Saturday, June 01, 2024

 AGRICULTURE

New method could significantly reduce agricultural greenhouse gas emissions



INTERNATIONAL INSTITUTE FOR APPLIED SYSTEMS ANALYSIS




Nitrogen fertilization leads to emissions of the greenhouse gas nitrous oxide (N₂O) from agricultural soils, accounting for a significant portion of total greenhouse gas emissions from agriculture. It has long been assumed that these N₂O emissions are unavoidable.

However, an international team of researchers led by NMBU has discovered a method to reduce these emissions. They have identified bacteria that can "consume" nitrous oxide as it forms in the soil, preventing the gas from escaping into the atmosphere. The researchers believe that this method alone has the potential to reduce agricultural nitrous oxide emissions in Europe by one-third.

The N₂O problem

Plants need a lot of nitrogen to grow. A productive agriculture, therefore, requires an abundant supply of nitrogenous fertilizer. This was a bottleneck in agriculture until Fritz Haber pioneered technology for the industrial production of nitrogen fertilizer from atmospheric nitrogen. This technology has contributed to the world's food production keeping pace with population growth for 120 years.

However, there are microorganisms in the soil that produce the greenhouse gas N₂O, and fertilization stimulates this production.

“This greenhouse gas has an effect that is about 300 times stronger than CO₂, and agriculture accounts for about three quarters of Europe’s N2O emissions,” explains Wilfried Winiwarter, one of the coauthors of the study and a senior researcher in the Pollution Management Research Group of the IIASA Energy, Climate, and Environment Program.

“Also, globally, agriculture is the primary source of nitrous oxide in the atmosphere. Nitrous oxide emissions are primarily regulated by soil bacteria, making reduction efforts challenging due to their elusive nature,” he adds.

Bacteria can do the job

Researchers at NMBU have been conducting basic research for over 20 years on how microorganisms in the soil convert nitrogen. They have, among other things, thoroughly studied what happens when the microbes do not have access to enough oxygen, a condition called hypoxia.

When fertilization occurs (and during rainfall), some parts of the soil become hypoxic. Since the microbes then do not have access to oxygen, they are forced to find other ways to get energy. Many microbes can use nitrate instead of oxygen, and through a process called denitrification, they convert the nitrate into other gases. One of these is nitrous oxide, and in this way, the microorganisms contribute to greenhouse gas emissions.

The researchers have made significant discoveries regarding the regulation of this process, and they have developed a unique way to study denitrification. They use, among other things, robotic solutions both in the laboratory and in the field, and have developed a special robot that can make real-time measurements of nitrous oxide emissions from the soil.

The solution to reduce N₂O emissions is to use a special type of bacteria that lacks the ability to produce nitrous oxide but can reduce nitrous oxide to harmless nitrogen gas (N₂).

"If we grow these microbes in organic waste used as fertilizer, we can reduce N₂O emissions. This could mean a solution to the problem of N₂O emissions from agriculture," says Lars Bakken, lead author of the study and a professor at NMBU.

"But it was not easy to find the right bacterium. It must be able to grow quickly in organic waste, function well in soil, and live long enough to reduce N₂O emissions through an entire growing season. It was also a challenge to go from testing this in the laboratory to trying it out in nature, and to ensure that it actually reduced N₂O emissions in the field,” Bakken adds.

The research team is now working to find more bacteria that consume nitrous oxide and to test these in different types of organic waste used as fertilizers worldwide. The goal is to find a wide range of bacteria that can function in different types of soil and with various fertilizer mixtures.

Adapted from a press release prepared by NMBU.

Reference:

Hiis, E., Vick, S., Molstad, L., Røsdal, K., Jonassen, K., Winiwarter, W., Bakken, L. (2024) Unlocking bacterial potential to reduce farmland N2O emissions Nature DOI: 10.1038/s41586-024-07464-3

IIASA researcher contact:

Wilfried Winiwarter
Senior Research Scholar
Pollution Management Research Group
Energy, Climate, and Environment Program
winiwart@iiasa.ac.at

Press Officer
Bettina Greenwell
IIASA Press Office
Tel: +43 2236 807 282
greenwell@iiasa.ac.at

About IIASA:

The International Institute for Applied Systems Analysis (IIASA) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policymakers to shape the future of our changing world. IIASA is independent and funded by prestigious research funding agencies in Africa, the Americas, Asia, and Europe.

 

 

New method makes hydrogen from solar power and agricultural waste



UNIVERSITY OF ILLINOIS CHICAGO





University of Illinois Chicago engineers have helped design a new method to make hydrogen gas from water using only solar power and agricultural waste, such as manure or husks. The method reduces the energy needed to extract hydrogen from water by 600%, creating new opportunities for sustainable, climate-friendly chemical production.

Hydrogen-based fuels are one of the most promising sources of clean energy. But producing pure hydrogen gas is an energy-intensive process that often requires coal or natural gas and large amounts of electricity.  

In a paper for Cell Reports Physical Science, a multi-institutional team led by UIC engineer Meenesh Singh unveils the new process for green hydrogen production. 

The method uses a carbon-rich substance called biochar to decrease the amount of electricity needed to convert water to hydrogen. By using renewable energy sources such as solar power or wind and capturing byproducts for other uses, the process can reduce greenhouse gas emissions to net zero.

“We are the first group to show that you can produce hydrogen utilizing biomass at a fraction of a volt,” said Singh, associate professor in the department of chemical engineering. “This is a transformative technology.” 

Electrolysis, the process of splitting water into hydrogen and oxygen, requires an electric current. At an industrial scale, fossil fuels are typically required to generate this electricity. 

Recently, scientists have decreased the voltage required for water splitting by introducing a carbon source to the reaction. But this process also uses coal or expensive chemicals and releases carbon dioxide as a byproduct. 

Singh and colleagues modified this process to instead use biomass from common waste products. By mixing sulfuric acid with agricultural waste, animal waste or sewage, they create a slurry-like substance called biochar, which is rich in carbon. 

The team experimented with different kinds of biochar made from sugarcane husks, hemp waste, paper waste and cow manure. When added to the electrolysis chamber, all five biochar varieties reduced the power needed to convert water to hydrogen. The best performer, cow dung, decreased the electrical requirement sixfold to roughly a fifth of a volt. 

The energy requirements were low enough that the researchers could power the reaction with one standard silicon solar cell generating roughly 15 milliamps of current at 0.5 volt. That’s less than the amount of power produced by an AA battery. 

“It’s very efficient, with almost 35% conversion of the biochar and solar energy into hydrogen” said Rohit Chauhan, a co-author and postdoctoral scholar in Singh’s lab. “These are world record numbers; it’s the highest anyone has demonstrated.” 

To make the process net-zero, it must capture the carbon dioxide generated by the reaction. But Singh said this too could have environmental and economic benefits, such as producing pure carbon dioxide to carbonate beverages or converting it into ethylene and other chemicals used in plastic manufacturing. 

“It not only diversifies the utilization of biowaste but enables the clean production of different chemicals beyond hydrogen,” said UIC graduate Nishithan Kani, co-lead author on the paper. “This cheap way of making hydrogen could allow farmers to become self-sustainable for their energy needs or create new streams of revenue.” 

Orochem Technologies Inc., who sponsored the research, has filed for patents on their processes for producing biochar and hydrogen, and the UIC team plans to test the methods on a large scale. 

In addition to Singh, Kani and Chauhan, the paper was co-authored by UIC graduate student Rajan Bhawnani. Other co-authors come from Stanford University, Texas Tech University, Indian Institute of Technology Roorkee, Korea University and Orochem Technologies Inc.

Written by Rob Mitchum

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