Observation of a self-generated current to self-confine fusion plasmas

Peer-Reviewed Publication

SEOUL NATIONAL UNIVERSITY

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CREDIT: SEOUL NATION UNIVERSITY

Nuclear fusion has drawn more attention in the era of carbon neutrality because of no carbon dioxide production during power generation and no generation of high-level radioactive wastes.

 

A tokamak, a torus-shaped nuclear fusion device, needs an electric current in the plasma to produce magnetic field around the torus for confining fusion plasmas. Plasma current is conventionally generated by electromagnetic induction.

 

However, for a steady-state fusion reactor, minimizing the inductive current is essential to extend the tokamak operating duration. Several non-inductive current drive schemes have been developed for steady-state operations such as radio-frequency waves and neutral beams. However, commercial reactors require minimal use of these external sources to maximize the fusion gain, Q, the ratio of the fusion power to the external power. Apart from these external current drives, a self-generated current, so-called bootstrap current, was predicted theoretically and demonstrated experimentally.

 

The research team led by Prof. Yong-Su Na in the Department of Nuclear Engineering at Seoul National University and Dr. Jaemin Seo at Princeton University have revealed that another type of self-generated current can exist in a tokamak which can not yet been explained by present theories. They discovered this in the experiments on the KSTAR tokamak in collaboration with Korea Institute of Fusion Energy, Princeton Plasma Physics Laboratory, and General Atomics.

 

While conducting an experiment on plasma turbulence, it was discovered by chance that an un-identified plasma current that could not be explained by existing theories and simulations occurred. As a result of the analysis, it was found that this comprises a significant amount up to 30% of the total plasma current, and appears when the turbulence was relatively low.

 

The discovery of a new plasma current generated by itself without magnetic induction shows a new possibility that the plasma confines by itself and continues the fusion reaction in long-pulse operations for a fusion reactor.

 

The new current source in this experiment was unusually observed only when the fuel was injected into the plasma and the exact cause is still unknown, so follow-up studies are planned to proceed actively in the future.

 

Prof. Yong-Su Na, the co-first author and corresponding author of the study, said, “This result was obtained from a unfamiliar experiment to the extent that the experiment proposal was not selected at KSTAR. If we had tried to look at it from a conventional point of view, we would not have found it. “We were able to discover new things by approaching with an open perspective rather than being confined to what we wanted to see or get.” Another co-first author, Dr. Seo Jae-min, said, “Big science such as the nuclear fusion research is being devoted to small steps that put an apple on the shoulders of giants. I hope that future scientists who can step forward together will be interested in and support the nuclear fusion research.”

Seoul National University

Once the physics mechanism is found, this new discovery is expected to significantly contribute to the long continuous operation of ITER and commercial reactors, which are exploring current drive ways that do not reoly on inductive current.

 

This work was supported by National R&D Program through the National

Research Foundation of Korea (NRF) funded by the Korean government

(Ministry of Science and ICT) (NRF-2021M1A7A4091135 and

2021M3F7A1084419). This work was also supported by the Ministry of

Science and ICT under the KFE R&D Program of “KSTAR Experimental

Collaboration and Fusion Plasma Research (KFE-EN2201-12)”.

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JOURNAL

Nature Communications

DOI

10.1038/s41467-022-34092-0 

ARTICLE TITLE

Observation of a new type of self-generated current in magnetized plasmas

Delgado-Aparicio appointed to national fusion advisory committee

DOE/PRINCETON PLASMA PHYSICS LABORATORY

 

IMAGE: PPPL PHYSICIST LUIS DELGADO-APARICIO view more 

CREDIT: ELLE STARKMAN / PPPL OFFICE OF COMMUNICATIONS

Luis Delgado-Aparicio, a principal research physicist at the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), has been named a member of the Fusion Energy Sciences Advisory Committee (FESAC), which advises the director of the United States Office of Science on complex scientific and technical matters related to America’s fusion energy sciences research program.

