Life cycle assessment of sugarcane ethanol production in India in comparison to Brazil

Abstract

India’s biofuel programme relies on ethanol production from sugarcane molasses. However, there is limited insight on environmental impacts across the Indian ethanol production chain. This study closes this gap by assessing the environmental impacts of ethanol production from sugarcane molasses in Uttar Pradesh, India. A comparative analysis with south-central Brazilian sugarcane ethanol is also presented to compare the performance of sugarcane molasses-based ethanol with sugarcane juice-based ethanol. Methods The production process is assessed by a cradle-togate life cycle assessment. The multifunctionality problem is solved by applying two variants of system expansion and economic allocation. Environmental impacts are assessed with Impact 2002+ and results are presented at the midpoint level for greenhouse gas emissions, non-renewable energy use, freshwater eutrophication and water use. Furthermore, results include impacts on human health and ecosystem quality at the damage level. Sensitivity analysis is also performed on key contributing parameters such as pesticides, stillage treatment and irrigation water use. Results and discussion It is found that, compared to Brazilian ethanol, Indian ethanol causes lower or comparable greenhouse gas emissions (0.09–0.64 kgCO2eq/kgethanolIN, 0.46–0.63 kgCO2eq/kgethanolBR), non-renewable energy use (−0.3–6.3 MJ/kgethanolIN, 1–4MJ/kgethanolBR), human health impacts (3.6·10−6 DALY/kgethanolIN, 4·10−6 DALY/kgethanolBR) and ecosystem impairment (2.5 PDF·m2·year/kgethanolIN, 3.3 PDF·m2·year/kgethanolBR). One reason is that Indian ethanol is exclusively produced from molasses, a co-product of sugar production, resulting in allocation of the environmental burden. Additionally, Indian sugar mills and distilleries produce surplus electricity for which they receive credits for displacing grid electricity of relatively high CO2 emission intensity. When economic allocation is applied, the greenhouse gas emissions for Indian and Brazilian ethanol are comparable. Non-renewable energy use is higher for Indian ethanol, primarily due to energy requirements for irrigation. For water use and related impacts, Indian ethanol scores worse due groundwater irrigation, despite the dampening effect of allocation. The variation on greenhouse gas emissions and non-renewable energy use of Indian ills is much larger for high and low performance than the respective systems in Brazil. Conclusions Important measures can be taken across the production chain to improve the environmental performance of Indian ethanol production (e.g. avoiding the use of specific pesticides, avoiding the disposal of untreated stillage, transition to water efficient crops). However, to meet the targets of the Indian ethanol blending programme, displacement effects are likely to occur in countries which export ethanol. To assess such effects, a consequential study needs to be prepared

Life cycle impact assessment of bio-based plastics from sugarcane ethanol

“…The production chain of ethanol in Brazil and India is described in detail in Tsiropoulos et al (2014). This section focuses on main differences between ethanol production in south-central Brazil and Uttar Pradesh, India.…”

“…For production of sugarcane ethanol we use cradle-to-gate results from our previous study, which focused on the comparison of Brazilian and Indian ethanol (Tsiropoulos et al, 2014). For conversion of ethanol to bio-ethylene in Brazil, data from technology licensors are used.…”

“…In the Indian ethanol product-system we are faced with the multifunctionality problem due to co-production of sugar and molasses. To account for these outputs we apply four different allocation approaches, which are explained in Tsiropoulos et al (2014). An overview is presented in Table 2.…”

“…2 and 3) should be compared with gross emissions of the petrochemical counterpart (shaded stacked bars, excluding end-of-life). Next to the base case ('Net') the graph shows high and low performance cases for mills and distilleries with high surplus electricity versus no surplus electricity and dependency on the grid based on Tsiropoulos et al (2014). Figs.…”

“…Brazil: ethanol 97.5%, electricity 2%, bagasse 0.5% India: sugar 85%, molasses 7.5%, bagasse 0.5% a In the system expansion approaches process electricity input in the foreground system and energy intensive material inputs has the same emission intensity with surplus electricity. Tsiropoulos et al (2014) present results for one economic allocation approach in which process electricity is supplied from the national grid. In this study we extend the analysis by assuming a) process electricity for bio-ethylene from the national grid and for bio-MEG from the regional grid in Uttar Pradesh (EA-C) and b) process electricity for bio-ethylene from natural gas and for bio-MEG from the national Indian grid (EA-O production, transport of bio-MEG from India to Europe, 12 PTA production and polymerisation to bio-PET in Europe.…”