By Christiana Briddell, Sr. Communications Manager, ACS Green Chemistry Institute, and featuring Yalinu Poya, Ph.D. student at the University of Glasgow.
When you start to scratch the surface of the U.N. Sustainable Development Goals (SDGs), the first thing that becomes apparent is that they are often interconnected and have synergistic relationships. A world without hunger is the ideal of Goal #2. This goal alone reaches beyond agriculture practices and touches social and financial systems, land development trends, equality and access issues; grapples with the threats from climate change (to which agriculture also contributes); and impacts the health of land, air, and water.
The key, however, to ending hunger has to be in developing a comprehensive, fundamentally sustainable food production system that is resilient to the effects of climate change, maintains and promotes biodiversity, water and land management practices, and can be applied by the small-scale farmers that make up the 40-85% of food production in many parts of Asia, Latin America and Africa.
Currently, the U.N. estimates that 1 in 9 people in the world are undernourished, a number that has risen over the last three years rather than declined. In Africa, 20% of the population is considered undernourished, but even in wealthy countries like the United States, food insecurity affects 11% of the population.
There are many areas related to Goal #2 that are relevant to chemists. Increasing agricultural production and fighting pests has been the focus of agricultural scientists for decades. New technology-assisted farming promises a smarter approach to fertilizer application, crop protection management, and water management.
Innovations such as Dow AgroSciences LLC’s Instinct Technology, (which won a Green Chemistry Challenge Award in 2016), helps reduce nitrogen pollution from fertilizer runoff by making the nitrogen in fertilizer applications more available to crops and slower to degrade into unusable forms.
Phosphorus, like nitrogen, is essential for plant growth and one of the main ingredients in fertilizer, but phosphorus will become increasingly difficult to mine in the future, with peak production estimated to hit between 10-60 years from now. Currently, most phosphorus that is not absorbed by plants, runs off into water bodies where it contributes to eutrophication. Research is needed to find ways to recover and recycle phosphorus from sewage treatment plants using low-energy, highly-efficient separations.
Alternative pesticides, fungicides and herbicides that are more environmentally friendly are another area of ongoing research and development. Biopesticides, derived from microorganisms that naturally attack crop pests and diseases, have been explored for a variety of applications. For example, Agraquest, Inc. (now Bayer CropScience) was an early Green Chemistry Challenge Winner for their biofungicide Serenade, which makes use of a naturally occurring bacteria. Companies like Marrone Bio Innovations have developed a number of bio-based solutions derived from microorganisms and plant extracts.
Genetic resilience is important to this goal, with a focus on preserving the genetic diversity of crop species for the future. Finding varieties and modifying genes in order to develop qualities such as drought resistance may be an important tool as some regions dry out. In other regions, there will be a need for salt-resistant crops, or protection from molds and fungus, and in all cases, increased yields.
Improving the Sustainability of Nitrogen Production through Catalysis
One of the biggest challenges to making the modern agricultural system more sustainable is the energy demands of a reaction at its heart—the Haber-Bosch Process for the production of ammonia. I asked Yalinu Poya, originally from Papua New Guinea, and currently a Ph.D. student in Prof. Justin Hargreaves research group at the University of Glasgow, U.K., to share her approach to this issue:
Catalysis is continuously making great contributions towards improving, or in some cases, resolving some of the world’s most common and demanding challenges that we continue to face. My specialty is in heterogeneous catalysis with my Ph.D. research focusing on synthesizing catalysts for ammonia production in the Haber–Bosch Process. The Haber–Bosch Process is a mature technology developed in the early 20th Century, however there are many currently pressing challenges to make it more sustainable. By addressing its catalyst component through my research, I believe many of the problems associated with the process can be solved, or my research could contribute to a greater solution.
The Haber–Bosch Process, which was developed in the early 1900’s, was a landmark achievement of the 20th Century. Currently, the process produces over 174 million tonnes of ammonia annually, establishing an accessible route for the production of over 450 million tonnes of synthetic fertilizer. In itself, this sustains food production for 40% of the global population.
The Haber–Bosch Process involves combining pure H2 and N2 feedstreams directly over a promoted iron catalyst at temperatures of around 400°C and reaction pressures of over 100 atmospheres. The reaction is exothermic and is equilibrium limited, thus it is thermodynamically favoured at lower reaction temperatures. Despite this, the temperature of operation is dictated by the requirement to achieve acceptable process kinetics.
Due to the reaction conditions involved in the process at a global scale, including the generation of feedstock, the operation of the Haber–Bosch Process currently consumes 1-2% of the world’s energy demand and produces 1.6% of man-made CO2 emissions. To reduce these harmful effects and yield massive rewards both in terms of economic and environmental benefits, there is great interest in the development of small-scale local ammonia production plants based on renewable hydrogen generated from water via electrolysis and powered by sustainable electricity sources such as wind energy. In such a context, which would facilitate the production of ammonia on a localized scale close to its point of use such as on a farm, it is necessary to develop novel ammonia synthesis catalysts which are active under less severe operational conditions appropriate to smaller scale reactors.
It is notable that a number of active ammonia synthesis catalysts are comprised of cobalt in addition to other active metals – a combination of cobalt and rhenium as a bimetallic catalyst shows high ammonia synthesis activity. Despite its low surface area, cobalt rhenium is an active catalyst in ammonia synthesis, however a more highly dispersed catalytic phase can be obtained by application of a suitable catalyst support. It can be anticipated that this would lead to enhanced catalytic performance.
The United Nations has designed and implemented 17 Sustainable Development Goals specifically to make the world a better place by facilitating a sustainable future for everyone. It is estimated that the world population will reach 9.1 billion by the year 2050, consequently food production will need to rise by 70% to keep up with global demands. Farmers will require more fertilizers to maintain fertile soil in order to produce healthy crops, which will result in an increased demand in the production of fertilizers. Since ammonia is the main component in fertilizers, it too will need to increase in production in order to fulfill Goal 2–Zero Hunger.
Picture: Sourced from https://www.greentalents.de/yalinu-poya.php