How Do I Prep Jerusalem Artichokes to Ferment into Ethanol?

Question

Ok, suppose I have a lot of Jerusalem Artichokes and I would like to turn them into fuel alcohol for farm use. What needs to happen between having the tuber in hand and throwing in yeast to begin the fermenting process? What prepping is needed?

Answer 1

To make ethanol, you need to ferment sugars under anaerobic conditions using brewer's yeast.  The main challenge you will face trying to ferment Jerusalem Artichokes, is that they are mostly starch (right?).  You are basically trying to make potato vodka.  The magic step in there is using conversion enzymes to turn the starch into sugar.  I've never done this before, but you can buy the enzymes or you can make your own with a malted grain starter with enough enzyme to convert your extra tuber starch into sugar.  You basically cook the starch with the enzymes at various temperatures and cycles to break down into simple sugars.  Directions are shown in the posted link below.  Note that the conversion process takes a lot of energy, so you have to do it on a large enough scale to get more energy out of your final fuel than you spend trying to make it.

After you have successfully fermented your tuber sugar into ethanol, you will likely need a fractional distiller.  Throw out the old family 'still because it won't get you the 95% ethanol that you'll need for fuel.  Only a fractional still can get you there.  Look it up on the internet and you can figure out how to build your own.  That step also takes a lot of cooking, so make sure you don't use more energy than you create.  

For the most truthful results, after your first batch, you should use only ethanol to cook and distill your next batch (as well as harvest your tubers).  You'll probably find out that you barely break even, but hey, good luck and have fun!  And if you don't give a darn about whether you break even or not, you'll have lots of jerusalem everclear to soothe your soul.

Answer 2

Clean, and shred or grind the tubers. Add amylase to convert the starch to fermentable sugars. Then add the yeast.