Search

Plastics account for 4.5% of global greenhouse gas (GHG) emissions, which are hard-to-abate due to the use of fossil fuels as feedstock. Our study develops a cradle-to-gate life cycle assessment of bioethylene production, exploring 33 pathways across Brazil, the EU, and the US. It aims to understand whether substituting fossil-based ethylene with bioethylene contributes to lowering carbon emissions, and in which of the relevant bioenergy-producing regions/countries the valorisation of biofuels as feedstocks would provide a less carbon-intensive bioethylene production. Results indicate that bioethylene production through catalytic dehydration of sugarcane bioethanol in Brazil presents lowest GHG emission. This pathway could deliver up to −2.1 kg CO 2 e/kg ethylene when accounting for biogenic carbon storage in long-lived applications such as infrastructure. In contrast, beef tallow performs the poorest as a raw material, regardless of whether land-use change (LUC) emissions are considered. When biogenic carbon storage is factored out, none of the pathways outperforms conventional fossil-based steam cracking; however, some are within the fossil-based range indicating potential indirect benefits through reduced refinery utilisation. Our study underscores that biomaterials production as a climate mitigation strategy must be on par with circular economy measures and the conservation of native forestry ecosystems. These results are particularly relevant to policymakers and industries seeking to align polymer manufacturing with sustainability objectives. • Bio-ethylene cradle-to-gate GHG emissions were assessed for 33 pathways. • Sugary, starch, lignocellulosic and oily crops are raw materials for bio-ethylene. • Local specificities such as biogenic carbon storage and land-use are critical to LCA GHG emissions. • Sugarcane bioethanol dehydration route yielded 2.1 kgCO 2 e captured per of kg ethylene. • Climate mitigation and circular economy policies must be designed coherently. [ABSTRACT FROM AUTHOR]

Future projections indicate an expansion for both food and energy demands, which can increase pressure on land use, while there is an urgent global need for climate change mitigation. Bioenergy is foreseen as key option to meet future energy demands and reduce greenhouse gas (GHG) emissions, however its sustainability depends on locations and regional characteristics. Simultaneously, agricultural production models that co-produce food, feed, and energy offer sustainability synergies and co-benefits, but site-specific sustainability assessments of their large-scale implementation are missing. This study presents a bottom-up approach to assess spatially explicit sustainability aspects of bioenergy-livestock integrated systems (BLI) in Brazil and shed light on their contribution to future energy demands, to climate change mitigation targets, and their impacts on selected ecosystem services, including bioenergy production, climate change mitigation, reduction of food competition, biodiversity conservation, and avoided deforestation. The proposed integration considers livestock intensification and use of biofuels by-products as animal feed supplement, taking advantage of synergies between these two value chains. The expansion of the BLI system in the Center-South region of Brazil produce up to 89 billion liters of ethanol, enough to meet future domestic ethanol demands from multiple shared socioeconomic pathways and generating surpluses for export. This production takes place on 16 million hectares of pastureland within the Sugarcane Agroecological Zoning, excluding the Amazon and Pantanal biomes, and biodiversity hotspots. BLI expansion mitigate up to 250 million tonnes of CO 2 eq and generate 15 billion dollars of profits. The best locations to maximize the selected ecosystem services are west of São Paulo, east of Mato Grosso do Sul, and the south-central region of the states of Goiás. This study may encourage the formulation of enhanced public policies for the integration of bioenergy and livestock value chains and guide a sustainable large-scale deployment of BLI systems. • Bioenergy and livestock integration (BLI): co-production of food, feed and energy. • BLI systems: 89 billion liters of ethanol and 250 million tonnes of CO 2 eq mitigated. • Enough ethanol to meet future Brazilian demands and surplus to be exported. • Biomass expansion only on pastureland inside Sugarcane Agroecological Zoning. • Without land displacement and deforestation of native vegetation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon sequestration potential of the clay fraction. • Determination of the carbon saturation deficit of each mineral of the clay fraction. • Identification of the equation for the prediction of carbon sequestration potential. • Identification of land uses with the greatest carbon sequestration potential. The capacity of soil to sequester carbon (C) is a key process that promotes the reduction of CO 2 in the atmosphere. Soils can absorb as much as 20% of anthropogenic carbon emissions, which can contribute to mitigate climate change. This capacity relies on the organo-mineral association, which includes different minerals, Fe and Al oxides, which have a critical soil organic carbon (SOC) sorption surface. Based on an equation of the potential C saturation deficit of fine soil particles (<20 μm/silt and clay fractions) for tropical regions, this study investigated the SOC sequestration potential of the clay fraction for soils in Piracicaba region, São Paulo State, Brazil as influenced by the clay minerals. This potential was fitted to a spatial regression model for soil depths 0–20 cm and 80 to 100 cm. In the surface layer, the sequestration potential was mostly explained by the relative abundance of soil minerals (Kaolinite, Hematite, Goethite and Gibbsite) determined using vis-NIR-SWIR spectroscopy. A direct relationship was observed with Goethite and Gibbsite, indicating that low concentrations would reduce the sequestration potential. At 80 to 100 cm depth, Kaolinite and Hematite explained most variation in SOC sequestration potential. Additionally, the C associated with the mineral fraction and the C saturation potential as a function of minerals were modeled and a strong importance of hematite in the C sequestration and stabilization cycle was identified at both depths. The individual mineral contribution to SOC sequestration potential was also mapped, which identified high contributions of goethite and gibbsite for deep soil layers. The influence of land use on the carbon sequestration potential of minerals was observed, with the greatest potential being found in areas with pasture and cropping mosaics and grassland and forest mosaics, with a high presence of kaolinite and hematite. These minerals have a greater potential for carbon sequestration at greater depths and, therefore, could be critical in climate change mitigation strategies. [ABSTRACT FROM AUTHOR]

