# Technology-Economy-Policy: Biochar in the Low-Carbon Energy Transition--A Review
## 6 Economy: Application of Biochar
### Application of Biochar in the Renewable Energy Sector
#### 6.1.3. Application of Biochar in Biorefinery  
Biomass pyrolysis produces biochar, bio-oil, and syngas. These products--bio-oil and syngas--are considered sustainable energy sources contributing to carbon neutrality. However, the economic feasibility of using biochar in these processes depends on a variety of factors, including the feedstock, energy market conditions, and the specific goals of the facility. Gasification may provide higher syngas yields, beneficial for energy generation, while pyrolysis produces a higher yield of biochar, ideal for long-term carbon sequestration. The economic outcomes of each process can vary based on the feedstock type, local energy markets, and technological approaches. An analysis of these trade-offs in real-world conditions would give clarity on the economic returns from both the gasification and pyrolysis pathways. For instance, facilities focusing on syngas production may find gasification to be more economically viable if energy prices are high. Conversely, pyrolysis may be favored in markets prioritizing sustainability and carbon sequestration, despite potentially lower short-term economic returns. To strengthen the economic feasibility claims regarding biochar utilization in energy production, it is advisable to include case studies from operational European facilities. For example, the Pyreg GmbH plant in Germany integrates pyrolysis technology to produce both biochar and syngas from organic residues, with the syngas being used for heat and electricity generation, enhancing the overall profitability of the system. Similarly, the Nettenergy company in the Netherlands operates mobile pyrolysis units that produce syngas on site for immediate energy use, while also generating marketable biochar. These examples demonstrate that pyrolysis systems can offer dual economic returns--through biochar as a soil amendment and syngas as a renewable energy source. Compared to gasification systems, which prioritize the syngas yield at the cost of solid residues, pyrolysis provides an additional revenue stream through biochar, particularly valuable for carbon sequestration schemes [174; 175; 176].  
Bio-oil and syngas are considered sustainable energy sources that can contribute to carbon neutrality [177]. Bio-oil is a dark brown liquid that consists of alcohol, phenol, hydroxy ketones, esters, and carboxylic acids, etc. [178]. Bio-oil can be used for combustion in engines and boilers. [PERSON] et al. [179] reported methods to improve the quality of bio-oil so that it can meet the criteria for hydrocarbon fuels. Researchers report that these criteria can be achieved through physical enrichment using density difference or chemical enrichment through catalytic cracking and hydrorefining. Syngas consists of hydrogen, methane, carbon monoxide, and ethene, etc., and can be used as a clean energy source [180]. [PERSON] and [PERSON] [181] found that the global warming potential with bio-oil is 55% lower compared to fossil fuels. Biochar acts as activated carbon and provides support for the metal catalyst. [PERSON] et al. [182] reported that a new Ru-ReOx catalyst was loaded onto rice straw biochar, and can generate value-added chemicals such as tetrahydrofuran and 1,4-butanediol. Catalysts on biochar were three times more active compared to on conventional activated carbon. Metal catalysts on biochar can be used in biorefining, transesterification, hydrogenation, and in hydrodeoxygenation gasification reactions [183].