By Sandra Steingraber, SEHN senior scientist

This essay is the second of two on climate change and the fertilizer crisis. See Part 1 here.

In my last column, we looked at how food and fracking ended up getting married. That story began with naval blockades of Chilean saltpeter (sodium nitrate) during World War I that created a national fertilizer shortage in Germany.

Enter the Haber-Bosch process. By harvesting hydrogen atoms from natural gas (methane), German chemists Fritz Haber and Carl Bosch were able to turn nitrogen floating around in the atmosphere, which is not available to help crops grow, into ammonia, which is, and so obviated the need to mine and import naturally occurring deposits of saltpeter from South America.

Atmospheric nitrogen travels as tightly bonded N2 molecules and refuses to react with other atoms. By contrast, ammonia is highly reactive NH3, which easily converts into nitrates sought by photosynthesizing plants. (Indeed, ammonia can be violently reactive. Not coincidentally, ammonia was also used by Germany to make bombs.)

Hence, with the introduction of Haber-Bosch into the global economy after the end of the war, agriculture became dependent on a petrochemical. More than a century later, Haber-Bosch is still the dominant method for making fertilizer all over the world. And this fact is why the price of food rises and falls with the price of natural gas.

To put a finer point on it: almost all commercial nitrogen fertilizers currently on the market are created using natural gas as a hydrogen feedstock. And, in North America, the dominant method for extracting that natural gas out of the earth is fracking, which is inherently leaky and invariably pours prodigious amounts of heat-trapping methane into the atmosphere. North American fracking operations are a big driver of the global climate crisis, and the demand for fertilizer is one of the big drivers of fracking.

Also, in addition to all the upstream methane leakage, the process of freeing hydrogen atoms from fracked gas for ammonia production requires immense pressure at 500 degree temperatures and releases into the atmosphere nearly two tons of carbon dioxide for every ton of ammonia manufactured. Making ammonia from natural gas is, all by itself, responsible for about 1.4 percent of global carbon emissions. It’s hard to name a more climate-destructive industry than Haber-Bosch fertilizer manufacturing.

As a spoils-of-war technology, Haber-Bosch fertilizer has probably done more to entrench fossil fuels and wreck the climate than any other wartime invention, including nylon.

There is an alternative: replace natural gas with water and use electricity sourced from renewable energy to split off the hydrogen atoms via electrolysis. Voilà! Green ammonia made from green hydrogen sourced from good old H20 with no carbon emissions at all.

And yet, vexing fundamental problems remain.

First, using electrolysis to break water molecules apart is much more expensive than Haber-Bosch and requires even more energy. With green hydrogen also being touted as a replacement for diesel fuel, the sheer number of solar panels and wind turbines required for all this energy-intensive hydrogen-splitting raises questions about land use.

Also, making green hydrogen to make green ammonia destroys water. Of course, so does fracking, which buries vast quantities of freshwater in geological strata far below the hydrological cycle, making it forever unavailable here on Earth’s surface.

Depleting precious water resources is one of the really bad things about fracking. Green ammonia raises the same objection. Does it really make sense, in a time of climate crisis, to use up fresh drinking water to make hydrogen? Is it wise to destroy vast sources of water in order to create fertilizer to grow crops that need water in a time of growing water scarcity?

Finally, however it gets made, ammonia is, at the end of the day, still a highly toxic, environmental contaminant. Which is to say, ammonia-based synthetic fertilizers, independent of the genealogy of their hydrogen atoms, are major pollutants of both air and water and are a proven cause of oceanic dead zones.

As an air pollutant, ammonia molecules are sticky and highly reactive. They swiftly combine with other air pollutants to create ammonium salts, a form of fine particulate matter that is linked to asthma, heart attack, irregular heartbeats, pneumonia, preterm birth, and stroke. There is no safe exposure level. Ammonia pollution appears as smog and haze, and global emissions have doubled over the past 70 years as demand for chemical fertilizers rises.

Liquefied ammonia gas is corrosive to skin, lungs, and eyes. Exposure to anhydrous ammonia fertilizer can cause blistering, necrosis, frostbite injury, cataracts, glaucoma, and corneal perforation. Accidents involving anhydrous ammonia fertilizers carry the risk of blinding the farmers spraying them (a major plot point in Jane Smiley’s 1991 Pulitzer Prize-winning novel, A Thousand Acres).

Stolen from farms and fertilizer warehouses, ammonia is a key ingredient in the illicit manufacture of methamphetamine, the scourge of rural communities across the nation.

As a water pollutant, liquid ammonia fertilizers freely run into rivers and streams. Ammonia is highly toxic to fish and contributes to toxic algal blooms and acidification of lakes. Ammonia fertilizer runoff, carried down the Mississippi River from farmland all over the Midwest, is a major contributor to the Gulf of Mexico’s dead zone, where decomposing algal blooms deplete oxygen and no life is possible in an oceanic area roughly the size of New Jersey.

So, even if ammonia made from water-sourced hydrogen with the help of solar panels can rightfully be called a green alternative to ammonia made from natural gas, this question still remains: can we redesign agriculture in ways that feed us all in a time of climate crisis and sidestep the need for synthetic ammonia fertilizer altogether?

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The RePercussion Section: On Fracking and Food, Part 2: Green Hydrogen and Green Ammonia