The problem is methanol CH3 and ethanol C2H5OH, both alcohols, are easy enuff to make from yeast and distillation or petroleum distillation.. The limestone-CO2 needs energy to release from i.e. heat, and the water needs electrolysis, so that is energy bound too, with the hydrogen bond being the problem to overcome -- and you need a good filtration/membrane system too to sequester the H2. So you have two energy drains and you don't get the same thing back out of ethanol that you had to put in to make it. Once you have the hydrogen, the most efficient conversion is electricity from a fuel cell. All you get from the H2 that is portability, ditto the ethanol, which is easier to handle admittedly. It is a loss of 52% to make the hydrogen from heat-electricity and then get back 70% in the fuelc cell, so you are at 36.4 max efficiency as it is a two way conversion to energy to get portable energy (fuel).
If you made CO2 from limestone, and H2 from water, you are at 40% on the H2 and 50% on the CO2, so you are averaging 45%, then you have to make motive-power from the methanol-ethanol. So you lose on the heat conversion or reforming the ethanol to use in a fuel cell. That is max 30%, so you are at 12.5%. Stick with H2 for portability and use fuel cells.
On the other hand if you are thinking in terms of availability of fuel, and running out of petroleum, then there is a good supply of CO2 and water. Biomass is plentiful too. However H2 when you burn it makes only water, so it is cleaner if you are worried about CO2.
They sell methanol at the pump with a mix of ethanol, so people don't drink it. If it was straight ethanol and potable it would be fair whiskey. Few Irishmen would get past the pumps.
Just my opinion, I am not a chemist-thermodynamicist.
EC<:-} |
