Hydrogen-driven Economy and Utilization

At present, the economy is dominated by carbon (coal, gasoline, petroleum) for generation of electricity and transport. These sections account for almost 56% of greenhouse emissions and contribute towards global warming. This realization that carbon dioxide leads to general increase in global temperatures was released from 1966 to the present day. Current awareness among the members of the general public policy makers and industrial captains has started a dialogue on transitioning from predominately carbon economy to hydrogen or electron (batteries) economy. This can be realized initially in the transport sector (26% of CO2 emissions). The key problem is generation of sustainable hydrogen with zero or lower CO2 emissions than current practice, which is geared towards industrial processes. A log fold increase in hydrogen production would be required from a diverse pool both fossil and renewable sources. Examples discussed include hydrogen production from biomass (glucose economy) through steam reformation (shown in Eq. 10.1), partial oxidation of hydrocarbon (Eq. 10.2), pyrolysis (Eq. 10.3), microbial (Eq. 10.4), and electrolysis (Eqs. 10.5a, 10.5b, and 10.5c). $$ 2{\mathrm{C}}_x{\mathrm{H}}_y\ \left(\mathrm{g}\right) + 2 x{\mathrm{H}}_2\mathrm{O}\ \left(\mathrm{g}\right)\ \to\ 2 x\mathrm{C}\mathrm{O}\ \left(\mathrm{g}\right) + \left(2 x+ y\right){\mathrm{H}}_2\left(\mathrm{g}\right) $$ (10.1) $$ 2{\mathrm{C}}_x{\mathrm{H}}_y\ \left(\mathrm{g}\right) + x{\mathrm{O}}_2\ \left(\mathrm{g}\right)\ \to\ 2 x\mathrm{C}\mathrm{O}\ \left(\mathrm{g}\right) + y{\mathrm{H}}_2\left(\mathrm{g}\right) $$ (10.2) $$ 2{\mathrm{C}}_x{\mathrm{H}}_y\ \left(\mathrm{g}\right) + 2 x\mathrm{C}+ y{\mathrm{H}}_2\ \left(\mathrm{g}\right)\to\ \mathrm{hydrocarbon} $$ (10.3) $$ 2{\mathrm{H}}^{+}\ \left(\mathrm{aq}\right) + 2{e}^{-}\to {\mathrm{H}}_2\left(\mathrm{g}\right) $$ (10.4) $$ \mathrm{Anode}\ \mathrm{reaction}:\ 4{\mathrm{O}\mathrm{H}}^{-}\left(\mathrm{aq}\right) + 4{e}^{-}\to {\mathrm{O}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}(l) $$ (10.5a) $$ \mathrm{Cathode}\ \mathrm{reaction}:\ 2{\mathrm{H}}_2\mathrm{O}(l) + \to {\mathrm{H}}_2\left(\mathrm{g}\right)+2{\mathrm{OH}}^{-}\left(\mathrm{aq}\right)+4{e}^{-}\left(\mathrm{g}\right) $$ (10.5b) $$ \mathrm{Overall}\ \mathrm{reaction}:\ 2{\mathrm{H}}_2\mathrm{O}(l)\to 2{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right) $$ (10.5c) The above processes could generate sufficient hydrogen to meet the needs of the transport sector, with hydrogen used as a fuel. Examples of hydrogen usage in this manner include: fuel cell powered automobiles either as hybrid (fuel cell – lithium ion batteries), plug-ins (Li-ion battery or hydrogen fuel cell vehicle with on-board storage. The function of the fuel cells such as proton exchange membrane fuel cells is to convert chemical energy to electrical energy spontaneously during electrochemical reactions (Eqs. 10.6a and 10.6b): $$ \mathrm{Anode}\ \left(\mathrm{hydrogen}\ \mathrm{oxidation}\ \mathrm{reaction},\ HOR\right):\ 2{\mathrm{H}}_2\left(\mathrm{g}\right)\to 4{\mathrm{H}}^{+}+4{e}^{-} $$ (10.6a) $$ \mathrm{Cathode}\ \left(\mathrm{oxygen}\ \mathrm{reducion}\ \mathrm{reaction},\ ORR\right):\ 2{\mathrm{O}}_2\left(\mathrm{g}\right)+4{\mathrm{H}}^{+}+4{e}^{-}\to 4{\mathrm{H}}_2\mathrm{O}(l) $$ (10.6b) While no single technology appears to be superior in all aspects, steam reformation and biomass gasification offer practical approaches to generate sufficient hydrogen to meet transportation needs in the near term. The steam reformation of natural gas coupled with CO2 capture can offer a sustainable method, while gasification of biomass using supercritical chromatograph with catalyst offers another approach to generate sustainable hydrogen. In the mid-term, the electrolysis of water using off-peak grid electricity offers a pathway to generate hydrogen with negligible greenhouse emission. In the long term, the biogeneration of hydrogen and splitting of water using photo electrolysis or thermochemical pyrolysis are feasible avenues. The development of these technologies also needs policy makers to create a favorable legislature environment such as tax incentives for end-user or product generator and wider disseminations on the need to transition away from carbon, particularly for nations that do not have a native supply of coal, or petroleum.