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Exactly. Ammonia gets produced from (mostly) grey hydrogen. And the most common application for ammonia is producing fertilizers. Making that process green, wou

Exactly. Ammonia gets produced from (mostly) grey hydrogen. And the most common application for ammonia is producing fertilizers. Making that process green, would cut down on a lot of carbon emissions (several percent of global emissions) and should be the first priority before considering inefficient ways to use hydrogen and ammonia like this. Ammonia as a fuel is quite inefficient due to all the energy conversions. You use renewable electricity to generate hydrogen. You use that to create ammonia. And you then burn that to produce mechanical energy. Each of those steps has poor efficiencies and they multiply. It is way less efficient than using renewable energy to charge a battery that powers an electrical motor. If you start with 10kwh of renewable electricity, you'd be struggling to get more than 1-2kwh delivered in the form of mechanical energy with ammonia. With battery electric it's more like 8kwh. Charging and discharging the battery loses some energy and electrical motors are of course also not 100% efficient. And when I say inefficient, I mean costly. You waste most of the energy that you put in. It's much more cost effective to use the energy in a more efficient way. By about a factor of 4-5. If you operate any business where energy cost is significant the value proposition of paying 4-5x more is not great. It's why ammonia as a fuel really barely makes any sense. And hydrogen as a fuel is pretty bad for the same reason. It's a really hard sell when battery electric is a feasible alternative. The economics are flawed. And the second law of thermodynamics means there is no technical fix for this either. There are some hard theoretical limits here.

tuatoru 4y ago
Efficiency is very important when your energy is costly. But other attributes like reliability, safety, environmental benignity, "fit" in the overall energy system, and aesthetics start to take precedence over energy efficiency at some point. The way things are trending with PV, efficiency may recede in importance in a couple of decades. Currently electricity costs tens of dollars per MWh. With developments in manufacturing and install protocols, and tech emerging from the lab, and using DC directly from PV panels, that cost may fall to $0.1 per MWh. Using that to manufacture your ammonia means you won't worry so much about pure efficiency I still prefer methane over ammonia. Much less toxic when things go wrong.
- jillesvangurp 4y ago
  Electrical motors are about as reliable and safe as it gets. I agree energy will eventually get very cheap and plentiful, which would enable more frivolous uses of excess energy. But still, that won't happen any time soon and the value proposition of paying several times more for energy is very limited. And while there is a shortage of green energy, using it for the creation of fuels seems like it is costly and wasteful.
  - dsfyu404ed 4y ago
    >Electrical motors are about as reliable and safe as it gets. Electricity isn't free. If you're already wasting sufficient amounts of the requisite elements as waste products of some other thing you're already doing then finding a way to bond those elements and then burn the resultant compound for rotary power may be more economically efficient.
    - danans 4y ago
      > If you're already wasting sufficient amounts of the requisite elements as waste products of some other thing you're already doing then finding a way to bond those elements and then burn the resultant compound for rotary power may be more economically efficient. Your sentence is a bit vague, but "some other thing you're already doing" sounds like petroleum refining, which is precisely what we need to do less for use as a fuel. Also, ammonia created from petroleum isn't being wasted today. It's used for making fertilizer, and the whole process has a high cost in CO2 emissions. When the time comes that we have so much carbon-free energy that we can afford to use the excess to generate ammonia, we ought to use it to displace petroleum based ammonia for fertilizer. There may be a few niches (ocean shipping) that require a liquid fuel like ammonia, but it makes little sense to use it for ground transportation. If a liquid fuel is required, things like sustainable biodiesel make more sense.
- pencilguin 4y ago
  Ammonia is fine for big industrial use: we process it in the many millions of tons, already. I would not like to see it pumped at gas stations.
pkphilip 4y ago
The advantage of ammonia is in the transportation and refueling. If you can refuel a car in the same amount of time that it would take to refuel it with gasoline, then it is a huge plus as it would allow a single fuel station to fuel many more vehicles in the same amount of time.. for instance, in the time it would take to fuel a EV to even 20% charge, you could conceivably fuel dozens of vehicles with ammonia. That apart, for fast charging or even standard charging you need a reasonably heavily power load from the grid - if you have even 4-5 vehicles charging simultaneously. This would require big changes in the electricity distribution infrastructure.. something which is not required if you continue to use the existing infrastructure used to take fuel to the fuel stations. Consider that you could easily fully refuel an 18-wheeler in a few minutes time with just a low powered pump.. which is not really possible if the 18-wheeler was a pure EV.
- jillesvangurp 4y ago
  But then consider that you need about 8x the electricity to pull that off; which you pay for at the pump and suddenly that 30-40 minute charging break sounds pretty sweet. Especially when considering your drivers are required to take such long breaks every 4-5 hours. Private drivers get irrational and emotional about this stuff. But most commercial transport is cost driven. 8x is a great argument. Ammonia doesn't stand a chance. As for the grid, a lot of charging infrastructure relies on batteries and some local production via renewables. That evens out the load on the grid and helps balance things.

