written by: Yumul, John Anthony M.
Atmospheric carbon dioxide concentration recently reached the highest level in recorded history (Kahn, 2017). Different technologies must be used to vary GHG emissions to safe levels. Researchers suggest that it is now necessary to approach near-zero future carbon emissions in order to stabilize climate (Haszeldine et al., 2018) suggesting that there may be a need to deploy negative emissions technologies (NETs).
Negative emission techniques (or technologies) are means of achieving net removal of GHGs from the environment such that atmospheric concentrations are reduced below the level that would have resulted without their deployment (McLaren, 2012). Biochar is a scalable NET that has received substantial attention in the scientific world mainly due to its significant potentials to combat climate change while simultaneously improving soil properties.
How does biochar mitigate climate change?
Carbon can truly be stored in soil as crop residues or humus (a more stable material formed in soil from decaying organic matter). But according to Jim Amonette of the Department of Energy’s Pacific Northwest National Laboratory, crop residues usually oxidize into CO2 and are released into the atmosphere within a couple of years, and the lifetime of carbon in humus is typically less than 25 years. When the biomass is instead pyrolyzed, a stable solid product is produced that largely consists of a recalcitrant carbon fraction with a half-life of a few centuries in soil. The carbon-rich product is called biochar when it is stored below the ground for long-term removal of atmospheric carbon.
According to Hillel and Rosenzweig, the primary reason for the stability of biochar in soils is their chemical recalcitrance, which is due to aromatic structures of varying properties. This is a relevant measure for its ability to prevent photosynthetically fixed carbon from being returned rapidly to the atmosphere. The stable storage of biochar in soils represents a long-term removal of atmospheric carbon due to the fact that the recalcitrant fraction present in biochar decomposes very slowly, typically with a half-life measured on the time scale of a few centuries. Hence, the production and application of biochar in soil is a significant carbon sequestration strategy and has been suggested as one possible means of reducing the atmospheric CO2 concentration.
What are the other benefits of storing biochar in soil?
The application of biochar in soil improves the physical, chemical and biological properties of soil such as increase in soil-water and nutrient holding capacities that result in improved crop yields and reduction of the need for fertilizers. According to Woolf and coauthors, direct sequestration in biochar coupled with beneficial secondary effects can potentially mitigate 130 Gigatons carbon over the course of the century.
These secondary effects result from the displacement of fossil fuels by energy co-products from biochar production, the suppression of natural soil N2O and CH4 fluxes when biochar is added to soil, the displacement of fossil fuel-intensive synthetic fertilizers due to improved soil fertility, and the reduction of energy requirement for irrigation due to improved water retention properties.
Because of the aforementioned secondary effects on greenhouse gas (GHG) emissions, the total potential for mitigation can be much larger than the physical carbon content of the biochar.
What are the existing challenges that can potentially hinder biochar application?
Although much has already been achieved, barriers to biochar application for environmental management still do exist. For instance, potential disadvantages of biochar application include albedo effects due to soil darkening, excessive pH elevation, as well as adverse effects on soil quality due to the introduction of contaminants such as salts, heavy metals and dioxins. The potential release of contaminants is possible since biochars are often prepared from a variety of feedstocks including waste materials. These agronomic and environmental risks thus necessitate the need to strategically match biochar sources with biochar sinks in order to minimize the adverse unintended consequences. This has led to the “designer biochar” concept, wherein biochar could be tailored with relevant properties to address specific soil quality improvements. There is a need to optimize the processing conditions in order to improve the properties of biochar to become suitable for agricultural use.
These barriers imply that there is a need for further research to optimally deploy biochar as a carbon sequestration technology and reap the co-benefits that come along with it.
What is the focus of your research and how did it address these challenges?
My study has developed a systematic framework for high-level planning and decision support in the synthesis of biochar-based carbon management network. The promising results of biochar application to soil can be potentially optimized through biochar-based carbon management networks (BCMNs) with the aid of mathematical programming. In my dissertation, the term BCMNs is proposed to describe systems that are intended to strategically plan carbon sequestration via systematic production and allocation of biochars for long-term storage to agricultural lands and for simultaneous improvement of soil properties. My dissertation focused on developing an optimization framework for BCMNs. My work is the first to integrate the relevant and practical aspects of biochar research into a systematic framework for the high-level planning of large-scale BCMNs. Such framework provides innovative biochar systems concepts to fill the research gap in the global biochar literature. The framework is comprised of mathematical models that capture the current features of biochar research.
The optimization framework I developed provides a sustainable strategy to facilitate the careful planning of BCMNs on a globally significant scale. The framework can guide policy formulation concerning biochar production and subsequent application to soil. To make biochar amendments more beneficial, I synthesize a biochar-based network wherein biochar (source) could be customized in order to fit certain soil conditions (sink). This can also minimize the potential for adverse unintended consequences. It can also provide useful insights to guide policymaking to incentivize commercial-scale BCMNs. Finally, the framework can aid the sustainable deployment of BCMNs to contribute on climate mitigation.
About the researcher
Dr. Beatriz A. Belmonte is a faculty member at the University of Santo Tomas under the Chemical Engineering Department. She is also a Researcher at the UST-RCNAS. She completed the requirements for the degree of Doctor of Philosophy in Chemical Engineering at De La Salle University last December 2018 under the Engineering Research and Development for Technology (ERDT) program of the Department of Science and Technology (DOST) from January 2016 – December 2018. Her dissertation was entitled “DEVELOPMENT OF AN OPTIMIZATION FRAMEWORK FOR BIOCHAR-BASED CARBON MANAGEMENT NETWORKS.” This work focused on developing computer models to provide decision support for the use of carbonized biomass as a soil enhancer and as a form of carbon sequestration. This strategy is regarded in the literature as a potentially effective way to reduce greenhouse gas emissions. The research she did during the course of her dissertation has led to five Scopus-indexed publications (h-index = 3) in major journals and conference proceedings, which have received a combined 24 citations in a relatively brief period of time. In addition, she has one more manuscript from her Ph.D. work currently in review, and is coauthor of a recently published article in the Journal of Cleaner Production. The latter work is outside of the scope of her Ph.D. research. She is also a Reviewer for the Journal of Cleaner Production published by Elsevier.
interviewed by:
Fidel, Jhoanna & Yumul, John Anthony
Comments