Catalogo Experimenta 06
Catalogo Experimenta 06
Catalogo Experimenta 06
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INDEX SCIENTIFIC STUDIES<br />
128<br />
The combustible cells - that form the Stack, the heart of the<br />
system, where hydrogen and oxygen are joined to generate<br />
electricity – are placed under the loading platform of the<br />
car: 360 cells in series, each of which gives a tension of 1.2<br />
Volts. Between the front wheels an electric induction motor:<br />
it has the shape of a cylinder functions with alternating current.<br />
Under the boot behind there is a storage tank, where<br />
the hydrogen is compressed at 350 atmospheres (contains 68<br />
litres of gas for a weight of 1.6 kilos). Distributed around we<br />
find numerous sub-systems: the separator hydrogen/water, the<br />
exchanger, the starter motor, filters, the injection flute, devices<br />
for safety sand control. In all about 50 auxiliary instruments, a<br />
number which gives the idea of the complexity of it all.<br />
The price? This is one of the most delicate points. Six hundred<br />
thousand Euros, half for the combustible cells and half for<br />
all the rest. We are speaking about a prototype; nearly every<br />
piece has been specially built. So, a Kilowatt of power costs<br />
5,000 Euros, already in small series it decreases to 3,000, with<br />
mass production to 500. A petrol engine costs 50 Euros per<br />
Kilowatt: hydrogen is already 10 times more expensive.<br />
The spaces to improve however are wide. Today hydrogen technology<br />
is at the level of an advanced artisan. We must think<br />
about a lot of time: in 2010 the first fleet of cars and buses, in<br />
2015 we will see a widespread development and will start to<br />
spread the network of distribution of hydrogen, in 2020 hydrogen<br />
in acquire a relevant part in the scenario of transportation.<br />
In order to implement this scenario it is necessary to start<br />
immediately with investments and research. The European<br />
Union has a seven year programme ready with financing of<br />
250 million Euros per year, to which should be added the<br />
same amount from the private sector. This would be the minimum<br />
to compete with the USA (three research programmes)<br />
Japan, France and India (till now in conventional motors one<br />
invests in research a sum 10 to 20 times more). But for now<br />
the Commission has blocked everything. Italy, then, is in still<br />
more difficulty because until now (summer 20<strong>06</strong>) it does not<br />
have an energy plan nor a transportation plan.<br />
How does a fuel cell function, that is to say a combustible<br />
cell? A little bit like a Volta battery, there are a lot of elementary<br />
cells connected in series. Each cell is composed of<br />
a metal plate, an electrode, a catalyser membrane, another<br />
electrode and another plate. This all has a thickness of half<br />
a centimetre. Greater is the surface of the cell, more is the<br />
power. The cost is high, above all because of the catalysers,<br />
which are of a platinum base, a precious metal today so scarce<br />
that it would not even be possible to start an industrial<br />
production of fuel cells.<br />
HOW TO FILL UP WITH HYDROGEN<br />
The main problem is how to procure hydrogen. Hydrogen can<br />
be obtained from methane with a process called reforming:<br />
but like this we again depend on a non renewable fossil source<br />
and the quantity of carbon dioxide that ends in the air<br />
is only half the in comparison with simple combustion. One<br />
could think of a treatment of bio combustibles such as ethanol<br />
and methanol, but to make a litre of bio combustibles you<br />
need a ton of water to irrigate the cultivation. Among the<br />
biomass sources of hydrogen seaweed appears to be particularly<br />
interesting. One can obtain hydrogen for electrolysis<br />
from water separating in its molecule the atom of oxygen<br />
from two atoms of hydrogen, but using electricity produced<br />
by the present power stations we will have an intolerable waste<br />
of energy and will not resolve the problems of pollution<br />
and exhaustion of the fossil resources.<br />
There remain two ways: make electrolysis out of water with<br />
electricity produced by solar panels (as we have mentioned) or<br />
otherwise splitting the molecules at a very high temperature<br />
(around a thousand C°). The first solution without doubt is absolutely<br />
the best for the environment, it requires a large development<br />
of solar cells, which should become much more econo-