Power Plants of the Future !!
HYDROGEN gas thought to be the green fuel for the world where air pollution is considered to be the major problem, global warming has already felt its presence and the environment has been damaged gloabally.Hydrogen and electricity could attach each other to provide a lucrative option for transpotation and energy generation.A challenging problem in establishing H 2 (hydogen gas)as the major source of energy is the renweable and environment friendly generation of hydogen in mass quantities.
The scintific name of microscopic green algae is Chlamydomonas reinhhardtii , and to a regular guy as pond scum was used for more than 60 years ago for the splitting of water into its major constituents that is Hydrogen and Oxygen under well controlled conditions.
A major breakthrough came in 1999 at the University of California ,when professor Tasios Melis, along with researchers ,discovered that depriving algae culture of sulphur and oxygen would enable it to produce hydrogen for sustained periods of time.
The Mechanism of H2 Production.
Stages in early biological evolution ,hydrogen was an abundant gas in earth atmosphere.Various Organisms developed mechanism to utilise this gas .The key enzyme in the process is hydrogenease ,which catalyses reversibly the simpliest of all chemical reaction : Splitting hydrogen gas into its subatomic particles.
Green algae can produce hydogen gas in a procedure called ‘biophotolysis‘ .This process is carried out by photosynthetic enzymes that split water to obtain electrons, which therefore reduce H+ ions into H 2 the reaction can be summarised as
2H+ + e - ———(sunlight)> H 2 (Hydrogen gas)
The reason for hydrogenease inactivity in green algae under normalphotosynt-etic conditions in still unknown.Hydrogenease is thought to become active in order to excreate excess reducing power under specific conditions , such as anar-obic conditions.
The problem was solved by depriving the algae culture of inorganic sulphur that revesibly inactivated the functioning of Photosystem ??, which evolves oxygen during photosynthesis ,without sulphur the metabolic pathways change, enabling the algae to function without generating oxygen. After about 24 hours of sulphur deprivation , the plant becomes anarobic , activating the enzyme that produces hydrogen in light.
Normally , algae cells use ultraviolet light to perform photosynthesis , which in turn produce sugar, oxygen and the very high energy molecule called ATP (adenosine triphospate) from carbon-di-oxide and water.ATP is the major energy source by which plants carry out vaital functions, including cellular maintenance, repair and very essential biosynthetic processes in the absence of normal photosynthetic activity (in the night).If this ATP is present in the plants then under unfavourable conditions a normal plant would die very easily.
However the green algae has an allternative that permit them to generate ATP ,giving off Hydogen as the end product .Researchers from the University of Bielefeld in Germany and the University of Brisbane ,Australia , have genetically modified the single-cell green algae in such a way it produces a huge amount of hydorgen .It has been known for a long time that certain algae can produce hydrogen during the photosynthetic process.But the catch was efficiency , as one litre of algae produces only about 100 ml of hydrogen. But the genetically modified variants boosts up to half a litre of hydogen.
Hydrogen as a FUEL.
Hydrogen is the ultimate clean energy carrier with respect to our present energy carriers such as nuclear and fossil fuels, in fuel cells the combination of hydrogen and oxygen produces nothing but electricity and pure , clean water.Hydrogen powered fuel cell vehicles will eliminate the ever increasing problem of massive air pollution , significnatlly reduces green house gas emissions.