At what point does it become cheaper...

[blackdog]

...to brew your own ethanol, than to buy petrol?

My thinking is the initial outlay is only a vessel and a condenser, what else needs to go into it?

[scissorhands]

A handy supply of raw materials, and cheap power to extract the ethanol.

Rural near crops, with a stream or wind power and the costs could stop at equipment only....

I always thought of a mobile unit on the back of a truck, plugs into the grid and generates power from pine branches during logging.

If the cut plantation is replanted, the old branches prolly make good mulch for the new plantings

[avgas]

Depending on how big your production is, a guy I did a job for can produce eth for $3/L (he reckons - I think its a little more than that). Setup sits under his house and runs 24/7 using a controller.

So not there yet.
But bio-diesel......thats def doable right now for less than what diesel is.....

[Oakie]

And remember, ethanol eats things. I seem to remember an advisory on Hyosungs saying not to use petrol with more than 3% ethanol or something as it attacked the fuel lines.

[scissorhands]

But you get a carbon free combustion chamber and exhaust, good for the environment and your engine

[Juzz976]

Ethanol in its pure state (which is really difficult to acheive) is hydroscopic (will absorb water). In normal atmospheric conditions usually down to 92%, plus with the ethanol having a lower boiling point than water if not sealed up will evaporate away.

So mapping your bike/car will need to know how diluted it is.

Distilling ethanol also means u have a highly volatile gas which poses a fire/explosion risk.

The energy required to boil off the alcohol is alot, when petrochemicals are fractionally distilled a fair amount of the product is used to heat the oil for distillation.
As with 14-18% alcohol brew there is a large amount of water that needs to be heated and this is where is becomes inefficient.

There are other means of producing ethanol, none of which will ever be cheaper than buying petrol or diesel. eg ethylene + water, still dangerous and expensive....also the expensive ingredient is made from oil.

[CookMySock]

If you can get free sugar/starch (potatoes?) and free energy (firewood?) then you should be able to get your costs right down.