Direct air capture (DAC) is, on its face, a very appealing way to pull carbon dioxide out of the atmosphere. All you need to do is build a factory. To make a dent in global emissions, however, you have to build more than a factory: you have to build an industry. How fast, realistically, could we do this? The history of ammonia synthesis might give us a clue. Catalytic ammonia synthesis has a lot in common with DAC. Both process atmospheric gases. Both require enormous amounts of energy.

For Figure 1: If we scale the growth of direct air capture to match the historical growth of ammonia synthesis (black and grey line), it exceeds most predictions for the rate at which direct air capture might be able to grow (blue area and green and black points).

For Figure 2: Thus far, the development of direct air capture (DAC) technologies has been much slower than that of ammonia synthesis. This suggests that it has less momentum in the present day, and maybe that it will therefore grow more slowly.

The first ammonia synthesis facility was opened at Oppau, Germany, in 1913. In its first year of operation, it produced 800 tons of ammonia. By 1990, the global ammonia synthesis industry produced over 800 million tons of nitrogen. If the global DAC industry grows from its first commercial facility (a one megaton plant under construction in Louisiana) at the same rate that ammonia synthesis grew throughout the twentieth century, then it would exceed most integrated assessment model projections for DAC deployment. It would reach one gigaton of carbon capture around the middle of the twenty-first century, and could reach one hundred times that by 2100.

There's a catch. Ammonia synthesis grew as fast as it did because its product (fixed nitrogen) had massive political and economic importance: It was crucial for both food production and national security. DAC is not nearly as crucial to national interests, which might be why it is already progressing more slowly than ammonia synthesis did. Therefore, the scenario shown by the black line in this chart is likely to be an optimistic upper bound for the future of DAC. Reaching it will require an enormous amount of political and financial commitment to support the technology. But if this commitment materializes, there could be potential for DAC to grow very quickly.

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