Why BiocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More Is Often Expensive

Biochar plays crucial roles in soil and the environment; however, it is often costly for many small projects and farmers. There are several reasons for its high price. Firstly, making biochar can be expensive. Various modern machines that produce high-quality biochar require significant capital to purchase and operate. Additionally, they also need skilled workers. Although these modern machines meet quality standards and produce consistent biochar, the cost can be too high for local communities and small farmers interested in making biochar. Moreover, obtaining raw biomassBiomass is a complex biological organic or non-organic solid product derived from living or recently living organism and available naturally. Various types of wastes such as animal manure, waste paper, sludge and many industrial wastes are also treated as biomass because like natural biomass these More can be costly because factories collect wood or crop residues from long distances, and transporting this material also costs money for labour and fuel, which results in the purchase price of biochar. For feedstockFeedstock refers to the raw organic material used to produce biochar. This can include a wide range of materials, such as wood chips, agricultural residues, and animal manure. More, it can be calculated in two ways: the value required to produce it specifically for pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, and the cost that could have been used for it if it were formerly availablefor something else (Kung et al., 2013).

In addition, biochar can cost more, particularly because oaf feedstock costs, which can range from $91 per ton for corn stover to $82–$100 per ton for brewery grains (Joseph, 2015). In addition, quality standards and certificationadd extra money. For selling biochar as a certified product or using it in carbon markets, producers need to evaluate it and keep records, which takes time and money.That is why transport, machinery, certification, and small-scale production are the primary reasons biochar is expensive. From this, we can understand that cost-effective feedstocks like rice husks and wheat straw are essential for making biochar more affordable.

Rice Husks are plentiful and low-cost feedstock

Globally, rice is one of the most widely consumed staple foods. Global rice consumption reached around 486 million metric tons between 2018 and 2019 (Muthayya et al., 2014). Behind this massive rice production, which results in a significant amount of waste. Rice production generates two types of residues: rice straw and rice husk. Straw is removed at the farm level and left there, while husk is removed at large mills, where it is usually collected and piled up. Rice husks, which are the outer protective shells of grains, make up nearly 20-30% of total rice production(Olivia et al., 2021).

High-carbon-content rice husks can be converted into energy-rich biochar through thermochemical processes such as pyrolysis. Here, one up-and-coming product is Rice Husk Biochar (RHB). RHB is widely regarded as sustainable, low-cost, and environmentally friendly, and is producedfrom agricultural waste (Mahsa et al., 2019). Therefore, using rice husks as a feedstock not only reduces the cost of raw materialsbut also avoids competition with food and other biomass uses. Especiallyif there are local rice mills available, this also lowers transportation costs and can make rice husks an ideal feedstock for community-scale biochar production.

Environmental and soil benefits of Rice Husk Biochar

A recent study found that the rice husk contains around 0.7 % of nitrogen, 38 % carbon, 19-20 % ashAsh is the non-combustible inorganic residue that remains after organic matter, like wood or biomass, is completely burned. It consists mainly of minerals and is different from biochar, which is produced through incomplete combustion.   Ash Ash is the residue that remains after the complete More, 18-20% silica as well have a pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More (6.4-7.0) which is slightly acidic which make them food for heating or burning without oxygen (pyrolysis) (Ramírez, Tovar and Silva-Marrufo, 2024). When heated to 400–600°C, they form biochar with 65–80% carbon, a higher pH (8–10), and a porous structure that helps soil hold water and nutrients. Biochar obtained from this can store carbon for a long period whilst improving the environment. In addition, at the same time, the process can produce heat and electricity efficiently, showing that rice husks can be both eco-friendly and economically useful.

What we can learn from Rice Husk Biochar Project in Cambodia

Based on recent data from Cambodia, HUSK and atmosfair have designed a special plant that produces biochar and natural fertilizers by turning leftover rice husk (Atmosfair, 2025). Rice husks are burned or thrown away, which results in environmental harm and wasted resources. This plant the husks to make biochar, which remains carbon in the soil for a long time and helps fight climate change. In addition, this process produces heat and electricity to run the plant, and the energy it does not waste. Biochar is used to make fertilizers that hold nutrients like nitrogen, phosphorus, and potassium, so farmers need less chemical fertilizer, saving money and protecting the soil.

Moreover, it has been found that the pyrolysis plant in Kampong Thom, Cambodia, converts “6tons of rice husks into 3 tons of biochar each day, resulting in a total of620 tons of biochar annually”. This biochar permanently locks 750 tons of CO₂ in soil every year, contributing to climate change mitigation. Located next to a rice mill, the plant benefits from a local supply of husks, which helps lower transportation costs. Additionally, following this model, a second plant is planned for Vietnam in 2026, which will produce 10 tons of biochardaily from 20 tons of rice husks (atmosfair, 2025). By building the plant next to a rice mill, they reduce transportation costs and make the system more efficient. This project shows that agricultural waste can be turned into a valuable resource, helping farmers, improving soil health, and reducing carbon in the atmosphere. HUSK also plans to expand this idea to Vietnam, showing that this solution can help many farmers across Southeast Asia.

References

Atmosfair (2025) Biochar production with rice husks. Cambodia. Available at: https://www.atmosfair.de/en/cambodia-biochar-rice-husks/.

Joseph, S. (2015) Biochar for environmental management: science, technology, and implementation. Routledge.

Kung,C.C.,McCarl,B.A. and Cao, X. (2013) ‘Economics of pyrolysis- based energy production and biochar utilization: a case study in Taiwan’, Energy Policy, pp. 317–323.

Mahsa et al. (2019) ‘Nitrate removal from aqueous solutions by adsorption onto hydrogel-rice husk biochar composite’, Water Environmental research [Preprint]. Available at: https://doi.org/10.1002/wer.1288.

Muthayya, S. et al. (2014) ‘An overview of global rice production, supply, trade, and consumption’, pp. 7–14. Available at: https://doi.org/10.1111/nyas.12540.

Olivia et al. (2021) ‘Study of rice husk continuous torrefaction as a pretreatment for fast pyrolysis’, 154. Available at: https://doi.org/10.1016/j.jaap.2020.104994.

Ramírez, A.T.O., Tovar, M.R. and Silva-Marrufo, O. (2024) ‘Rice husk reuse as a sustainable energy alternative in Tolima, Colombia’, Scientific Reports, 14(1), pp. 1–13. Available at: https://doi.org/10.1038/s41598-024-60115-5.

Sovu et al. (2012) ‘Facilitation of forest landscape restoration on abandoned swidden fallows in laos using mixed-species planting and biochar application’, Silva Fennica, 46(1), pp. 39–51. Available at: https://doi.org/10.14214/sf.444.