| The rural biogas project shoulders the heavy responsibility of ecological civilization construction in the rural revitalization,which has multiple functions including saving energy,reducing emission,and promoting the green development of agriculture.However,inefficient energy development efficiency has made the development of rural biogas projects in China enter a bottleneck period.In 2015,the state put forward the direction of transformation and upgrading of rural biogas industry,but the transformation results are not optimistic.Exploring the spatial and temporal differences of rural biogas projects of different scales and the energy development efficiency and influencing factors of regional rural biogas projects is of scientific significance for understanding the regional development of rural biogas projects in China,and can provide policy support for the sustainable development of rural biogas projects in China.However,there is a lack of systematic research on the spatial and temporal differences of rural biogas projects of different scales,the energy development efficiency of regional rural biogas projects and the configuration of influencing factors.Based on this,this study focuses on rural biogas projects in China,and analyzes the development status of China’s biogas industry through literature and statistical data.The temporal and spatial differences of rural biogas projects of different scales are analyzed.Then the energy development efficiency of regional rural biogas project is evaluated.The configuration factors that affect the energy development efficiency of biogas project are analyzed.Finally,under the background of dual-carbon strategy and rural revitalization,the transformation path of China’s biogas industry of"2030-2060"is discussed.The main results are as follows:(1)The transformation and upgrading of biogas projects has a certain effect,and biogas projects are developing in the direction of large-scale.However,in terms of volume gas production rate,only large biogas projects have significantly improved.The total gas production of rural biogas projects accounted for the proportion of total gas production of rural biogas from 4.1%in 2006 to 23.11%in 2018,and rural biogas projects have gradually become the leading biogas industry.Large-scale is the main direction of biogas engineering transformation.In terms of average pool capacity,the average pool capacity of total biogas engineering,industrial biogas engineering,rural biogas engineering,large and extra-large biogas engineering,large biogas engineering,small and medium-sized biogas engineering,medium-sized biogas engineering and small biogas engineering during2011-2018 is compared with the average pool capacity during 2006-2010.The growth rates were 34.43%,42.33%,45.43%,41.79%,29.38%,184.31%,51.54%,81.60%,indicating that biogas projects were shifting towards large-scale,and the changes of small and medium-sized biogas projects were the most obvious.In terms of volumetric gas production rate,the volumetric gas production rate of rural biogas projects,small and medium-sized biogas projects,medium-sized biogas projects and small biogas projects had no significant difference from that of 2006 to 2010 during 2011-2018,but the volumetric gas production rate of large biogas projects had a significant increase,with an increase rate of 19.05%.This indicates that not only the pool capacity of large-scale biogas projects is increasing,but also the overall gas production efficiency is improving.In addition,the volume gas production rate of all scales is lower than the volume gas production rate standard in NY/T 667-2011,indicating that there are widespread technical defects in the gas production of China’s biogas projects.(2)Different regions have obvious tendencies for the construction of biogas projects of different scales,and the southern regions or regions with better integration of agriculture and animal husbandry are more active in large-scale biogas projects;In areas where large-scale biogas projects are more active,the gas production efficiency of biogas projects is higher.By comparing the spatial differences of different scale of biogas projects in China,it is found that the average pool capacity of biogas projects in all regions increased from 2011 to2018 compared with that in 2006 to 2010.Taking rural biogas projects as an example,the average pool capacity of rural biogas projects in South China increased by 59.51%to 257.42m~3;The average pool capacity of rural biogas projects in North China increased by 57.64%to 231.89 m~3.The average pool capacity of rural biogas projects in central China increased by 57.30%to 103.18 m~3.The average pool capacity of rural biogas projects in East China increased by 36.31%to 158.95 m~3.The average pool capacity of rural biogas projects in southwest China increased by 25.47%to 219.67 m~3;The average pool capacity of rural biogas projects in northwest China increased by 12.69%to 222.67 m~3.The average pool capacity of rural biogas projects in Northeast China increased by 3.84%to 281.09 m~3;It shows the difference in the development of biogas projects in different regions.In terms of volume gas production rate,the volume gas production rate of rural biogas project is the highest in North China,which is 0.49 m~3/(m~3·d).The average volume gas production rate of large biogas projects was the highest in North China(0.72 m~3/(m~3·d))and the lowest in Northwest China(0.27 m~3/(m~3·d).The lowest value was 0.22m3/(m~3·d)in Northeast China.The average volume gas production rate of medium-sized biogas projects is the highest in North China,reaching 0.55 m~3/(m~3·d),which is the only area that exceeds 0.5 m~3/(m~3·d)in medium-sized biogas projects.The lowest value was 0.15 m~3/(m~3·d)in Central China.The average volume gas production rate of small-scale biogas projects is the highest in South China,reaching 0.28 m~3/(m~3·d),and more than 0.25 m~3/(m~3·d)in North China and South China.The lowest value was 0.11 m~3/(m~3·d)in northwest China.The above results show the difference of gas production efficiency of large-scale biogas projects in different regions.