Integrated fossil fuel and solar thermal systems for hydrogen production and CO2 mitigation

Abstract

In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of the hydrogen production process is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steaam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO2 emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H2) of coal gasification and steam methane reforming is provided by solar thermal energy.Various solar thermal energy based reactors are discussed for different types of production cycles as well.

Local fuel concentration measurement through spark-induced breakdown spectroscopy in a direct-injection hydrogen spark-ignition engine

“…Hydrogen has long been considered as one of the most promising energy carriers and investigated as a fuel for internal combustion engines (ICEs) due to its potential for high engine efficiency and greenhouse gas reduction [1][2][3][4][5]. There are some initiatives in Japan to move towards the "dream of a hydrogen-based society" and to accelerate the installation of hydrogen stations for fuel-cell vehicles that run on electricity, generated by burning hydrogen.…”

“…In addition, the mixture distribution around the spark plug, together with fluid motion, strongly influences the combustion initiation, which subsequently affects the engine performance, efficiency, and emissions. Thus, a fundamental [4] understanding of mixture formation processes is necessary to optimise DI-H 2 ICE operation. To better understand how to both achieve an optimal local mixture and control the large-scale stratification, a diagnostic tool for providing information on the mixture distribution in practical engines should be developed.…”

Industrial decarbonization via hydrogen: A critical and systematic review of developments, socio-technical systems and policy options

“…Alternatively, the secondary unit operations systems associated with thermochemical energydependent pathways may themselves be powered using renewables, partially offsetting the energy demand from the fossil feedstocks [161]. Carbon capture and storage interventions to mitigate emissions from fossil fuel-based power stations are also included here.…”

“…• For existing thermochemical production pathways, decarbonizing hydrogen production will rely on adoption of renewable and waste feedstocks [42,71,148,149,187], use of CCS technologies [162,171,[188][189][190], switch to renewable and nuclear energy [191], or a combination of these interventions [152,161,169,182,192]; • In case thermochemical production coupled with CCS technology does not meet regulatory criteria for classification as low-carbon hydrogen (further discussed in Section 6) or are unacceptable for other reasons, methane pyrolysis and hightemperature electrolysis may be suitable for hydrogen production with high heat processes [43,80,81,123,128,179,193,194]; • Electrolysis produces high-purity hydrogen and can be directly used for fuel cell applications (electric vehicles, electricity generators, distributed heat and power units) [120,[195][196][197]; • Biohydrogen pathways have much lower hydrogen production yields than other alternatives and will therefore have niche applications when coupled with the treatment of wastewater and industrial effluents, as well as the uptake of recalcitrant biomass feedstocks [86,93,102,138,172,[198][199][200][201]; • Renewable energy availability (in particular solar and wind energy) will impact technology adoption…”

Thermodynamic and environmental impact assessment of steam methane reforming and magnesium-chlorine cycle-based multigeneration systems

“…Lifetime and storage efficiencies and maximum temperatures are also favorable compared with other options. However, molten salts should carefully be employed for the systems because they have comparatively higher freezing point [16]. The upper critical temperature range of molten salts is 550-600°C, which makes these HTFs suitable for medium-temperature and low-temperature thermochemical water splitting cycles.…”