9 gennaio 2016

Hydrogen

 

SPI Consulting has developed and realized internally an electrolytic stack for the production of gaseous hydrogen through electrolysis of water. Using energy from renewable sources and guaranteeing in this way the possibility to produce hydrogen without producing CO2 and SPI develop its products with the lowest possible environmental impact. The AMES stack is designed, perfected and implemented directly by the technicians of SPI Consulting, and thanks to its modularity can be integrated into machines for the production of hydrogen and oxygen at different flow rates. AMES stack uses a solid polymer membrane anion exchange to produce hydrogen and oxygen. Our electrolytic stack can produce up to 200 Nl/h (3,4 Nl/min) of hydrogen gas and 100 Nl/h (1,6 Nl/min) of oxygen from an aqueous solution of potassium hydroxide at 1% weight. The gases are produced separately. Oxygen is vented through the water pipe return and hydrogen is released on its port. AMES can withstand up to 20 bar (290 psi) internal pressure avoiding the need of a gas compressor for the storage of gas at this pressure nominal. The minimum hydrogen purity is 99.5%, without dehydrating or purifying cartridges.  Better performance can be realized with a desiccant for water.

Details and drawings of AMES products on this page.

hydrogen-periodic-table1What is Hydrogen?

The natural hydrogen is a colorless, odorless and non-poisonous. It ‘very light, 14.4 times lighter than air. For this reason, hydrogen is not found on Earth, because it is dispersed in space, and is the most abundant element in the Universe.
Bound to other elements, however, it is present in great abundance: each water molecule, for example, is constituted by an oxygen atom and two hydrogen atoms. In addition to water, the hydrogen is present in the mineral substances, hydrocarbons and in biological molecules.
Therefore, if you want to get natural hydrogen, it is necessary to remove it from substances containing it, consuming energy. For this reason, hydrogen is not a primary source of energy, but an “energy carrier,” or a form of energy that is not found directly in nature (as it happens, instead, for natural gas, oil or coal ).
The gaseous state is a good fuel: when burned produces a quantity of heat that is 2.6 times higher than that produced by burning methane.
The use of hydrogen as fuel was already known in the middle of last century. Until the fifties, for example, the houses in large Italian cities were heated with the “town gas” consisting of 50% hydrogen. Hydrogen also swelled the great airships, such as the famous Zeppelin, were making incredible journeys.
Today, hydrogen is an excellent fuel. When it combines with oxygen releases much energy that can be used to produce electricity and heat through special devices called “fuel cell”. Hydrogen combustion is clean because it releases only water. That is why today many hopes are betting on hydrogen, as it could provide clean and plentiful energy for the future.

auto_idrogeno_full_cellFuel cells
Hydrogen can be used to power vehicles provided with a motor with fuel cells. Liquid hydrogen is also used on board spacecraft to feed fuel cells that provide the necessary electricity for the functioning of on-board instrumentation. The water obtained as by-product from said fuel cells can be drunk by the crew.
The hydrogen could power many electronic devices in common use, such as laptops, mobile phones and toys, which now require heavy and expensive batteries. A cell in combustibileminiaturizzata is light, cheap and of duration longer than that of a common battery. Mobile phones, for example, could operate continuously for months and periodically suffice buy a vial of a hydrogen-rich fuel (such as methane or methanol), to be inserted in the apparatus, to feed the small fuel cell.
The devices that use hydrogen to produce electricity directly are called “fuel cell”.
The fuel cell hydrogen is an electrochemical generator in which electrical energy is produced by the reaction between a fuel (hydrogen) and a gaseous oxidizing compound (oxygen or air). Together with electricity, heat and water are also produced.
A fuel cell consists of two electrodes of porous material, the cathode (negative pole) and the anode (positive pole). The electrodes act as catalytic sites for cell reactions that mainly consume hydrogen and oxygen, with production of water and passage of electric current in the external circuit. Between the two poles there is an electrolyte, which has the function of conducting the ions produced by a reaction (the one occurring at the anode) and consumed by the other (the one occurring at the cathode), closing the electric circuit inside of the cell. The electrochemical transformation is accompanied by the production of heat, which is necessary to extract for maintaining a constant operating temperature of the cell. This structure is similar to that of common electric batteries but, unlike the latter, hydrogen fuel cells consume substances that come from outside and are therefore able to function without interruption until are supplied fuel and oxidant.
The cell has a flat structure with three layers: the central one, comprised between the cathode and the anode, constitutes or contains the electrolyte. The individual cells are superimposed on each other and connected in series so as to obtain a voltage of the current of the desired value. More cells stacked are called stack (or “stack”).
The technology that uses hydrogen as an energy source is rapidly developing both for stationary applications (not moving, as industries, housing) and moving systems (transport).
The fuel cells are of considerable interest for the purpose of production of electrical energy, as energy and environmental characteristics such as to make it potentially advantageous for the adoption:
•electrical efficiency high, with values ​​ranging from 40-48% (referred to the calorific value of the fuel) for plants with cells at a low temperature, until reaching more than 60% for those with high-temperature cells;
• reduced environmental impact, both from the point of view of gaseous emissions that of the acoustic parts, which enables to place the plants in residential areas, making the system particularly suitable for the production of electricity distributed;
• possibility of cogeneration (associated production of electricity and heat): the co-generated heat can be provided at different temperatures, in the form of steam or hot water, and used for sanitary use, conditioning of environments, etc.

Hydrogen and security
There are still many doubts about the safety aspects because of unfamiliarity with this energy carrier. However a closer analysis resizes the concept of hydrogen dangerousness.
This gas is less flammable than gasoline (it has a higher ignition temperature).
Hydrogen is the lightest element and therefore it is diluted and is dispersed very quickly in open spaces.
It is almost impossible to make it explode, if not in confined spaces (to identify potentially dangerous concentrations using sensors that can easily be controlled adequate security systems).
In addition, when it burns, hydrogen is consumed very quickly, always with direct flames upwards. By contrast materials such as gasoline, diesel, LPG or natural gas is heavier than air and does not disperse, they remain dangerous for much longer. E ‘was calculated that the burning of a petrol vehicle lasts 20 to 30 minutes while a hydrogen vehicle does not last more than 1-2 minutes.
In addition, in the case of flames from hydrogen, there is little chance that neighboring materials may in turn be burned, thus reducing, in addition to the duration of the fire, also the danger of toxic emissions.
Hydrogen, unlike fossil fuels, is not toxic, nor corrosive and any losses from the tanks do not cause problems of pollution of soil or groundwater aquifers.