Delgado-Aparicio will specifically provide advice about confining plasma, ultra-hot gas sometimes known as the fourth state of matter, within doughnut-shaped fusion facilities known as tokamaks. Scientists around the world use tokamaks and other devices to try to harness the fusion process that powers the sun and stars to create electricity with producing greenhouse gases and long-lived radioactive waste.

Delgado-Aparicio will also provide expert counsel about the movement of heat and particles within plasma, as well as magnetohydrodynamics, a set of physical laws that describe plasma’s behavior and is used to create computer simulations that help improve tokamak performance.

The committee meets approximately three times a year in Washington, D.C. His three-year term began in October 2022 and will extend until June 2025.

“I am extremely honored to join the FESAC committee,” Delgado-Aparicio said. “It’s a huge responsibility and a wonderful opportunity.”

In addition, in October Delgado-Aparicio was named the new head of PPPL’s Department of Advanced Projects, replacing PPPL physicist David Gates. The department oversees the Lab’s efforts to build a new type of twisty stellarator fusion facility that incorporates permanent magnets, similar to those used on refrigerator doors. The department also manages PPPL’s collaboration with stellarators around the world, including Germany’s Wendelstein 7-X and Japan’s Large Helical Device, as well as PPPL’s efforts to provide plasma sensors that rely on powerful light known as X-rays. Other divisions within Advanced Projects include Fusion System Studies and Next-Step Project Development.

PPPL, on Princeton University's Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science

New approach to fabricating ion conducting ceramic membranes for stable hydrogen production

Peer-Reviewed Publication

CHINESE ACADEMY OF SCIENCES HEADQUARTERS

 

IMAGE: FABRICATION OF A MULTILAYERED CERAMIC MEMBRANE WITH AN ION CONDUCTING DENSE THIN LAYER USING AN INTERFACE-REACTION-INDUCED REASSEMBLY APPROACH. view more 

CREDIT: HE GUANGHU

Hydrogen has attracted much attention due to its potential as a clean energy carrier. To date, the majority of hydrogen is produced from fossil fuels, such as natural gas, coal and oil. Such fossil-derived hydrogen must be purified from common contaminants (e.g., CO2, CH4, CO and H2S) for further fuel cell applications.

Fossil-derived hydrogen-assisted water splitting using a dense oxygen-ion-conduction ceramic membrane is a promising H2-purification technique due to the membrane's 100% oxygen selectivity for directly obtaining pure hydrogen. However, existing oxygen-conducting membranes suffer from chemical stability issues under the above harsh operating conditions.

Recently, researchers from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences (CAS) have developed a new "Interface-reaction-induced reassembly" approach to fabricating multilayered ceramic membranes with ceria-based thin-film for stable hydrogen production.

The study was published in Angewandte Chemie International Edition on Nov. 3.

"Multilayered ceramic membranes are typically fabricated using layer-by-layer deposition methods. However, these methods often require a serial procedure, and the thickness of the dense thin layers is commonly between 10 and 1000 μm. In addition, the deposited thin layers often delaminate from the support layers during co-sintering," said corresponding author Prof. JIANG Heqing from QIBEBT.

Inspired by the architectural structure of the rooted grasses in soil, the researchers developed an interface-reaction-induced reassembly approach to fabricating a three-layered ceramic membrane with an oxygen-conducting dense thin layer rooted in its parent layer, directly resulting from a single-step sintering of dual-phase ceramic precursors.

"In this new approach, by deliberately applying a proper etchant Al2O3, the surface Fe-containing grains in the pressed pellet were selectively etched via interface reactions at high temperatures, producing reaction enthalpy," said Associate Professor HE Guanghu from QIBEBT, first author of the study. "The heat is expected to increase the local temperature for driving the reassembly of the surface-isolated fluorite-type grains into a dense thin layer that cut off the interface reactions, avoiding the continuous growth of the thin layer."

With this interface-reaction-induced reassembly approach, the researchers found that the resulting ceria-based layers were very thin (~1 μm), highly dense and adhered strongly to the parent layers, not only significantly reducing ionic transport resistance, but also ensuring the structural integrity of the multilayered membranes for various applications.

