THE HYDROGEN CYCLE.
Global warming is caused by the build-up of Greenhouse gasses in the atmosphere. These gasses are the inevitable result of our use of carbon based materials [coal, petroleum, natural gas] to generate the energy which drives our society. These materials generate heat by combining with oxygen in an exothermal reaction [ie: gives off heat - which we want !], the by-product of the reaction being carbon dioxide [the most important greenhouse gas - which we emphatically do not want !]. There is no practical way around this - if you want to get energy from carbon [ie: coal, petroleum, natural gas], you have to burn it [ie: combine it with oxygen in the atmosphere] and the inevitable result is carbon dioxide.
The purpose of this paper is to demonstrate that an alternative energy generation cycle is possible, based on hydrogen combining with oxygen in the atmosphere, again in an exothermal reaction [ie: giving off heat] but with the only by-product being water.
The hydrogen cycle is generally the basis of fuel cell technology, in which hydrogen and oxygen [air] are combined to produce an electrical output. This technology is not new, it has been used on all the NASA space missions. It is particularly important to note that, although we have alternative ‘clean' technology available for electrical power generation [solar cells, wind, biogas etc.], the hydrogen cycle/ fuel cell technology is a possible technology for powering cars and trucks [demonstration vehicles are on the road in the USA and Europe now] when petroleum becomes too scarce or too expensive for that application [some time in the next 25 years ?]. The hydrogen cycle is also one of a limited number of sustainable methods for generating base load electricity. It naturally follows that introducing this technology requires significant government involvement - it is not something which individuals can do. The big question for our government is - "what are you doing about the big tasks required to move to a clean, sustainable technology, where we can keep our society running at a reasonable level of comfort and progress, without destroying our children's society ?'
This paper is based principally on the following references -
THE SOLAR HYDROGEN CYCLE.
The diagram below illustrates the Solar Hydrogen Cycle on the basis of the hydrogen being generated from water using electric power from photovoltaic solar panels. It does not have to be generated that way and most of the [quite considerable quantity] of hydrogen used today in the chemical industry is manufactured chemically. However, this is the only sustainable method and it is possible that a significant industry could be established in the desert regions of Australia, generating hydrogen by the method shown in the diagram and shipping it to points of use [in Australia and overseas] in a manner similar to the way we now ship natural gas.
In this typical schematic process, electricity from photovoltaic panels is used to power an electrolyzer, a device which splits water (H20) into its elemental parts, hydrogen (H2) and oxygen (O2).
The oxygen is released into the air and the hydrogen is pumped into storage tanks, where it can be kept on site or transported to regions that need energy.
At night or in bad weather, when solar energy is not available, the hydrogen is recombined with oxygen from the air in a fuel cell, which directly converts the chemical energy in hydrogen into electricity. The only byproduct of this process is pure water.
Electricity from fuel cells can be used in the same ways as power from a utility company or other type of generator, to run appliances and light bulbs, electric motors, and to power cars. Solar hydrogen allows us to use the power from the sun twenty-four hours a day, and provides us with an abundant, clean, efficient, locally produced, sustainable source of energy.
Hydrogen is the most common element in the universe - it is eminently sustainable since at the end of the process the hydrogen ends up where it began, as water. It is not like carbon fuels where the carbon, at the end ot the cycle is locked away in carbon dioxide, or some even nastier forms such as carbonic acid.
The favoured approach by current policy makers is to make hydrogen in the cheapest way, by distillation from coal. This manufacturing process produces large quantities of CO2 which negates the environmental advantage of the carbon cycle. Only hydrogen produced cleanly and sustainably should be considered.
This whole process is still in the experimental stage - we do not have enough experience with this technology to implement it on a large scale immediately. In particular, widespread use of hydrogen powered vehicles will require building a network of hydrogen filling stations. All this simply highlights the necessity of motivating our politicians to adopt a more focused and commited attitude to the whole problem of building a sustainable society to replace the temporary, exploitive society which we now have and which is approaching its inevitable end. A big ask !!
John M Kelly, BE, BA. 3 December 2007.