BuiltWithNOF
Coal System Efficiency

Coal mine-to-wheels efficiency. Which is more efficient: to convert coal to electricity for a BEV, or to gasify coal to make hydrogen for a fuel cell EV?

The chart below compares these two options based on full-function 5-passenger cars with 250 miles range[1].  It takes approximately 1.27 MBTUs of coal energy to make electricity to power a battery EV 250 miles, while only 0.88 MBTUs of coal would be required to make enough hydrogen to power a fuel cell EV for 250 miles. Thus coal-to-hydrogen for a FCEV is 44% more efficient than coal-to-electricity for a BEV.

Coal gasification to H2 efficiency = 57%  [Ref: P. Chiesa, S. Consonni, T. Kreutz, R. Williams, "Co-production of hydrogen, electricity and CO2 from coal with commercially ready technology”]

The coal plant electrical efficiency in this model is based on the US average coal plant for 2008 of 32.5% [2].  EPRI estimates that an integrated gasification combined cycle IGCC plant could achieve 38.8% by 2010 and up to 66.4% by 2050. However, adding carbon capture and storage (CCS) to these IGCC plants that will be necessary in the future takes the net system efficiencies down to 30.2% in 2010 and to 41.2% by 2050 with CCS. Even at the higher 41.2% efficiency, the coal to electricity for a BEV pathway still would require 1.0 MBTU of coal energy, so the hydrogen/FCEV pathway would still be 14% more efficient by 2050.

By 2050, the coal gasification plant efficiency of 57% with today’s technology [3] would undoubtedly be improved, too. We have not included an estimate for advanced coal gasification plants.

[1] Vehicle parameters: 2.13 m2 cross section area; 0.33 drag coefficient; 0.0092 rolling resistance and 0 to 60 mph acceleration in 10 seconds.

[2] EIA Annual Energy Outlook 2009.

[3] P. Chiesa, S. Consonni, T. Kreutz, R. Williams, "Co-production of hydrogen, electricity and CO2 from coal with commercially ready technology

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