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Making Biodiesel - Pros & Cons


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Hi again.  So this post is about the pros and cons of making and using biodiesel for whatever machine you plan on using it in.  I thought I’d start with an update.  I mentioned last time that I had made a chemical order and this is what controls the cost of the biodiesel I make.  Well, I guess things have been going well in methanol production.  After that order, and for the next 6-9 months, my homemade fuel cost will be fixed at about 54 cents per gallon ($0.54/gal).

I’m sure at this point many of you are thinking something along the lines of, “That’s reason enough for me!  Let’s get going.”  Hold on.  Let me paint an at least fuller if not clearer picture for you.

Large vat

First off, half of a garage bay is taken up with all the “stuff”.  I have a 125 gallon mixer, a 30 gallon hot water heater as the distillery’s pressure vessel, six (6) 55 gallon drums (2 for raw oil, 2 for methanol, and 2 for biodiesel), and some buckets and other miscellanea.  I could gain space through some reorganization and changing to the large home heating oil tanks, but that would take a commodity I’m pretty short on these days – Time.  Speaking of, it takes time to make fuel.  I have to collect the oil (and before I did that I had to go around asking places if I could get their oil), fill the mixer, mix the reagents (make fuel), come back and drain off the by products (glycerin and methanol), put them in the still (methanol reclamation), keep an eye on it so I don’t boil glycerin or overflow my collection vessels, and finally move the finished fuel to storage.  This all takes in the neighborhood of 3-4 hours to produce around 100 gallons of fuel – or not quite a months worth.

I’ve been doing it for a while now, so I’ve got it down pretty good.  Where I collect oil is along my regular routes of travel so I don’t have to make special trips or go out of my way.  Way back in the beginning I did pick up from one such out of the way place.  That one trip alone was an hour to go there, get the oil, and bring it home each week.  And there inevitably always seems to crop up some unanticipated, time-eating happenstance.  Last time it was that the new methanol barrels came with plastic bungs.  My wrench did not adequately fit them without bending the tabs on the bung so, that day anyway, the show was over until the chemical supplier shipped me a proper wrench.  (it took two tries, by the way, backing my production up two weeks and forcing me to go to the pump…which really hurt).  That, of course, didn’t cost me much time directly, but it did cost me money…and some serenity.

Then there is the mess in the space.  Trust me, no matter what precautions you take – and they will improve and increase with time – you are going to make a mess.  We are dealing with oil people – oil with bits of food in it.  Good old-fashioned clay kitty litter will become a mainstay in your garage or wherever you set up production for its oil-absorbing ability.  There is also dealing with the flux of oil jugs that come in and out of your home now.  My neighbors have become used to the sight of empties piled in front of the garage before they go back to the restaurant from whence they came.  Those containers are used for post-still glycerin as well.  On more than one occasion I have tried to drain the still too soon and the plastic jug melted spilling food-particle infused glycerin all over the floor and sometimes down the driveway.  Not to worry…Its soap!  But it is extra time to clean it up.  I generally do a quarterly cleaning anyway, but that is more time to consider.

MixerChemical handling: in general you will be dealing with an alcohol (flammable and mildly caustic) and a base-catalyst (extremely caustic).  I use methanol, which is incredible flammable and whose molecule is small enough to penetrate skin, and sodium hydroxide – the stuff the mob pours on your body so you’re unrecognizable when the police find it. And what do we do with these chemicals?  We mix them.  Creating an extremely caustic, potentially explosive mixture that can penetrate skin.  I can understand if you’re a bit squeamish at this point.  I was too.  Allow me to relate a couple of stories:

One day, I’m in my garage making fuel when I think to myself, “These safety goggles are a pain!  I can barely see through them!”  along with the usual rhetoric about nothing ever really happens.  You know, the kind of thinking that precedes an accidents.  I got lucky.  I was “shown” what could-possibly-happen.  As I poured the next bucket of the above described mixture into the mixing tank with the veggie oil in it an interesting fluid dynamics phenomena occurred.  Some how, and I know you’ve all seen this, while I was pouring the mixture, from above, and all that fluid was moving downwards into the oil, somehow a drop flung itself back out of the mixer in seeming defiance of gravity and all it’s other friends flowing downward and impacted my goggles directly in front of my right pupil.  That’s why I wear these things.  So now I keep them clean or replace them if I can’t see.  The point? Proper safety equipment, including body coverage, is an absolute must at this stage.  Once mixed with oil the whole thing becomes inert and there is no danger. 

The other story is a friend of mine, who also makes his own fuel, accidently added too much sodium hydroxide to a volume of methanol he had prepared.  As the reaction is exothermic (creates heat from the reaction) his mixture began to boil due to the low boiling temperature of methanol.  Did I mention the fumes are incredibly toxic?  I wear a respirator and have open ventilation when I mix these chemicals.  Obviously, boiling the mixture adds more of these fumes to the air and methanol vapor is VERY explosive.  The cure?  Don’t put in too much.  Portion out equal volumes of alcohol and catalyst and mix them slowly.

The method I’ve been describing is a very low cost, but high vigilance method of mixing the “meth-oxide” in 5 gallon buckets with a paint mixer on a drill (sealed-motor or no-spark drill of course) and dumping these into the main reactor which holds the oil.  The main dangers of this approach can be avoided by more sophisticated setups.  For instance, one could use a recirculation pump on the main mixer instead of motor with a propellered shaft.  In this setup, we could mix the methanol and sodium hydroxide in a reticulating fashion, away from potential human contact, with the added benefit of a sealed system to mitigate fumes as well.  Alternately, as those types of pumps are pricey due to their ability to withstand such harsh chemicals, we could employ a pair of traditional mixing tanks – one for meth-oxide and one for biodiesel.  The variety of arrangements and details of the rest of the systems are beyond the scope of this article, but I will speak to this in a future post with some figures to illuminate the ideas I’ve speaking about here.

Ok, supposing some of you die-hards are still with this idea let’s talk about money.  I’ve already mentioned what it costs to produce.  However, that only takes into Water heater tank filling jugsaccount the cost of ingredients.  I don’t charge myself labor and I have long since amortized the cost of my setup…but there was a cost.  This is an incredibly variable subject.  For the scrappier, industrious folks out there, you could probably put together a functional setup for near nothing.  In the end of the story we are talking about a vessel of some volume and some means to mix it.  The amount you want to make at a time will drive up the cost.  It will also drive down the time involved and the opposite is true.  You will have to make that determination.  The middle of the road is, for a few hundred to maybe over a thousand dollars, you put something together that is really quite professional looking AND functional.  This could include a fee to someone to design it for you.  On the upper end of the spectrum (~$5000) one can buy a pre-engineered, sometimes pre-assembled, turnkey package that gets drop-shipped to your door and all you provide are the ingredients and assembly if needed.

Quite a lot to mull over.  I didn’t at all mention the importance of buy-in from affected parties (wife, husband, kids, friends, etc.) but bear in mind that, at least at first, this is going to be more of an inconvenience than a panacea.  Consult with those people, please, before taking action.

Next time, I will go the other way with this hoopla.  Namely, lets skip all the chemicals and big mixers and such and just use straight veggie oil (SVO) or waste veggie oil (WVO).  What are those implications?  Tune in next time.  And, of course, feel free to ask questions.

Wally is a professor at RPI during the daytime, a new day most of the night, and mountain climber on weekends he can get away. He is also operating a very small biodiesel reactor in his garage, 500,000 miles and counting... He can be reached through the Member email.


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