American Biochar Institute

Introduction to biochar

Understanding the physical product, its co-benefits, and how it is made.

Biochar is a stable, carbon-rich material that often looks and feels a lot like charcoal. It is made via pyrolysis or gasification, the process of heating biomass (wood, manure, crop residues, solid waste, etc.) with limited to no oxygen.

The modern-day material is modeled after a material produced by Indigenous people in the Amazon Basin of South America as long as 2,500+ years ago. Islands of rich, fertile soils called terra preta (dark earth) were discovered in the Basin, the first evidence of biochar being used as a soil amendment. The result was soil with high fertility and carbon content — remaining so nutrient-rich that it is still highly valued today.

Biochar’s physical and chemical properties make it resistant to microbial decay in the environment, persisting for hundreds or thousands of years. It has a unique ability to attract and hold moisture, nutrients, microbes, and can even lock away harmful pollutants and other chemicals. This ability, in addition to its long lifetime, makes it effective in a growing number of applications in agriculture, horticulture, soil and water remediation, built environment materials, and more.

Through biochar, biomass becomes a sustainable and value-added product that creates jobs, builds community resilience, and supports circular rural economies.

Explore biochar by application

Biochar use in concrete

When added to concrete mixtures, biochar reduces cement demand and lowers the construction carbon footprint – without compromising structural performance.

Learn more

Biochar production

The first key ingredient to biochar production is feedstock. Biochar is made from biomass, or organic waste from agricultural or forestry residues, manures, and other materials. Common feedstocks include wood chips, sawdust, forest thinnings, crop residues (such as corn cobs, rice husks, or wheat straw), livestock waste like chicken or cow manure, and other wastes like pallets.

Biochar is made through pyrolysis or gasification, thermochemical processes that heat biomass in a zero or low-oxygen environment, typically between 400°C and 700°C. Because there’s very little to no oxygen, the material doesn’t combust. Instead, it decomposes into the carbon-rich product we know as biochar and into combustible vapors.

Pyrolysis itself is exothermic, meaning that it produces more energy than it requires to produce, which can be used to produce renewable heat, electricity, or biofuels.

Production technology and equipment

From small-scale kilns and cooking stoves, to mobile air curtain units to industrial-scale stationary rotary kilns, biochar production can vary greatly. Each system is best suited to specific feedstock situations, but they can all produce high quality biochar.

Energy and co-product recovery

Biochar production creates several other outputs that can be harnessed: non-condensable gases (syngas) and condensable vapors (often refined into bio-oil). These are frequently combusted to provide heat for the production process, but advanced production systems also produce heat for other processes, biomass electricity, fuels, and even agricultural chemicals.

Key properties and how they vary

The chemical and physical properties of biochar vary based on the type of feedstock used to make it and the conditions under which it is produced (such as the temperature). Key biochar properties include carbon content, macro and micronutrients, pH, ash content, surface area, H:C ratio, and the absence of certain contaminants. Biochar made from woody feedstocks tends to have a high carbon content and low ash content whereas biochar made from manures often contains less carbon and more ash.

Physically, biochar is a highly porous granular material with particles that can be as large as several inches or as small as a fine powder. At a microscopic level, biochar has an immense amount of surface  area, up to 400 m2/g or more, providing an enormous amount of sorption capacity.

In total, biochar can be more than 80% pore volume, with a complex distribution of pores ranging from larger pores between particles, to larger internal pores based on the cellular structure of the feedstock, to nanopores that are not much wider than 100 molecules of water. This complex pore structure creates habitat for micro-organisms and fungi, holds plant available water, and retains nutrients.

Biochar, biocarbon, and charcoal

Biochar can be nearly identical to biocarbon and charcoal, especially when produced from wood feedstock. The key difference between these materials is based on their end uses, specifications, and quality controls. 

Biochar is intended to be used as a long-lived material in agriculture, industry, and the built environment. Biocarbon is used as an input to steel manufacturing as a replacement for anthracite coal or coke, both of which are hydrocarbons. Charcoal is made mainly as a fuel for heating or cooking, and its production is focused on maximizing burn efficiency and energy content.

Where biochar is used

Across the United States, industries, farmers, and communities are facing growing pressure to do more with fewer resources. Farmers face increasing fertilizer costs alongside pressure to increase yields under an increasingly variable climate. Industries are working to create green product lines without sacrificing performance or cost. Communities are looking for better ways to manage problematic organic waste and reduce wildfire risk. Water systems must handle increasing loads of nutrients and new forever chemicals, all without increasing costs.

Biochar offers a practical tool to address these challenges. When used appropriately, biochar can improve soil performance, support water management, and create new pathways for productive use of biomass that might otherwise be wasted. 

At the same time, biochar can help revitalize rural communities by creating biochar manufacturing jobs and increasing agricultural productivity. The material has many cross-industry applications. 

Large-scale agriculture and corporate producers

Commercial farms and food companies use biochar to improve soil health, water retention, and nutrient efficiency. Because biochar persists in soils for hundreds of years, it can support long-term increases in yield, and be a part of regenerative land management, helping improve soil quality over time. On-farm biochar production is also a circular approach to managing waste biomass such as orchard trimmings, in-field residues, and agricultural processing wastes like nut shells and rice hulls. 

Small-scale agriculture and specialty growers

Market farms, orchards, vineyards, and greenhouse operations incorporate biochar into soils and compost blends to improve moisture management, increase yields and nutrient holding capacity, and reduce fertilizer and input costs. Application rates and benefits vary by crop type and soil conditions. Many small scale orchards and vineyards can also produce biochar on site and then reincorporate that material into soil.

Retail and consumer products

Biochar is sold in soil blends, fertilizer products, and horticultural amendments for gardeners, landscapers, and turf managers. Retail uses typically focus on soil conditioning for gardening and improving growing media performance for potted plants. Biochar can also be a key component of sustainable peat-free and perlite-free potting media blends. 

NGOs and public agencies

Municipalities, conservation organizations, and land managers use biochar in tree planting and turf management, stormwater systems, and soil restoration projects. It can support water quality management, waste diversion, and local biomass utilization initiatives that deliver community-level benefits. These organizations can also become biochar producers, providing an opportunity to upcycle waste biomass such as arborist trimmings in urban areas. 

Forestry and land management

Biochar can be produced from wood products, manufacturing waste, in-forest residues, thinning operations related to wildfire mitigation, and invasive species removal initiatives. Converting excess woody biomass into biochar provides an alternative to pile burning, reducing harmful particulate air pollution. Biochar produced from this material can also generate carbon credit revenue and be sold for other uses, creating an economic opportunity from this otherwise low value material, and supporting fuel load reduction and forest management strategies. 

Construction and building materials

Biochar is being incorporated into concrete, asphalt, and other building materials to develop greener construction products and new material formulations for critical infrastructure and housing. Some biochar formulations are being developed to produce high performance concrete and asphalt blends. 

Variability, quality, and standards

“Biochar” represents a class of materials, with substantial variability between materials. The key chemical and physical properties of biochar are greatly affected by what it is made from, conditions of the pyrolysis process, how it is processed following production, and more. 

Some of the key material considerations for biochar include the carbon content, the H:C ratio, pH, ash content, micro- and macro-nutrient concentrations, and particle size distribution. Biochar made from manure or biosolids will have a lower carbon content and higher nutrient content than biochar made from woody residue. Biochar made from wood chips is likely to have higher carbon content and greater surface area for retaining nutrients and water. 

Even though biochar can be made from nearly any biomass, most biochar today is made from wood waste, agricultural processing residues, and manures.

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