Hydrogen- A New Biofuel and its Production

Read this article to learn about Hydrogen and its production. Some of the methods used for the production of bio-hydrogen are: (1) By Photosynthetic Bacteria (2) By Fermentation and (3) By Legume Crops

Hydrogen is a simple molecule which can be easily collected, stored (as a gas or liquid) and transported. It is highly combustible and can be used as a fuel or for the production of electricity. Hydrogen, on mixing with oxygen, provides around 30,000 calories per gram as compared to 11,000 and 8,000 calories per gram of gasoline and coal respectively.

Further, use of hydrogen is environmental friendly, since it is a non-pollutant. Hydrogen is truly a versatile fuel. It can be used for automobiles, aero planes, helicopters, buses, cars and scooters. Liquid hydrogen is considered to be an ideal fuel for subsonic and supersonic aircrafts world over.

Production of Bio-hydrogen:

1. By photosynthetic bacteria:

Biological production of hydrogen can be achieved by photolysis of water by photosynthetic algae and bacteria, a phenomenon referred to as bio-photolysis. Certain microalgae, and cyanobacteria (e.g. Chlorella, Chlamydomonas, Scenedesmus, Microcystis, Oscillatoria, Aneboena) can generate molecular hydrogen. Water is the source of raw material.

The action of hydrogenase can be inhibited by creating oxygen pressure. This condition favours release of free hydrogen. Isolated chloroplasts along with the bacterial enzyme hydrogenase have also been used for production of hydrogen.

2. By fermentation:

It is possible to produce hydrogen from glucose, by bacterial action. However, the yield is less and uneconomical. Hydrogen can also be generated by anaerobic fermentation, by a process comparable to that of methane production. This is also not economical, besides being low in efficiency. Photosynthetic bacterium Rhodospirillium can be used to produce hydrogen from organic wastes.

3. By legume crops:

The leguminous plants convert N₂ to NH₃ and H₂. This reaction is catalysed by the enzyme nitrogenase. In the normal circumstances, this H₂ gas, a byproduct of nitrogen metabolism is lost in the soil. It is estimated that from a soybean crop in one hectare field, about 30 billion m³ hydrogen is generated and lost annually. As such, there are no methods available to trap such huge quantities of hydrogen produced in agricultural fields.