"Titre du document / Document title
Auteur(s) / Author(s)
Résumé / Abstract
"Robert H. Williams and Eric D. Larson
Princeton Environmental Institute, Princeton University Guyot Hall, Washington Road, Princeton, NJ 08544-1003, USA.
Direct and indirect liquefaction technologies for making synthetic liquid fuels from coal are compared. It is shown that although direct liquefaction conversion processes might be more energy-efficient, overall system efficiencies for direct and indirect liquefaction are typically comparable if end-use as well as production efficiencies are taken into account. It is shown that some synfuels derived via indirect liquefaction can outperform fuels derived from crude oil with regard to both air-pollutant and greenhouse-gas emissions, but direct liquefaction-derived synfuels cannot. Deployment now of some indirect liquefaction technologies could put coal on a track consistent with later addressing severe climate and other environmental constraints without having to abandon coal for energy, but deploying direct liquefaction technologies cannot. And finally, there are much stronger supporting technological infrastructures for indirect than for direct liquefaction technologies. Prospective costs in China for some indirect liquefaction-derived fuels are developed but not costs for direct liquefaction-based synfuels, because experience with the latter is inadequate for making meaningful cost projections. Especially promising is the outlook for the indirect liquefaction product dimethyl ether, a versatile and clean fuel that could probably be produced in China at costs competitive with crude oil-derived liquid fuels. An important finding is the potential for realizing, in the case of dimethyl ether, significant reductions in greenhouse gas emissionsrelative to crude oil-derived hydrocarbon fuels, even in the absence of an explicit climate change mitigation policy, when this fuel is co-produced with electricity."
"Study on co-feed and co-production system based on coal and natural gas for producing DME and electricity"
Li Zhou, Shanying Hu, Yourun Lia and Qihong Zhou
Chemical Engineering Department, Tsinghua University, Beijing 100084, China
Abstract
China, an oil and NG scarcity country, is coal dependent, and this situation will remain for a long time. DME, as an ideal replacer of liquid fuel, is considered to develop. The efficient way of producing DME from coal is under research. Considering the components of coal and natural gas (NG), we choose co-feed (coal and NG) and co-production (electricity and DME) system (Co–Co system) to be studied on. Three systems which are the standalone system, co-generation system and Co–Co system are simulated by Aspen-Plus. The simulation results concerning material flows, exergy flows, CO2 emission and the evaluation indexes are obtained. It is found that Co–Co system has higher exergy efficiency, higher economic benefit, and it is environmental friendly because of releasing the least CO2.The analysis illustrates that Co–Co system has obviously advantage over the other two kinds of systems."