28 April 2013

The Gas We Eat

Posted by John Freeland

Anhydrous ammonia fertilizer tanks. Source; State of Minnesota.

Nearly half of the world’s population owes its existence to food grown with industrial nitrogen fertilizer produced from natural gas. (1)

In 2004, journalist Richard Manning published an intriguing, if somewhat controversial, article in Harpers magazine called The Oil We Eat: Tracing the food chain back to Iraq. Manning notes that growing our food under the usual practices requires about 10 calories of fossil fuel energy for every calorie of food energy. Preparing the soil to grow grains, especially corn and wheat, requires a lot of energy and maintenance to rip up the soil every year in order to exclude other plants and create a non-competitive environment for the seed to grow. In the case of no-till farming, energy is spent to make herbicides that, like the plow, block the natural process of ecological succession.

Manning puts it this way:

Corn, rice, and wheat are especially adapted to catastrophe. It is their niche. In the natural scheme of things, a catastrophe would create a blank slate, bare soil, that was good for them. Then, under normal circumstances, succession would quickly close that niche. The annuals would colonize. Their roots would stabilize the soil, accumulate organic matter, provide cover. Eventually the catastrophic niche would close. Farming is the process of ripping that niche open again and again. It is an annual artificial catastrophe, and it requires the equivalent of three or four tons of TNT per acre for a modern American farm. Iowa’s fields require the energy of 4,000 Nagasaki bombs every year.

Natural Gas, Haber-Bosch, and Nitrogen Fertilizer
In addition to the fuel used to run equipment to plow, plant, cultivate, spray, and harvest croplands, natural gas is required to produce nitrogen fertilizer. Nitrogen, a major plant nutrient, is contained in amino acids, the building blocks for all plant and animal proteins. Roughly half of the protein in our bodies comes from industrial nitrogen. It’s a strange thought: our bodies are, in no small way, industrial products.

Fritz Haber

Carl Bosch

The Haber-Bosch process has been around for about a century. Fritz Haber, a German chemist, whose complicated career included personally ushering in the age of chemical warfare and inventing the poison gas used in Nazi death camps, found that ammonia, a plant-available nitrogen source, could be made from atmospheric nitrogen and hydrogen. The process, scaled up and commercialized by engineer Carl Bosch, involves heating air and hydrogen from natural gas at high pressures, in the presence of a catalyst, to form ammonia. Haber and Bosch each won Nobel Prizes at different times.

I’d like to see Martin Scorcese make a movie based on the brilliant, enormously consequential, and tragic life of Fritz Haber.

Natural Gas Stewardship
Given the importance of natural gas in feeding the world, we, as a society, would be wise to manage the resource more carefully than we do now. Estimates of natural gas reserves are rough because recovery rates at individual wells come with no guarantee. Economic growth rates, exports, and policy decisions will further determine how fast natural gas reserves are depleted.

For now, about 5% of the natural gas used in the U.S. goes to making fertilizer. That doesn’t sound like much but as natural gas becomes the fuel of choice, replacing coal and petroleum for environmental and economic reasons, the proportion of gas used for agriculture to feed a growing world population will likely rise. Already, farmers are complaining of high fertilizer prices.

As I noted here, the current widespread practice of flaring off natural gas as a waste product is poor stewardship of a vital resource.

Someday, we’ll wish we had that.