tuatoru 4y ago

Efficiency is very important when your energy is costly. But other attributes like reliability, safety, environmental benignity, "fit" in the overall energy system, and aesthetics start to take precedence over energy efficiency at some point. The way things are trending with PV, efficiency may recede in importance in a couple of decades. Currently electricity costs tens of dollars per MWh. With developments in manufacturing and install protocols, and tech emerging from the lab, and using DC directly from PV panels, that cost may fall to $0.1 per MWh. Using that to manufacture your ammonia means you won't worry so much about pure efficiency I still prefer methane over ammonia. Much less toxic when things go wrong.

jillesvangurp 4y ago
Electrical motors are about as reliable and safe as it gets. I agree energy will eventually get very cheap and plentiful, which would enable more frivolous uses of excess energy. But still, that won't happen any time soon and the value proposition of paying several times more for energy is very limited. And while there is a shortage of green energy, using it for the creation of fuels seems like it is costly and wasteful.
- dsfyu404ed 4y ago
  >Electrical motors are about as reliable and safe as it gets. Electricity isn't free. If you're already wasting sufficient amounts of the requisite elements as waste products of some other thing you're already doing then finding a way to bond those elements and then burn the resultant compound for rotary power may be more economically efficient.
  - danans 4y ago
    > If you're already wasting sufficient amounts of the requisite elements as waste products of some other thing you're already doing then finding a way to bond those elements and then burn the resultant compound for rotary power may be more economically efficient. Your sentence is a bit vague, but "some other thing you're already doing" sounds like petroleum refining, which is precisely what we need to do less for use as a fuel. Also, ammonia created from petroleum isn't being wasted today. It's used for making fertilizer, and the whole process has a high cost in CO2 emissions. When the time comes that we have so much carbon-free energy that we can afford to use the excess to generate ammonia, we ought to use it to displace petroleum based ammonia for fertilizer. There may be a few niches (ocean shipping) that require a liquid fuel like ammonia, but it makes little sense to use it for ground transportation. If a liquid fuel is required, things like sustainable biodiesel make more sense.
pencilguin 4y ago
Ammonia is fine for big industrial use: we process it in the many millions of tons, already. I would not like to see it pumped at gas stations.

pkphilip 4y ago

The advantage of ammonia is in the transportation and refueling. If you can refuel a car in the same amount of time that it would take to refuel it with gasoline, then it is a huge plus as it would allow a single fuel station to fuel many more vehicles in the same amount of time.. for instance, in the time it would take to fuel a EV to even 20% charge, you could conceivably fuel dozens of vehicles with ammonia. That apart, for fast charging or even standard charging you need a reasonably heavily power load from the grid - if you have even 4-5 vehicles charging simultaneously. This would require big changes in the electricity distribution infrastructure.. something which is not required if you continue to use the existing infrastructure used to take fuel to the fuel stations. Consider that you could easily fully refuel an 18-wheeler in a few minutes time with just a low powered pump.. which is not really possible if the 18-wheeler was a pure EV.

jillesvangurp 4y ago
But then consider that you need about 8x the electricity to pull that off; which you pay for at the pump and suddenly that 30-40 minute charging break sounds pretty sweet. Especially when considering your drivers are required to take such long breaks every 4-5 hours. Private drivers get irrational and emotional about this stuff. But most commercial transport is cost driven. 8x is a great argument. Ammonia doesn't stand a chance. As for the grid, a lot of charging infrastructure relies on batteries and some local production via renewables. That evens out the load on the grid and helps balance things.