The reaction consumes water, which isn't exactly abundant on a space station or space vessel. You can regain the water by burning the alcohol, which can be done in a combustion chamber without reintroducing the CO2 to the air of the habitat. That's a rather exothermic reaction – and I'm guessing that the bionic leaf also generates excess heat – which might be a problem. Space vessels can only cool down by radiating heat, which I gather to be a quite complex problem. Nevertheless, it might be workable for all I know...
You're overcomplicating this hugely. It's much simpler to burn the alcohol within the astronauts, converting it to a small amount of heat, CO2 and happiness.
You missed the key distinction here, ethanol is not the greatest substance, but is relatively safe for animals. Other side chain alcohols metabolize into byproducts like formaldehyde and well, are highly toxic. This whole distinction is the basis for the sale of "denatured alcohol" / "wood alcohol" and its much cheaper price.
"In some countries, sales of alcoholic beverages are heavily taxed. In order to avoid paying beverage taxes on alcohol that is not meant to be consumed, the alcohol must be "denatured", or treated with added chemicals to make it unpalatable."
Ethanol is normal drinking alcohol. You are thinking of methyl alcohol, methanol.
As little as 10 mL of pure methanol, ingested, is metabolized into formic acid, which can cause permanent blindness by destruction of the optic nerve. 30 mL is potentially fatal, although the median lethal dose is typically 100 mL (3.4 fl oz) (i.e. 1–2 mL/kg body weight of pure methanol)..
And on a space station, most of your heat differential is created by active cooling, so recovering that via Peltier elements is a bit… counter productive.
It's actually the complete opposite - space is not "infinitely cold" it's more like "infinitely isolating" - like the perfect giant thermos. Space suits for example have a whole layer of water tubes just to cool down the astronaught, otherwise they will pass out from their own body's temperature.
Some of it probably could be, but the effiency of those processes are low enough that you'd still have a heat problem. Also, recall that the energy originated with the solar panels to start with. It's a very wasteful way of generating electricity compared to the solar panels, so although it might be worth considering to recover some of the energy investment and eliminate a fraction of the heat, the net output of such a process will probably be an order of magnitude lower than the initial energy investment.
