Cluster analysis and descriptive statistics of lignocellulosic crop residue in agriculture sector for the production of renewable energy (case study of Golestān province)

Background and purpose: The utilization of lignocellulosic crop residues, which remain after the final product in the agricultural sector, can be considered as a valuable resource for generating renewable energy. However, due to their dispersed distribution and the high cost associated with their collection, this task poses significant challenges. Currently, the application of spatial modeling to assess the sustainable potential of lignocellulosic residue biomass for renewable energy production in the agricultural sector is limited. Moreover, no such studies have been reported in the country to date. Therefore, the objective of this study is to assess the renewable energy production potential and identify suitable locations for bioenergy facilities that process lignocellulosic residues using cluster analysis within a geographic information system (GIS) environment.
Materials and methods: To accomplish the objectives, descriptive-quantitative data regarding the production level and production area in the agricultural sector for the crop year 2020-21, as published by the Ministry of Agriculture, were collected and analyzed. Furthermore, spatial information pertaining to agricultural farms in Golestān province was gathered through satellite imagery, which was subsequently processed using cluster analysis and hotspot analysis within a geographic information system (GIS) framework. The biomass quantity in each field was estimated for four conventional crops: wheat, rapeseed, rice, and soybean, on a per-unit area basis. Subsequently, separate projection was conducted for each of these crops within the case study of Golestān province.
Results: In the crop year of 2020-21, the total arable land area amounted to 12.9 million hectares, with a nationwide crop harvest of 91.8 million tons. Cereals accounted for the highest proportion (71%), while grain products had the lowest share. Golestān province, ranked 7th, possessed an agricultural area of 661 thousand hectares, contributing 4.27% of the country's total crop production, which amounted to 3.9 million hectares. Among the cereal production group, wheat had the highest production level at 63%, while grain corn had the lowest. Notably, Gonbad-e-Kavoos and Bandargaz counties exhibited the highest production levels and the largest areas for the cereal production group. Through the spatial analysis, the estimated amount of harvestable residue biomass was 840,000 Mg, derived from a total of 84,104 identified farms, with the largest proportion being wheat straw. The cluster analysis of the identified farms revealed that out of a total of 35,508 clusters, 15% belonged to the cold cluster category, while 18% fell into the hot cluster category. Furthermore, hotspot analysis identified four suitable sites for bioenergy sites within the study area. The available biomass can be transported to these potential sites at an average cost of $20.83 per kilometer per megagram.
Conclusion: The findings of this study highlight there is substantial biomass quantity within the agricultural sector of Golestān province, a significant portion of which is currently burned annually, resulting in the generation of large amounts of greenhouse gases and widespread environmental pollution. However, this biomass resource holds significant potential for the production of renewable energy if effectively harnessed with support from both the public and private sectors.