Non-conventional approaches to producing biochars for environmental and energy applications

Abstract As demand for biochar and its suitability for a wide range of applications increases worldwide, biochar production is subject to continuous optimization. However, unlike the cutting-edge technologies in specialized industries, old-fashioned practices with low-cost devices are the main techniques used for biochar production in developing countries and other vulnerable contexts. Until recently, these traditional biochar syntheses had not received much academic attention, as they were considered inefficient, non-reproducible, and polluting. However, recent studies have demonstrated that unconventional pyrolysis techniques, including artisanal plants, microwave-assisted pyrolysis, and solar-assisted pyrolysis, can be optimized to reduce emissions and environmental impacts and can produce materials with yields and performance similar to conventional and commercial materials in several environmental and energy applications, which is of particular interest for developing countries. This review compiles the latest advances in sustainable biochar production with unconventional pyrolysis approaches and highlights some environmental and energy applications.