Synthesis of hydrocarbons
The solutions for the safeguard of the environment are valid also in the future habitable bases on the Moon and Mars and viceversa.
Extraction of oxygen from the ilmenite ones, the diffused mineral more on the Moon
Links on motor vehicles working with fuel cells
The Fishers and Tropsch have set, in 1923 a procedure to transform the coal in hydrocarbons: benzine, diesel oil, naphta.
Such procedure is based on the vapor breaking in within one filled up coal furnace carried at least 900°C -1000°C with one combustion with the minimal necessary oxygen amount; to this temperature the vapor dissociates in hydrogen and oxygen thanks to the action of the carbon that joining to oxygen forms oxide of carbon; shape therefore the "water gas" composed exactly from hydrogen and carbon monoxide, used like fuel in the first examples of lighting system of the cities at the beginning of the nine hundred.
Pumping such "gas of water" within a container to the pressure of 10 or 20 atm (but go well also the pressure atmospheric, only with a reduced speed of reaction) and heat to temperature comprise between 190°C and 250°C in presence of catalyst made up of iron (as an example the common straw hat of iron) and other element in smaller amount form the hydrocarbon, that is compose characterize you from the formula:
Cn H2n+2
from methane CH4 to several compounds of the GPL (propane, butane), to benzines but above all diesel oil, with a percentage that would have to be gone around to 80%.
This process of synthesis interests also the waste "gasification", in how any organic compound, heated in absence of oxygen to temperatures comprised between 700°C and the 900°C dissociates in hydrogen and carbon monoxide.
Moreover to my opinion it is applicable also to mixtures of hydrogen and carbon dioxide (less dangerous then carbon monoxide) in how much the second oxygen atom is legacy to carbon less strongly of the first one and therefore it can come still more easy removed from hydrogen.
In this case the problem would be resolved of accumulates of carbon dioxide released in the atmosphere because the carbon would come newly converted in hydrocarbons.
Extraction of oxygen from the ilmenite ones, a mineral much diffusing on the Moon:
The Prof. Giovanni De Maria, Ordinary of Physical Chemistry near the University "La Sapienza" in Rome and its collaborators B. Brunetti, G. Trionfetti and Daniela Ferro (of the CNR, Center for the Chemical Thermodynamics to the High Temperatures) has published in the article "Solar Energy Fluized Bed Reduction of Ilmenite Whith Hydrogen and Methane at Hight Temperatures" (01 Ices-226) turns out you of the search turns to extract oxygen from the ilmenite ones, a mineral composed from iron, titanium and present oxygen with the percentage of 14% on the lunar ground, at least in the region where Apollo 11 landed.
This would remarkablly facilitate the transport of the fuel on the Moon, since it would remain to carry only hydrogen to you, 16 times lighter, to parity of molecule number.
The solar furnace from they used is visible in the image, with to the equipment used (for kind concession of the Prof. Giovanni De Maria):
The adjustable platform (11) is constituted from with of 8 mirrors rectangular plans (0,5 x 1 m) for a total of 4 m² of flat surface that convogliano the solar light towards the parabolic mirror (4) of the diameter of 1,5 meters that is in a position to concentrating a total nominal power of 1,5 Kw in a surface of single 15 milimeter of diameter to the distance of 0,641 meters from the parabola, through the quartz walls of the column where the reduction reaction happens. In truth with an intensity of the directed solar light of 850 W/m² obtains an intensity of the light reflected towards the parabola of 700 W/m² (with a coefficient of reflection = 0,823); therefore the power effectively concentrated to the inside of the quartz column after the second reflection and the attenuation through the quartz window (3) and the quartz wall is of approximately 1 Kw.
A cylinder mullite cable of with a conical opening in correspondence of the quartz window supplies to the thermal isolation.
A generator of acoustic waves (7) supplies to generate sonorous waves that contribute to maintain compact with of ilmenite grains of (of the dimensions of 90-105 µm) subordinates to the reduction process that is possible is by means of hydrogen is by means of methane.
The corrected guideline of the reflector is guaranteed from the 4 fotoresistenze placed to the point (10) that receive a bundle of circular light passing through a pierced disc place to the same height but to the income of the premises; when all the 4 fotoresistenze equally turn out illuminated, the platform correctly turns out oriented and the parabolic mirror completely illuminated.
By means of hydrogen the reduction process begins to 800°C and happens with one sufficient speed to 900°C, with the water formation:
FeTiO3 + H2 → Fe + TiO2 + H2O
From successive electrolysis of the water hydrogen and oxygen can be obtained; the hydrogen can then be red-use in a successive process of reduction while oxygen can be accumulated in an opportune tank.
By means of methane the reduction process has been obtained to the temperature of 1223°K (996°C) for two various pressures (0,13 and 0,2 atm) and various speeds of feeding of the gas; in such case, after a slow start which had to the oxide layer that covers the iron, the reaction proceeds with a good speed thanks to the presence of the progressively freed iron from oxygen, that it works from catalyst, obtaining a carbon monoxide mixture and hydrogen, that eventual synthesis of hydrocarbons is adapted to one successive:
FeTiO3 + CH4 → Fe + TiO2 + CO + 2H2
This last process of reduction demonstrates as it is possible to obtain, beyond to oxygen, also the compound Fe + TiO2 much poroso and adapted to work as efficient catalyst also in the reaction of synthesis of hydrocarbons.
The ilmenite ones is however present on the Earth in Australia, in sands of Brasi them, in Canada; in Italy it is present in some sands of the Sicily.
