Evaluation And Prediction Of Biomass Energy Potential In China Based On Time Series Data

Nowadays,the world is faced with the double pressures of fossil energy exhaustion and environmental pollution.It is the time for renewable energy to replace fossil energy while biomass energy plays an important role.Bioenergy has the characteristics of green,low-carbon,clean and renewable.China produces a large number of crop straw,excrement of animals,agricultural product processing residues,living organic wastes and other biowastes every year.Clarifying the situation of biomass resources is the foundation of developing biomass industry together with the reasonable estimation and prediction of biomass energy potential and comprehensive benefits are conducive to the development and utilization of biomass resources,effectively promote energy production,improve environmental quality,relieve the pressure of fossil energy depletion,and achieve sustainable development of environment and economy.Based on the data of China Statistical Yearbook and so on from 1991 to 2020,this study quantitatively estimated the biomass resources of crop straw,agricultural product processing residues,excrement of animals,catering waste oil,municipal household waste and industrial wastewater/domestic sewage.The energy supply potential of these bioresources were predicted through grey model,time series model,neural network model and combined model.Furthermore,the emission reduction and fertilizer benefits were analyzed.The purpose of the present study is to provide scientific basis for the policy formulation and industrial distribution of the biomass energy.The main conclusions are shown as follows:(1)The biomass resources in China are highly collectible with strong supply capacity.From 1991 to 2020,the average standard coal quantity of biomass resources in China was 902.55 million tons,which reached 947.62 million tons in 2020.In 2020,the six types of biomass resources followed the order of excrement of animals>crop straw>agricultural product processing residues>industrial wastewater/domestic sewage>urban household waste>catering waste oil which accounted for 60.8%,29.3%,6.1%,0.4%,0.3%and 0.3%of the total bioresources respectively.The amount of standard coal quantity converted from crop straw and excrement of animals accounted for 91.1%of the total bioresources.(2)The combined model EMD-NAR-ARIMA was applicable to predict the total standard coal quantity of biomass resources in China.The MAPE and MSE of the EMDNAR-ARIMA combined model were both smallest when comparing to the gray model,time series model,neural network model,ARIMA-NAR model and the sum of the fitting results of each biomass resources.According to the prediction,the national biomass resources discount standard coal amount in 2025 and 2030 will be 887.23 and 878.69 million tons,decreasing by 6.3%and 7.3%compared with 2020,respectively.(3)The comprehensive utilization rate of agricultural waste such as crop straw and excrement of animals was constantly improving.From 1991 to 2020,the average nutrient amounts of N,P and K brought by crop straw and excrement of animals as fertilizer raw materials were 1138.5,430.8 and 11.005 million tons,respectively.In 2020,the N,P and K fertilizers produced by main crop straw were 2.898,1.178 and 4.419 million tons respectively,accounting for 15.8%,18.0%and 81.5%of the actual application amount of N,P and K fertilizer in China.N,P and K fertilizer produced by the composting of collectable excrement of animals were 3.32,1.160 and 1.920 million tons,accounting for 18.2%,17.7%and 35.5%of the actual N,P and K fertilizer application,respectively.From 2021 to 2030,the proportion of crop straw and excrement of animals that can be collected for biomass fuel production will continuously rise.The emission reduction benefits of crop straw and excrement of animals can be predicted by grey model and neural network model respectively.They are expected to bring a total of 79699.3 and 101.135 million tons of CO2 emission reduction benefits in 2025 and 2030,respectively.When China reaches the"carbon peak" in 2030,the CO2 emission reduction benefit brought by the utilization of biomass waste will account for 0.82～0.98%of the total CO2 emission.Based on long term large-scale statistical data,this study clarified the situation of biomass resources and total energy supply capacity in China by estimating all kinds of biomass resources using the unified measurement i.e.discount standard coal amount.Grey model,time series model,neural network model and combined model were used to predict the bioenergy potential.The environmental and fertilizer benefits generated by the utilization of agricultural residues as well as their contributions to carbon emission reduction were analyzed.Th results of the present study are expected to provide theoretical basis for rational development and utilization of biomass resources.