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Hydrogen Energy
Hydrogen is
the lightest and the most plentiful of all gases. Hydrogen is not freely
available but it is found in compound
forms such as in water (H2O).,
fossil fuels including methane(CH4),
propane, coal and petroleum and in biomass.
Hydrogen is a powerful energy carrier which has been used variously
in the past for industrial activities and as fuel for automobiles. It is
a clean-burning fuel and is therefore considered
environmentally friendly.
Hydrogen can be considered only "partially renewable energy resource".
Since Hydrogen is not freely available, its "extraction" from certain
compounds (e.g. methane and/or water) requires the use of energy from
fossil fuel sources which release greenhouse gases to the atmosphere. However,
during usage, hydrogen, burns very cleanly releasing very little GHGs emission
to the atmosphere.
Obtaining Hydrogen:
The two approaches that have been used for obtaining
Hydrogen from compounds are:
Stream reforming
(ref:
Encyclopedia
of Earth) to separate hydrogen from fossil fuels and carbon compounds
e.g. methane(CH4)
and electrolysis (ref:
US DoE Energy, Efficiency and Renewable Energy) to separate hydrogen from water.
In Stream reforming, hydrogen containing compounds (e.g.
methane or natural gas) are heated
to
very high temperature and pressure
to separate the hydrogen gas from the carbon chains.
This gas then goes through a clean-up process to remove substances such as
sulphur. After the clean-up, the two remaining gases
(hydrogen
and carbon dioxide)
are separated, by stripping the carbon from the hydrogen atoms.
The hydrogen is burned in a specially modified gas
turbine to make electricity
or transformed to hydrogen fuel cells.
The carbon dioxide is compressed and transported
through a pipeline and then injected deep underground into the depleted
oil and gas fields or coal beds, where it is stored safely and
permanently
(sequestration or carbon capture and storage).
The
Carbon
dioxide
(CO2)
resulting from this process can also be
injected into the reservoirs
to flush out reserves of oil or gas that would otherwise be left behind.
One disadvantage of Stream
Forming is that it generates GHGs thereby aiding global warming. Electrolysis is
seldom practiced because it is an expensive process.
Using Hydrogen
Hydrogen can be combusted in an ordinary car
in an internal combustion engine like the fossil fuels - gasoline or
diesel. However, it this is not an efficient way to use the hydrogen fuel.
Alternatively, fuel cells are manufactured to convert the hydrogen into
electricity, and then the electricity is used to power an electric motor,
used to run electric cars.
Improving Hydrogen production
The major downside of hydrogen as a clean
fuel is the production of GHGs when fossil fuels are used for stream
reforming and /or electricity. However, stream reforming does not have to use fossil fuels.
Other energy sources such as wind energy, solar energy, nuclear energy and
other forms of cleaner energy sources can be used to perform the heating
during stream reforming. Using cleaner fuels reduces the amount of GHG
production and makes hydrogen a viable renewable clean energy source. |
