Emergy evaluation of straw collection, transportation and storage system for power generation in China

Highlights: • According to the field survey and emergy analysis as the main research method. • In the given case, the theoretical prediction and actual calculation for the straw recycling system. • Constructed and analyzed the emergy indicator system of the straw recycling system. • The emergy input and output of the straw recycling company is not balanced. • The market price emergy of straw is too low and the value of straw itself is seriously underestimated. Straw is the main resource of fuel for biomass power generation plants in China's agricultural areas. Field survey and emergy analysis were employed to investigate the operation situation of the straw collection, transportation and storage system based on the case of Laifa Straw Recycling Company. In the condition of collecting 2 × 10⁸ kg of straw production, the emergy input of the artificial model of the company was 173.02 × 10¹⁸ sej, which was higher than the emergy input of the mechanical model, 148.11 × 10¹⁸ sej. According to the emergy indicator system, the mechanical model had a high development degree of internal resources and environment, high productivity, high sustainable development ability, but a lower proportion of renewable resource emergy input than the artificial model. The emergy value of 1 kg commercial straw calculated from the commercial price was 0.25 × 10¹² sej, which was only one third of the average input of the company to produce 1 kg commercial straw (0.74 × 10¹²–0.87 × 10¹² sej). It was difficult for straw recycling company to survive in the market due to the low price of the commercial straw. Therefore, the government was suggested to take effective economic policies to support local straw recycling enterprises.