Bioenergy production from sugarcane can be one of the sustainable means of mitigating climate change. This was the central idea of the Conference, "Carbon Balance in the Sugar-Energy Sector," held in Brazil on September 14, 2021. The various panels showed that sugarcane stakeholders, including scientists, farmers, industrialists, and investors, are committed to making large-scale sugarcane production a key ingredient in the mitigation of climate change. Their strategies include sustainable land use and management practices to increase soil carbon sequestration; the large-scale production of biofuel, bioelectricity and bioproducts; negative emission industrial technologies; industrial waste recycling; and sector-specific policies rewarding farmers with carbon credits for avoided greenhouse gas emissions. Therefore, the sugarcane sector is not only key to promoting the social-economic development of Brazil, but also to promoting energy transition, curbing greenhouse gas emissions and consequently, reducing global warming and climate change. • Conference Report: 2021 Carbon balance in the sugar-energy sector. • Carbon Balance in the Sugar-Energy Sector 2021 Conference held by Luiz de Queiroz College of Agriculture (Esalq), University of São Paulo (USP), Piracicaba-SP, Brazil on September 14, 2021. • Sugarcane-derived bioenergy is a key ingredient in fighting climate change while simultaneously maintaining a balanced ecosystem (including enhanced soil health and increased capacity to sequester carbon) and promoting socio-economic development [ABSTRACT FROM AUTHOR]

This study aims to quantify the environmentally sustainable and economically feasible potentials of agricultural and agro-industrial residues to generate electricity via direct combustion in centralised power plants in Brazil. Further, the energy savings and greenhouse gas (GHG) reduction potential of replacing natural gas-based electricity by bioenergy have been assessed. To this end, a methodology has been developed based on an integrated evaluation, incorporating statistical and geographical information system (GIS)-based analysis, and a life-cycle-assessment approach. Results reveal that the environmentally sustainable generation potential is nearly 141 TWh/year, mainly concentrated in the South, Southeast, and Midwest regions of the country. Sugarcane, soybean and maize crop residues are the major feedstocks for available bioenergy. On the other hand, the economic potential is far lower, accounting to 39 TWh/year. The total GHG mitigation is nearly 18 million tonne CO 2 e and could reach 64 million tonne CO 2 e yearly, if the technical potential is considered. The gap between technical and economic potentials implies that constraints to bioenergy are not related to a lack of resources, but rather associated to economic, logistical, regulatory and political barriers. [ABSTRACT FROM AUTHOR]

Through its NDC, Brazil pledged to reduce its GHG emissions by 43% below 2005 levels in 2030, respectively. Carbon pricing could play a key role in meeting this objective. However, a range of issues can emerge when introducing it. Among these issues, the distributional impact has been frequently highlighted as an obstacle to the public acceptance of such a mitigation policy. This paper examines the short-run welfare and emission effects of an economy-wide carbon tax on Brazilian households. The distributional impact is examined by estimating the tax burden relative to annual expenditures and changes in total GHG emissions across income levels, using tax rates consistent with the Paris Agreement and considering a lump-sum rebate that keeps the government revenue neutral. For this, we calculate energy-related GHG emissions coefficients from fossil fuel burning for the whole household consumption basket, and price and expenditure elasticities which account for the zero-expenditure and underdeclaration problems. Our results indicate that the incidence of the carbon tax is effective in reducing emissions in the short run, but imposes welfare losses, especially on the poor. The consideration of compensation mechanisms is critical when designing this type of environmental tax, specially in the context of a highly complex tax-system. [ABSTRACT FROM AUTHOR]

