Hydrogen as a Fuel

NOVEMBER, 2014

HYDROGEN AS A FUEL Er. Mayadhar Swain

Introduction We use petroleum oil to run our vehicles. It has become scarce material and is available only in a few parts of the globe. People of other parts depend on them for this fuel. In our country, production of petroleum oil in 2012-13 was 37.862 million metric ton (MMT) and demand was much more so that we had to import 184.795 MMT of petroleum oil. A major part of our foreign exchange is used for import of petroleum oil. For example, in 2012-13, value of imported oil was Rs. 784652 crore. Not only India, the economy of most of the countries is affected by this. To get rid of this, scientists started research to find alternate fuel for vehicles and they have found one. This is hydrogen.

3.

Production of Hydrogen

Pure hydrogen does not occur in Nature and so it has to be manufactured by some processes. Fortunately, there are many sources of hydrogen and many processes have been developed for its production. Industrially, hydrogen is mainly produced from fossil fuels, biomass and electrolysis of water. At present, ninety percent of hydrogen is produced from natural gas or light oil fractions. However, there are some other methods developed recently for its production. Some of the processes are described here. 3.1 Hydrogen from Methane Hydrogen is generated from natural gas or from other hydrocarbons. Methane is an important component of natural gas. At high temperatures (7000C - 11000C)

2.

Advantages of Hydrogen as Fuel

steam (H2O) reacts with methane (CH4)

i.

A given weight of hydrogen in liquid form contains about three times as much energy as the same weight of petroleum oil. Hence, it can be suitable for use in aircrafts where it is important to keep weight as minimum as possible.

in an endothermic reaction and produces carbon monoxide (CO) and hydrogen. In

ii.

When hydrogen is burned, it produces heat and water. So engines running on hydrogen do not cause air pollution.

ii.

Hydrogen can be transported easily th ro ugh pi pe li nes an d hen ce transportation cost will be less.

iv.

Hydrogen can be produced by a variety of processes from different sources.

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the second stage, additional hydrogen is also generated through lower temperature which also produces carbon dioxide (CO2). The complete reactions are:In presence of nickel catalyst and at 7000C -11000C, CH4(g) + H 2O(g)

o CO(g)

+ 3H2(g)

At lower temperature, CO(g) + H2O(g) o CO2 (g) + H2(g) This process is the major source of hydrogen at present. 29

NOVEMBER, 2014

3.4 Hydrogen from Fuel Cell

3.2 Hydrogen from Coal Hydrogen is produced from coal by coal gasification. In this process coal is heated at high temperature and pressure to produce syngas.

Thenewest, andpossiblythemostpromising, source of hydrogen is fuel cell. It uses the energy in sunlight to split water directly into hydrogen and oxygen. The reaction is:

Coal + H 2O(g) + O2(g)

o

syngas

Syngas = H2 + CO + CO2 + CH 4

light energy 2H2O  o2H 2  O2

3.5 Biohydrogen

This is also current method of mass production of hydrogen. 3.3 Electrolysis of Water

commonly by algae, bacteria and arches, is known as biohydrogen. Biohydrogen

When electric current is passed through

is a potential biofuel, obtainable from

water, the water molecules split into

both cultivation and waste organic

hydrogen and oxygen, which can be

materials. Biomass can be converted into

collected separately. This is called

biohydrogen with biomass gasification

electrolysis.

process.

electric current 2H2O(1) o 2H (g) O (g) 2 2

The microorganisms convert biomass into hydrogen though dark-fermentation

This method hasthe advantage that plenty

or photo-fermentation.

of water is available on the Earth (nearly two-third of the globe). But major

Dark-fermentation is the process of

disadvantage is the cost of electricity. But this method can be used when there is surplu s of electrical power, particularly during night time. Further, if electricity produced from fossil fuels is used for this, then it negates the environmental benefit from this. Hence, electricity from renewable sources such as solar and wind energy should be used for this purpose. 30

Hydrogen produced biologically, most

production of hydrogen by anaerobic bacteria, grown in dark on carbohydraterich substrates. The reaction is: C 6H12O 6  2H 2O o 2CH3COOH  4H2  2CO2

Photo fermentation is the method of fermentation by micro-organisms where light is required. The reaction is: light energy C H O  2H O  o12H  6CO 6 12 6 2 2 2

light energy CH COOH  2H2O  o4H  2CO 3 2 2 Science Horizon

NOVEMBER, 2014

4.

Problems of Hydrogen as Fuel

Hydrogen has a great potential as a fuel, but it has also some problems. Hydrogen in gaseous form takes large space and hence for most purposes it has to be stored as liquid, but it cannot be liquefied at temperature higher than -2530C. So the vehicle using hydrogen as fuel has to be fitted with insulated fuel tank, which increases both weight and cost. Further, the tank size will be increased as a given volume of liquid hydrogen contains less energy than the same volume of conventional petroleum oil. One solution to the problemof liquefying hydrogen is to combine the gas with a metal, forming a hydride. Generally some alloys of nickel and magnesium react with hydrogen at room temperature, but releases the gas when heated. These alloys can be stored in motor vehicle tanks. When engine runs, the heat from the exhaust can be used to heat the alloy and release hydrogen. 5.

Conclusion

Any alternate fuel, to be popular must be technically feasible, economically viable, safe to use and cheap. Hydrogen can definitely achieve these in near future. It is being considered as the 'energy of the future' since it is a clean energy source with high energy content as compared to hydrocarbon fuels. But unlike fossil fuels it is not readily available in nature. Therefore, new processes need to be developed for its cost-effective production. „ Deputy General Manager, PP & EE Section, MECON Limited, Ranchi-834002 Mobile - 09470193755

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AWARD OF NOBEL PRIZE IN CHEMISTRY - 2014 Dr. Baidhar Sahu

The development of super-resolution fluorescence microscopy by two American scientists Eric Betzig and William E.Moerner with one German scientist Stefan W.Hell has by-passed a presumed scientific limitation according to which an optical microscope can never yield a resolution better than 0.2 micrometers. By this, they have taken optical microscopy into nano dimensions using fluo resc ent mole cule s. Fo r th e ab ove pioneering work the Royal SwedishAcademy of Sciences have recommended for the award of Nobel Prize in Chemistry to the above three scientists for the year 2014. The Nobel laureate Eric Betzig, born in AnnArbor of USAin 1960 was awarded Ph.D. degree from Cornell University, New York and at present he is the Group Leader at Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, USA. The other American Nobel laureate William. E. Moerner born in Pleasanton of USA in 1953 got his Ph.D. degree from Cornell University, New York, USA. At present he is Harry. S. Mosher Professor of Chemistry and Professor of Applied Physics at Stanford University, USA. The German citizen and Nobel Laureate Stefan W.Hell born in 1962 in Arad, Romanic obtained his Ph.D. degree in 1990 from 31