Putting the life back in science fiction

This is another spun-off “strange attractor” from Antipope. It had nothing to do with the thread it was on, but the topic is interesting enough–if you’re into futuristic science fiction–that I wanted to summarize it here.

The basic idea is using ammonia as an alternate, carbon-free fuel. This isn’t as weird as it sounds, and there are a bunch of industrial efforts out there that might well project us into an ammonia age rather than a hydrogen one. Unfortunately, ammonia isn’t a panacea, so switching from fossil fuels to ammonia synthesized using solar or wind energy won’t be problem free. For those looking for dramatic conflict, ammonia has it.

Anyway, the fundamentals. Ammonia is NH3. If like me you’re lazy, you can go to Wikipedia’s article on energy densities, and find out that liquid ammonia has about 11.5 MJ/L of energy, slightly better than compressed natural gas (9 MJ/L) and liquid hydrogen (8.5 MJ/L), and less than propane (25.3 MJ/L) or gasoline (34.2 MJ/L), among many others.

As for making NH3, right now we make it in huge plants using the Haber-Bosch process, which makes ammonia using natural gas. Nitrogen is ubiquitous as N2 in the atmosphere, but N2 is a very stable molecule, and it takes a lot of energy to break it and turn it into NH3. Still, people are looking for better ways to do it. NH3 Canada is developing a miniature ammonia synthesizer that’s about four cubic meters in size and can produce 500 liters of ammonia per day, with each liter of ammonia taking 2 liters of water and 7.5 KWhrs of electricity to produce it. As a comparison, the average US home uses 909 kWhr per month or about 30 kWhr per day, which is about what it would take to make a gallon of ammonia using NH3 Canada’s technology. If it works.

To save you the math, that’s about 30% conversion efficiency, which isn’t bad. Ammonia synthesis could be used to store electricity from, say, wind turbines. The nice thing about NH3 Canada is that they want to use small units and stack them in banks, while the older technology uses huge furnaces to get efficiencies of scale.

What can you do with ammonia? You can actually mix it with gasoline and use it to run your car, if you get the mix right, and other researchers are working on creating engines that can run on pure ammonia. While there’s less energy in ammonia than there is in propane, it can be handled similarly. Pure (anhydrous) ammonia is fairly dangerous stuff, but then again, so is liquid hydrogen, and so are giant batteries if they’re fully charged. Energy density makes things dangerous.

Of course, ammonia has many other uses. We all know of it as a cleaner and fuel, and it used to be used in refrigerators before people switched to the much more efficient and dangerous CFCs [but see comments]. But it’s primary use is as a fertilizer and to make explosives, including gunpowder. Industrial nitrogen fixation underlies Big Ag all over the world, and it also underlies industrial warfare. Without huge amounts of gunpowder, things like machine guns don’t work, because there isn’t enough ammunition to make them fully functional killing machines.

Similarly, without huge amounts of nitrogen, the huge amounts of corn, wheat, and soy that are required to feed all seven billion of us wouldn’t exist. Some calculate that at least a third of us wouldn’t exist without fixed nitrogen in our food. The US has taken full advantage of this, and forcing huge supplies of cheap food on the world has been a major part of our foreign policy since the Eisenhower Administration. It was one way of beating communism, and protecting our high-yielding corn from things like being pirated by the Chinese is a matter of national security today.

I’m not a huge fan of Big Ag, even though I’d probably be dead without it. Still, if we want to switch from fossil fuels to renewables, adapting and expanding our existing fixed nitrogen infrastructure is a lot easier than trying to build the infrastructure needed to handle hydrogen.

That’s the good part. There are some downsides.

One is that when you burn ammonia in an engine, it produces NOx, which is a major source of air pollution. This can be fixed if there’s a catalytic converter on the exhaust pipe. I suppose, if you’re powering agricultural equipment, it might be possible to capture the NOx, convert it to nitrate or urea, and use it as fertilizer on the fields, thereby getting a second use from the fixed nitrogen.

One big problem with an ammonia economy is the same problem with renewables, which is that you’re capturing energy from the modern sun, and that’s all you get to play with. Fossil fuels use fossil sunlight from the last few hundred million years, and that’s a lot more energy. There’s no fossil ammonia, so we’d be stuck working in a lower energy environment. Currently, industrially fixed nitrogen takes about 1% of the global energy supply, but that’s a fixed 1%, and if it’s used for other purposes, people can starve. We’d have to ramp up NH3 production to store captured renewable energy, not depend on what’s already being made.

Still, I can envision a world where giant farms host an overstory of huge wind turbines, all hooked up to ammonia synthesizers. The farmer uses the ammonia to run his equipment, then uses nitrates captured from the exhaust to fertilize his fields. Aside from the scale and all the problems with nitrogen runoff and pollution, this isn’t a bad setup.

There are some interesting follow-ons.
–One is politics. If most of the world switches to synthesizing ammonia from sunlight or wind, the countries that depend on petroleum exports are out of luck. The only parts of the Middle East that would continue to matter to the US (and possibly China and Russia) are Egypt and Israel, due to the Suez Canal. This means that the burgeoning crises in the region would have to be dealt with semi-regionally, if at all. And that’s bad for all those refugees. Russia is likely to be a hold-out in switching off fossil fuels, since they get so much power from oil and natural gas, but switching to ammonia would change international politics as much as did the switch to using oil in the early 20th Century.
–A second issue is fertilizer. It is feasible to synthesize huge amounts of ammonia, but other elements are essential for plant growth, and the world is starting to run short of minable phosphorus. We may well have phosphorus wars in the future, but the simpler solution is to recycle sewage and manure onto fields. This has all sorts of public health and disease vector implications, but it will keep people from starving And there are menu implications–you want to eat raw salad from a field that receives sewage? It’s a common practice in the developing world.
–A third issue is air pollution. I can easily see people using ammonia to power things like home generators in areas where the power grid is failing, but if these machines don’t have decent filters on their exhaust, they will put out a lot of air pollution. The resulting smog will degrade the performance of any local solar panels, but it might be simpler than investing in huge batteries and a smart grid to provide power when the sun doesn’t shine.

And who will control the ammonia? A nitrogen-based economy has less energy than does the current oil-based economy. Energy becomes power when it is scarcer, even more than it is currently. Right now, we’re seeing how Big Oil distorts politics all over the world. Small ammonia generators, like the NH3 Canada machine, change the current game that is dominated by a few huge producers, because they mean that small-scale producers can make small amounts of fuel, at least in the short term. Probably this means that the advantage shifts from those who produce ammonia to those who build ammonia synthesizers and can best ship the ammonia from producers to consumers. Over time, I suspect that a few big ammonia producers will dominate the industry in any one area. They will be, quite literally, power brokers.

Still, switching to ammonia could slow down global warming, because the great advantage of NH3 is there’s no carbon emission from using it. It beats things like bio-diesel and biomass cold. Unfortunately, we’re seeing increasing methane emissions from the Arctic, so even if we get civilization’s carbon emissions under control, we may be passing the tipping point as you read this. We’ll see.

If you want to write a SF-thriller set in the next few decades, you could do worse than to power the world with ammonia, and make the Politics of N a centerpiece of the story. After all ammonia isn’t just a fuel, it’s a cleaner, fertilizer, and a refrigerant. Who wouldn’t want to get rich off it? Something to think about.