System analysis of grain straw for centralised industrial usages in China

This paper provides analysis of the availability of grain straw resources for centralised industrial usages and suitable areas in China at the prefectural level. China has abundant straw resources for both decentralised and centralised usages. Decentralised usages are inefficient and cannot absorb enough straw. However, centralised usages have technological and economic problems, such as product cost and resource supply, and therefore, a system analysis of the economic available resources and suitable areas are needed. Three main grain crops – rice, wheat, and corn – and three typical centralised usages – paper making, direct combustion power generation, and bioethanol – are investigated in this study. An optimal model is established on the basis of straw resource characteristics and techno-economic characteristics of the usages and used to calculate the distribution of suitable prefectures and the largest supply of resources for each usage. The study focuses on prefectures in 13 provinces with relatively abundant grain straw resources. The suitable areas for paper making are in North China, for direct combustion power generation are in North and Northeast China, for bioethanol are in Northeast China. The largest economic available resources for paper making, direct combustion power generation, and bioethanol are 47.5, 221.4, and 164.4 million tons, respectively. The operation cost and the ratio of straw actually collected from production are selected for conducting a sensitivity analysis. The impacts of other factors, including the geographical environment, local product demand, existing industry, change in total straw production, technical progress and straw from other crops, are discussed.