Using the developed multilayered membrane, the researchers demonstrated hydrogen production from water splitting assisted by oxidation of simulated coke oven gas containing H2, CH4, CO2, CO and H2S. They found that the membrane with a CGO dense thin layer showed very long durability (>1000 hours), underscoring the promise of high-performance membrane reactors for hydrogen production in practical conditions.

"These results suggest that this technique paves the way for the development of high-performance multilayered ceramics with functional layers for various applications, for example solid oxide fuel cells and solid oxide electrolysis cells. This is also the focus of our future work," said Prof. JIANG Heqing from QIBEBT, who led the study.

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JOURNAL

Angewandte Chemie International Edition

DOI

10.1002/anie.202210485 

ARTICLE TITLE

Multilayered ceramic membrane with ion conducting thin layer induced by interface reaction for stable hydrogen production

Hormone discovery could predict long term health of men

Hormone discovery could predict long term health of men

Peer-Reviewed Publication

UNIVERSITY OF NOTTINGHAM

Researchers have discovered the vital role of a hormone, that develops in men during puberty, in providing an early prediction of whether they could develop certain diseases in later life.

Scientists from the University of Nottingham have discovered that the novel insulin-like peptide hormone, called INSL3, is consistent over long periods of time and is an important early biomarker for prediction of age-linked disease. Their latest findings have been published today in Frontiers in Endocrinology. 

INSL3 is made by the same cells in the testes that make testosterone, but unlike testosterone which fluctuates throughout a man’s life, INSL3 remains consistent, with the level at puberty remaining largely the same throughout a man’s life, decreasing only slightly into old age. This makes it the first clear and reliable predictive biomarker of age-related morbidity as compared to any other measurable parameters.

The results show that the level of INSL3 in blood correlates with a range of age-related illnesses, such as bone weakness, sexual dysfunction, diabetes, and cardiovascular disease. 

The discovery of the consistent nature of this hormone is very significant as it means that a man with high INSL3 when young will still have high INSL3 when he is older. But someone with low INSL3 already at a young age, will have low INSL3 when older making him more likely to acquire typical age-related illnesses. This opens up exciting possibilities for predicting age-related illnesses and finding ways to prevent the onset of these diseases with early intervention.

The research was led by Professor Ravinder Anand-Ivell and Professor Richard Ivell and is the latest of three recent studies* into this hormone. Professor Ravinder Anand-Ivell explains: “The holy grail of aging research is to reduce the fitness gap that appears as people age. Understanding why some people are more likely to develop disability and disease as they age is vital so that interventions can be found to ensure people not only live a long life but also a healthy life as they age. Our hormone discovery is an important step in understanding this and will pave the way for not only helping people individually but also helping to ease the care crisis we face as a society.”

The team analysed blood samples from 3,000 men from 8 regional centres in north, south, east, and west of Europe, including the UK, with two samples taken four years apart. The results showed that unlike testosterone, INSL3 remains at consistent levels in individuals 

The study also showed that the normal male population, even when young and relatively healthy, still shows a wide variation between individuals in the concentration of INSL3 in the blood – almost 10-fold. 

Professor Richard Ivell adds: “Now we know the important role this hormone plays in predicting disease and how it varies amongst men we are turning our attention to finding out what factors have the most influence on the level of INSL3 in the blood. Preliminary work suggests early life nutrition may play a role, but many other factors such as genetics or exposure to some environmental endocrine disruptors may play a part.”

 

 

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JOURNAL

Frontiers in Endocrinology

DOI

10.3389/fendo.2022.1016107 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

The Lydia cell biomarker INSL3 as a predictor of age-related morbidity: Findings from the EMAS cohort

ARTICLE PUBLICATION DATE

8-Nov-2022

Study confirms that processed foods key to rising obesity

‘Protein hunger’ drives overeating, large-scale population study shows

Peer-Reviewed Publication

UNIVERSITY OF SYDNEY

 

IMAGE: DAVID RAUBENHEIMER (RIGHT) AT WORK IN NEPAL’S ANNAPURNA CONSERVATION AREA [DAVID RAUBENHEIMER] view more 

CREDIT: DAVID RAUBENHEIMER

A year-long study of the dietary habits of 9,341 Australians has backed growing evidence that highly processed and refined foods are the leading contributor of rising obesity rates in the Western world.

