Life cycle analysis of renewable natural gas and lactic acid production from waste feedstocks

JOURNAL OF CLEANER PRODUCTION

卷:311

Article

Lee, Uisung¹  Bhatt, Arpit²  Hawkins, Troy Robert¹  Tao, Ling³  Benavides, Pahola Thathiana¹  Wang, Michael¹ 

[1] Syst Assessment Ctr, Div Energy Syst, Argonne Natl Lab, 9700 South Cass Ave, Lemont, IL 60439 USA

[2] Strateg Energy Anal Ctr, Natl Renewable Energy Lab, Golden, CO 80401 USA

[3] Natl Renewable Energy Lab, Natl Bioenergy Ctr, Golden, CO 80401 USA

关键词: Renewable natural gas;    Lactic acid;    Waste;    Life cycle analysis;    Greenhouse gas emissions;    Anaerobic digestion;    Lactic acid fermentation;    Carbon intensity;   

DOI  :  10.1016/j.jclepro.2021.127653

来源: Elsevier

【 摘 要 】

Producing fuels and chemicals from waste is considered economically favorable, due to low feedstock cost, and environmentally favorable, due to avoided emissions from conventional waste management practices. In this study, we evaluate the life cycle greenhouse gas (GHG) emission reduction benefits of renewable natural gas (RNG) and lactic acid (LA) production from four types of wet waste feedstocks (wastewater sludge, food waste, swine manure, and fats, oil, and grease [FOG]) via anaerobic digestion (AD) and LA fermentation, respectively. RNG can be used as an alternative to fossil natural gas, while LA from waste feedstocks can displace conventional LA production pathways (mainly from corn via fermentation). Providing comprehensive life cycle GHG emissions of the combinations of waste feedstocks and products through different routes helps identify the GHG hotspots and show where emissions savings come from. The results show that the carbon intensities (CIs) of waste-derived RNG and LA are much lower than those of their counterparts. We estimated the life cycle GHG emissions for RNG to be between -146 and 27 g carbon dioxide equivalent (CO2e)/MJ, much lower than the CI of fossil fuels. Waste-derived LA pathways also show substantially lower CIs, ranging from -4.2 to -1.4 kgCO2e/kg LA, compared to the CIs of LA from corn and corn stover (1.2 and 0.3 kgCO2e/kg LA, respectively). We will also discuss that the low CIs of waste-derived products can come from low yields leading to high emission credits. Thus, life cycle analysis results presented per weight of treated waste can be used to support decisions about which waste feedstocks and products are to be used for sustainable waste valorization. In addition, we found that monetary emission reduction credits can play an important role in driving waste valorization.

【 授权许可】

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