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Biodiesel production faces environmental and economic challenges due to the use of homogeneous catalysts, such as NaOH, KOH, NaOCH 3 , and KOCH 3. Despite their good activity, these catalysts are toxic and almost impossible to recycle/reuse. Heterogeneous catalysts, otherwise, can be reused and easily separated from the final product, resulting in more sustainable and cost-effective production. However, these catalysts leach, losing activity through reaction cycles and contaminating the biodiesel This review has therefore addressed the use of CaO – a promising catalyst for biodiesel synthesis – and various biochar-derived catalysts. Particular attention was paid to studies involving the use of CaO in a biochar matrix (CaO/Biochar), given the support essential role in making the CaO use feasible. The use of catalysts derived from sugarcane bagasse biochar was also highlighted, given this biomass importance, especially in Brazil. Studies have shown that biochar-derived catalysts have good activity, excellent stability, and can be reused for up to 10 cycles. Concerning CaO/Biochar, it was found that biochar significantly reduced Ca2+ leaching, but there is still a need to further reduce the Ca2+ release into biodiesel. There is also a need to give more focus on CaO leaching. Finally, a lack of studies on the use of catalysts derived from sugarcane bagasse biochar is notiable, showing no study involving the CaO-embedded sugarcane bagasse biochar. • There are no studies about biodiesel synthesis with CaO/Sugarcane biochar. • Biochars from different sources significantly reduced the Ca2+ leaching. • Biochar-based catalysts provided nearly 100 % biodiesel yield under relatively mild conditions. • Biochar support significantly increases catalysts' reusability. • Ca– O –Si bonds may be associated with the CaO anchoring. [ABSTRACT FROM AUTHOR]

Production of biofuels via biomass pyrolysis has received a strong emphasis since it may produce a wide variety of renewable fuels in liquid (bio-oil), solid (biochar), and gas (syngas) forms. Sugarcane bagasse, waste from the sugar-alcohol industry, is largely produced in Brazil, India, and Thailand and appears as a great biomass option for pyrolysis due to its properties, abundance, and current underutilization. However, sugarcane bagasse properties and pyrolysis operating conditions may directly affect the product properties, distribution, and further application as fuels and chemicals. Thus, it is necessary a thorough study of these subjects. This review brings an overview of biomass and pyrolysis concepts, as well as a collection of improvements in the production of products (bio-oil, biochar, and gas) via sugarcane bagasse pyrolysis. In addition, this review discusses the interaction between process operating conditions and this biomass type to address how the products' properties and yields are affected. • Fast Pyrolysis: an efficient thermochemical process for bio-oil, biochar, and gas production. • Fast Pyrolysis concepts, operational conditions, and reactor configurations were reviewed. • Bio-oil, biochar, and gas production as an alternative for renewable energy world matrix. • Focus on sugarcane bagasse as a raw material for bio-oil, biochar, and gas production. • Upgrading methods for bio-oil, challenges, and future works in the pyrolysis field. [ABSTRACT FROM AUTHOR]

Greenhouse gas removal technologies are needed to reach the targets of the UNFCCC Paris Agreement. Among existing technologies, the use of biochar is considered promising, particularly biochar derived from the large quantities of sugarcane residues available in South America and elsewhere. However, the net greenhouse gas removal potential of sugarcane biochar has not been assessed hitherto. We use a scenario-based anticipatory life cycle assessment to investigate the emissions associated with a change from the combustion of sugarcane residues in a combined heat and power plant to the pyrolysis of these residues for biochar production and field application in São Paulo State, Brazil. We define scenarios based on different mean marginal electricity production and biochar production share. The results indicate that emissions from covering the electricity deficit generated by partial combustion of biomass during biochar production is the main emitting process. Overall, the processes associated with biochar production lower the net greenhouse gas benefits of the biochar by around 25%. Our analysis suggests that allocating 100% of the available sugarcane residues to biochar production could sequester 6.3 ± 0.5 t CO 2 eq ha−1 yr−1 of sugarcane in São Paulo State. Scaled up to the entire State, the practice could lead to the removal of 23% of the total amount of GHGs emitted by the State in 2016. • First LCA of sugarcane biochar for GHG removal in Brazil. • Covering the energy deficit created by pyrolysis is the most GHG emitting process. • Lifecycle emissions reduce the net carbon sequestration benefits of biochar by 25%. • Sugarcane residue biochar in São Paulo State, Brazil could sequester 36 Mt CO 2 eq yr−1. [ABSTRACT FROM AUTHOR]

With the advent of mechanized sugarcane harvesting in Brazil around 70 Mt of straw each year is left on the field, and ∼70% of its carbon (C) is decomposed and returned to the atmosphere on the same timeframe. The adoption of a stabilised C product such as biochar as a vehicle for nutrient delivery might address two ends of a problem: to increase nutrient use efficiency by plants while creating a viable and efficient strategy to increase stable C in soil. This study proposed a production route for a biochar fertiliser (BF) from sugarcane straw biochar (SSB), by activation of SSB with KOH and subsequent neutralisation with H 3 PO 4. The phosphorus (P) content of BF (8.6% P) was superior to SSB. It was also noticed that structure of SSB matrix was altered, creating increased sorption capacity, with the fertiliser bound to the biochar rather than physically mixed. The BF was tested in a controlled condition experiment with sugarcane for 120 days using three low P soils with different clay contents (147, 326 and 528 g kg−1). BF led to higher biomass yield (15%) and P use efficiency (PUE) (∼10%) compared to standard P source (triple superphosphate – TSP) in the most clayey soil. The adoption of a fertiliser based on a nutrient enriched biochar can increase the effectiveness of crop production. Enhanced delivery of crop nutrients increases the attractiveness of increased soil C. Image 1 • A novel P rich biochar fertiliser with enhanced features is produced. • Biochar fertiliser and TSP are tested in sugarcane for different soils. • Mean soil pH, over 120 days, for biochar (∼7) is higher than in TSP (∼5). • Biochar fertiliser presents PUE 15% superior than TSP. [ABSTRACT FROM AUTHOR]