The new study, in the latest issue of the journal Obesity conducted by the University of Sydney’s Charles Perkins Centre (CPC), was based on a national nutrition and physical activity survey undertaken by the Australian Bureau of Statistics (ABS), and further backs the ‘Protein Leverage Hypothesis’.

First put forward in 2005 by professors Raubenheimer and Stephen Simpson, the Protein Leverage Hypothesis argues that people overeat fats and carbohydrates because of the body’s strong appetite for protein, which the body actively favours over everything else. Because so much of modern diets consist of highly processed and refined foods – which are low in protein – people are driven to consume more energy-dense foods until they satisfy their protein demand.

Processed foods lack protein and drive craving

“As people consume more junk foods or highly processed and refined foods, they dilute their dietary protein and increase their risk of being overweight and obese, which we know increases the risk of chronic disease,” said lead author Dr Amanda Grech, a Postdoctoral Research Fellow at the CPC and the university’s School of Life and Environmental Sciences.

“It’s increasingly clear that our bodies eat to satisfy a protein target,” added Professor David Raubenheimer, the Leonard Ullmann Chair in Nutritional Ecology at the School of Life and Environmental Sciences. “But the problem is that the food in Western diets has increasingly less protein. So, you have to consume more of it to reach your protein target, which effectively elevates your daily energy intake.

“Humans, like many other species, have a stronger appetite for protein than for the main energy-providing nutrients of fats and carbohydrates. That means that if the protein in our diet is diluted with fats and carbohydrates, we will eat more energy to get the protein that our bodies crave.”

Protein essential to good health

Proteins are the building blocks of life: every cell in the body contains them, and they are used to repair cells or make new ones; and it’s estimated that over a million forms of protein are needed to allow a human body to function. Protein sources include meats, milk, fish, eggs, soy, legumes, beans, and some grains such as wheat germ and quinoa.

The University of Sydney scientists analysed data from a cross-sectional survey of nutrition and physical activity in 9,341 adults, known as the National Nutrition and Physical Activity Survey which was conducted from May 2011 to June 2012, with a mean age of 46.3 years. They found the population’s mean energy intake was 8,671 kilojoules (kJ), with the mean percentage of energy from protein being just 18.4 percent, compared with 43.5 percent from carbohydrates and from 30.9 percent from fat, and just 2.2 percent from fibre and 4.3 percent from alcohol.

They then plotted energy intake versus the time of consumption and found that the pattern matched that predicted by the Protein Leverage Hypothesis. Those who consumed lower amounts of protein in their first meal of the day went on to increase their overall food intake in subsequent meals, whereas those who received the recommended amount of protein did not – and, in fact, declined their food intake throughout the day.

‘Protein hunger’ found to drive overeating

They also found a statistically significant difference between groups by the third meal of the day: those with a higher proportion of energy from protein at the start of the day had much lower total energy intake for the day. Meanwhile, those who consumed foods low in protein at the start of the day proceeded to increase consumption, indicating they were seeking to compensate with a higher consumption of overall energy. This is despite the fact the first meal was the smallest for both groups, with the least amount of energy and food consumed, whereas the last meal was the largest.

Participants with a lower proportion of protein than recommended at the first meal consumed more discretionary foods – energy-dense foods high in saturated fats, sugars, salt, or alcohol – throughout the day, and less of the recommended five food groups (grains; vegetables/legumes; fruit; dairy and meats). Consequently, they had an overall poorer diet at each mealtime, with their percentage of protein energy decreasing even as their discretionary food intake rose – an effect the scientists call ‘protein dilution’.

Effect seen in other studies

Professor Raubenheimer and colleagues have seen this effect before in other studies for more than a decade, including randomised control trials.

“The problem with randomised controlled trials is that it treats diet as a disease, when it’s not,” said Dr Grech. “Laboratory studies may not be indicative of what people are actually eating and doing at a population level. So this study is important as it builds on work, showing that people do seek out protein. And it confirms that, at a population level, as the proportion of energy from protein increases in the diet, people eat less fats and carbohydrates.”

