Environmental Engineering Reference
In-Depth Information
However, what is important for the balance sheet on the environment is not what
comes out at the end but what is put in at the beginning. When steam reforming is
used to produce hydrogen from natural gas, around 300g of carbon dioxide are
created per kilowatt hour of hydrogen (g CO
2
/kWhH
2
); with partial oxidation of
heavy oil this rises to even 400 g CO
2
/kWhH
2
(Dreier and Wagner, 2001). This is
clearly more than is created through the direct use of natural gas and crude oil. If
hydrogen is extracted by electrolysis using average electric current in countries like
Britain or Germany, the carbon dioxide fi gure rises to between 500 and 600 g CO
2
/
kWhH
2
. Hydrogen as an energy source then ends up being far from ideal for the
environment. For the climate balance sheet it ultimately makes more sense to con-
tinue driving petrol and natural gas-powered cars than to change over to those run
on hydrogen.
Hydrogen only offers a true alternative if it is extracted using pure renewable energy
sources, such as through electrolysis using energy from wind turbines and solar
power plants. However, as long as hydrogen is produced using methods that can
create carbon dioxide, it will at best be suitable for testing prototypes.
Many manufacturers are developing products that allegedly rely on clean hydrogen
as an energy source and fuel cells for generating electricity. They owe us an expla-
nation of how they intend to make suffi ciently large quantities of reasonably priced
carbon-free hydrogen available soon.
In the foreseeable future renewable energies will be able to compete fully with fossil
and nuclear energy plants on the basis of open competition. As a result, the produc-
tion costs for hydrogen produced with renewable electricity will drop. This will then
enable hydrogen and fuel cells to become an interesting component of sustainable
energy supply. Therefore, it is already a good idea to encourage the development
of these technologies.
13.5 Markets, Outlook and Development Potential
Hydrogen production is currently at a total of 30 million tons worldwide. In
comparison, crude oil consumption at 3953 million tons worldwide in 2007 was
higher by several orders of magnitude. As the chemical industry uses the bulk
of the available hydrogen, a market for it does not yet exist in the energy sector.
The capacity for hydrogen production using renewable energies is very low, and
there is also no infrastructure for the transport and storage of large volumes of
hydrogen.
Only a small number of hydrogen refuelling stations currently exist to supply
hydrogen for fi lling the tanks of hydrogen test vehicles (Figure 13.9). The cost of
developing a comprehensive network of stations that could provide hydrogen fuel
is estimated in the billions of euros in countries like Germany and Britain alone. In
larger countries such as the USA this sum would be even higher. As long as hydro-
gen is still much more expensive than conventional fuels, the chances of this kind
of investment are very low.
