I've been reading about Aleks Kac's Foolproof Biodiesel process on www.journeytoforever.org. It's a 2 stage process; the first stage involves using sulfuric acid catalysis, the second stage methoxide. Has anyone tried it? What do people think of it?

Hi Ben,

Thanks for telling me about this cause IVe tried to make BD from waste oil and the yield rarely goes above 80%. Sounds like an interesting process but is increased cost worth the effort in yield return? Have tried acid catalysis and it is a lot longer, than basic reaction, also the removal of sodium sulphate would mean a filtration step.

I tried this recipe, found a few issues and got into an argument about it elswhere (sounds familiar eh?).

1 I don't think you can get a successful result without titrations. Low values would run the acid for 1.5 hours and use more NaOH. High values run the acid for 3 hours (or more) and use less NaOH.

2 I found that my fuel's energy value was low. The car felt like it had a cork in the exhaust. That could have been caused by my working methods. But it could also be that acid processed ester does not have the same calorific value as base reacted ester.
There are lots of other possibilities, but I have never made a low energy batch when using alkali only reactions.

3 I found that my ester mixed with water more easily than alkali only product. It took hours for a mixed sample to settle out.

It's possible that I had stripped out the FFA but had not converted it to ester. FFA has a similar affinity for water.

Before anybody bites about my "claims". I'm not saying the recipe is rubbish. I am saying however that it's not foolproof and you can't realistically avoid titrations.

I think it's best kept for heavily used oil with a high FFA content.