While many factors contribute to excess weight gain – including eating patterns, physical activity levels, and sleep routines – the University of Sydney scientists argue the body’s powerful demand for protein, and its lack in highly processed and refined foods, is a key driver of energy overconsumption and obesity in the Western world.

Explanation for obesity

“The results support an integrated ecological and mechanistic explanation for obesity, in which low-protein, highly processed foods lead to higher energy intake in response to a nutrient imbalance driven by a dominant appetite for protein,” said Professor Raubenheimer. “It supports a central role for protein in the obesity epidemic, with significant implications for global health.”

Seeking to understand how protein drives human nutrition has also sought taken Professor Raubenheimer to study the diets of people in some of the most remote places, from the Congo to the Himalayas. “The protein mechanism in appetite is a revolutionary insight,” he said. “Obesity, diabetes, cardiovascular disease - they’re all driven by diet, and we have to use what we’re learning to bring them under control.”

The CPC team’s study was chosen by the editors of Obesity as one of the year’s top five papers, with the study’s leader, Professor Raubenheimer, invited to speak at the annual Obesity Journal Symposium in San Diego on November 4

David Raubenheimer with hunter-gatherers in the Congo basin

CREDIT

David Raubenheimer

Researchers at the Charles Perkins Centre, University of Sydney

CREDIT

University of Sydney

Prof Stephen Simpson, co-founder of the theory 

CAPTION

Prof Stephen Simpson, Academic Director of the Charles Perkins Centre at the University of Sydney

CREDIT

University of Sydney

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JOURNAL

Obesity

DOI

10.1002/oby.23578 

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Macronutrient (im)balance drives energy intake in an obesogenic food environment: An ecological analysis

ARTICLE PUBLICATION DATE

2-Nov-2022

Violence on TV: the effects can stretch from age 3 into the teens

Peer-Reviewed Publication

UNIVERSITY OF MONTREAL

Watching violent TV during the preschool years can lead to later risks of psychological and academic impairment, the summer before middle school starts, according to a new study led by Linda Pagani, a professor at Université de Montréal’s School of Psycho-Education.

The study is published in the Journal of Developmental and Behavioral Pediatrics. 

Before now, "it was unclear to what extent exposure to typical violent screen content in early childhood—a particularly critical time in brain development—can predict later psychological distress and academic risks," said Pagani.

"The detection of early modifiable factors that influence a child's later well-being is an important target for individual and community health initiatives, and psychological adjustment and academic motivation are essential elements in the successful transition to adolescence," she added.

"So, we wanted to see the long-term effect of typical violent screen exposure in preschoolers on normal development, based on several key indicators of youth adjustment at age 12."

To do this, Pagani and her team examined the violent screen content that parents reported their children viewing between ages three-and-a-half and four-and-a-half, and then conducted a follow-up when the children reached 12.

Two reports were taken

At the follow-up, two reports were taken: first, of what teachers said they observed, and second, of what the children themselves, now at the end of Grade 6, described as their psychological and academic progress.

"Compared to their same-sex peers who were not exposed to violent screen content, boys and girls who were exposed to typical violent content on television were more likely to experience subsequent increases in emotional distress," said Pagani.

"They also experienced decreases in classroom engagement, academic achievement and academic motivation by the end of the sixth grade," she added.

"For youth, transition to middle school already represents a crucial stage in their development as adolescents. Feeling sadness and anxiety and being at risk academically tends to complicate their situation."

Pagani and co-authors Jessica Bernard and Caroline Fitzpatrick came to their conclusions after examining data from a cohort of children born in 1997 or 1998 who are part of the Quebec Longitudinal Study of Child Development, coordinated by the Institut de la statistique du Québec.

Close to 2,000 children studied

In all, the parents of 978 girls and 998 boys participated in the study of violent TV viewing at the preschool age. At age 12 years, the children and their teachers rated the children's psychosocial and academic achievement, motivation and participation in classroom activities.

