94
Water for Energy and Fuel Production
carbon monoxide, and hydrogen chloride. Because reforming is not a combustion process, neither fuel, nor air, nor oxygen needs to be supplied to the reactor. Thus, unlike
incineration, solar-driven, high-temperature catalytic reforming produces neither
NO x nor products of incomplete combustion (PICs). Furthermore, variable absorber
thickness and adjustable gas flow rates mean that residence times within the absorber
and thus reaction times and destruction efficiency can be controlled [192–194].
4.7.3.4 Open-loop solar syngas Production
The applications of open-loop solar syngas production include the following
[188,189,192,199,214]:
1. Natural gas reforming for power plants—A number of European countries have imported natural gas via pipelines from North Africa and have
reformed this gas to either syngas or hydrogen, increasing its calorific value
by about 25% before combustion in gas turbine or FC power plants [192].
2. Syngas production from municipal, agricultural, and organic industrial
waste—In sunbelt countries, concentrated waste streams can be gasified to
syngas with solar energy at potentially acceptable costs and with essentially
no emissions to the atmosphere [192].
3. Soltox type processing—It provides an option for environmentally acceptable disposal of a number of toxic organic materials [192].
Open-loop syngas production can also be used for the generation of synthesis gas that
is being supplied worldwide for the production of hydrogen, methanol, ammonia,
and oxyalcohols.
4.7.3.5 Other solar reforming Processes
A number of studies have focused on the production of hydrogen by steam reforming
of methane and other hydrocarbons using solar reactor [189,192,193,199–201,212,213]
(Yeheskel et al., 2012, pers. comm.). A schematic of the solar reactor used by Seinfeld
and coworkers is depicted in Figure 4.4. Yeheskel et al. (2012, pers. comm.) studied the chemical kinetics of high-temperature hydrocarbon reforming using a solar
reactor. Watanuki et al. [189] examined methane steam reforming using a molten
salt membrane reforming reactor. In this type of the reactor, the reforming reaction
takes place in tubular reactors that consist of selective membranes, generally palladium, which separates hydrogen as it is produced. The principal advantages of a solar
membrane reforming process compared to the conventional reforming process are as
follows:
1. The reforming is carried out at a lower temperature (550°C). This means a
significant reduction in the energetic consumption. Low-temperature reactors also use less costing materials for the reforming reactor tubes.
2. Hydrogen is obtained with a higher purity due to highly efficient membrane
separation process.
3. Methane conversions up to 90% can be reached due to high hydrogen
extraction through the membrane.
Water for Energy and Fuel Production
carbon monoxide, and hydrogen chloride. Because reforming is not a combustion process, neither fuel, nor air, nor oxygen needs to be supplied to the reactor. Thus, unlike
incineration, solar-driven, high-temperature catalytic reforming produces neither
NO x nor products of incomplete combustion (PICs). Furthermore, variable absorber
thickness and adjustable gas flow rates mean that residence times within the absorber
and thus reaction times and destruction efficiency can be controlled [192–194].
4.7.3.4 Open-loop solar syngas Production
The applications of open-loop solar syngas production include the following
[188,189,192,199,214]:
1. Natural gas reforming for power plants—A number of European countries have imported natural gas via pipelines from North Africa and have
reformed this gas to either syngas or hydrogen, increasing its calorific value
by about 25% before combustion in gas turbine or FC power plants [192].
2. Syngas production from municipal, agricultural, and organic industrial
waste—In sunbelt countries, concentrated waste streams can be gasified to
syngas with solar energy at potentially acceptable costs and with essentially
no emissions to the atmosphere [192].
3. Soltox type processing—It provides an option for environmentally acceptable disposal of a number of toxic organic materials [192].
Open-loop syngas production can also be used for the generation of synthesis gas that
is being supplied worldwide for the production of hydrogen, methanol, ammonia,
and oxyalcohols.
4.7.3.5 Other solar reforming Processes
A number of studies have focused on the production of hydrogen by steam reforming
of methane and other hydrocarbons using solar reactor [189,192,193,199–201,212,213]
(Yeheskel et al., 2012, pers. comm.). A schematic of the solar reactor used by Seinfeld
and coworkers is depicted in Figure 4.4. Yeheskel et al. (2012, pers. comm.) studied the chemical kinetics of high-temperature hydrocarbon reforming using a solar
reactor. Watanuki et al. [189] examined methane steam reforming using a molten
salt membrane reforming reactor. In this type of the reactor, the reforming reaction
takes place in tubular reactors that consist of selective membranes, generally palladium, which separates hydrogen as it is produced. The principal advantages of a solar
membrane reforming process compared to the conventional reforming process are as
follows:
1. The reforming is carried out at a lower temperature (550°C). This means a
significant reduction in the energetic consumption. Low-temperature reactors also use less costing materials for the reforming reactor tubes.
2. Hydrogen is obtained with a higher purity due to highly efficient membrane
separation process.
3. Methane conversions up to 90% can be reached due to high hydrogen
extraction through the membrane.