Análise técnico e econômica da codigestão anaeróbia da cama de frangos com culturas energéticas para geração de energia
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Data
2020-04-16
Autores
Montoro, Stela Basso [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
As demandas por energia e alimento aumentarão com as projeções do crescimento populacional mundial. O Brasil está entre os países com o desafio de atender essas demandas. O tratamento dos resíduos gerados na agropecuária tem potencial para produção de biogás e biofertilizante por meio de biodigestores, insumos essenciais para alavancar a produção de alimentos e o desenvolvimento sustentável. Com isso, analisou-se a viabilidade técnica e econômica da codigestão de cama de frango com batata doce ou mandioca visando aumentar a produção de energia e reciclagem de nutrientes dos resíduos da produção de frangos. A utilização de culturas energéticas para codigestão anaeróbia é uma inovação para geração de energia renovável em propriedades rurais e tem ganhado atenção em economias emergentes, que tem como desafio suportar a produção de alimentos com sustentabilidade. O ensaio foi realizado com três tratamentos, cama de frango, cama de frango com batata doce e cama de frango com mandioca. A codigestão com as culturas energéticas foram mais eficientes que a monodigestão. A mandioca superou a batata doce em 17,09% no rendimento médio de biogás diário e reduziu 12 e 3,32% mais sólidos totais e voláteis, respectivamente. No entanto, o potencial de biogás da batata doce 0,449 m3 kg-1SVad e da mandioca 0,457 m3 kg-1SVad não apresentaram diferença significativa, assim como os teores de metano com 61,92 e 61,79%, respectivamente, demonstrando o potencial equivalente das duas culturas na geração de bioenergia. Além da geração de energia renovável, o processo de codigestão produziu um biofertilizante com concentrações médias de 1,24% de N, 3,09% de P e 3,11% de K. Para avaliar se esse sistema é economicamente viável realizou-se a análise econômica pelo método do Fluxo de Caixa Descontado e estocástica com o suporte da Simulação de Monte Carlo, definindo como variáveis de incerteza do modelo os preços de energia elétrica, adubo mineral e biodigestores, com reflexos no Valor Presente Líquido (VPL) e Taxa Interna de Retorno (TIR). Foram elaborados 30 cenários referentes aos três tratamentos do ensaio de digestão anaeróbia em 10 escalas animais, a fim de contemplar pequenos, médios e grandes avicultores. Os resultados dos VPLs anualizados incrementais demonstraram que a codigestão anaeróbia da Cama de frango com batata doce e mandioca melhora os lucros dos médios e grandes produtores em 56 a 275%, quando comparado ao custo oportunidade da venda da cama aviária. Os resultados estocásticos validam a viabilidade econômica de médios e grandes avicultores com 100% de probabilidade, mesmo com variações nos preços de receita e custo do investimento. Aos pequenos produtores é vantajoso o uso das culturas energéticas e a venda do resíduo do processo de preparação do substrato dos biodigestores, como adubo orgânico, para que o investimento seja viável em 64,3 a 100% das possibilidades. Não obstante, a digestão anaeróbia possibilitou a produção de energia renovável 80% mais barata que a média nacional.
