What is “biochar”?
Biochar is the solid product remaining after biomass is heated under oxygen-deprived conditions, a process known as “pyrolysis”. Biochar falls into the spectrum of materials called “charcoal” or “black carbon”.
Biochar can be produced from almost any types of feedstock including agricultural wastes and even urban green waste.
Production systems range in scale, from small household cook-stoves, to large industrial pyrolysis plants. Because it can be created over a wide range of temperatures, and could be applied to a diversity of soil types, it is important to understand how different production conditions can result in different types of biochars, and how these chars interact with different types of soils.
The practice of amending soils with charcoal for fertility management goes back millennia. Some of the most remarkable properties of biochars include their effects on soil nutrient dynamics and the high stability of the carbon of which they are composed. Nowadays biochar is a form of black carbon that is produced intentionally to manage carbon for climate change mitigation purposes combined with a downstream application to soils for its agricultural effects.
Why this recent interest and development of biochar projects?
Using biochar is identified as a tool to fight climate change while also improving soil fertility and results in increased crop yields from previously degraded soils for smallholder farmers. Biochar systems are particularly relevant in developing country contexts and could be leveraged to address global challenges associated with food production and climate change.
Cooking energy dominates at the household scale, and projects generating electricity occurring at larger scales. Both of these results could be beneficial to forests. By decreasing wood gathering from forests already in decline.
What are the benefits and risks related to the development of biochar systems?
Biochar projects can influence, both positively and negatively four main parameters:
- soil health and agricultural productivity; Soil pH, nutrients availability, soil moisture, soil organic matter, amount of biochar applied;
- climate change; Carbon storage and stabilization is probably the most direct and important quality for climate change mitigation efforts based on biochar, which is one of the few GHG reduction strategies that can actually withdraw carbon dioxide from the atmosphere. However, emissions of methane and nitrous oxide could be associated with inefficient pyrolysis and degradation of soil organic matter after biochar application.
- the social impacts; biochar systems can affect energy, health, economics, and food security by reducing pressure on wooded ecosystems and decreasing the burden (mainly on women) of fuel gathering an improving crop yields and resilience against crop shortages and hunger. Improved cook-stoves can also reduce indoor air pollution even if biochar use can lead to potential emission of toxins and inhalation of dust and small particulate matter. Energy produced from biochar could potentially be used for refrigeration of vaccines, water pumping and lighting after sunset.
- competing uses of biomass. biochar production could, among others, divert food crops for fuel production, divert arable land from food crops, affect direct and indirect land use change. For example, the costs and benefits of leaving biomass in situ versus using it to produce biochar that is then added to the soil must be weighed.
What are the lessons learn from existing projects of biochar?
Regarding climate impact, all systems analysed demonstrate that the emissions from biochar production are minimal compared to the net balance of the system. Avoided emissions from traditional biomass management practices can also play an important role, such as when comparing cooking with biochar to traditional fuels like wood that are either non- or slowly renewable resources.
Regarding the economic dimension, the most important result is that each project has a very short payback period—within one year of when surplus crops are monetized. The yield of the crops to which the biochar is applied plays the largest role in determining the economic balance, implying that the farmer’s choice of crops can be as important as the type of soil to which the biochar is applied. Overall, the economics of biochar projects analyzed in the case studies are largely determined by the price farmers receive (or lack thereof) for surplus crops due to biochar additions to the soil.
Are there socio-cultural barriers to the adoption of biochar projects?
Implementation of biochar systems requires a highly location-specific understanding of people and their needs, values, and expectations. The barriers identified in a survey included lack of awareness of biochar and a need for education and demonstration projects; extra labour required to operate slash-and-char systems and gather dispersed feed-stocks; restricted availability of biochar production technologies or environmental concerns related to changing resource use patterns.
Among the perceived benefits of biochar systems are: respondents cited soil improvement, increased crop yields, decreased fertilizer use, improved water use efficiency, clean cook-stoves, income benefits, and environmental hygiene.
What should be done to implement these projects in practice?
Development institutions such as the World Bank could engage in knowledge - and technology - oriented services, as well as in financing of biochar projects, facilitating research, and providing knowledge services. Such initiatives could help forge effective alliances between the research community and development practitioners on the ground.
Involving the private sector will be crucial in bridging the funding gap that typically constrains the implementation of new technologies with long lead times and considerable research requirements. Innovative financing solutions will be needed. Given the wide-ranging potential of biochar systems, it is important to build synergies with other projects and programs and learn from lessons given by existing projects.
“This is an adaptation of an original work by The World Bank. Responsibility for the views and opinions expressed in the adaptation rests solely with the author or authors of the adaptation and are not endorsed by The World Bank.”