Background
The authors write that "interest in bio-ethanol as a substitute energy supply for nonrenewable fossil fuels has been growing since [the] 1990s in China," and they say that "after Brazil and the US, China has recently become the third largest ethanol producer and consumer." In this regard, however, they note that after it was suggested by Chambers et al. (1979) that the production of corn-ethanol might use more energy than it delivers, "numerous studies of the net-energy value of the bio-ethanol have been reported in many countries," and they cite a group of 26 reports that "provide very different results, with net energy values ranging from highly positive to negative."

What was done
In the present study, in the words of Yang and Chen, "nonrenewable energy cost instead of overall energy cost is calculated and compared with the amount of energy delivered to society through the sum of nonrenewable energy (NE) embodied in all resources entering the supply chain of corn-ethanol processes in China, including agricultural crop production, industrial conversion, and wastewater treatment," while "an indicator of nonrenewable energy investment in energy delivered is devised to reveal the extent of NE cost of corn-ethanol over that of the energy produced."

What was learned
The two researchers determined that "corn-ethanol production requires 0.70 times more nonrenewable energy (NE) production than the energy content of ethanol produced," leading them to conclude that "the goal of NE conservation could not be achieved by corn-ethanol production with the technology conditions prevailing in China." In addition, they say that "NE cost is just one aspect of biofuels production," and that "more questions concerning water crises and cultivated land use have emerged, with the most serious problem of competition for land between corn-ethanol and food," since "food security is an inevitable concern for China with limited land resources compared with a huge population."

What it means
In light of these several "facts of life," as one could call them, Yang and Chen say that China's Ministry of Agriculture has "insisted on developing biofuels without competing with grain for land," citing Wei (2008); and they indicate that this policy has "substantially dampened the momentum of corn-ethanol development in China," noting it is clear that the country's central government "ruled out the feasibility for China to use staple food grains for fuel because of the paramount priority of food security."

References
Chambers, R., Herendeen, R., Joyce, J. and Penner, P. 1979. Gasohol: does it or doesn't it produce positive net energy? Science 206: 790-795.

Wei, Z.A. 2008. Speech on Chinese biomass energy development. 2008 International Proseminar of Chinese Country Biomass Energy. This speech is available at: http://www.caass.org.cn/tabid/155/InfoID/620/frtid/90/Default.aspx.