8
Water for Energy and Fuel Production
energy carrier and/or reactor moderator. New nuclear reactors may use supercritical
water as the next generation of reactor coolant and thermal energy carrier.
Water has also been used as a medium to transfer geothermal energy to heat
pumps, air conditioners, or electrical devices by carrying geothermal energy in the
form of steam for a subsequent energy conversion process. In future, the development of “enhanced geothermal systems” will require water not only as a geothermal
energy carrier but also as a fluid required to open up deep compressed geological
structures that carry geothermal heat. This dual role of water will make its use larger
and more important in the recovery of geothermal energy. New geothermal recovery
systems will also use existing underground infrastructure for oil and gas recovery for
geothermal energy recovery.
Water can also be an effective “energy storage” device for renewable energy
sources such as wind and solar energy that are time and location dependent. The electricity generated from these sources can be stored in the form of hydrogen through
water dissociation, and this hydrogen can then be used to generate electricity during
“off-time” periods. The stored energy can also be used for “peak energy” needs.
While conversion of electrical energy into hydrogen is not the most efficient process,
it provides another option for storing electrical energy instead of using conventional
power grids, batteries, or capacitors. Unlike these conventional sources, once the
electrical energy is stored by hydrogen, it will not dissipate over time. Water can also
be used for thermal storage of excess electricity. Solar energy has also been used for
heating and cooling homes and industrial buildings through the use of water. Water
is once again an important thermal energy carrier for this use of solar energy.
Finally, steam turbine has been an effective device that uses steam to drive turbine which in turn generates electricity. Steam in this process is often produced using
combustion heat generated from the burning of coal, oil shale, biomass, waste, and
so on. Once again, steam is an effective energy carrier in the combustion processes
to generate power. As mentioned earlier, the EMR [1] has predicted that by 2040,
nearly 40% of our energy consumption will be in electric power. This expanded use
of electricity will require a significant growth in the use of steam turbine. All of
these benign roles of water as an energy carrier are briefly examined in Chapter 3.
1.2.3 ChAPTer 4: STeAm For SynTheTiC gAS ProduCTion
While the “steam gasification and reforming” process has been in place since the
beginning of the fossil fuel industry, steam gasification and reforming of coal was
not as popular and productive as steam reforming of natural gas. In the recent years,
steam gasification and reforming of biomass has become more popular and productive for hydrogen generation.
The use of steam to recover gaseous synthetic fuels of different compositions is
outlined in Chapter 4. Steam gasification and reforming of carbonaceous fuels (fossil as well as biomass) either alone or in combination with air (or oxygen), carbon
dioxide, or hydrogen is a commercially accepted process. Depending on the nature of
feedstock and operating conditions, the process generates gaseous fuel largely consisting of methane, carbon monoxide, carbon dioxide, water, and hydrogen. Minor
Water for Energy and Fuel Production
energy carrier and/or reactor moderator. New nuclear reactors may use supercritical
water as the next generation of reactor coolant and thermal energy carrier.
Water has also been used as a medium to transfer geothermal energy to heat
pumps, air conditioners, or electrical devices by carrying geothermal energy in the
form of steam for a subsequent energy conversion process. In future, the development of “enhanced geothermal systems” will require water not only as a geothermal
energy carrier but also as a fluid required to open up deep compressed geological
structures that carry geothermal heat. This dual role of water will make its use larger
and more important in the recovery of geothermal energy. New geothermal recovery
systems will also use existing underground infrastructure for oil and gas recovery for
geothermal energy recovery.
Water can also be an effective “energy storage” device for renewable energy
sources such as wind and solar energy that are time and location dependent. The electricity generated from these sources can be stored in the form of hydrogen through
water dissociation, and this hydrogen can then be used to generate electricity during
“off-time” periods. The stored energy can also be used for “peak energy” needs.
While conversion of electrical energy into hydrogen is not the most efficient process,
it provides another option for storing electrical energy instead of using conventional
power grids, batteries, or capacitors. Unlike these conventional sources, once the
electrical energy is stored by hydrogen, it will not dissipate over time. Water can also
be used for thermal storage of excess electricity. Solar energy has also been used for
heating and cooling homes and industrial buildings through the use of water. Water
is once again an important thermal energy carrier for this use of solar energy.
Finally, steam turbine has been an effective device that uses steam to drive turbine which in turn generates electricity. Steam in this process is often produced using
combustion heat generated from the burning of coal, oil shale, biomass, waste, and
so on. Once again, steam is an effective energy carrier in the combustion processes
to generate power. As mentioned earlier, the EMR [1] has predicted that by 2040,
nearly 40% of our energy consumption will be in electric power. This expanded use
of electricity will require a significant growth in the use of steam turbine. All of
these benign roles of water as an energy carrier are briefly examined in Chapter 3.
1.2.3 ChAPTer 4: STeAm For SynTheTiC gAS ProduCTion
While the “steam gasification and reforming” process has been in place since the
beginning of the fossil fuel industry, steam gasification and reforming of coal was
not as popular and productive as steam reforming of natural gas. In the recent years,
steam gasification and reforming of biomass has become more popular and productive for hydrogen generation.
The use of steam to recover gaseous synthetic fuels of different compositions is
outlined in Chapter 4. Steam gasification and reforming of carbonaceous fuels (fossil as well as biomass) either alone or in combination with air (or oxygen), carbon
dioxide, or hydrogen is a commercially accepted process. Depending on the nature of
feedstock and operating conditions, the process generates gaseous fuel largely consisting of methane, carbon monoxide, carbon dioxide, water, and hydrogen. Minor