Emergy Depletion and Offset of Fossil Energy Assets in China

Coal, petroleum and natural gas are the three main sources of fossil energy. This paper classified fossil energy sources as eco-assets. Using ecological economics, it was calculated that the cumulative emergy wastage of fossil energy sources in China from 1953 to 2006 was 7.08 times 1025sej. This paper considered agricultural residue to be a substitute for fossil energy sources. The results showed that during the earlier period studied, the emergy of agricultural residues could almost offset that of consumption. However, with social-economic development, the disparity in emergy between wastage of fossil energy assets and supply of agricultural residue was shown to be increasing. In 2006, the wastage emergy from energy assets was 7.7 times that supplied by agricultural residue. Fossil fuels are a one-time non-renewable energy source that may be nearing depletion. Hence it is important to substitute bio-energy for fossil energy sources. Assuming that the emergy wasted each year by fossil energy assets was substituted completely by energy from corn stalks, in 1987, the required cultivated area of corn was already three times than that of the actual crop. In addition, due to the increase in emergy demand, the corn acreage also needs to increase. Since 2000, the required acreage for corn has exceeded the acreage of China´s entire rural area. The results are stark, showing the necessity for reasonable and efficient use of fossil energy and the urgency of ecological compensation.