Greenhouse Gas Assessment and Strategies to Achieve CO₂ Sequestration in the Brazilian Palm Oil Life Cycle

As the palm oil production is expanding in Brazilian Amazon region, this study aimed to determinate the greenhouse gas (GHG) emissions since the agricultural phase to transportation of crude palm oil (CPO) and then indicate strategies to achieve the CO2 sequestration. The scope of this study comprised since the stage of oil palm seedlings production until the transportation of CPO. Inventory data for the year of 2009 included the agricultural production of fresh fruit bunches (FFB) and the extraction and transportation of CPO. The management of palm oil mill effluent (POME), use of fertilizers, fuels, pesticides, and electricity contributed to 66.5, 17.9, 15.1, 0.4, and 0.1% of the total emissions, respectively. Agricultural phase, CPO extraction, and transportation emitted 32,131, 79,590, and 1,104 t CO2-eq, respectively. The carbon (C) footprint was 0.79 t CO2-eq / t CPO, and the highest GHG emissions were associated to the management of POME. On the other hand, the use of all residues from the mill as fertilizer substitute can minimize the GHG emissions and increase soil C stocks. In addition, the methane (CH4) from POME captured and used for steam or electricity is also a viable alternative to reduce the GHG emissions

Emissões de gases de efeito estufa na cultura da soja e influência dos resíduos culturais nas emissões de óxido nitroso pós-colheita

Brazil is one of the world\'s largest producers and exporters of soybeans. The oil and meal obtained from grains are important components of biodiesel and animal feed chains. In recent years, international standards and certifications were developed to promote sustainability in the agricultural supply chain. In this context, greenhouse gases (GHG) emissions in the products life cycle has been the main point of interest to the scientific community and consumers. Few studies have evaluated the GHG emissions in soybean cultivation with specific data for the Brazilian reality. The aim of this study was to evaluate the main sources of GHG in soybean production in the State of Mato Grosso, Brazil. We evaluated 55 farms in the crop years of 2007/08, 2008/09 and 2009/10, accounting for 180,000 hectares of soybean cultivation area and totaling 114 individual situations. The results indicated that the largest source of GHG in the soybean production is the decomposition of crop residues (36%), followed by fuel use (19%), fertilizer application (16%), liming (13%), pesticides (7%), seeds (8%) and electricity consumed at the farms (<1%). The average GHG emissions considering the three crop years were 0.186 kg of CO2eq kg-1 of soybean produced. Based on these results, field experiments were conducted to quantify N2O emissions from the decomposition of soybean crop residues in different climatic regions and harvest periods in Brazil. Our results show that, in field conditions, the contribution of N2O emissions from senesced and desiccated residues that remain on field after soybean harvest are unlikely to represent a significant source of N2O loss above normal background soil emissions. These results were also supported by the laboratory incubation experiment, indicating that the IPCC methodology for estimating N2O emissions from soybean crop residues may provide overestimations for the Brazilian conditions. The results of this study provide relevant and specific information to producers, industry and scientific community regarding the environmental impacts associated with soybean production in BrazilO Brasil é um dos maiores produtores e exportadores mundiais de soja. O óleo e farelo obtidos dos grãos são componentes importantes das cadeias do biodiesel e ração animal. Nos últimos anos, normas e certificações internacionais foram desenvolvidas para promover a sustentabilidade na cadeia de produção agrícola. Nesse contexto, as emissões de gases de efeito estufa (GEE) no ciclo de vida dos produtos tem sido o principal ponto de interesse para a comunidade científica e consumidores. Poucos estudos avaliaram as emissões de GEE no cultivo da soja com dados específicos para a realidade brasileira. O objetivo deste estudo foi determinar as principais fontes de GEE na produção de soja em Mato Grosso, principal estado produtor brasileiro. Foram coletados dados de 55 fazendas nos anos-safra de 2007/08, 2008/09 e 2009/10, totalizando 114 avaliações. Os resultados indicaram que a maior fonte de GEE na produção de soja é a decomposição de resíduos culturais (36%), seguido pelo uso de combustível (19%), aplicação de fertilizantes (16%), calagem (13%), pesticidas (7%), sementes (8%) e eletricidade consumida nas fazendas (<1%). A emissão média considerando os três anos-safra avaliados foi 0,186 kg de CO2eq kg-1 de soja produzido. Com base nesses resultados, foram desenvolvidos experimentos em campo para quantificação das emissões de N2O proveniente da decomposição dos resíduos culturais da soja em diferentes regiões climáticas e períodos de colheita no Brasil. Adicionalmente, foram realizadas incubações em laboratório com materiais de soja em diferentes estágios de desenvolvimento. Os resultados indicaram que resíduos culturais de soja que permanecem no campo após a colheita não representam uma fonte significativa de N2O. Os resultados obtidos neste estudo fornecem informações relevantes para produtores, indústria e comunidade científica quanto aos impactos ambientais associados à cultura da soja no Brasi