(3)The proportion of primary industry,urbanization rate,average temperature,per capita GDP and per capita electricity generation all affect the energy development efficiency of rural biogas projects;The energy development efficiency of rural biogas projects did not improve from 2011 to 2018,and scale efficiency is the main factor restricting the energy development efficiency of rural biogas projects.Three-stage DEA was used to evaluate the energy development efficiency of rural biogas projects.With the number of rural biogas projects,government investment and cumulative installed power generation capacity as inputs,and the total amount of rural biogas gas production and power generation as outputs,the adjusted DEA of the third stage was 18.56%lower than that of the first stage,and the results were very different.The environmental factors and statistical noise adjusted by stochastic frontier model have significant effects on the energy development efficiency of rural biogas projects.Therefore,the results of the third phase should be used to analyze performance evaluation and improvement strategies in each region.Compared with Chen Yu’s plan on the suitability of rural household use zoning in China and the"13th Five-Year Plan for the Development of Rural Biogas",the ranking of energy development efficiency in the third stage is more reasonable.From the perspective of the Malmquist index model,which reflects dynamic changes,the overall growth rate of the total factor productivity of rural biogas engineering capacity in China from 2011 to 2018 is not stable enough,and the overall trend is negative.Scale efficiency is the biggest constraint factor for the development of total factor productivity,which is consistent with the results of the third stage DEA model.(4)The way of high energy development efficiency of rural biogas project mainly consists of reasonable breeding structure and planting structure,and the combination of planting and cultivation is the condition of high energy development efficiency of rural biogas project;Large-scale farms are the more core conditions for the high energy development efficiency of rural biogas projects.It is explored that the development efficiency of rural biogas projects is affected by the relative external environmental factors in each region.This study takes the results of the third stage DEA as the result variable,and considers from six dimensions:management strategy,aquaculture structure,planting demand,renewable energy ratio,scientific and technological input,and environmental protection input.According to the analysis of system configuration,no single condition is sufficient and necessary for high energy development efficiency.All the high energy development efficiency configurations were in the form of configuration,including reasonable breeding structure and reasonable planting structure.32.6%of the high energy development efficiency configurations were simple cultivation driven,and 24.2%were government-led cultivation driven.According to the panel qualitative comparative analysis(QCA)results,at this stage,the scale of farming structure is more important for the high energy development efficiency of rural biogas projects.(5)According to the pressure on the stable system of China’s biogas industry,the transformation path of China’s biogas engineering is prospected in combination with the dual carbon strategy.The scale of farming structure is very important for the high energy development efficiency of rural biogas projects.How the farming structure affects the biogas projects is explored.According to the transformation pathway theory,the functional vision of biogas and the basic situation of the niche market of biogas industry in China,the function of biogas production technology based on anaerobic digestion is divided into four categories of expectations:waste management,resource utilization,energy recovery and climate benefit.The results of this study indicate that China’s biogas needs to consider the transformation path before 2030 to develop a sustainable multi-functional combination at this stage;We will need to take a refactoring path between 2030 and 2050,experimenting with different functional combinations on a large scale.Take the technology alternative path in 2050 and promote the full functional portfolio.To sum up,this study found that all kinds of rural biogas projects are transforming to large-scale,but there are generally defects in technology.Reasonable breeding structure is an important way to promote the energy development efficiency of regional rural biogas projects.China’s rural biogas industry should not be too dependent on the single function of energy recovery.In the future,it is necessary to establish a multi-functional combination including nutrient recovery,pollution reduction and carbon reduction. |
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