Abstract
This study investigates the decomposition of methane using solar thermal energy as a heat source. Instead of the direct thermal decomposition of the methane at a temperature of 1200 °C or higher, a catalyst coated with carbon black on a metal foam was used to lower the temperature and activation energy required for the reaction, and to increase the yield. To supply solar heat during the reaction, a reactor suitable for a solar concentrating system was developed. In this process, a direct heating type reactor with quartz was initially applied, and a number of problems were identified. An indirect heating type reactor with an insulated cavity and a rotating part was subsequently developed, followed by a thermal barrier coating application. Methane decomposition experiments were conducted in a 40 kW solar furnace at the Korea Institute of Energy Research. Conversion rates of 96.7% and 82.6% were achieved when the methane flow rate was 20 L/min and 40 L/min, respectively.
Highlights
The increasing reality of global warming effects owing to the burning of fossil fuels has prompted the need to invest in renewable energy sources in order to reduce greenhouse gas emissions
Instead of direct thermal decomposition of methane at a high temperature of 1200 ◦ C and above, methane was decomposed using a catalyst to lower the temperature and activation energy required for the reaction, and to increase the yield
A catalyst coated with carbon black (CB I) on NiCrAl metal foam was installed to reduce the reaction temperature and activation energy required for methane decomposition [29]
Summary
The increasing reality of global warming effects owing to the burning of fossil fuels has prompted the need to invest in renewable energy sources in order to reduce greenhouse gas emissions. Hydrogen can be produced without carbon emission, by supplying heat through concentrated solar energy and using the CMD process [4,5]. Magg et al developed a 5 kW direct heating solar methane decomposition reactor of a cylindrical cavity shape, with quartz mounted in a circular opening. Yeheskel et al developed a direct-heated volumetric reactor optimized through CFD and conducted an experiment to convert methane into hydrogen and carbon particles using a reactor characterized by high reaction temperature, quartz protection, no boundary layer separation, and directional flow [20]. A secondary concentrator was installed on the front of the reactor to reflect light from a 10 kW solar furnace In their experiment, a methane conversion rate of 90% was achieved at 1860 ◦ C, with a methane flow rate of 1 L/min [21].
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