Assessing the greenhouse gas emissions of Brazilian soybean biodiesel production.

Soybean biodiesel (B100) has been playing an important role in Brazilian energy matrix towards the national bio-based economy. Greenhouse gas (GHG) emissions is the most widely used indicator for assessing the environmental sustainability of biodiesels and received particular attention among decision makers in business and politics, as well as consumers. Former studies have been mainly focused on the GHG emissions from the soybean cultivation, excluding other stages of the biodiesel production. Here, we present a holistic view of the total GHG emissions in four life cycle stages for soybean biodiesel. The aim of this study was to assess the GHG emissions of Brazilian soybean biodiesel production system with an integrated life cycle approach of four stages: agriculture, extraction, production and distribution. Allocation of mass and energy was applied and special attention was paid to the integrated and non-integrated industrial production chain. The results indicated that the largest source of GHG emissions, among four life cycle stages, is the agricultural stage (42-51%) for B100 produced in integrated systems and the production stage (46-52%) for B100 produced in non-integrated systems. Integration of industrial units resulted in significant reduction in life cycle GHG emissions. Without the consideration of LUC and assuming biogenic CO2 emissions is carbon neutral in our study, the calculated life cycle GHG emissions for domestic soybean biodiesel varied from 23.1 to 25.8 gCO2eq. MJ-1 B100 and those for soybean biodiesel exported to EU ranged from 26.5 to 29.2 gCO2eq. MJ-1 B100, which represent reductions by 65% up to 72% (depending on the delivery route) of GHG emissions compared with the EU benchmark for diesel fuel. Our findings from a life cycle perspective contributed to identify the major GHG sources in Brazilian soybean biodiesel production system and they can be used to guide mitigation priority for policy and decision-making. Projected scenarios in this study would be taken as references for accounting the environmental sustainability of soybean biodiesel within a domestic and global level

Schematic representation of the four pathways for distribution of final B100.

<p>Schematic representation of the four pathways for distribution of final B100.</p

Main inputs and yield per hectare of soybean in Mato Grosso state, Brazil (growing season of 2007/08, 2008/09 and 2009/10).

<p>Main inputs and yield per hectare of soybean in Mato Grosso state, Brazil (growing season of 2007/08, 2008/09 and 2009/10).</p

Summary of conversion factors used in this study.

<p>Summary of conversion factors used in this study.</p

Life cycle of soybean biodiesel produced in Brazil, highlighting GHG emission sources within the four stages: agriculture, extraction, biodiesel production and distribution.

<p>Life cycle of soybean biodiesel produced in Brazil, highlighting GHG emission sources within the four stages: agriculture, extraction, biodiesel production and distribution.</p

Life cycle GHG emission of biodiesel production, considering a domestic B100 scenario (MT-PA) and an exported B100 scenario (MT-EU).

<p>Life cycle GHG emission of biodiesel production, considering a domestic B100 scenario (MT-PA) and an exported B100 scenario (MT-EU).</p

Relative share of GHG emissions in each stage (agriculture, extraction, biodiesel production and distribution) for B100 produced from integrated and non-integrated plant considering the MT-PA and MT-EU scenarios.

<p>Relative share of GHG emissions in each stage (agriculture, extraction, biodiesel production and distribution) for B100 produced from integrated and non-integrated plant considering the MT-PA and MT-EU scenarios.</p

Life cycle GHG emission of B100 based on four different transportation routes.

<p>Life cycle GHG emission of B100 based on four different transportation routes.</p