Thread: biodiesel
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Old 10-24-2010, 11:04 PM
C Sean Watts's Avatar
C Sean Watts C Sean Watts is offline
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Quote:
Originally Posted by benzhacker View Post
Adam,

I think we may have a terminology problem here. Any diesel can run on biodiesel (fuel lines often need to be changed anyway), did you perhaps mean waste vegetable oil/straight vegetable WVO/SVO) when you said "conversion?" If you run on biodiesel, the only thing that needs changing is your fuel hoses and injection seals, which on an old diesel need changing anyway (flurocarbon/Viton is guaranteed good for any liquid fuel you can run in a diesel).

There are two routes for running biofuels in a diesel: Convert the car or convert the fuel. The cost for converting a diesel to run WVO/SVO ranges from $1500 (yes, you can do it for less, but the results are not satisfactory in my view) to $3500 depending on the system (single or dual tank, electronic, automatic fuel heat controls vs. manual switch over, number of heat stages prior to injection pump, etc.). The cost of building a proper biodiesel processor runs $500-$3500, depending on how much fuel you need to produce per day and chemicals and fuel storage containers you will need. Pick your poison, there are upfront costs for each. I started with one, then the other and now run the primary tank on B100 and the secondary tank on clean, dry WVO.

Biodiesel is a transesterification process - chemical conversion. WVO/SVO is just filtered and dehydrated vegetable oil soybean is the most common, it's the cheapest). It is not accurate to describe biodiesel as "vegetable oil with methanol mixed in" - it is not. Biodiesel is the end result of a chemical conversion of the free fatty acids in the vegetable oil into a different molecule, removing the glycerin that causes much of the gelling, coking and ash that can result with WVO/SVO that is not pre-heated. If used vegetable oil from fryers is used (you can usually get this for free by asking the restaurant if they'd like you to haul it away for them), the oil is filtered, water is removed chemically or through flash evaporation and then converted by transesterification. If you have more than 500 parts per million of water, you will have problems. Dry oil is needed for either good biodiesel conversion or for direct use as WVO/SVO - water kills the reaction and destroys injector nozzles.

When you first start out, you need to titrate your oil to determine free fatty acids. You will learn to distinguish "good oil" from bad during this time - oxidized oil is often not usable. Don't be afraid to reject oil that you can't salvage. It needs to be conveyed to whomever you have a relationship with to pick up their oil that there may be times you just can't use it. If they change oil once per week, this is seldom a problem.

Titrating also gives you a value that can determine how much Potassium Hyrdoxide or Sodium Hydroxide (I prefer KOH, aka Potassium hydroxide, slower but very complete conversion if your quantities are right) you need in the methanol to form the catalyst. You can obtain chemicals from several places, everyone has their favorites. The reactor you will need can either be built (many folks build them) or you can buy a complete system for a few grand. Unless you drive quite a lot, 40 gallons of fuel a day processor sizing is probably abundant and will take up less room in a shed or garage. http://www.dudadiesel.com/ for chemicals is my favorite.

You can read up on the various methods for converting vegetable oil into a diesel fuel you can use in ANY diesel engine here: http://journeytoforever.org/biodiesel_make.html#start
I use the two step "foolproof method" having tried the others, it works well and the results are good (titration not required, but intended for "advanced" users that are well familiar with the process). Read more here:
http://journeytoforever.org/biodiesel_make2.html#which

You start by doing things totally manually and in a small batch. Start with a 1 liter quantity (not a gallon, that's later, keep it small). You can buy kits from Dudadiesel to start you off for the test batch cheaply. To have your batches chemically verified, Dudadiesel have a lab they can point you to to test it. Cost is about $100.00 (at least it was a few years ago) so that once you get a good batch without making soap or incomplete fuel, you can chemically verify your results against BQ9000 or ASTM D6751. There are also simple visual and chemical tests to check yourself. Read the Quality Testing section about half way down.
http://journeytoforever.org/biodiesel_vehicle.html

I won't get into WVO vehicle conversion here, it's a lengthy discussion.

Final note on obtaining vegetable oil from restaurants: ALWAYS communicate with restaurant management, even draw up a contract and read up on local laws for grease hauling and how you are in compliance. Re-assure the owner that any problems with your car that results from use of the oil you will hold the restaurant harmless, etc. Don't engage in mid-night dumpster diving, or grab oil cubes from the back alley of the restaurant - you are likely breaking the law and at least irritating the local restaurant owner. Oil dropped in dumpsters is often in a very poor state, there are better ways.

Warm regards,

-bh
Well stated clarification - with one caveat. Most diesels can run on bio diesel. Common rail systems are temperamental, to say the least. I know there are updates nearly weekly but lots of common rail systems are rated for 'up to B5' or no more than 5% bio content and ZERO svo/wvo. Someone did post what Love***** did to an E320 CDI, their denial of any wrongdoing (and all the hilarity that ensued.)
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