Fuel From Air (Or: The Final Agricultural Revolution)

Though I tried to motivate it, my post Food From Fuel must have seemed strange. When would we really need this? Is this worth studying? Who would eat synthetic cooking oil?

I have a confession: I am interested in food-from-fuel for a different reason than I stated in the post. Food-from-fuel is the first step towards eliminating the need for agriculture entirely.

Let’s recap: in Food From Fuel I discuss the possibility of converting hydrocarbons into edible products like cooking oil using standard industrial reactions. But this isn’t that exciting since hydrocarbons are limited in supply, non-renewable, and not very tasty.

But what if we could produce fuel efficiently from the CO2 in air using energy?

This is called the CO2 reduction reaction and it would change everything. By pulling CO2 out of the atmosphere and converting it into hydrocarbons, we can then use our new fuel in the food-to-fuel pipeline to feed the population.

Why is this so exciting? Think about how agriculture works today: plant leaves take CO2 from the atmosphere and energy from the sun, create edible molecules, humans harvest the plants, eat them, and exhale CO2. But with efficient CO2 reduction, plants are no longer needed since we can convert our own exhaled CO2 into food again. By combining fuel-from-air with food-from-fuel, we have created a closed loop where we can feed ourselves using only energy, entirely eliminating the need for agriculture while achieving ecological balance. This is the dream of Artificial Photosynthesis in a nutshell.

The implications are huge.

The number of people needed for agriculture has been falling for centuries, but fuel-from-air would make the number of people required to feed the world astronomically low, freeing up more people to work on other problems.

Humanity’s land use would fall dramatically since there is no longer a need for agricultural land, allowing both natural ecosystems and cities to expand.

Space travel and colonization becomes much more feasible as travelers need only carry or produce enough energy to regenerate food from their exhaled CO2.

The amount of food which can be created is limited only by the amount of energy which can be harvested, greatly increasing the maximum feasible population.

Cheap fuel can also be used to make cheap chemical products (pharmaceuticals, plastics, etc), as well as store energy.

Why aren’t we doing this already? Because plants currently produce food from air and sunlight more efficiently than we can. However, I am confident that further research on this topic will allow us to discover the many tricks biology uses and then beat plants at their own game. It’s worth noting that the bar is pretty low, since plants are only about 1% efficient at converting sunlight into food.

Two other reactions are important for feeding civilization with energy: Nitrogen fixation (see also: Turning air into bread)and water splitting. Fortunately, both of these are intensely studied today, while CO2 reduction is much more neglected because of a lack of commercial value; fuel is a cheap source of carbon for producing chemical products today so there is no need to take carbon out of the air. However, because hydrocarbons are limited in supply, we will eventually have to get all of our carbon from CO2 reduction or plants.

In sum, fuel-from-air offers an opportunity to radically change society by giving humanity more room to grow on earth and beyond while reducing the strain on terrestrial ecosystems. Let’s get to work.

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