The use of biochar as a soil improver and as a renewable carbon source in industrial applications is increasing in Europe, driven by EU circular economy initiatives such as the Carbon Removals and Carbon Farming (CRCF) Regulation.1 While biochar offers significant potential as a carbon sink and as a more sustainable alternative to fossil coal and traditional charcoal, there are currently no harmonized EU-wide compositional criteria that would apply across all uses.
As a result, quality assurance is guided primarily by application-specific requirements. Some of these are defined in EU legislation, such as Regulation (EU) 2019/1009 on fertilizing products, while others are determined by technical performance requirements in industrial processes, for example, in iron and steel production.
This article summarizes commonly applied biochar quality criteria across key applications, together with analytical methods used to verify that these requirements are met.
Biochar definition and applications
Biochar (or biocoal) is a carbon-rich solid produced by thermally treating biomass under low-oxygen conditions. Production parameters such as pyrolysis temperature and feedstock strongly influence the physical and chemical properties of the resulting material and therefore determine its suitability for different applications:2
Biochar produced through pyrolysis at approximately 400–700 °C is used in multiple applications, including soil improvement, metallurgical processes, and as an additive in animal feed and construction materials.
Biochar can be further treated at even higher temperatures (typically >800 °C) to produce biobased activated carbon, which can be used as an adsorbent in wastewater treatment and gas purification, as well as in other technically demanding applications, such as pharmaceutical and cosmetic processing.
High-purity biochar (from feedstock such as lignin or bio-oil) can be further processed at approximately 1,000–3,000 °C to produce biographite, which can replace fossil-based graphite as an anode material in batteries and energy storage solutions.
Torrefied biomass produced at lower temperatures (typically < 300 °C) through torrefaction rather than full pyrolysis is primarily used as a solid fuel.
Biochar testing for REACH registration
Companies that manufacture or import biochar in the EEA in quantities above 1 ton per year must submit a Substance Registration to the European Chemicals Agency (ECHA) to comply with the REACH Regulation.3 The submission can be made under the charcoal dossier (EC No. 240-383-3) if the biochar has been produced through a conventional pyrolysis process and meets the applicable compositional criteria.4
As part of REACH registration, companies must provide ECHA with analytical information on substance identity and composition. A typical testing sequence includes the following analyses:
Carbon and total CHNO content
Moisture, volatiles, and ash content
Structural analysis with XRD
Metal content with XRF
Further contaminant analysis covering PAH compounds and other relevant impurities
For submission under the charcoal dossier, biochar’s carbon content should be between 30% and 95%, and the total CHNO content should be greater than 96%. Impurities must not be present in amounts that would trigger hazard classification under the CLP Regulation.5
Biochar testing for soil improvement applications
According to industry estimates, the vast majority of biochar marketed globally is used for soil improvement.6 When placed on the EU market as a CE-marked fertilizing product for this purpose, biochar must comply with Regulation (EU) 2019/1009. Relevant testing requirements are specified in Annex II, CMC 14 (pyrolysis and gasification materials) and Annex I, PFC 3(A) (organic soil improver).7
Table 1: Regulatory testing requirements for biochar-based fertilizing products under Regulation (EU) 2019/1009
Parameter | Limit/criterion | Notes |
Molar ratio of hydrogen to organic carbon (H/Corg)* | < 0.7 | Testing required if Corg < 50%, performed on dry, ash-free fraction |
PAH 16 content* | ≤ 6 mg/kg of dry matter | PAH 16 = sum of 16 polycyclic aromatic hydrocarbons identified as high-priority pollutants by the US EPA |
Dioxin and furan (PCDD/F) content* | ≤ 20 ng WHO-TEQ/kg of dry matter | WHO-TEQ = World Health Organization toxicity equivalents |
Chloride (Cl−)* | ≤ 30 g/kg of dry matter | In the finished fertilizing product |
Thallium (Tl)* | ≤ 2 mg/kg of dry matter | In the finished product, if > 5% pyrolysis/gasification additives are used |
Cadmium (Cd) Hexavalent chromium (Cr(VI)) Mercury (Hg) Nickel (Ni) Lead (Pb) Inorganic arsenic (As)** | 2 mg/kg 2 mg/kg 1 mg/kg 50 mg/kg 120 mg/kg 40 mg/kg | All limits on a dry matter basis |
Copper (Cu) Zinc (Zn)** | 300 mg/kg 800 mg/kg | Both limits on a dry matter basis |
Salmonella** | Absent | In 25 g or 25 ml, when 5 samples are tested |
E. coli/enterococci** | ≤ 1,000 CFU | In 1 g or 1 ml, when 5 samples are tested |
* Material component-related requirement from Annex II, CMC 14
** End-use-related requirement from Annex I, PFC 3(A)
Beyond fulfilling the regulatory compositional and purity criteria, biochar intended for soil improvement should have suitable physical properties. High specific surface area and porosity are particularly important, as they are linked to improved water holding capacity and sorption behaviour. In some cases, depending on the feedstock, biochar may also contribute nutrients such as nitrogen, phosphorus, and potassium.8
Measurlabs offers several methods for comprehensive physico-chemical characterization of biochar to assess both regulatory compliance and performance in soil improvement applications. Examples include ICP-OES for elemental analysis, GC-HRMS for dioxin analysis, and the BET method for specific surface area determination.
Biochar in iron and steel production
For biochar to effectively replace some of the fossil-based coal used in steel production, its properties must be consistent across batches and meet stringent technical performance requirements. As metal production processes are plant-specific, there are no universal criteria; instead, the material must be tailored to the specific production process.