Pagani’s team then analyzed the data to identify any significant link between problems with those aspects and violent content they were exposed to at preschool, while trying to account for as many possible biases and confounding influences as possible.

"Our goal was to eliminate any pre-existing conditions of the children or families that could have provided an alternative explanation or throw a different light on our results," Pagani said.

Watching TV is a common early childhood pastime, and some of the children in the study were exposed to violence and some were not.

Psychological and academic impairment in children is of increasing concern for education and public-health sector workers. According to Pagani, problems starting middle school are rooted in early childhood.

Identifying with fictional characters

“Preschool children tend to identify with characters on TV and treat everything they see as real," she said. "They are especially vulnerable to humorous depictions of glorified heroes and villains who use violence as a justified means to solve problems.

"Repeated exposure,” she added, “to rapidly paced, adrenaline-inducing action sequences and captivating special effects could reinforce beliefs, attitudes and impressions that habitual violence in social interactions is ' normal'. Mislearning essential social skills can make it difficult to fit in at school."

Added Bernard: “Just like witnessing violence in real life, being repeatedly exposed to a hostile and violent world populated by sometimes grotesque-looking creatures could trigger fear and stress and lead these children to perceive society as dangerous and frightening.

"And this can lead to habitually overreacting in ambiguous social situations."

She continued: "In the preschool years, the number of hours in a day is limited, and the more children get exposed to aggressive interactions (on screens) the more they might think it normal to behave that way."

Pagani added: "Being exposed to more appropriate social situations, however, can help them develop essential social skills that will later be useful and ultimately play a key role in their personal and economic success.”

About this study

"Prospective associations between preschool exposure to violent televiewing and psycho-social and academic risks in early adolescent boys and girls" was published Nov. 8, 2022 in the Journal of Developmental and Behavioral Pediatrics. Universite de Montréal professor Linda Pagani, Ph.D., is lead author of the study; Jessica Bernard, M.Sc., is a graduate student under her supervision, and Caroline Fitzpatrick, Ph.D., is Canada Research Chair in Education at Université de Sherbrooke. Pagani is also a researcher at the UdeM-affiliated CHU Sainte-Justine Research Centre and with the Research Group on Learning Environments of the Fonds de recherche du Québec—Société et culture. Fitzpatrick is an assistant professor at both Université de Sherbrooke's Department of Preschool and Elementary School Education and at the University of Johannesburg's Department of Childhood Education.

The authors wish to acknowledge the sponsors funding the larger public data set. The Quebec Longitudinal Study of Child Development was made possible thanks to the funding provided by the Fondation Lucie et André Chagnon, the Institut de la Statistique du Québec, the Ministère de l’Éducation et de l’Enseignement supérieur (MÉES), the Ministère de la Famille (MF), the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), the Centre hospitalier universitaire Sainte-Justine, the Ministère du Travail, de l’Emploi et de la Solidarité sociale (MTESS) and the Ministère de la Santé et des Services sociaux du Québec (MSSS). Source: Data compiled from the final master file ‘E1-E22’ from the Quebec Longitudinal Study of Child Development (1998–2019), ©Gouvernement du Québec, Institut de la statistique du Québec.

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JOURNAL

Journal of Developmental & Behavioral Pediatrics

METHOD OF RESEARCH

Survey

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Prospective associations between preschool exposure to violent televiewing and psycho-social and academic risks in early adolescent boys and girls

ARTICLE PUBLICATION DATE

8-Nov-2022

Should maize farmers in Sub-Saharan Africa store or sell their grain?

Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

 

IMAGE: MAIZE STORAGE STRUCTURES AT THE ZAMBIA AGRICULTURE RESEARCH INSTITUTE IN CHILANGA, ZAMBIA. view more 

CREDIT: PROTENSIA HADUNKA. UNIVERSITY OF ILLINOIS.

URBANA, Ill. – Many maize farmers in Sub-Saharan Africa sell their crop at harvest, often because they need funds to pay expenses. Development agencies often support or sponsor harvest-time loans that encourage farmers to store some of their grain for later sale, on an assumption that its market value will increase in months to come. But that’s not a sure bet, as a new University of Illinois study reveals.

