The potential for bioenergy generated on marginal land to offset agricultural greenhouse gas emissions in China

Rational use of marginal land for cultivation of bioenergy crops is an effective means to solve land use competition and is an important way to reduce greenhouse gas (GHG) emissions and improve energy supply. This study conducted an evaluation of the suitability of marginal land for growing energy crops in China during 1990–2020 using the GIS and multi-factor analysis method and revealed the quantitative relationship between bioenergy produced by marginal land energy crops and carbon reduction potential. The Intergovernmental Panel on Climate Change (IPCC) coefficient method and life cycle method were applied to measure the biofuel yield of the Jatropha curcas and assessed its potential to offset agricultural greenhouse gas emissions. The findings are: (1) The marginal land area available for energy crops in 2020 is 1.63 × 10⁶ km², which is 8.35 % lower than the area planted in 1990. (2) When the reclamation index is 60 %, all suitable marginal land can be used to grow energy crops, and biofuels can replace 3.31 × 10¹¹ tons of conventional energy. (3) In 2020, agricultural greenhouse gas emissions will be 9.02 × 10⁸ tons, and the potential of bioenergy crop cultivation to offset agricultural greenhouse gas emissions amounts to 4.31 × 10⁸ tons, or 47.88 %. In the future, the pressure of agricultural GHG emission reduction will be further exacerbated by population growth and agricultural land supply, etc. Rational use of marginal land and development of bioenergy crops are effective ways for China to cope with climate change and realize its renewable energy strategy.