# Unravelling the Environmental Application of Biochar as Low-Cost Biosorbent: A Review
## 7 Economic Analysis and Future Prospects  
The cost analysis is an important aspect to evaluate the production and implementation of the proposed materials. The global biochar market was USD 1.39 billion in 2019, and it is expected to increase to USD 3.46 billion in 2025. This product is mainly used in agriculture application (71.1% in 2018), but other areas such as water and wastewater treatment have shown an increase in the demand of the products, mainly in emerging economies [135]. There are several processes for the production of the biochar as it is displayed in Figure 2, but pyrolysis is the most effective process actually used.  
Biochar obtained by pyrolysis presents excellent adsorptive properties for organic and inorganic compounds, which suggests an increase in this use in the near future and can be considered as a feasible cheaper alternative to the more expensive activated carbons. [PERSON] et al. [136] reported a biochar production cost of 350-1200 USD/ton, which is lower than the reported value for activated carbon--USD 1100-1700 per ton. Other studies showed even lower biochar production prices as 90 USD/ton in the Philippines and higher values for those produced in the UK, at 8850 USD /ton [137]. From an economic point of view, the market price of the biochar depends on the effectiveness of the generated material and is an important factor correlated with the biochar cost. Moreover, several aspects related to biochar production, such as the selected feedstock, pyrolysis production conditions and transport, considerably affect the production costs. [PERSON] et al. [138], using life cycle assessment analysis, reported that most of the production cost is related to the pyrolysis process, but also significant cost is related to the storage/processing of the biochar and feedstock. Similarly, [PERSON] et al. [139] considered these aspects in their economic analysis of biochar production from Canadian black spruce forest. The reported results imply that the pyrolysis stage is the most costly, attaining 36% of the cost, followed by feedstock collection (12%) and transportation cost (9%), which resulted in a biochar cost of 762.20 USD/ton. Thus, the reduction in the cost may rely on the use of new production technologies and the selection of appropriate and suitable low-cost materials. The use of wastes is aligned with circular economy principles and the goals of \"2030 Agenda for Sustainable Development\" adopted by the United Nations for reducing carbon emissions, favoring the reuse of materials and avoiding the generation of waste.  
The future prospects of biochar require researchers to face several challenges associated with these materials for proper use. One of these challenges is the search for potential feedstock materials and wastes as low-cost materials for the production process attaining good adsorptive properties. Based on this, the design of engineered biochar adsorbents (via activation) for the removal of specific compounds is also required due to the wide variety of pollutants that are being released to the environment. The management of the spent biochar adsorbents by regeneration is another aspect to be considered and is required to tackle with. All these issues also require the performance of an economic analysis of the biochar production including activation and regeneration costs, which is an important factor to be considered in the development of these biochars and have been scarcely studied.