Analyzing maize prices across more than a thousand Sub-Saharan African markets over a 20-year period, the researchers found not only that maize prices do not always rise after the harvest season, but also that farmers cannot fully predict whether prices are likely to rise or fall. As a result, there is significant risk associated with storing grain for later sale, and farmer risk tolerance can impact the decision, says Hope Michelson, associate professor in the Department of Agricultural and Consumer Economics  (ACE) at Illinois and co-author on the study.

“There is a long-standing assumption in the agricultural development literature that grain prices always rise after harvest in these rural grain markets,” Michelson notes. “In a given region, people grow maize and harvest it on essentially the same schedule. Many of them also sell at the same time because this is when buyers are ready and bills at the farm have to be paid. And when lot of maize hits the marketplace at once, selling prices can drop sharply. 

“Because prices tend to rise over the course of the year and peak before harvest, small-scale farmers may be forced to buy maize back from the market a few months later for their own consumption, when the price has gone up significantly.”

Policy interventions that provide farmers with access to credit at harvest could prompt them to retain some of their crop, either to meet their own household’s food needs or to sell when prices rise later. However, this strategy works only if prices actually and reliably go up.

From her field work in Malawi, Michelson observed the unpredictability of market prices after the high season of harvest and crop-sale. She teamed up with then-doctoral student Lila Cardell, who is now a research economist with the USDA Economic Research Service, to gather data from markets across the region to track post-harvest maize price trends over a range of nations and years.

“Many agricultural development initiatives in low-income countries and associated academic papers assume farmers are leaving money on the table by selling all their maize at harvest,” says Cardell, who is lead author on the paper.  “We looked at that assumption carefully, asking, ‘What if the farmers are right? What if the dilemma they face is not just a credit issue?’”

Michelson and Cardell reviewed price data from 1,038 markets over 20 years in 30 African countries. While they found that prices do generally rise after harvest, they also found that prices fell 16.3% of the time, ranging from a frequency of 10.9% in Mozambique to 50% in Mauritania. They argue consequently that for poor farmers, average trends provide no reassurance about present or future market conditions. 

“It may be true that on average maize prices go up after harvest, but averages are not the only thing that matters. One bad year may actually have a lot of consequences for a poor household that can’t borrow across years. To opt for crop storage, risk-averse farmers may need firm assurances of more than the average payoff,” Michelson says.

“We show that the phenomenon of maize prices not rising after harvest does not occur only in a handful of years or in one particular cluster of markets. We see it happening in all countries in Sub-Saharan Africa. It is more likely to happen in some years and some places, but the fact is that maize prices don't always rise after harvest,” Cardell states.

Because markets are unpredictable, farmers essentially have to guess whether it makes sense to sell or store their grain. In addition, there are storage expenses and risks of spoilage and loss to consider.

Cardell and Michelson conclude that though storing maize grain at harvest may be a sound strategy as a general rule, development organizations should consider local marketplace dynamics and observe how traders, farmers, and maize millers see the market and what kinds of strategies they adopt or prefer to protect themselves from risk.

Circumstances may require different kinds of interventions: For example, forward contracting agreements or multi-year credit could help buffer against price fluctuations.

“We need to spend more time understanding the nature of what's going on and how people respond to it,” Michelson concludes.

The Department of Agricultural and Consumer Economics is in the College of Agricultural, Consumer and Environmental Sciences, University of Illinois.

The paper, “Price risk and small farmer maize storage in Sub-Saharan Africa: New insights into a long-standing puzzle,” is published in the American Journal of Agricultural Economics [https://doi.org/10.1111/ajae.12343].

This research was supported in part by the U.S. Department of Agriculture, Economic Research Service. The findings and conclusions in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.

 

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JOURNAL

American Journal of Agricultural Economics

DOI

10.1111/ajae.12343 

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

American Journal of Agricultural Economics American Journal of Agricultural Economics Article Open Access Price risk and small farmer maize storage in Sub-Saharan Africa: New insights into a long-standing puzzle

ARTICLE PUBLICATION DATE

6-Sep-2022