most realistic hydrogen electro-fuels are more likely to be Ammonia (NH4) or Methane (CH4) than hydrogen gas.

The race is between battery cost per kwh and capital cost of solid state electrolysis technology, since the approach of over-supplying intermittent renewable capacity like windpower and PV and using surpluses to generate electro-fuels depends on the economics of electro-fuel production on a 25%-40% duty cycle.

Add the extra energy cost of compressed natural gas on top of that, and that sets the economics of hydrogen as an electrofuel an additional substantial step behind that of ammonia or methane. And some solid-state technologies produce syngas ( http://www.ceramatec.com/technology/ceramic-solid-state-ionic-technologi... ) which is in some ways better suited for production of ammonia or methane than for production of hydrogen gas.