Establishment and application of crops straw supply model for north China plain area

Abstract: Straw is important biomass feedstock. Due to the collection, storage and many other problems, their supply system can't be steady, and there are more than 200 million tons of straw resources not utilized effectively. In order to ensure a steady supply of straw and to increase the utilization rate of straw resources, we established a straw supply model based on straw collection in field - straw centralized storage - straw utilization. And taking the area of the North China Plain (Feicheng, Shandong Province) as an example, we got the site selection and the number of the straw collection and storage station and power plant, and analyzed the cost and energy consumption in the process of straw supply, which included field collection, primary transportation, storage in straw collection and storage station, secondary transportation and straw handling. The results showed that the straw supply model could reasonably analyze the point of straw application site, build and optimize the location and number of storage stations, and could reduce the construction investment, personnel and equipment of storage stations effectively, thus saving supply costs and energy consumption. So the straw supply model could be applied in practical calculation. The annual yield of corn stalk was up to 453 000 t in Feicheng, Shandong Province. Among them, the collectable amount was 100 000 t. The geographical coordinate of the optimal location was 116.741°N, 36.069°E when the available quantity of straw resource was about 100 000 t. The analytic hierarchy process was used to get the optimal location when the number of collection and storage stations was 10, and the transportation cost of straw delivery was about 169.14 yuan/t. Among them, analyzed by supply chain, the portions of straw collecting costs and transportation costs were higher, accounting for 55% and 23% of the total costs respectively. Analyzed by economic evaluation index, the portions of straw purchasing costs, labor costs, and fuel and power costs were higher, accounting for 41.39%, 30.14% and 25.90% of the total costs respectively. The total energy consumption of straw supply system was 186 MJ/t, among which the higher fuel consumption occurred in links of transportation and baling, accounting for 45% and 34% of the total energy consumption respectively. Through optimization, we centrally established 10 collection and storage stations. Compared with the original program that collection and storage station was established in every township, this program could reduce costs by 4.6%, and reduce energy consumption by 4.12%. It could save the initial investment cost of collection and storage stations by 25.85%; the primary transport costs increased by 4.81%, but the secondary transport costs was reduced by 19.68%. The straw supply model in this paper provides an instructional reference for establishing a reasonable straw supply model in different areas in China, and has a positive guiding significance for keeping steady straw supply, effectively reducing the cost of supply, and reducing energy consumption.