Research On Resource Estimation, Distribution And Utilization Potential Of Crop Residue

Crop residues with tremendous nutrients are important resources and energy feedstock. China is a large agricultural country with abundant crop residues about800million tons (Mt) a year. However, waste of crop residue by openly burning emits air pollutant, harms human health and leads to serious resource waste. The rational use of crop residues can benefit to both reducing environmental pollution and to conserving natural resources. Therefore, the accuracy of quantifying the amount of crop residue and analyzing spatial distribution and estimating corresponding resource-energy potential are significant for further utilization of crop residues.Based on the statistics of23crops in overall342prefecture-level cities in China (i.e. approximate69,000production data) and2,123data of residue to production (i.e. R/G), the total quantity of crop residue in China was simulated by Monte Carlo method to estimate the total quantity of crop residue with uncertainty covered. Then, the average of simulation results were further used for estimating spatial distribution facilitated by high resolution image of cultivated land by Geographic Information System (GIS). The spatial distribution of crop residue was generated. Finally, the grey forecasting method was used to evaluate resource potential of crop residues in the future, on which the related suggestions for comprehensive use of straw were put forward. All the research conclusions are as follows.(1) From the year of1949-2009, the overall production of crop residue in China quadrupled rising from157Mt to802Mt. In2009, the average estimated resources of crop residue is802Mt with95%CI of679-947Mt. By comparing with the previous ten estimate by using single coefficient of R/G for each crop, the estimate result of our study with uncertainty by Monte Carlo simulation is more objective.(2) In term of the straw structure, rice, wheat and corn dominated the national crop residue resources with respective amount of224Mt,219Mt and155Mt, accounting for27.96%,27.29%and19.32%respectively. The other crop residues were totally about204Mt. The period from1949to2009witnessed the variation of national straw structures. The proportion of rice decreased by11.58%, contrast to the increased straw proportion of wheat and corn by16.84%and7.43%, respectively. A good fitting results of crop residue against time (i.e. years) is presented with high correlation coefficient achieved R2>0.9. The spatial distribution of crop residues is uneven in national level, with mean density of228t·km-2, standard deviation of238t·km-2and range from1t to4,065t. (3) A good result by grey projection model is presented to estimate the potential of crop residue resource based on the three indicators of national total straw, the straw amount of per capital and per area of cultivated land, with correlation coefficient being0.625,0.529and0.720, respectively. With respect of technical potential to energy generation, the dual techniques of compression combustion and gasification illustrate high conversion efficiency of60.41%for the former and58.29%for the latter,1.95×108and1.870×108ton of standard coal can be conversed annually in China.