Efficiency analysis of bioenergy potential on winter fallow fields: A case study of rape.

Rape is a non-grain feedstock with several characteristics that make it suitable for biofuel production, such as high oil yields and low environmental impact. Planting rape on winter fallow fields could allow for seasonal rotation between the bioenergy production and agricultural production. In the present study, the Global Agro-Ecological Zones model was used to estimate the production potential of rapeseed on winter fallow fields in the Yangtze River region from 2010 to 2015. Life cycle assessment was then conducted to calculate energy efficiency and greenhouse gas emissions from the entire energy-producing process and to estimate the number of bioenergy enterprises and their spatial distribution. The results indicated that the total area available of winter fallow fields in the Yangtze River region was 24.93millionha, accounting for 34.2% of the total cultivated land area. The total yield of winter rapeseed was up to 46.41milliontons (an average yield of 1.86tons/ha). Thus, the study area could potentially produce net energy of up to 3564millionMJ with energy return on energy investment (EROEI) as high as 1.52-1.84. The total reduction of greenhouse gas emissions may be up to 23.28milliontons, and the total number of bioenergy enterprises could be 589, from which the total biodiesel output could be 167.5milliontons. Hubei, Henan, Anhui and Jiangxi should be prioritized for generating biofuels from rapeseed planted on winter fallow fields.