Liquid Fuels from Coal and Biomass

Because of the Williams Group’s unexpected opportunity to contribute to the National Research Council study America’s Energy Future (discussed above), some previously planned work was postponed. The postponed work included finalizing of two manuscripts for publication reporting on collaborative research undertaken with Professor Li Zheng’s group at the BP-Tsinghua Clean Energy Center. Professor Li hosted a 12-month visit by Cathy Kunkel (ended in September 2007) that launched an effort to explore the prospects for extending to China the concept of making low GHGemitting synthetic fuels from coal + biomass (CBTL) with CCS. During the visit period Kunkel, supervised by Larson and interacting with Prof. Li and others at Tsinghua, gathered data and carried out preliminary analyses relating to CBTL strategies for low-carbon liquid fuels supply from two coal-rich regions in China: agricultural Shandong Province, where crop residues are a potential biomass feedstock, and Inner Mongolia, where mixed native prairie grasses may be a potential biomass resource.

Before she left China, Kunkel began the process of preparing manuscripts reporting on these two geographically diverse case studies, but was unable to commit time to the effort after she left China to pursue a year of graduate study in physics at Cambridge University (UK). Kunkel is now pursuing a PhD with the Energy and Resources Group at the University of California, Berkeley. In the coming year Larson will restart the work to complete the manuscripts for publication.

For the Shandong case study, the focus was on developing a comparative analysis of alternative cropresidue-based cooking fuel strategies for rural households—motivated largely by concerns about severe adverse health impacts of indoor air pollution from the direct burning of coal or crop residues for cooking. The analysis is comparing health impacts, cooking fuel costs, and GHG emissions for six cooking fuel strategies: (i) direct coal burning, (ii) direct crop residue burning, (iii) burning pelletized crop residues in cleaner-burning stoves, (iv) burning dimethyl ether (DME) produced from crop residues via gasification, (v) burning DME produced from crop residues + coal via gasification, and (vi) burning DME from coal via gasification. For the options involving coal, both CO2 venting and CCS approaches are being considered. This analysis includes developing models of the logistical costs of crop residue collection and delivery under conditions for Shandong Province.

The case of Inner Mongolian mixed prairie grasses used for coal/biomass-based synfuels production involved developing an extensive biogeophysical database for Inner Mongolia that includes current grassland yields, potential yields if degraded lands are restored, the locations of major coal deposits and potential underground CO2 storage sites, and other relevant data. Grasslands account for about 40% of China’s land area, and 30% of China’s grasslands are in Inner Mongolia—much of which are heavily degraded and the restoration of which is a high political priority in China. Although yields on restored grasslands in Inner Mongolia are low (~1.5 tonnes per hectare per year on average), preliminary calculations suggest plausibly attractive economics for farmers growing grasses for energy relative to what is being done with the land at present—if the oil price is high and the value of CO2– equivalent GHG emissions is high (at least ~ $30/t CO2).