农业生物质能温室气体减排潜力

Potentiality of agricultural biomass energy for greenhouse gas emission reduction

中国拥有丰富的农作物秸秆和畜禽粪污等农业废弃物资源。农业生物质能技术是促进农业废弃物资源有效利用的重要途径,既能够解决农业废弃物的环境污染问题、减少因焚烧或无序堆放排放温室气体,又能够替代化石能源减排CO_(2)、提升土壤固碳能力,未来在“双碳”背景下发展潜力很大。该研究基于LCA全生命周期评价方法,研究8种不同生物质能技术的温室气体排放因子,核算农业生物质能转化与利用过程消耗能源的排放、抵扣化石能源减排、副产物土壤碳汇3个方面,并基于秸秆和畜禽粪污两大类农业废弃物资源禀赋及能源化利用潜力,预测3种不同情景下,农业生物质能替代化石能源的潜力,以及减排温室气体的贡献。结果表明,从减排因子看,热解炭气联产和规模化沼气/生物天然气技术的温室气体减排贡献最大。其次为成型燃料、捆烧供暖、生物质发电、炭化和燃料乙醇等技术,而户用沼气的减排贡献相对较小,8种不同生物质能技术的温室气体排放因子分别为-3.47、-3.20、-2.57、-2.63、-2.58、-2.48、-2.42 t/t(单位为标准CO2当量/标准煤当量);基于现有政策及规划情景、技术水平提升情景、能源需求结构变化情景等3种不同情景下,评价农业生物质能对温室气体减排贡献潜力。结果显示,2030年农业生物质能替代化石能源潜力为6490×10^(4)~7664×10^(4) t,温室气体减排贡献为1.97×10^(8)~2.34×10^(8) t;2060年替代化石能源潜力为9073×10^(4)~10763×10^(4) t,温室气体减排贡献为2.79×10^(8)~3.36×10^(8) t。该研究为实现农业农村领域碳达峰碳中和目标提供数据支撑。

Agricultural wastes are cost-effective,renewable,and abundant in China,such as crop straw and livestock manure.Biomass energy technologies can be widely utilized for the effective disposal of agricultural waste resources.The environmental pollution of agricultural wastes can be reduced by the emission of greenhouse gas(GHG),due to the traditiopnal incineration or disorderly stacking.It is also likely to replace fossil energy for much fewer CO2 emissions during soil carbon sequestration in the future.In this study,a systematic evaluation was made for the potential reduction in the GHG from the agriculture biomass energy,according to the“2006 IPCC Guidelines for National Greenhouse Gas Inventories”and the Life Cycle Assessment(LCA).The GHG emission factors were also calculated in the eight biomass energy technologies from the three scenarios,including the energy consumption emissions during the conversion and utilization of agricultural biomass energy,the deduction of fossil energy emissions reduction,and the carbon sinks of by-products to the soil.The potential of agricultural biomass energy to replace fossil energy and the contribution of GHG emission reduction were then predicted under three scenarios using the resource endowment and energy utilization of straw and livestock manure.The results showed that the largest contributions of GHG reduction were achieved by the pyrolysis of carbon gas for cogeneration,and large-scale biogas/biogas,followed by the molding fuels,bundle heating,biomass power generation,carbonization,and fuel ethanol.There was only a relatively small contribution of household biogas to the emissions reduction.The contributions of GHG emission reduction were 3.47,3.20,2.57,2.63,2.58,2.48,and 2.42 t/t for the eight technologies of biomass energy,respectively.The potential of agricultural biomass energy to the reduction of GHG emissions was evaluated under three scenarios,including the existing policies and planning,technological improvement,as well as the energy demand structure.It was found that the potential to replace fossil energy in 2030 and 2060 were 6490×10^(4)-7664×10^(4) t and 9073×10^(4)-10763×10^(4) t,respectively,where the contributions of GHG emission reduction were 1.97×10^(8)-2.34×10^(8) t and 2.79×10^(8)-3.35×10^(8) t,respectively.Based on the principle of agricultural waste priority,the energy utilization potential of agricultural waste was predicted conservatively.It is predicted that the energy utilization potential of crop straw in 2030 will be 1.2×10^(8) t,accounting for 13.3%of the total straw resources.The resource potential of energy utilization of livestock manure was 2.12×10^(8) t,accounting for 11.2%of the total resources of livestock manure.By 2060,the energy utilization potential of crop straw resources will remain stable,and the energy utilization amount of livestock manure will increase to 3.27×10^(8) t,accounting for about 15.3%of the total livestock manure.Agricultural biomass energy can not only replace fossil fuels as a clean and renewable energy,promote the reduction of energy carbon intensity,but also through the return of by-products to the field,improve soil carbon sink,achieve negative carbon emissions,GHG emission reduction potential is huge.The research provides data support for achieving the goals of carbon peak and carbon neutral in agriculture and rural areas.