With an ambitious target of one million hydrogen-fuelled vehicles on roads and 1,000 MW electricity from hydrogen energy by 2020, research for cost-competitive hydrogen fuel cells is sure to be stepped up. Several countries like Canada, Germany, Japan, UK and US are supporting comprehensive research, technology development and demonstration programmes for new hydrogen energy technologies and applications.

India might be the latest to join, but is not lagging behind. National Hydrogen Energy Board has just drafted a national hydrogen energy roadmap.

Hydrogen has the highest energy content per unit mass of all the known fuels and has been demonstrated to cause near zero pollution. Burnt hydrogen produces water as a byproduct and is, therefore, environmentally benign. The objective is to produce enough hydrogen in an eco-friendly manner so that no carbon dioxide or any other greenhouse gases are emitted in the process. Hydrogen as an energy is eco-friendly, but needs safe handling as in its gaseous form, it is 14 times lighter than air and its flame is invisible in daylight. Hydrogen is flammable over a very wide range of mixtures in air (4% to 75% hydrogen in air) and is also explosive over a wide range (15% to 59%) at normal temperatures. At higher temperatures, small leaks of hydrogen can cause burning or explosion. Hydrogen in its liquid form cannot be stored indefinitely. "Therefore, technologies should be developed for safe handling, transportation and storage," says principal advisor and special secretary in the Union ministry of new and renewable energy, SK Chopra.

Hydrogen, however, has an edge especially in the transport sector. It can be used directly in the existing internal combustion engines and turbines in place of fossil fuels or as blended mixture with fossil fuels. It can be used in fuel cells for electricity generation and in automobiles. Low temperature fuel cell systems are suitable for automobiles and have inherently higher energy conversion and more efficient than internal combustion engines or turbines. Besides industrial applications, it can be used to produce heat.

The quantity of hydrogen currently produced in the country is just sufficient to meet the needs of the user industries. It is not enough to replace the use of fossil fuels in automobiles and in electricity generation. Also, it is costly and is delivered to end users at about Rs 240 per kg. This is too costly to make it economically and commercially viable for use in automobiles and in power generation. "The cost needs to be reduced by a factor of 3 to 4 for making hydrogen a viable option," says Union minister for new and renewable energy resources, Vilas Muttemwar.

Ironically, hydrogen is available in abundance in the environment, particularly in water. But it is not found in elemental form and therefore needs to be separated. Worldwide, more than 95% hydrogen is produced from hydrocarbon, which is not an eco-friendly process and only 4% hydrogen is produced through electrolysis of water, which is very costly. Steam reforming of natural gas or naphtha, partial oxidation of heavy hydrocarbons constitute about 78% hydrogen production in the world.

Ratan Tata, who is also the chairman of the National Hydrogen Energy Board's steering panel, however, feels that the challenges posed in the way of making hydrogen energy viable are surmountable. He says, "India is one of the few developing countries along with China and Brazil which has a strong hydrogen energy research and development programme. Hydrogen-powered motorcycles, three-wheelers, small generators, fuel cells and battery hybrid vans have been developed in the country. We had several demonstration projects for production and application of hydrogen."

Several technologies are available for producing hydrogen. Steam methane reforming is at present the most common and least expensive method. Electrolysis of water is most eco-friendly process, but it is about three to five times more expensive compared to the cost of fossil fuel feedstock. Photo-electrochemical processes involving wet photovoltaic systems can produce hydrogen through splitting of water in one step. Producing hydrogen from water using alkali metal sodium holds promise for future as a viable process. High temperature nuclear reactors have the potential to produce clean hydrogen.

Other possible methods for producing hydrogen are partial oxidation of heavy hydrocarbons and gasification of coal. Integrated Gasification Combined Cycle (IGCC) for coals is under development in India. Generation of hydrogen from biomass is one of the emerging production technologies. No single production technology is likely to meet the needs of hydrogen for the new emerging applications in power and transport sector. We need to take help of multiple technologies.

Fuel cells require relatively pure hydrogen free of contaminants such as sulphur and carbon compounds. Therefore, appropriate cleaning technologies should be in place for hydrogen produced from hydrocarbons, gasification of coal and biomass, say experts.

Most common method of storage of hydrogen is in gaseous form in pressurised cylinders and tanks. However, since hydrogen is the lightest element, gaseous storage requires large volumes and high pressure. Worldwide, research efforts are in progress to develop tanks and materials that can store hydrogen at a pressure higher than 700 bar. Hydrogen is also stored in liquid form, but not for an indefinite period, and it requires low temperatures with cryogenic storage systems. It is also possible to store hydrogen in certain solidstate materials and chemicals like cyclohexane, methanol, ammonia, which needs moderate temperature and pressure. Global researches are in progress to use nano-carbons as viable hydrogen storage system. Glass microsphere storage system is another area where researchers are working. Other areas for bulk storage of hydrogen like in gas pipelines and underground tanks with adequate safety devices are also engaging the attention of researchers.