HYDROGEN

6.0 HYDROGEN

Hydrogen is the most abundant element in the universe, but is rarely found in its uncombined form on the earth. Hydrogen gas (H2) is being explored for use in combustion engines and fuel cell electric vehicles. When combusted (oxidized) it creates only water vapor as a by-product. When burned in an internal combustion engine, however, combustion also produces small amounts of nitrogen dioxides and small amount of unburned hydrocarbons and carbon monoxide because of engine lubricants but the exhaust is free from carbon dioxide. It is a gas at normal temperature and pressure, which presents greater transportation and storage hurdles. Storage systems being developed include compressed hydrogen, liquid hydrogen and chemical bonding between hydrogen and a storage material (for example, metal hydrides).

Two methods are generally used to produce hydrogen- electrolysis and synthesis gas production from steam reforming or partial oxidation. Electrolysis uses electrical energy to split water molecules into hydrogen and oxygen. The electric energy can come from any electricity production sources including renewable fuels. The predominant method for producing synthesis gas is steam reforming of natural gas, although other hydrocarbons can be used as feedstocks. For example, biomass and coal can be gasified and used in a steam reforming process to produce oxygen.

Another development using hydrogen is a blend of hydrogen and methane (natural gas) called Hythane.

6.2 Emissions:

Hydrogen is one of the simplest and the lightest fuel. On combustion it produces only water vapor as the by-product. It has the greatest potential for reducing emissions. There may be small amount of unburned hydrocarbons and carbon monoxide, which may be attributed to the engine lubricants.

6.3 Advantages of Hydrogen:

Some of the advantages of hydrogen as a fuel include:

- Very less emissions.
- High octane rating.
- High energy content.
- Large base source for production is available.

6.4 Disadvantages of Hydrogen:

Disadvantages of hydrogen fuel are:

- Infrastructure.
- Problem of fuel storage.
- Vehicle range and power loss.
- Wider flammability limits.
- Costly production.
- Limited field trial experience.

6.5 Operation & Performance:

Operational and performance data are not adequate, as no vehicle exists currently that run on hydrogen as a fuel excepting some test vehicles in the USA. But some studies found operation and performance of hydrogen vehicles very promosing.

6.6 Safety Issues:

Especially for hydrogen, safety is mainly a function of storage method, and both refueling and vehicle storage system require extensive development. Storage technologies include high-pressure storage, cryogenic liquid storage and low-pressure metal hydride storage systems.

6.7 Vehicle Experience:

There are no commercial vehicles currently available that use hydrogen as fuel, however automobile manufacturers have experimented with developing vehicles that use hydrogen. Research vehicles have been produced by Daimler-Benz, BMW and Mazda. The Mercedes-Benz and BMW vehicles use liquid hydrogen. The Mazda vehicle stores its hydrogen as a gas in a metal-hydride lattice of shaved metal. Other vehicles have been built using compressed hydrogen, including two vehicles in Arizona operated by the American Hydrogen Association.

6.8 Storage & Distribution:

Hydrogen is a gas at normal temperature and pressure. It can be stored as a compressed gas like CNG or in liquefied cryogenic form or in the form of metal hydrides. Lot of developments is needed for efficient and effective storing of hydrogen. Economic and safe storing of the fuel on board a vehicle is the main challenge now. Extensive research is going on in this field and researchers are hopeful of getting a breakthrough soon.

6.9 Indian Initiative on Hydrogen:

Researchers in India have developed a hydrogen-powered motorbike that its developers believe is ready for commercialization. The technology, based on a novel metallic hydrogen storage system, may also be modified for use in cars. As a part of a R&D project, a photo bioreactor for producing hydrogen from distillery wastes treatment was installed at Nellikuppam in Tamil Nadu. Other projects were also taken up for the production of hydrogen using solar energy and water through photo electrochemical/photocatalytic methods. Government of India is also funding a project at BHU, Varanasi for performance improvements of hydrogen/metal hydride-based vehicles. Another research project for pilot scale production of hydrogen by photo catalytic decomposition of water using semiconductor photo catalyst, which can be activated by radiation, is under implementation at BHU. Moreover, BHU has also taken up a project for the development of hydrogen storage materials and systems for vehicular applications.

MNES proposes to launch a field operations programme on hydrogen energy for vehicular applications.