Monday, March 10, 2008
My buddy Duane in England is a biodiesel homebrewer, something which i know very little about. I asked him to write something up and he sent along this little biodiesel homebrewing primer. It's by no means a tutorial, but a really good overview on what it takes to brew your own fuel and what the pros and cons are.
I bought a FuelMeister 40gallon machine from Biodiesel Solutions just before moving to the UK in 2005. Once in the UK, the trick was sourcing waste oil as it is a big business here and virtually all of it is assiduously collected from pubs and the usual suspect sources and sent to Germany where the biodiesel industry is huge. I'll spare the boring details of sourcing oil which will be different depending where you live and jump right to the immutable particulars:
I bought my machine three years ago for about $4000. Waste oil costs will vary - I pay about £0.28 per liter ($2.35/gal). In the UK, a 55gal drum of Methanol costs about $240; 8gal of Methanol are required for every 40gal batch of biodiesel. Costs for NaOH (caustic soda, aka drain opener) are nominal. Each 40gal batch uses about 600grams of NaOH, depending on the acidity of the waste oil. Another big cost, not necessary in warmer climates, was $1500 for a blanket to heat the oil stock in its 1000 liter container.
Once you get the hang of it, the actual hands-on time to make a batch is minimal - less than half an hour. You have to: (1) pump 40gal of stock oil into the processing tank, (2) test the acidity of the oil (kinda like testing your pool water's pH), (3) pump 8gal of Methanol into its premix tank while adding in an amount of NaOH determined by the acidity test, (4) draw the Methanol/NaOH mix in with the oil (this is the catalyst that separates out the glycerin). That's it. You then can come back about 12hrs later to draw off the glycerin that has settled out. Here's the bitch though, both in terms of technique and time:
WASHING THE BIODIESEL
I have found that I must dedicate almost another full day to the washing - returning to drain the wash water every 2-4 hours. The FuelMeister has a hookup for your garden hose and creates a gentle mist that filters down through the biodiesel, washing out any remaining impurities and neutralizing the pH. In England, this process is a pain (esp in winter) because the water is very cold and tends to promote the creation of a lot of soapy foam. The process is much easier in the summer. I can only assume that if my machine were in a heated environment and the water were warmer, this would all be a lot simpler.
The basics are very simple; when I first started, I had flashbacks to being a pimply 9th grader in science class. I only had one wasted batch - my first. And had I followed the instructions and done only a half batch on the first try as suggested, I would have cut my losses by 50%! The second batch went into the car and there's been no looking back.
You've got to be sure that you open and close the various valves in the right order! If you don't, oil can get sucked into places it's not meant to go and all sorts of gooey, plasticy weirdness gets created that is a big pain to clean out. I've actually gotten pretty good at disassembling the valves to give them a good cleaning every 1000 liters or so - and I'm not terribly mechanical. Another acquired technique is the art of pouring the NaOH into the Methanol at a rate such that it all dissolves evenly. The tendency is to pour too much too quickly. You end up with cakey caustic residue at the bottom of the premix tank and not enough NaOH in the catalyst mixture to properly draw out all the glycerin.
I run both my cars on my homebrew: a little Audi A2 and a much larger Audi A6 wagon. There has been no discernable decrease in power or performance of either car. However, when temperatures hover around freezing, both cars seem to suffer about a 15% decrease in mileage over what they got on petrodiesel. They operate at about a 10% decrease in temperatures around 45-55 Fahrenheit. In the summer months, there's maybe a 5% decrease in mileage. Even at its worst, though, the A2 gets about 53-55mpg and the A6 about 30mpg. In summer, the A2 gets almost 65mpg and the A6 closer to 35mpg. I get great pleasure knowing that I'm driving carbon neutral; even the electricity I use to warm the oil and run the machine's pump is green-sourced! Also, with petrodiesel costing £1.13/litre and climbing (over $8/gal!!), I'm only paying about £0.52 - closer to US prices. But my cars get twice the mileage that their US counterparts got when I was living there, so I rationalize my way into believing I'm driving at 1/2 price in both places...
Happy brewing! ~Duane