Hi all,
I'm giving up making biodiesel. Don't ask, it's me not the biodiesel. :-)

But!

I have an experiment I wanted to see tried.

you see, it's always struck me that of the two methods of making biodiesel, the base method and the acid method, that if it wasn't for the longer times and lower yields, the acid method is superior as it does not produce any soap.

so what I propose is this...

1) use a hot box as a source of heat
2) process the BD in multiple steps until no more glycerine forms
3) recover methanol from the glycerine to make the multiple processing less costly

What I had in mind was something like this.

take a fridge, gut it, line it with black plastic, place a shower screen on top and leave it in a sunny place.

3/4 fill up a 20 litre car boy with VO and place it in the box so that it gets hot.

this much I have already done. the oil gets to about 50 oC on summer days. My main concern was not boiling off methanol.

so, add appropriate amounts of methanol and acid - 98% conc sulphuric by choice as it is low water content.

what should happen is that the transesterification should occur slowly over a few weeks, depending on the weather and a layer of glycerine should form at the bottom. the limit on how far the reaction proceeds - i.e. the equilibrium point - is how much water or FFA there is in the system.

drain off the oil/BD, place in a new drum with fresh metho and acid and repeat. recover methanol from the glycerol and dry over e.g. zeolite.

repeat until no more glycerol forms.


the beauty of this method should be that it handles FFAs as well as oil. FFAs will esterify and release water. the water should transfer to the glycerine phase along with lots of the metho and the acid. And becazuse you are not making any soap, you get BD that requires less washing and is higher yield than should be obtained from the base method for all manner of disgusting WVOs. also no fuel or power required to heat or mix teh BD, and less water required to wash.

what I want to know is...

1) does it work as described.
2) does the oil need mixing - e.g. give it a shake every day or so - to re-disperse the acid and metho from the glycerol phase that settles at the bottom and
3) does enough of the water come out into the glycerol phase between batches to allow the reaction to proceed to near completion.

anyone want to take on this challenge?