In general, at least the following properties should be monitored and optimized when biochar is used in metallurgical applications:9
Fixed carbon content, energy density, and calorific value should be high to achieve the required heat potential and reductive capacity during high-temperature processing
Ash, moisture, and volatile matter content should be low, as these can hinder furnace operation, for example, through slag formation, unstable combustion behaviour, or diminished energy efficiency
Porosity should be controlled, as very high porosity can lead to excessive reactivity and low mechanical strength instead of the desired, more controlled reduction behaviour
Physical characteristics, such as particle size and bulk density, should fall within the specifications of the feeding system
Several of these properties (volatile matter, ash, moisture, fixed carbon) can be determined using thermogravimetric analysis (TGA), for example, following the ASTM D7582 standard method. Other applicable test methods include bomb calorimetry (ISO 18125) for calorific value and sieving or laser diffraction for particle size distribution analysis.
Incorporation of biochar into construction materials
In the construction sector, biochar can be added to cement, concrete, asphalt, and other composites to lower the carbon footprint and contribute to permanent carbon removal under the CRCF Regulation.10 However, its addition can influence critical material properties, including mechanical strength, durability, and fire performance. Laboratory testing is therefore required both to characterize the biochar and to verify the properties of the final construction product.
Beyond the basic physico-chemical parameters discussed in the above sections, biochar-containing construction materials may require application-specific testing, such as:
Fire classification according to EN 13501-1, and the required reaction-to-fire tests such as EN ISO 1182 (non-combustibility), EN ISO 1716 (gross heat of combustion), and EN 13823 (Single Burning Item test)
Determination of mechanical properties according to relevant product standards, for example, EN ISO 10545 series when biochar is incorporated into ceramic tiles
Emission testing for indoor air quality, such as VOC emissions according to EN 16516
Measurlabs’ solutions for biochar testing
Measurlabs supports producers of biochar and related circular economy products, including biocoke, bio-based activated carbon, torrefied biomass, and pyrolysis oil, with a comprehensive range of analytical services. Examples of popular biochar analyses include:
Determination of basic quality parameters (e.g., ash, moisture, fixed carbon, and volatiles content)
Determination of chemical composition and purity, including bulk composition (CHNOS), elemental impurities (Cd, Cr(VI), Hg, Ni, Pb, As, etc.), and organic contaminants (PAH, PCDD/F, phthalates, bisphenols, PFAS, etc.)
Characterization of physical properties, such as particle size, bulk density, porosity, and surface area
Application-specific performance testing, including reaction-to-fire behavior and emissions from biochar-containing construction materials
Handling and transportation safety tests, including dustiness (EN 15051-2), combustibility and explosibility screening, determination of further explosion parameters, and self-heating behavior
Through partner laboratories that are certified under the European Biochar Certificate (EBC) scheme, Measurlabs can also arrange the analytical testing required for EBC certification.
For more information or a quote, please contact our experts using the form below.
References
1 Regulation (EU) 2024/3012 establishing a Union certification framework for permanent carbon removals, carbon farming and carbon storage in products. Biochar production is one of the activities that qualify as permanent carbon removal under the regulation, as long as the set quality criteria are met. Detailed technical requirements for biochar-based carbon removal will be specified in an upcoming Delegated Regulation.
2 Different sources give slightly different values for typical production temperatures of biochar vs. torrefied biomass, etc. These definitions are based on a Technical Research Centre of Finland (VTT) report titled “Biohiili osana suomalaista biotaloutta” (in Finnish).
3 Regulation (EC) No 1907/2006 on the Registration, Evaluation, Authorisation and Restriction of Chemicals
4 The requirements for REACH registration under the charcoal dossier are outlined in a presentation by Coalster GmbH, the leading registrant. Torrefied biomass, biochar produced through hydrothermal carbonisation (HTC), and hazardous biocoke cannot be registered under the joint registration.
5 Testing requirements and criteria are outlined in the presentation by Coalster. The CLP Regulation refers to Regulation (EC) No 1272/2008 on classification, labelling and packaging of substances and mixtures.
6 According to the VTT report “Biohiili osana suomalaista biotaloutta” (in Finnish), 85 % of biochar was used for soil improvement in 2023.
7 Annex II & Annex I to Commission Regulation (EU) 2019/1009 on fertilizing products. CMC refers to a “Component Material Category” and PFC to a “Product Function Category”.
8 Kabir et al. “Biochar as a tool for the improvement of soil and environment”, published in Frontiers in Environmental Science (2023)
9 Sarker et al. “Decarbonization of Metallurgy and Steelmaking Industries Using Biochar: A Review”, published in Chemical Engineering Technology (2024) and Wajda & Brągoszewska “Insight into the Potential Use of Biochar as a Substitute for Fossil Fuels in Energy-Intensive Industries on the Example of the Iron and Steel Industry”, published in Energies (2025). Research indicates that even with optimized properties, biochar cannot fully replace fossil carbon in most metallurgical processes. Instead, partial substitution of up to around 50% can be feasible depending on the process and furnace configuration without compromising product quality.
10 Draft Delegated Regulation establishing methodologies to certify carbon removal activities under Regulation (EU) 2024/3012 on carbon removals, carbon farming and carbon storage in products. Incorporation of biochar into cement, concrete, or asphalt qualifies as permanent carbon removal if the applicable criteria are met.