As cities continue to expand and face rising environmental pressure, scientists are seeking innovative solutions that can help urban areas become cleaner, greener, and more resilient. A new perspective paper highlights biochar, a carbon rich material made from organic waste, as a transformative tool that could significantly improve the environmental future of cities around the world.
The study, published in Biochar X, synthesizes global research and case studies to show how biochar contributes to cleaner air, healthier soils, improved water quality, and reduced greenhouse gas emissions. The authors examined applications across major cities such as New York, Singapore, Beijing, Alexandria, and Tokyo, providing one of the most comprehensive overviews to date of biochar's role in sustainable urban development.
Biochar is produced by heating agricultural, municipal, or industrial waste under low oxygen conditions, creating a stable form of carbon that can remain in the environment for long periods. This process not only reduces waste sent to landfills but also locks carbon into a solid material that can support a wide range of environmental functions.
One of the most striking findings comes from recent studies on air quality. Asphalt surfaces are increasingly recognized as a source of urban air pollution because they release volatile organic compounds during hot weather and road construction. The new paper reports that certain biochars, particularly those rich in metals or engineered for high surface area, can absorb up to 76 percent of harmful volatile organic compounds emitted from asphalt. This insight opens a new pathway to reduce pollution in dense urban centers and to extend the lifespan of road infrastructure.
Biochar also shows strong promise in the construction sector. When added to cement and concrete, it improves material strength, enhances durability, and increases long term carbon storage. Researchers have demonstrated that biochar provides reactive surfaces that speed up carbonation processes within concrete, helping to trap carbon dioxide while supporting the structural quality of buildings.
In urban agriculture and soil restoration, biochar helps improve soil porosity, water retention, and nutrient availability. These benefits are especially important in compacted or degraded city soils. Field trials described in the study show that biochar can increase crop yields, such as a fifty percent improvement in chili production when used together with organic compost.
Water purification represents another area of rapid advancement. Biochar has demonstrated high efficiency in removing heavy metals, dyes, nutrients, organic pollutants, and even emerging contaminants like PFAS from water and wastewater. In some systems, biochar based treatments reached more than seventy percent removal of lead and achieved up to ninety five percent removal of dye pollutants. Biochar also boosts methane production in anaerobic digestion systems by more than twenty seven percent, supporting renewable energy generation from organic waste.
Despite its promising performance, the paper notes that large scale adoption still faces challenges. These include the need for standardized production methods, better economic incentives, and clearer policy frameworks. Differences in feedstock, temperature, and manufacturing techniques can produce biochars with very different characteristics, making consistent quality a key issue for future applications.
Overall, the study positions biochar as a versatile and foundational material that could help cities transition toward more sustainable and climate resilient futures. By integrating biochar into circular economy models, cities can reduce environmental footprints, recover valuable resources, and support healthier communities.
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Journal reference: Alayaki FM, Hajikarimi P, Meky N, Rashid S, Fini EH. 2025. Global applications of biochar in sustainable cities of the future: a perspective. Biochar X 1: e010
https://www.maxapress.com/article/doi/10.48130/bchax-0025-0009
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About the Journal:
Biochar X is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.
