Solar hydrogen production and CO recycling - Solar Energy Sciences and Engineering Applications - page 257

Solar hydrogen production
and CO 2 recycling
ZhaolinWang 1 & Greg F. Naterer 2
1 Faculty of Engineering and Applied Science, University of Ontario Institute of
Technology, Oshawa, Ontario, Canada
2 Faculty of Engineering and Applied Science, Memorial University of Newfoundland,
St. John's, Newfoundland and Labrador, Canada
9.1 SUSTAINABLE FUELSWITH SOLAR-BASED HYROGEN
PRODUCTION AND CARBON DIOXIDE RECYCLING
The need for energy will continue to increase rapidly as the world aims to improve its
living quality. As the usable fossil fuel resources are diminishing due to the ongoing
depletion, the scenario of using carbon-based fuels is unsustainable. It was estimated by
the International Energy Agency (IEA) and the US Energy Information Administration
(EIA) that the global primary energy demand will be still met primarily by fossil fuels
in the medium term before 2035 (IEA, 2011, 2012; EIA, 2012). In addition, the
usage of fossil fuels generates toxic pollutants threatening the ecobalance and our
health. The CO 2 emissions induce undesirable climate effects. Therefore, clean energy
alternatives and carbon recycling are needed for solving the future energy sustainability
problems.
Among several clean energy substitutes such as nuclear, hydroelectric, geothermal,
and solar, nuclear fission energy has been well proven as a technology widely used in the
world. However, nuclear waste disposal challenges and unpredictable accidents such as
Three Mile Island, Chernobyl, and Fukushima are often cited by the public (Bodansky
2001; Grady, 2011; Makhijani, 2009; Pearce, 2008). As to hydroelectric power, it
is limited by the availability of waterways. River dams may also cause unpredictable
influences on the aquatic ecosystems, fisheries, and river transport. Regarding deep
underground geothermal electricity, the usable energy is often located kilometres below
the surface and there are concerns about seismic impacts. In comparison, solar energy
is a safe, clean and unlimited resource (Roeb et al., 2010). However, the availability of
sunlight on the earth's surface is intermittent because it is not available at night and on
rainy and cloudy days. The energy distributed on various areas may differ significantly.
Therefore, if the solar energy captured at daytime or regions rich in sunlight can be
stored, then the intermittency issue would be resolved. The usage of solar energy for
hydrogen production is a good option for solar energy storage, because hydrogen has
a much higher mass energy density than most current fossil fuels (Envestra, 2010;
EVWorld, 2010; ForestBioEnergy, 2010). The only product of hydrogen combustion
is water vapour, which can be recycled to produce hydrogen with solar energy. It was
reported that the efficiency of a hydrogen internal combustion engine could be 10-40%
higher than a gasoline engine. The hybrid electric motor and fuel cell vehicle could even
be 2 to 3 times more efficient than an internal gasoline combustion engine (Berger,