Demand for energy and food will increase with projections of world population growth. Brazil is among the countries with the challenge of meeting these demands. The treatment of waste generated in agriculture has the potential to produce biogas and biofertilizer through biodigesters, essential inputs to leverage food production and sustainable development. With this, the technical and economic feasibility of codigestion of chicken with sweet potatoes or manioc was analyzed in order to increase energy production and recycling nutrients from chicken production residues. The use of energy crops for anaerobic codigestion is an innovation for the generation of renewable energy in rural properties and has gained attention in emerging economies, which have the challenge of supporting sustainable food production. The trial was carried out with three treatments, chicken bed, chicken bed with sweet potato and chicken bed with cassava. Codigestion with energy crops was more efficient than monodigestion. Cassava exceeded sweet potatoes by 17.09% in the average daily biogas yield and reduced 12 and 3.32% more total and volatile solids, respectively. However, the biogas potential of sweet potato 0.449 m3 kg-1SVad and cassava 0.457 m3 kg-1SVad did not show any significant difference, as well as the methane contents with 61.92 and 61.79%, respectively, demonstrating the equivalent potential of both cultures in the generation of bioenergy. In addition to the generation of renewable energy, the co-management process produced a biofertilizer with average concentrations of 1.24% N, 3.09% P and 3.11% K. To assess whether this system is economically viable, the economic analysis using the Discounted and Stochastic Cash Flow method with the support of the Monte Carlo Simulation, defining the electricity uncertainty, mineral fertilizer and digestors prices as variables of uncertainty in the model, reflecting the Net Present Value (NPV) and Rate Internal Return Rate (IRR). Thirty scenarios were elaborated referring to the three treatments of the digestion test in 10 animal scales, in order to contemplate small, medium and large poultry farmers. The results of the incremental annualized NPV showed that the anaerobic codigestion of the chicken bed with sweet potatoes and cassava improves the profits of medium and large producers by 56 to 275%, when compared to the opportunity cost of selling poultry litter. The stochastic results validate the economic viability of medium and large poultry farmers with 100% probability, even with variations in revenue prices and investment costs. Small producers have the advantage of using energy crops and selling the residue from the digestor substrate preparation process, as organic fertilizer, so that the investment is viable in 64.3 to 100% of the possibilities. Nevertheless, anaerobic digestion enabled the production of renewable energy 80% cheaper than the national average.
Demand for energy and food will increase with projections of world population growth. Brazil is among the countries with the challenge of meeting these demands. The treatment of waste generated in agriculture has the potential to produce biogas and biofertilizer through biodigesters, essential inputs to leverage food production and sustainable development. With this, the technical and economic feasibility of codigestion of chicken with sweet potatoes or manioc was analyzed in order to increase energy production and recycling nutrients from chicken production residues. The use of energy crops for anaerobic codigestion is an innovation for the generation of renewable energy in rural properties and has gained attention in emerging economies, which have the challenge of supporting sustainable food production. The trial was carried out with three treatments, chicken bed, chicken bed with sweet potato and chicken bed with cassava. Codigestion with energy crops was more efficient than monodigestion. Cassava exceeded sweet potatoes by 17.09% in the average daily biogas yield and reduced 12 and 3.32% more total and volatile solids, respectively. However, the biogas potential of sweet potato 0.449 m3 kg-1SVad and cassava 0.457 m3 kg-1SVad did not show any significant difference, as well as the methane contents with 61.92 and 61.79%, respectively, demonstrating the equivalent potential of both cultures in the generation of bioenergy. In addition to the generation of renewable energy, the co-management process produced a biofertilizer with average concentrations of 1.24% N, 3.09% P and 3.11% K. To assess whether this system is economically viable, the economic analysis using the Discounted and Stochastic Cash Flow method with the support of the Monte Carlo Simulation, defining the electricity uncertainty, mineral fertilizer and digestors prices as variables of uncertainty in the model, reflecting the Net Present Value (NPV) and Rate Internal Return Rate (IRR). Thirty scenarios were elaborated referring to the three treatments of the digestion test in 10 animal scales, in order to contemplate small, medium and large poultry farmers. The results of the incremental annualized NPV showed that the anaerobic codigestion of the chicken bed with sweet potatoes and cassava improves the profits of medium and large producers by 56 to 275%, when compared to the opportunity cost of selling poultry litter. The stochastic results validate the economic viability of medium and large poultry farmers with 100% probability, even with variations in revenue prices and investment costs. Small producers have the advantage of using energy crops and selling the residue from the digestor substrate preparation process, as organic fertilizer, so that the investment is viable in 64.3 to 100% of the possibilities. Nevertheless, anaerobic digestion enabled the production of renewable energy 80% cheaper than the national average.
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Palavras-chave
Biogás, Biofertilizante, Batata doce, Mandioca, Simulação de Monte Carlo, Biogas, Biofertilizer, Sweet potato, Cassava, Monte Carlo simulation