Porphyrins and alternative energy

Humans have always used fire, if only to keep warm. With the industrial revolution, combustion of coal provided the energy necessary to make steel. In this century, oil and gas have begun to replace coal as the prime combustible material, especially for electricity generation. However, the problem of how to manage the products of combustion is now one of the most important environmental issues. Increasing carbon dioxide concentrations in the atmosphere from the burning of fossil fuels, are thought to be one of 

Nuclear burning — the atomic fission of uranium and plutonium, which releases much larger quantities of energy than ordinary chemical combustion—has yet to fulfil its promise, not only in terms of cost but also in trust. How to dispose of dangerous radioactive waste safely and cleanly is still an insoluble problem. 

Hydrogen could be the ideal answer to these problems. When it is burnt (delivering more energy per mole than hydrocarbon fuels or coal), there is no waste, as the product of combustion is water. And if water could be used as a source of hydrogen, then we should possess a truly clean, renewable energy source in virtually inexhaustible supply. 

The practical realisation of such a dream is inevitably beset with problems. First, hydrogen has a bad image. This may seem surprising in the light of global warming and acid rain, but the vision of burning airships. 

The main problem, however, is to produce hydrogen cheaply enough to compete with fossil fuels. The most promising way is to crack water, but that usually requires electricity to decompose the water into hydrogen and oxygen. Only if there is a cheap source of electricity, such as hydroelectricity, does hydrogen gas become a viable fuel, and only then if the storage problem can be economically overcome. 

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