From the description of the motor to Brayton cycle supplied in this internet site it emerges that, when the demanded power is not elevated, like in the city traffic, the relationship between the pressures maximum and minimal used can be elevated until as an example to 25 or 30, correspondent to an equal or advanced theoretical rendering to 60%; if used in a motor vehicle in presence of a good thermal isolation, the part to high temperature can arrive to 750°C, guaranteeing a good thermal flow immesso in the motor, and therefore one good power beyond to the optimal rendering.
The advantage of I use of this type of motor regarding the entirety fuel cells - electric motor is that one of having to recover and to store liquid carbon dioxide anzichè to use liquid hydrogen, much more dangerous and subject one to continuous evaporation in case I do not use of the motor vehicle.
In a hybrid motor vehicle that used the entirety internal-combustion engine - motor to Brayton cycle, the carbonic recovery dell.anidride and its liquefaction could be realized with the following modalities:
- in the city traffic, the hypothesis to proceed with the internal-combustion engine extinguished (with relative remarkable fuel saving) carrying the temperature of exhaust gaseses to the ambient temperature by means of an opportune radiator and therefore cooling the mixture of nitrogen and carbon dioxide;
- in freeway or proceeding to one advanced speed to one minimal, with both motors working, before using l.energia thermal present in exhaust gaseses (equivalent to 35%. 40% dell.energia altogether consumed) in order to make to work a motor to Brayton cycle and subsequently being carried the temperature of exhaust gaseses to the ambient temperature by means of an opportune radiator and therefore cooling the mixture of nitrogen and carbon dioxide after a preventive one condense of the watery vapor that, dispersing itself in the air employs much time before condensing in clouds and participates to aggravate the phenomenon greenhouse effect.
It arrives you to the temperature of carbonic liquefaction dell.anidride to the atmospheric pressure (- 78,5 °C; but to the pressure of 20 atm the temperature of liquefaction knows them to -20°C, to 35 atm Tliquefazione = 0°C, 44,5 atm Tliquefazione = 10°C) this could be collection in a tank while the energia spold in order to cool nitrogen it would be recovered bringing back it in the air at ambient temperature after to have cooled the mixture of nitrogen and coming from carbon dioxide from the radiator by means of an opportune heat exchanger.
The total energetic expense would be therefore inferior or not advanced to that relative to the car air conditioning and wide would be covered by the produced energy by the Brayton motor; the exceding energy produced it would contribute to improve the total rendering of the propulsori internal-combustion engine - motor to Brayton cycle of the car.
To favor dell.utilizzo dell.idrogeno nell.autotrazione, is pure in a hybrid version that dell.elettricità produced from the fuel cells previews l.utilizzo with catalyst to platinum above all in the city traffic remains the remarkable efficiency of chemical conversion dell.energia of the reaction between hydrogen and oxygen in electric power (60%); but l.insieme of the electric motor (it is pure to permanent magnei) and dell.elettronica of control does not allow to a conversion rendering del.energia electrical worker in advanced mechanical energy all,85%-90% in the better cases; therefore the total rendering of conversion in mechanical energy would be reduced to 50%; moreover it would go conteggiata l.energia necessary to the liquefaction dell.idrogeno or its jam in bottles to pressures of 300 or more atm.
Considered also the costs encrease of used platinum as catalyst in case the production of the photovoltaic cells exceeded a determined volume, it can be concluded that it can go for small or means well volumes of production but not for great volumes of production.
Better it turns out can be obtained to you with the fuel cells to fused carbonate, working to the temperature of 600°C - 650°C that they do not need of catalyst to platinum but only electrodes made up of nichel; an essential other quality of these fuel cells is that one of being able to work directly with diesel oil, treaty in order to eliminate sulfur, source of corrosion, best still with the synthesis diesel oil.
In fact to that temperature the hydrogen is dissociated from carbon, in presence of electrolytes it uses you, and therefore the products of the reaction are electricity (with rendering 45% - 60%), water and carbon dioxide.
The high operating temperature moreover allows to transform the residual heat in mechanical energy, to es. with a motor to Brayton cycle, encreasing the total rendering.
After all in order to face a problem of the emissions of CO2 produced from the motor vehicles on world-wide scale the better choice to my opinion is that one of a combination of traditional internal-combustion engine and the motor to Brayton cycle or of the combination fuel cells to fused carbonate and of the motor to Brayton cycle described on my Internet site, even if the effective yield was of 45% or 50%, using a part of the energy produced from this last one for the liquefaction of carbon dioxide, than once pumped in a sturdy tank it could be conserved also to ambient temperature, having critical temperature = 31,1°C and critical pressure = 73 atm, exceeding which could gradually be gradually emitted without problems.
In more the carbonic tank dell.anidride it would be an antifire dispositive profit in emergency case. The same considerations are worth are for road transport or wherever it is necessary to store energy in order then to use it as mechanical energy also on Mars or where also atmosphere is also rarefied that guarantees a cooling for convention, the use of hydrocarbons is more reliable and less expensive solution respect the use of liquid hydrogen, being the liquid oxigen store energetically less expensive then the first one.
On the Moon, in atmosphere absence and being single the cooling for radiation, the entirety fuel cells - electric motor remains the best solution in order to transform the chemical energy in mechanical energy, using fuel cells to high temperature that would exactly dissipate for radiation the heat developed during the chemical reaction, less than to use the sand of the lunar ground in order to remove the heat of the part to inferior temperature of the motor to Brayton cycle.
links on motor vehicles working with fuel cells:
http://www.fuel-cell-bus-club.com/html/body_new_generation_fuel_cell_buses.html
(schema and caracteristiques)
(fuel cell cars photos)
http://www.ecotrasporti.it/necar.html
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