Неее... Надценяваш ме, никакво време и средства нямам за развойна дейност...
Едното е PDF (верно ли не отваряш), потвърждение, че с повишаване на темп, необх енергия пада.. Не толкова, колкото ни се иска, разбира се. Sorry за формата копнах от pdf
Другото са резултати от Гугъл за високотемпературна електролиза - High temperature electrolysis - с тези думи търси и виж резултата..
A REVIEW ON WATER ELECTROLYSIS
Emmanuel Zoulias
1, Elli Varkaraki1, Nicolaos Lymberopoulos
1
,
Christodoulos N. Christodoulou
2
and George N. Karagiorgis
2
1
Centre for Renewable Energy Sources (CRES), Pikermi, Greece
2
Frederick Research Center (FRC), Nicosia, Cyprus
Abstract. Electrolysis is an electrochemical process in which electrical energy is the driving force of chemical
reactions. Substances are decomposed, by passing a current through them. The first observation of this phenomenon
was recorded in 1789. Nicholson and Carlisle were the first who developed this technique back in 1800 and by the
beginning of the 20
th
century there were already 400 industrial water electrolysis units in use.
As mentioned before, water is decomposed to hydrogen and oxygen, by passing a current through it in the presence of
suitable substances, called electrolytes. Electric current causes positively charged hydrogen ions to migrate to the
negatively charged cathode, where a reduction takes place in order to form hydrogen atoms. The atoms formed then
combine to form gaseous hydrogen molecules (H2
). On the other hand, oxygen is formed at the other electrode (the
positively charged anode). The stoichiometry of the reaction is two volumes of hydrogen to one volume of oxygen. The
most important part of the construction of electrolysis units is to use adequate electrodes to avoid unwanted reactions,
which produce impurities in the hydrogen gas. Another necessary component of such a unit is a separating membrane
that allows the passage of ions, or electrons and not oxygen, or hydrogen atoms. This membrane allows the gases to be
kept separate in order to avoid the risk of an explosive mixture being formed in the electrolysis unit.
In the initial discovery of electrolysis, an acidic water solution was used, but nowadays there is a trend towards
alkaline electrolytes such as potassium hydroxide (KOH). This technology offers the advantages of materials which are
cheaper and less susceptible to corrosion compared to those required to handle acids. Electrolysis plants with normal or
slightly elevated pressure usually operate at electrolyte temperature of 70-90
o
C, cell voltage of 1.85-2.05 V and
consume 4-5 KWh / m
3
of hydrogen, which is obtained at a purity of 99.8% and more. Pressure electrolysis units run at
6-200 bar and there is no significant influence on the power consumption. Because of its high energy consumption and
also of the quite substantial investment, water electrolysis is currently used for only 4% of world hydrogen production.
Nowadays research and development into high efficiency electrolysers is flourishing in many areas. A way of
improving electrolysis units efficiency is by increasing the process temperature which lowers the voltage required to
electrolyse the water, but also requires more expensive materials. Despite the fact that the total energy needed for the
electrochemical decomposition of water decreases only slightly with increasing temperature, the reversible part of the
energy requirement (∆F), which is supplied as electrical energy, decreases considerably. Therefore an increasing
amount of the total energy could be supplied as heat. At elevated temperatures (800-900
o
C) the electric power
consumption is approximately only 3 kWh / m
3
of hydrogen. It must be noted that this technology is still in the
development stage.
Electrolysis is considered as the ìcleanestî way to produce hydrogen, when the required electricity is derived from
renewable energy sources. In countries with a lot of waterfalls, hydroelectricity can be used as the energy source for
water electrolysis. Other renewable sources that could be used for supplying electrolysis units are solar, aeolic and
geothermal energy. Photoelectrolysis, in which the photovoltaic cells are also electrodes that decompose water to
hydrogen and oxygen gas could be used for the production of hydrogen. These technologies could be used in order to
store energy as hydrogen, which can be transformed to electricity in fuel cells, when the natural source of energy is not
available. The production of hydrogen through electrolysis using renewable energy sources has the smallest impact on
the environment.