Hydrogen Energy

Hydrogen Economy

  A bridge to sustainable and clean energy

                 

Hydrogen is considered a clean fuel that has minimum impact on the environment nearly eliminating the level of carbon di-oxide and other green house gas emissions. Further, it is safe to manufacture, reliable and environmentally friendly. Hydrogen is the new talk of todays’much environmentally concerned scientific world as prospective fuel for the future.

Hydrogen is considered as an alternative fuel due to the following reasons-

Highly abundant in nature.                                   

Lightest element of all the elements known

Versatile, converts easily to other energy forms at the user end

High utilisation efficiency

Environmentally compatible (zero or low emission.

  

Hydrogen production method

Hydrogen can be produced from variety of process technology, including chemical biological, electrolytic, photolytic, and thermo chemical. These process include fossil resources such as natural gas and coal, as well as reasonable resource, such as biomass and water with input from renewable energy source (e.g. solar, wind, wave, or hydro power).

Hydrogen from fossil fuels

Production from natural gas –steam reforming uses thermal energy to separate hydrogen from the carbon components in methane and methanol, and involves the reaction of these fuels with steam on catalytic surfaces. The reaction decomposes the fuel into hydrogen and carbon mono-oxide. Then “shift reaction “changes the carbon monoxide and water to carbon dioxide and hydrogen.

Production from coal

Hydrogen can be produced from coal through a variety of gasification processes. In practice, high temperature entrained flow processes are favoured to maximise carbon conversion to gas.

From splitting of water hydrogen

Water electrolysis – electrolysis separate the elements of water- Hydrogen and oxygen by charging water with an electric current. Adding an electrolyte such as salt improves the conductivity of the water and increases the efficiency of the process. The charge breaks the chemical bond between the hydrogen and oxygen and gathers at cathode and the anode respectively.

Photo –electrolysis- Photo –electrolysis of water is the process whereby light is used to split water directly into hydrogen and oxygen. Such system offer great potential for cost reduction of electrolytic hydrogen.

Photo-biological production- Photo-biological production of hydrogen is based on two steps: photosynthesis and hydrogen production catalysed by hydrogenease in, for example, green alga and cyanobacteria.

Biomass to hydrogen

In biomass conversion processes, hydrogen –containing gas is normally produced in a manner similar to the gasification of coal. However, no commercial plants exist to produce hydrogen from biomass. Currently the pathways followed are steam gasification (direct or indirect) , entrained flow gasification, and more advanced concept such as gasification in supercritical water, application of thermo chemical cycles, or the conversion of intermediate (e.g. ethanol, bio-oil or terrified wood).

Hydrogen from splitting of water

 Water splitting solar panels have important advantages over existing technologies in terms of hydrogen production. Right now, the primary way to make the hydrogen is to separate it from natural gas, a process that generates dioxide and undercuts the main motivation for moving to hydrogen fuel cell vehicle: ending dependence on fossil fuels. The current alternative is electrolysis, which uses electricity to break water into hydrogen and oxygen, with two gases forming at opposite electrodes. Although electrolysis is efficient method, it can be cleaner if the source of the electricity is wind, sun or some other carbon free source. But if the source of the electricity is the sun, it would be much more efficient to use solar energy to produce hydrogen. PV electrolyser is one of the promising method to produce hydrogen with zero pollution emission. Hydrogen production from PV electrolyser system depends on the efficiency of the electrolyser and photovoltaic array, and sun irradiance at the site.

Since the feedstock for electrolysis is water, there are no harmful pollutants emitted during the use of fuel. Furthermore, it has become evident that concentrator photovoltaic (CPV) systems have a number of unique attributes that could shortcut the development process, and increase the efficiency of hydrogen production to a point where economics will then drive the commercial development to mass scale.

Hydrogen application

                          

Barriers

                                         

§  Hydrogen is an energy carrier rather than an energy source. While hydrogen always exists in conjunction with other elements, such as in water, it must be separated from these elements and is therefore considered an energy carrier, as opposed to an energy source.

§  Costly to convert to liquid. Because hydrogen is a gas, it cannot be compressed into a liquid form without intensive cost and energy input. Hydrogen is the lightest element on earth. As a gas, it dissipates rapidly. To compress this gas is very difficult.

§  Fossil Fuels May be needed to produce Hydrogen - Most methods to produce hydrogen must use energy to separate the hydrogen from the oxygen. This may require fossil fuels such as coal or oil. So, in a sense, we are spinning our wheels in trying to get away from fossil fuels. Along with that, coal, which is a major feedstock for hydrogen, is a major contributor to pollution.

§  Existing infrastructure has not been built to accommodate hydrogen fuel

§  Hydrogen is difficult to store and distribute.