GLOBAL FOOD SECURITY

OVERVIEW

In the 20th century, the invention of the Haber-Bosch process for converting atmospheric nitrogen into ammonia, together with the Green Revolution that dramatically improved agricultural yields, eliminated natural limits on bioavailable nitrogen and enabled an expansion of world population from 1.6 billion to 7 billion. Globally, the amounts of chemically and biologically fixed nitrogen in our food supply are now comparable, meaning that chemically-fixed nitrogen feeds about half of the world’s population. However, when one limiting element becomes abundant, another becomes limiting: that element is now phosphorus. It is extracted from phosphate rock (phosphorite), a sedimentary deposit. The world’s largest producers, China and the US, are expected deplete their reserves in the next 50 years, assuming continued extraction at current rates (we note that this is an optimistic scenario, and does not account for further population expansion, increased dietary protein, or the demand for phosphate-based fertilizers from the emerging biofuels industry). The most productive of the US mines, located in Florida, will be depleted within 20 years, and the US recently became a phosphate importer. China now imposes seasonal tariffs exceeding 100 % on exported phosphate, in order to conserve its resources for domestic use. Globally, phosphate appears to be more geographically concentrated than crude oil; if industry estimates are accurate, a single country (Morocco) controls a higher fraction (70 %) of global reserves than the crude oil in all 12 member states of OPEC combined. This represents an important supply interruption risk, and a potential threat to global food security. We urgently need to develop sustainable chemistry to enable the recovery and reuse of phosphorus. Human consumption and excretion of phosphorus amounts to 3 million tons annually, turning our cities into valuable sources of this essential and completely non-substitutable element in human nutrition, via recovery during wastewater treatment. New phosphate recovery technologies, possibly including adsorption, ion exchange, and nano-filtration, followed by precipitation or crystallization, are urgently needed.

CHEMICAL INDUSTRY SUSTAINABILITY

The US chemical industry is a cornerstone of American manufacturing, and the scale of chemical production is immense. The chemical industry produces commodities (large-volume, low-cost basic organic building blocks, such as ethylene, methanol, etc., as well as inorganics such as ammonia...

INTEGRATING PHYSICAL AND SOCIAL SCIENCE

Replacement of conventional technologies by more sustainable versions is by no means automatic or rapid. New approaches must be cost-competitive; in manufacturing, this often means considering large existing capital investments, as well as supply risks. Changing or uncertain regulatory...

REDUCING DEPENDENCE ON CRITICAL METALS AND MATERIALS

The precious metals (Ru, Rh, Pd, Os, Ir, Pt) make highly effective catalysts in a wide range of chemical reactions, due to their readiness to change oxidation states and their reluctance to form recalcitrant oxides. Unfortunately, they are also some of the least abundant elements in the Earth’s crust...

CONSERVING ENERGY

AND FRESH WATER

Many chemical industry practices are highly energy- and water-intensive. For example, the Haber-Bosch process (described above), which produces 500 million tons of ammonia-based fertilizer annually, consumes 1-2 % of the entire world energy supply. Light olefins (ethylene and propylene) are...

USING RENEWABLE RAW MATERIALS

The vast majority of synthetic carbon-based materials are currently made from a handful of petroleum-derived building blocks, including ethylene, propylene, butenes, benzene, toluene, xylene and methanol. These components are converted, using chemistry, into polymers...

REDUCING RISK THROUGHOUT THE SUPPLY CHAIN

Reduced risk of exposure and minimal environmental toxicity are important dimensions of sustainable chemistry. Cradle-to-grave life cycle assessments and fate and transport studies must be employed to quantify potential emissions of chemicals at different life cycle stages...

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