Waste Vegetable Oil Fuels

I recently received a comment question on my blog to which I replied with some basic info about alcohol. I received a reply email with a question to which I did not know the answer. I did some research and decided to expand my reply a bit and make a blog post out of it. The question was basically, “Isn’t Shellac Thinner pure alcohol?”

From what I found, the answer is maybe!? A couple (1, 2) of paint chemical products websites list “Shellac Thinner” as Denatured Alcohol. So the answer depends on what they denatured the Ethanol with and if the Ethanol was 200 proof to start with. Is seems to me that by definition if the Ethanol (200 proof) is denatured with Methanol (200 proof) (or another alcohol) then yes it is “pure” alcohol. However, most of the looking I’ve done has led me to belive that the Ethanol in Denatured Alcohol is not 200 proof. For this reason I wouldn’t use it for biodiesel production.

A side note: I actually found the MSDS for Lynsol a SLC Sterling “pure” denatured alcohol and they list 200 proof or 190 proof. Since 200 proof is much more expensive, what do you think they put in there? 190 with 5% water by weight. Another site lists a much cheaper (before shipping) 200 proof denatured.

Alcohols and making biodiesel

Why do we use alcohol to make biodiesel? I’ll let wikipedia tackle this one!

Almost all biodiesel is produced using base catalyzed transesterification as it is the most economical process requiring only low temperatures and pressures and producing a 98% conversion yield. Transesterification is crucial for producing biodiesel from biolipids. The transesterification process is the reaction of a triglyceride (fat/oil) with a bioalcohol to form esters and glycerol.

So, basically 98% of all biodiesel is made by transesterification using an alcohol.

What is alcohol? I thought Pharmco had a great definition! In fact, overal their FAQ has been enlightening!

The term “Alcohol” can literally mean Pure Ethanol, Denatured Ethanol (Alcohol) as well as other alcohols which are not Ethanol (Ethyl Alcohol). The term “Alcohol” can mean Pure Alcohol which is undenatured Ethanol. This means that it is suitable for consumption. The term “Alcohol” can refer to pure alcohol at any level of concentration (proof). Therefore, pure alcohol is a correct term for 100% Ethanol (200 proof), 95% Ethanol (190 proof) and any concentration of Ethanol (Vodka is 40% Ethanol). The term “Alcohol” can mean Denatured alcohol. Denatured alcohol is Ethanol which has been made unsuitable for consumption by addition of toxic solvents to the pure alcohol. The term “Alcohol” can therefore refer to any denatured ethanol product, regardless of the proof of Ethanol and the concentration of Ethanol in the denatured product (i.e., SDA-39C is referred to as Specially denatured “Alcohol”, even though it contains 1% Diethyl Phthalate as a denaturant and even though the Ethanol content of this mixture can be 190 proof or 200 proof.) There are several hundred standard formulas of denatured alcohol (Ethanol). All of them can be called “Alcohol”. The term “Alcohol” can also refer to other solvents which are non Ethanol based but which are chemically classified as Alcohol’s. For instance, Isopropyl Alcohol, Methyl Alcohol, Butyl Alcohol, & Propyl Alcohol are all “alcohol” but none are ethanol (Ethyl Alcohol). Since Pharmco manufactures a wide range of Alcohol products, care must be taken when using the term alcohol, to communicate what product or class of products is being requested.

Here are a list of some common alcohols and their “street” names:

• Methanol - Wood Alcohol, Methyl Alcohol
• Ethanol - Grain Alcohol, Ethyl Alcohol
• Denatured Alcohol - Shellac Thinner
• Methylated Spirits - A type of denatured alcohol
• Isopropanol - Rubbing Alcohol, Isopropyl Alcohol

Transesterifcation in the presence of water

A quote from the wikipedia “biodiesel production” page:

Any water in the process promotes the saponification reaction and inhibits the transesterification reaction.

I also found this paper out of the University of Idaho Department of Chemical Engineering. The have a cool biodiesel page! Here are some good bits that I read!

Page 5 - First sentence of last paragraph

Inspection of Equation (1) shows that water content of alcohol is the most important independent factor affecting degree of conversion and that increasing water content (lowering proof) decreases degree of conversion.

Page 6 - Optimum Conditions for Ethyl Ester Preparation - Transesterification (3rd paragraph)

The presence of water in the reaction mixture markedly reduces the conversion of oil to ester (see Equation 1). 200 proof ethanol must be used in order to obtain a high degree of conversion. The experiments in which different amounts of excess alcohol were used in the reaction mixture showed that an amount in 50% excess of the stoichiometric ratio gave a high conversion when sodium methoxide was the catalyst. Potassium hydroxide catalyst required 100% excess alcohol to achieve similar conversion and phase separation from the glycerin.

All that I’m getting at here is that any alcohol with water in it, will lead to lower conversions, more soap (saponification) which can lead to problems with separtaion of the product and with emulsification when washing the final proiduct. Now for the biggie! Co$t

What alcohol costs:
This is a very non scientific method and was taking WAY to much time. If anyone has good sources to try and get an apples to apples cost comparison (i.e. 55 gallons) then please let me know.

Denatured - $24.53 / gallon - MSDS states possibility of 190 proof, $10.99 / gallon -200 proof, but look at the shipping

Pure Ethanol (200 Proof, 0.02% water) - $151.85 / 4 liters

190 (5% water by weight) – $151.85 / 4 liters Don’t ask me why they are the same price!?!

Methanol (99.8%) Racing Fuel - $71.00 / 5 gallons - though I bought a 55 gallon drum for somewhere around $120 last year.