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Introduction to Hydrogen Economy
The concept of utilizing hydrogen on a large scale, as a fuel, an energy carrier, and in industrial processes like ore reduction, ammonia synthesis and fossil fuel up gradation is the basis of a HYDROGEN ECONOMY. The fast depletion of world’s fossil fuel reserves is the greatest techno-economic concern of our day. Crude prizes soaring over 100 dollars per barrel, and the prospect of even reduced oil production necessitated by dwindling oil reserves compel the world to look for alternate energy sources. The available alternatives are nuclear energy and renewable sources like the sun, wind and ocean for producing electricity. However, electricity forms only 10 to 25 % of our total energy consumption. The rest 75 to 90 % are non-electrical energy which needs an efficient carrier for utilization. Hydrogen seems to be the most promising energy carrier of the future.
Hydrogen is almost inexhaustible, non-polluting, fully recyclable, and distributable through pipe lines as gas, or as a solid metal hydride. Like oil, hydrogen can be applied universally as an energy source for automobiles as well as for domestic and industrial uses. Several hydrogen powered cars and buses have been built and their performance evaluated. Besides being a fuel, hydrogen is a convenient and environment-friendly medium of storing, transporting and using energy. Hydrogen economy facilitates the convenient storage of electricity. Excess electricity available during off-peak hours may be used to electrolyze water or other suitable media to produce hydrogen, stored as metal hydride and later transformed back to electricity via fuel cells to meet the demands of peak hours. Hydrogen stored as metal hydrides enables optimum utilization of energy through, i) waste heat recovery in industrial processes, ii) heating and cooling of houses and offices without consuming primary energy, and iii) up grading of low quality heat energy such as those from sun light and ocean temperature differences.
The functioning of the hydrogen economy depends on the large-scale production, storage, transport and usage of hydrogen. This requires several classes of materials, like, catalysts, solid electrolytes, semi-conductors, hydrogen storage materials, and structural materials. Many of these may be available now, but many may have to be developed.
Catalysts are needed in the production, storage and use of hydrogen. Electro-catalysts like platinum, palladium, gold, silver, nickel, NiCO2O3, and WO3 have been used. Also materials highly resistant to sulfur, sulfo-spinels, layered transition metal sulfides and rare-earth sulfides have been used as catalysts for production of hydrogen by coal-gasification Research is continuing in the improvements in performance as well as cost reduction of catalytic materials.
For the production of hydrogen by water electrolysis, a suitable electrolyte is needed. Solid electrolytes will be preferable for large portable electrolytic cells. A Teflon-like solid polymer electrolyte was developed by the General Electric Company for this purpose in the 1970s. Other polymers and inorganic defect solids like yttria, zirconia and thoria are also being tried as solid electrolytes for water electrolysis.
A novel way of producing hydrogen from water is by electrolysis using solar energy, i.e. photo-electrolysis. A light –sensitive semi-conductor which is electro-chemically stable is needed for this process. TiO2, chlorophyll-coated layer compounds, Fe2O3 coated Si, and TiO2-Fe2O3 coated alumina are some of the semi-conducting materials under investigation. Intensive research is needed to develop suitable photo-sensitive semi-conductors so that the inexhaustible solar energy could be used to electrolyze ocean waters to produce all the hydrogen needed.
One of the essential requirements of a flourishing hydrogen economy is the availability of suitable hydrogen storage materials. Such storage materials must be light, absorb large quantities of hydrogen and release the hydrogen easily without getting damaged so that they can be reused. Metal hydrides can store hydrogen and release it by thermal decomposition. Hundreds of metal-hydrogen systems exist which are capable of reversible hydriding. Generally complex alloy hydride systems like Fe-Ti-H or Li-Ni-H systems are required to meet all the essential requirements of a hydrogen storage material. LaNi5 has excellent hydrogen storage properties but is very expensive. So cheaper mischmetal-Ni systems are being developed for hydrogen storage.
In spite of the development of a solid hydride storage and transport system for hydrogen, extensive high pressure storage and transport through pipe lines of gaseous hydrogen is inevitable in a hydrogen economy. Hydrogen production by coal-gasification involves high temperatures and pressures. All these require the availability of cheap structural materials which are mechanically stable in constant contact with hydrogen at temperatures ranging from liquid hydrogen temperature to 1000 oC or more and pressures over several thousand atmospheres. Most of the structural materials available today, like steels, and titanium alloys are susceptible to degradation in properties in contact with hydrogen. So methods have to be developed to design structures and monitor damage on a continuing basis for safe and reliable use of these materials for use in a hydrogen economy.
Hello Everybody
I am starting a new blog titled "Hydrogen Economy" today. Welcome.
The fossil fuel reserves of the earth are fast depleting. Today crude oil has touched a price of 110 dollars/barrel. OPEC countries are forced to regulate production of crude so that the reserves will last for may be two or three more decades. But it will dry up before the end of this century. Then what do we do?. Similarly good quality coal is also becoming more rare. In such a scenario, we are forced to look for other sources of energy which will run our technology. Nuclear energy is one source which is already in use. Uranium reserves are also limited and unless we develop fusion reactors fast, nuclear energy may also not last for ever. This brings us to renewable energy sources like the sun, the wind and the ocean. Besides these well-known sources,we have hydrogen as a source of energy. Hydrogen is a source of energy and also a convenient carrier of energy, like petrol. Nuclear, solar, wind and ocean energy are used to generate electricity and cannot be used in automobiles or buses. But hydrogen can be used as an energy carrier.
Large scale use of hydrogen for producing energy and for other industrial needs is basis of the HYDROGEN ECONOMY. Many people believe that hydrogen will be our future source of power.
I plan to write about this exciting possibility and collect new writings from others on hydrogen economy. All interested people are welcome to contribute.
GBLOGGER
The fossil fuel reserves of the earth are fast depleting. Today crude oil has touched a price of 110 dollars/barrel. OPEC countries are forced to regulate production of crude so that the reserves will last for may be two or three more decades. But it will dry up before the end of this century. Then what do we do?. Similarly good quality coal is also becoming more rare. In such a scenario, we are forced to look for other sources of energy which will run our technology. Nuclear energy is one source which is already in use. Uranium reserves are also limited and unless we develop fusion reactors fast, nuclear energy may also not last for ever. This brings us to renewable energy sources like the sun, the wind and the ocean. Besides these well-known sources,we have hydrogen as a source of energy. Hydrogen is a source of energy and also a convenient carrier of energy, like petrol. Nuclear, solar, wind and ocean energy are used to generate electricity and cannot be used in automobiles or buses. But hydrogen can be used as an energy carrier.
Large scale use of hydrogen for producing energy and for other industrial needs is basis of the HYDROGEN ECONOMY. Many people believe that hydrogen will be our future source of power.
I plan to write about this exciting possibility and collect new writings from others on hydrogen economy. All interested people are welcome to contribute.
GBLOGGER
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