Biochar Research Is On The Rise

Dr. Abhilasha Tripathi, Research Coordinator, IBI

Abhilasha Tripathi, Ph.D. has been providing monthly research updates for IBI members since Dec, 2019. 

For the past two decades, interest in biochar research and application has increased greatly. This article gives insight into statistics related to biochar based peer-reviewed publications  and emerging research topics related to biochar. 

Fig. 1 displays scientific publications related to biochar since 2000. These publications include research articles, review papers, meta-analyses, conference proceedings, book chapters, etc. The research articles include novel findings like innovations and mechanism studies; while the review articles, meta-analysis and book chapters are detailed articles that give a bird eye view of the research topic by summarizing several research articles.

Fig. 1 Biochar based research publications (Year 2000-2023)

Scientific research is crucial to optimizing operational conditions before technology becomes widely accepted to solve real-world problems. Earlier, the research interest in biochar increased gradually, but as the researchers explored multiple opportunities within, post 2010 an exponential increase in the number of research publications is observed (Fig. 1). 

Biochar’s popularity is diffusing beyond just academia, it has piqued the interest of novice researchers, industrialists, and agriculture lovers alike. The filtration properties and carbon sequestration of biochar fits it as a solution for numerous environmental remediation applications.

Most popular topics related to biochar research

The most popular research topics about biochar are shown in Fig. 2. Within these topics, the common subareas are discussed in further sections.

Fig. 2 Categories of biochar based research publications

Soil Amendment

With more than 2400 publications in 2023, soil amendment usage is the most researched topic about biochar. The reason biochar is so prevalent in this field is twofold: first, its remediation and soil-enhancing properties make it suitable for a range of applications, from improving crop yields in unfavorable soil conditions to reducing the Phyto availability of soil pollutants; and second, its capacity to sequester carbon has made it a low-cost CDR technology that has permanence for 100 to 1000 years. 

Lately, modified biochar has been used for several targeted soil remediation studies because of enriched functional groups on the surface. The  most prevalent research areas for 2023 associated with soil application is as follows:

Fig. 3 Most studied parameters in Soil application of biochar

Water and wastewater treatment

The second most investigated biochar topic is water and wastewater treatment. 

Biochar is appropriate for water filtration due to its high BET surface area (surface area per unit weight) and functional groups. However, surface-modified biochar has become significantly more popular for nearly a decade because of its improved qualities. In most cases, biochar loaded with contaminants is regenerative, making it a sustainable filter medium. The biochar loaded with nutrients can also be used for soil application. Fig. 4 illustrates the various pollutants that can be adsorbed using Biochar/ surface-modified biochar.

Fig. 4 Most studied parameters in water and wastewater treatment using biochar (The pollutants mentioned within the concentric circles are frequently examined, while the ones in the parallel bars are gaining attention and are emerging contaminants.)

Electrode and electrical applications

Due to its conducting properties, biochar has been studied as an electrode in lithium-ion, lithium-sulfur, zinc, and other types of batteries for energy storage. The application of biochar in sensors or capacitors has also been documented in a couple of investigations.

Anaerobic digestion

Given its liming qualities, biochar has become popular as a supplement for anaerobic digestion (AD) systems. Consequently, when biochar is added, AD systems exhibit decreased volatile fatty acid (VFA) formation and elevated methane generation. With modified biochar, anaerobic digestion systems have reportedly been further enhanced.

Construction materials

By incorporating biochar into building materials, the Carbon Dioxide Removal (CDR) potential of biochar can be leveraged to help decarbonize the construction industry. Frequently studied biochar-based composites are lightweight mortar, cement-based composites, biochar-plastic composites, epoxy composites, etc. Certain composites can also be used as flame retardant. This expands the applications of biochar in green buildings. Additionally, combining biochar with asphalt has several excellent benefits for roadways application along with decarbonization.

Depending on the particular material and end-use performance requirements, numerous variables are considered when determining if biochar is a viable additive, what types of biochars work best and how much biochar should be used to optimize performance and carbon sequestration. Biochar composites are tested for several performance metrics including workability, adhesion, moisture susceptibility, mechanical behavior, tensile strength, cement hydration, carbon capture potential, among others.

Greenhouse gas emissions

Approximately 18% of worldwide greenhouse gas emissions are attributed to the agricultural sector, according to Climate Watch, The World Resource Institute (2020). Using biochar presents a number of potential ways to lower greenhouse gas (GHG) emissions from the agricultural sector.

The incorporation of biochar in cattle feed may reduce methane emissions by improving the digestibility of ruminants. The pyrolysis of agrarian residues also prevents GHG emissions that are otherwise released due to uncontrolled decomposition and biomass burning. There is a great deal of research on rice growing with biochar, and lower greenhouse gas emissions, particularly methane, are noted.

When fertilizers are combined with biochar, greenhouse gas emissions are reduced versus when fertilizer treatment is applied alone. It is observed that biochar populates the methanotrophs that can feed on methane. The well-aerated state that biochar creates in the soil lowers denitrification activity, which limits the releases of N2O.

The practice of co-composting with biochar has grown in acceptance over time. It has been shown to lower greenhouse gas emissions, lessen leachate production, and preserve nutrients. Enhanced compost quality is observed in terms of improved maturation and reduced composting duration, making it superior to conventional composts.

Other research fields associated with biochar

Other research topics where biochar is quite often studied are as a catalyst, medium for CO2 capture, LCA and cost-benefit analysis, biochar production technologies, pyrolysis and co-pyrolysis of different biomasses, surface modification, etc.

A plethora of additional uses for biochar are also being discovered every year, including its use in food packaging, flame retardants, soundproofing, shield against electromagnetic radiation, etc. Additionally, studies exploring the global biochar potential, permanence of biochar, emissions from Kon-tiki kiln, etc are some of the other significant research contributions in 2023.

Top Publishers: Journals and Countries

The other observations from research statistical data are about the Journals and countries involved in biochar research. The top 10 journals contributing to the publication of biochar research are:  

  • Science Of The Total Environment, 
  • Bioresource Technology, 
  • Chemosphere, 
  • Environmental Science And Pollution Research, 
  • Journal Of Hazardous Materials, 
  • Journal Of Environmental Management, 
  • Chemical Engineering Journal, 
  • Journal Of Cleaner Production, 
  • Biomass Conversion And Biorefinery, and 
  • Environmental Pollution.  

Fig. 5 shows the country-wise contribution to biochar research (Year 2000-2023). China has been contributing most to the research publications followed by US, India, Australia and South Korea.

Fig. 5 Country wise Biochar based research publications

The International Biochar Initiative (IBI), United States Biochar Initiative (USBI), the European Biochar Certificate (EBC), and many other regional biochar initiatives are actively working to raise consciousness about biochar, to advance supportive policies, and promote the adoption of biochar for carbon sequestration. With due efforts, the IPCC acknowledged biochar as a carbon dioxide removal technology in 2018.

Scientific inquiry plays a pivotal role in showcasing the vast potential of biochar across an increasing array of applications. Furthermore, the biochar community eagerly anticipates the exploration of new biochar applications and the identification of pertinent characteristics for various end-uses.