What is Biodiesel?

What is biodiesel anyways?

Well, biodiesel is a wonderful diesel fuel made from an organic oil, an alcohol, and a catalyst. In my case, and the case of most home-brewers, the oil is waste vegetable oil (WVO), the alcohol is methanol, and the catalyst is either NaOH (sodium hydroxide) or KOH (potassium hydroxide).

Biodiesel is compatible in most diesel engines. People talk about converting an engine for biodiesel, but this is inaccurate. There is no conversion necessary unless the fuel lines in the car are older than 1985 and are still rubber lines. All you have to do in that case is switch them to Viton or some other plastic that won’t be corroded by the biodiesel. Many recent cars come with engines that are for ultra-low sulfur diesel; these don’t go well with biodiesel. Other than that, switching to biodiesel is rather easy, and so is making the biodiesel.

In a nutshell all you have to do to make biodiesel is filter the oil, heat the oil, mix the catalyst and alcohol, add that to the heated oil, let all this react, drain the glycerin, and wash the fuel. Now, it’s a lot more than just that, but that’s the gist of it. You do have to make sure you get all the water out of your oil, that you use the right mount of catalyst, use compatible plastics, etc.

I go over the process of making the fuel in much more detail here.

The oil can be hard to get your hands on, legally. You want to make sure you use oil that’s still high enough quality that it will react to make biodiesel. Fast-food places like Macdonalds or Burger King tend to burn their oil quite badly. They do this mainly to get all the life out of the oil that they can, but by doing this they’ve made it unusable for most biodiesel home-brewers. Find a nice restaurant that will let you take their oil; write up a contract if you can. Asian restaurants typically have the best oil. REMEMBER, never just take oil! People have been arrested, tried, and sentenced in the past year simply for ‘helpfully’ removing oil from restaurants. This is stealing, so I recommend against it. Note: One gallon of oil makes one gallon of biodiesel.

NaOH and KOH are both just basically lye, which is getting harder and harder to find because of the problems meth labs pose. Fortunately you can mail order it, and there are places in the US where you can still buy it.

Methanol is also a little tricky to get your hands on. Methanol is race car fuel, and you can buy it from anyone who sells racing fuel. There are also places that sell grade 2 methanol. Grade 2 methanol has 2% or less propylene glycol, and, I’m told, is typically mixed with water and used in tractor tires, to keep them from freezing. When you make biodiesel, the propylene glycol comes out with the glycerin. The difference between race-quality methanol and grade 2 methanol is the difference between $4.30-$5.00 a gallon and $1.25 a gallon. One thing to keep in mind is that you always use 5 parts oil to 1 part methanol. So, since it’s a gallon of methanol to 5 gallons of biodiesel that’s only $0.25 worth of methanol per gallon of biodiesel, plus other chemical costs.

One other thing you must always do is wash the fuel. Once you’ve made it, you need to get any excess anything out of it. There are several different methods for washing. Traditionally people have used water, and that pulls all the particulates and stuff out of the fuel. you do have to do this several times, and you have to dry it to get all the water out. It can be time consuming and can produce quite a bit of waste water.

The other method for washing is called dry washing. You can use magnesol or something similar and mix that with your fuel. This does the same thing as the water wash in a shorter amount of time. The downsides: magnesol adds to your cost, $0.15-$0.25 a gallon. Plus, you have to filter down to about one micron to get all the magnesol back out. Bag filters also add to the cost, but are reusable, so it’s not too bad.

All in all, biodiesel is looking like a good solution for a handful of people. The thing is, there’s not enough waste oil in the world for this to be a viable option for large quantities, but it’s a great option for DIY enthusiasts like me who can and want to do it.


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Filed under alternative energy, Biodiesel, biofuel, diesel, green, SVO, Uncategorized, vegi oil, WVO

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