High Efficiency Direct Carbon and Hydrogen Fuel Cells for Fossil Fuel Power Generation

摘要

Fossil fuels including coal, oil and natural gas make up 85% of the U.S. energy supply and it is projected they will continue to supply this fraction for the next 20 years. Improving efficiency in conversion and utilization of fuel is recognized to be of prime importance in reducing costs to the consumer, reducing polluting emissions, and extending the resource supply. Generation of electrical power currently consumes about 24% of the total annual fossil fuel supply. Of all power conversion devices, the fuel cell promises maximum conversion efficiency because it can in principle convert the free energy of the combustion reaction into electrical energy. The hydrogen fuel cell has emerged as the leading electrochemical conversion technology for the utilization of fossil fuels. However, generation of hydrogen from fossil fuels is inherently inefficient if hydrogen is the sole fuel used for electricity generation, because of the high carbon content of fossil fuel. To push efficiency to the limit, we propose the decomposition of hydrocarbons derived from fossil fuels into carbon and hydrogen streams. The carbon would be used in a direct carbon conversion cell (DCC) and the hydrogen would be used in an efficient solid oxide fuel cell (SOFC). This sequence enables the conversion of fossil fuels to electricity at efficiencies far in excess of those of conventional fuel cells.