Hydrogen Is Not an Appropriate

Hydrogen Is Not an Appropriate Energy Source to Replace Fossil Fuels

The population is growing and so are its power needs. Fossil fuels are being used, their end products are increasing green house emissions, and there will come a time when they will be depleted. Further, oil spills, such as the current British Petroleum Gulf Coast Spill are becoming more common and more costly. Scientists have been searching for an appropriate alternative form of energy with less harmful global effects and many have focused on hydrogen. However, the use of hydrogen as an energy source will likely not replace fossil fuels. The overall hydrogen fuel process is inherently costly and inefficient, increases green house gas emissions and because of the low output would require extensive development of hydrogen processing plants.

The Hydrogen Fuel Cell

There is potential for the use of hydrogen in small scale powering, but it's potential for powering car engines of households is unlikely Hydrogen fuel cells are a storage battery for energy derived from other sources. In a fuel cell, hydrogen and oxygen are sent to the anode and cathode of each cell. Electrons stripped from the hydrogen produce direct current electricity that can be used in a DC electric motor, such as in a kitchen appliance.

However, as an energy source for powering cars, hydrogen is an inefficient source partly because it is very reactive. When hydrogen gas makes contact with metal it decomposes into hydrogen atoms, which are small enough to penetrate metal (and most other materials) causing it to leak from even well insulated containers. For this reason, hydrogen in storage tanks will always evaporate, at a rate of at least 1.7% per day.

Additioanlly, the necessary size of the required fuel tanks is rather prohibitive. In gaseous form, a volume of 6,2873 gallons of hydrogen gas is necessary to replace the energy capacity of 20 gallons of gasoline.

Compressed hydrogen has been the primary source of hydrogen-powered cars to date.

Because of its low density, compressed hydrogen will not give a car as useful a range as gasoline. Moreover, a compressed hydrogen fuel tank would be at risk of developing pressure leaks that could result in explosions. Additionally, the energy costs of liquefying the hydrogen and maintaining it in a liquid state are likely to decrease the energy return on hydrogen fuel.

Producing Hydrogen for Use

Hydrogen does not freely occur in nature in useful quantities, therefore hydrogen must be split from molecules, either molecules of methane derived from fossil fuels or from water. Currently, most hydrogen is produced by the treatment of methane with steam, following the formula: Chapter 4 (g) + H2O + e > 3H2(g) + CO (g).

Carbon monoxide gas [CO (g)] is a byproduct of this reaction which defeats the intent of alternative fuel sources to eliminate production of greenhouse gases. Following the first and second laws of thermodynamics, this procedure results in a severe energy loss. The first law of thermodynamics says that the energy output from any process can't exceed the energy input, and the second law focusing in part on decay states that each process decays energy.

The production of the methanol from natural gas results in an initial 32% to 44% net energy loss, then the steam treatment process to procure the hydrogen results in a further 35% energy loss.

Several processes are being explored to derive hydrogen from water, as an inexhaustible source. However, this reaction, 2H2O + e = 2H2(g) + O2(g), requires a substantial energy investment per unit of water (286kJ per mole).

This energy investment is again required by both the first and second laws of thermodynamics and renders the electrolysis of water unprofitable in terms of energy return based on the energy invested.

Any effective hydrogen economy would require an infrastructure that could use zero-carbon power to electrolyze water into hydrogen, convey this highly diffuse gas long distances, and pump it at high pressure into a car or into our large fuel cells in our homes. Next, the hydrogen would have to be converted back into electricity to drive an electric motor or electric utilities. The cumulative process of electrolysis, transportation, pumping and fuel-cell conversion would render only 20 to 25% of the original electricity as functional.