Biofuels are predicted to constitute a large proportion of fuel consumption in the global transport sector under stringent climate mitigation polices in future. In Brazil, sugarcane ethanol has been widely deployed at large scale and an oriented expansion of sugarcane is considered to be a key measure to ensure the expected positive outcomes from biofuels. In this study, more recent and accurate georeferenced information were combined with an enhanced land use classification system to update the original Sugarcane Agroecological Zoning (SAEZ). We also excluded environmentally relevant areas (ERA) in our updated SAEZ to create a new set of reference maps for supporting future prioritization of areas for sugarcane ethanol expansion. We mapped 41.7 Mha as suitable land for sugarcane expansion in center-south region of Brazil, differently from the 50 Mha indicated in the original SAEZ. After excluding the ERA, 33.7 Mha was found to be suitable for sugarcane expansion, of which 20 Mha is currently occupied with pasture lands. About half of these areas were located in Mato Grosso do Sul and Minas Gerais states and an exploratory assessment of two microregions from these states demonstrated the importance of conducting regional assessments to prioritize the areas for a more sustainable sugarcane expansion to meet future bioenergy demands. • Our analysis identified an area 17% smaller than original agro-ecological zoning suitable for sugarcane expansion. • By excluding environmentally relevant areas, the total suitable area for sugarcane expansion is reduced to 33.7 Mha. • About two thirds of that area is currently occupied with pasture lands. • About half of suitable areas occupied with pasture lands are in two Brazilian states. • Local conditions are fundamental for oriented expansion of bioenergy production. [ABSTRACT FROM AUTHOR]

Enhanced weathering is a simple and scalable negative emissions technology with an estimated carbon dioxide removal potential of multiple gigatons per year. To date, the only life-cycle assessment of enhanced weathering was published by Lefebvre et al. (2019) in this journal. They estimated the carbon dioxide removal potential in Sao Paolo State in Brazil to be 1.3–2.4 Mt/y, examined the penalty from transportation greenhouse gas emissions, and pointed out that using life-cycle assessment can give more reliable estimates of climate change mitigation potential of enhanced weathering systems. In this letter, we discuss the limitations of life-cycle assessment of enhanced weathering, and then propose a more comprehensive life-cycle optimization approach, where the system configuration can be automatically synthesized to maximize environmental performance. This concept can be extended further to life-cycle sustainability optimization by including economic and social dimensions. • The first life cycle assessment of enhanced weathering was reported in 2019. • Life cycle optimization and life cycle sustainability assessment are also needed. • A combined life cycle sustainability optimization framework should be developed. • Hybrid models can be used to address future issues in enhanced weathering. [ABSTRACT FROM AUTHOR]

Agriculture provides an array of ecosystem services including the sequestration and storage of carbon in the biomass of plants. Research has focused on commercial crops, especially tree crops, for their potential to mitigate the impacts of climate change. In Brazil interest is growing in the commercial cultivation of macauba (Acrocomia aculeata), a palm native to the tropical regions of the American continents with fruit that can be used as the primary ingredient in the production of oils and bioenergy. However, we did not find any prior studies that had assessed macauba's carbon sequestration potential nor any exploration in the literature of the income generation potential for commercial macauba producers to sell carbon credits. In order to understand opportunities to commercialize carbon credits from macauba, research was needed on the palm's long-term carbon sequestration and stock capacity. In this study we measured the accumulation of carbon in commercially cultivated macauba's biomass both below and above-ground using a selection of plants of different ages. An assessment was also made of the crop's potential to generate carbon credits. Macauba plants were sampled in a nursery with seedlings aged 3 and 8 months, and with more mature plants cultivated in fields aged 1.6, 4.8, and 9 years. The samples were fully harvested by complete removal (including roots and above ground structures), followed by separation, quantification and carbon analysis of the different plant biomass components. The data obtained allowed for estimating the production of carbon credits and the resulting annual income. Findings indicated a differential distribution of both biomass and carbon below and above-ground in field-cultivated macauba palms. The stock of carbon in the plants aged 9 years reached 61.6 t C ha−1 with a corresponding sequestration of 226.17 t CO 2 eq ha−1. The expected generation of carbon credits of palms from 1.6 to 9 years was 28.73 t CO 2 eq. ha− 1 per year, which could result in an annual gross income of € 761.06 per hectare. Significant amounts of stored carbon were found in both the above and below-ground biomass, suggesting that the macauba has significant potential to generate carbon credits and contribute to the mitigation of the effects of climate change. [ABSTRACT FROM AUTHOR]

Brazil is one of the world's major food-exporting countries that could be negatively impacted by climate change, and is also a leading greenhouse gas emitter through its agriculture. Crop diversification, as an agricultural practice, could lead to climate adaptation and mitigation. The aim of this study was to analyze the influence of climatic variability on categories of crop diversification so as to understand its role as an adaptive measure in response to climate change. An ordered probit model which allows for the separation of different categories of crop diversification was used for the 2006 period. The results showed that increases in temperature and precipitation did not affect each category in the same way. However, diversification intensity increases with climate variability: the greater the climate variability, the greater the likelihood of a municipality being in the very diversified category. Therefore, crop diversification appears as an adaptation strategy because it is influenced by climatic shocks. These results could be used to recommend Rural Extension programs to promote diversified systems as a resilient and cleaner type of agricultural production to improve climate risk management in Brazilian agriculture. [ABSTRACT FROM AUTHOR]