Production and use of biogas from vinasse: Implications for the energy balance and GHG emissions of sugar cane ethanol in the brazilian context

Abstract

Indicators, such as the energy balance (EB) and greenhouse gases emissions avoided (GHGEA), are frequently used to evaluate the benefits and sustainability of biofuels. Many important papers and reports have been published in recent years to demonstrate the environmental and energetic benefits of biofuels, such as ethanol from sugar cane. EB and GHGEA often include other sugar cane products, such as electricity and bagasse. The anaerobic digestion of vinasse can generate considerable amounts of biogas but is not a common practice in Brazil. This study evaluates the potential benefits to the EB and GHGEA of ethanol by the production of biogas from vinasse and its use to produce electricity or biomethane. Biomethane can be injected on the Natural Gas Grid or used as a fossil diesel oil replacement in the mill operations of harvesting and transportation of sugar cane. The results show that biogas from vinasse can represent improvement in both indicators, which ranges from 3.5% improvement in EB by electricity generation with biogas to 27.5% improvement in GHGEA by replacing diesel in the mill operations. © 2019 American Institute of Chemical Engineers Environ Prog,39:e13226, 2020

A spatially explicit assessment of sugarcane vinasse as a sustainable by-product

“…Besides the fossil energy replacement in ARC, a GIS study case, like the one here presented, contributes to a better environmental management and the development of new policies to address the sugarcane residues. Although vinasse and biogas conversion into electricity and biomethane are not standard practices in Brazil, the AD technology presents an outstanding potential to improve the environmental and energetic sugarcane chain operation ( da Silva Neto et al, 2020 ). Furthermore, other industries and countries present successful experiences with AD commercial technologies to support a broad adoption of vinasse AD, biogas use and biodigested application in the sugarcane Brazilian production chain.…”

“…Among the agro-industrial by-products, vinasse generated during the ethanol distillation process after the fermentation of sugarcane juice is especially interesting. Energy recovery from the anaerobic digestion (AD) of vinasse can reduce greenhouse gases (GHG) emissions and may produce positive impacts on socioeconomic regional, and local levels ( Dias et al, 2013 ; Ekman et al, 2013 ; Moraes et al, 2014 ; Leme and Seabra, 2016 ; Fuess et al, 2018a ; da Silva Neto et al, 2020 ).…”

“…AD of vinasse is relevant from the economic, energetic, and environmental perspectives ( Leme and Seabra, 2016 ; Parsaee et al, 2019 ; da Silva Neto et al, 2020 ). Biogas has high heat content from the energy side and can be used as fuel for electric energy generation or heat for boilers in production processes.…”

“…Despite there are various possibilities for different agro-industrial AD arrangements and specific project requirements (depending on climate and substrate characterization among other features), biogas versatility figures as a promising solution to the Brazilian biofuel industry ( da Silva Neto et al, 2020 ). AD is efficient in reducing the organic load of vinasse, reaching more than 85% of reduction depending on the reactor technology ( Moraes et al, 2014 ).…”

“…It also optimizes bioenergy recovery from biogas, reaching over 30% of electric energy surplus, enhancing both the environmental and economic aspects ( Fuess et al, 2018b ). Moreover, AD technology might provide outstanding GHG mitigation, close to 48%, when biodigested vinasse is applied before its storage and transportation to soil disposal ( Moraes et al, 2017 ), and as much as 27% when biomethane replaces diesel in a given scenario recently assessed by da Silva Neto et al (2020) .…”