Briquettes production from green coconut shells: technical, financial, and environmental aspects

ABSTRACT The United Nations Sustainable Development Goals emphasize the need to better understand and propose solutions for the growing demand for resources and the generation of waste by anthropic systems at any scale and intensity. Although it can be considered as secondary importance problem, hundreds of tons of green coconut shell residues annually generated in the Brazilian coastal cities are transported and dumped in landfills, wasting their energy potential and resulting in economic and environmental problems – this approach is known as take, make, disposal, or “linear” production model. This work proposes a “circular” model by using the biomass from green coconut shells generated by the cities of Baixada Santista region as a raw material for briquettes production. Technical-operational, environmental, and financial aspects are considered to assess the proposed “circular” model in comparison with the existing “linear” model. Results show that technical-operational aspects of the “circular” model are viable due to already existing technologies in the market that can be easily adapted for the purposes in converting green coconut shells into briquettes. The “circular” model proposed allows a reduction in greenhouse gases emission by ∼40 thousand tons year−1 when compared to the “linear” model, besides avoiding leachate generation. Furthermore, the 66% profitability, 195% rentability, and 6 months of investment payback suggest the financial viability of briquettes production. Together, all these indicators claim for public policies incentives and private investments to make the proposed “circular” model a reality, which is aligned with the objectives of 2030 agenda.

摘要 联合国可持续发展目标（United Nations Sustainable Development Goals）强调，需更好地理解并提出解决方案，以应对任意规模与强度的人类系统日益增长的资源需求及废弃物产生问题。尽管常被视为次要问题，但巴西沿海城市每年产生的数百吨青椰壳残渣仍被转运并填埋至垃圾填埋场，不仅浪费了其能源利用潜力，还引发了经济与环境问题——这种模式被称为“取用-制造-废弃”或“线性”生产模式。本研究提出一种“循环”模式，以桑蒂斯塔湾（Baixada Santista）地区各城市产生的青椰壳生物质为原料，生产成型燃料（briquettes）。研究从技术运营、环境及财务三个维度，对所提出的“循环”模式与现有“线性”模式进行评估对比。结果表明，“循环”模式在技术运营层面具备可行性：当前市场已有技术可轻松适配，将青椰壳转化为成型燃料。与“线性”模式相比，该“循环”模式每年可减少约4万吨温室气体排放，同时避免了渗滤液的产生。此外，66%的利润率、195%的资产收益率及6个月的投资回收期，均证明成型燃料生产具备财务可行性。综上，各项指标均呼吁出台公共政策激励与私人投资，以推动所提出的“循环”模式落地，这一目标与2030年议程的宗旨高度契合。