• How does it compare with natural gas and petroleum products as fuel?

First of all, natural gas is a naturally occurring fuel; whereas hydrogen is not. Hydrogen can, of course, be produced from natural gas, which is predominantly methane, through the steam-reforming process, with a conversion ratio of only 60 to 70 per cent. This means that 30 to 40 per cent of the energy of natural gas is lost in the production of hydrogen. Furthermore, energy is required for storage and transportation of hydrogen as opposed to natural gas. Also, there is no significant benefit environmentally since CO2 is emitted during its production. Thus, producing hydrogen from natural gas is neither energy efficient nor environmentally beneficial. Hence, it is better to use natural gas directly.

Similarly, petroleum, used for producing hydrogen, has to be gasified into synthesis gas and then steam-reformed to produce hydrogen. Again, the whole process consumes energy with no net benefits in energy efficiency or emissions.

• Can we use hydrogen in IC engines of transport vehicles?

Theoretically, yes. However, the IC engine would require design modifications. Very few automobile companies in the world are working on development of engines for this purpose. Hydrogen can be blended in small percentages with CNG and can be used in CNG fired IC engines with very minor modifications.

• Why are advanced countries like the US, Japan and Europe engaged in development of hydrogen-based vehicles?

Most developments in advanced countries are based on Fuel Cell technology. The overall efficiency of Fuel Cell based automobile vehicles is higher than the IC engine, even with conversion of hydrocarbon fuels to hydrogen. This gain thus leads to overall reduction in GHG emissions. The main hindrance today in the commercialisation of Fuel Cell vehicles is cost, which will have to be brought down 15 to 20 times to make these competitive.

... contd.