Back to www.myturbodiesel.com home
back to 1000q: turbodiesel FAQ and VW "how
to" index
Introduction to biodiesel
I find that many diesel drivers first become interested in diesel cars through a few paths. Some are interested in the mechanical aspects of diesels or have exposure to diesels through work or friends/family. Some want a car with greater fuel economy with similar performance to a gasoline car. Some others want to reduce their use of petrol oil and want to use waste veggie oil (WVO) or biodiesel as a gasoline alternative. I was interested in all three, so after I bought a diesel car I began to learn as much as I could about WVO and biodiesel, which I have condensed here. If you have a question about biodiesel, get an answer at the myturbodiesel discussion forums
Table of Contents
Related links: 1000q: making biodiesel yourself
Introduction to biodiesel
To dispel one of the biggest myths about biodiesel, it is not the same as used grease or straight veggie oil. That would be like saying that gasoline is the same as crude oil. Biodiesel is a fuel that can be used diesel engines or boilers and is refined from oils or grease. It is one of the most commonly used alternative fuels that will, in my opinion, gain more widespread use in the future. Note that I did not say that it was a magic fuel from the future. In other words, it is not a magic bullet that will solve all of the world's energy problems. Even if it never becomes a mainstream fuel, it still is very valuable as a fuel additive to petrol diesel. Having said that, as diesels become more common in the US market, biodiesel and other diesel fuels will also become more popular, especially once people learn about the advantages of using biodiesel and diesel cars in general. Higher fuel economy legislation and high fuel prices are among the reasons why car makers are bringing back diesel cars to the US market in large numbers. VW, Dodge, Ford, Jeep, and Mercedes Benz all have diesel cars/trucks in the US. Honda, Acura, BMW, Audi, and others are planning to bring models soon.
Biodiesel is cleaner burning than petrol diesel, mostly domestically grown and processed, and a 100% renewable fuel. It can be used in modern diesel engines and oil-fired home heating systems with little or no modifications. It is also biodegradable, less toxic than table salt by mass, and with greatly reduced odor and emissions compared to diesel fuel. It also has a higher cetane than most US diesel available and most TDI engines will run better on it. From an environmental perspective, it is greener than petrol diesel. From a cost perspective, it can be cheaper than petrol diesel. From an engineering perspective, it is often better for the engine. And from a geopolitical and national security perspective, it can be domestically grown and produced.
Unlike veggie oil, it's viscosity is much closer to that of diesel fuel, reducing the chance of stressing the mechanical fuel pumps, and requires no modification to a modern diesel car. Unlike a grease car, or greaser, it does not require modification to the car or require the car to be started and stopped on diesel fuel to flush the fuel lines. If the fuel lines are not flushed prior to shut down, a grease car may not be able to start with veggie in the fuel lines. The only current major negative of biodiesel is that it gels at a higher temperature than diesel. Diesel fuel begins to gel at -20oF, 100% biodiesel without winterization begins to gel anywhere from 14oF to 50oF depending on its source. Biodiesel available at retail fuel pumps, usually 20% biodiesel/80% diesel does not suffer from these problems because it has winterization additives added.
More details about biodiesel
One of the advantages of biodiesel over petrol diesel is that it is a green
fuel less toxic by mass than table salt. Through a chemical process called transesterification, it is refined from
veggie oils and grease. Vegetable oils primarily consist of triglycerides: three
carbon chains connected by a glycerin molecule. In the reaction process, an
alcohol (methanol or ethanol) is used with a catalyst (potassium or sodium
hydroxide) to separate the glycerin molecule from the carbon chains. The long
carbon chains in biodiesel have a very similar profile to petroleum middle
distillates. The fatty acid alkyl esters, the chemical name for biodiesel, is
then separated from the co-product glycerol. The glycerol mixture can be refined
into glycerin - a valuable pharmaceutical ingredient used in soaps and other
health and beauty products.
Biodiesel fuel also burns up to 75% cleaner than conventional diesel fuel made
from fossil fuels. Biodiesel substantially reduces unburned hydrocarbons, carbon
monoxide and particulate matter in exhaust fumes. Since biodiesel contains no
sulphur, it eliminates sulphur dioxide emissions. And biodiesel is plant-based
and adds little or no CO2 to the atmosphere. Plants take up carbon dioxide from
the atmosphere; burning plant (or animal) products in an engine releases the CO2
uptake back into the atmosphere, to be taken up again by other plants. The CO2
is recycled, atmospheric CO2 levels remain constant. Thus biodiesel does not
increase global warming like fossil fuels, which release large amounts of new
(or rather very old) CO2 which has been locked away from the atmosphere for
aeons. The ozone-forming potential of biodiesel emissions is nearly 50% less
than conventional diesel fuel. For a fact sheet from the National Biodiesel
Board's complete evaluation of biodiesel emissions, refer to this pdf file: http://www.biodiesel.org/pdf_files/fuelfactsheets/emissions.pdf
There is a controversy about how green biodiesel is because of the carbon accounting. In some areas, forest may be cleared to make biodiesel producing crops and there is an inherent cost to producing, manufacturing, transporting, and consuming fuel. To dispel a major myth about the current controversy, biodiesel and other green fuels are not the leading factor in higher food costs. Food costs experienced a spike due to world economic factors, a rise in commodities, politically motivated subsidies and trade tariffs, with diversion of acreage to green fuels being a minor contributor. The primary reason for the increase in food cost is the increase in crude oil prices and increased worldwide food and fuel demand. I'm sure that there are many small factors that I am leaving out and a full explanation is beyond the scope of this article.
While ethanol feedstock was never destined for human consumption, it does take away from acreage destined for human consumption and animal feedstock. The counterargument to this is that the same acreage or cleared forest may have been used for some other industrial use so it's wrong to say that the latest carbon accounting is the correct one. Because biofuels and their impact are so new, at this point it's best to do what you want because no single argument is conclusively the correct one. In addition, biofuel use should be adaptable. Ethanol production with sugarcane in Brazil is much more green than ethanol producion in the US with corn. Geothermal energy is a no-brainer in Iceland but it wouldn't work in Texas, where wind farms are becoming a major source of energy. Hydroelectric is great at a waterfall but a bad idea in Death Valley Desert. In any case, I am sure that biodiesel has a place in the future.
Biodiesel's ease of use is the same as a gasoline pump if purchased at a retail or fleet pump. It requires no modification to any modern diesel car at all. You can pump it into the fuel tank and mix it with petrol diesel in any proportion. Older cars, typically before 1995, that used rubber fuel lines require any rubber fuel lines to be replaced with a biodiesel safe line. One of the more common mixtures sold at commercial pumps is B20, a mixture of 20% biodiesel, 80% diesel. Some pumps even offer 100% biodiesel, called B100. It is a sulfur free fuel. It can also be cheaper than both gasoline and diesel. Many people make their own biodiesel at home with costs of anywhere from 25cents/gallon to 75cents/gallon. More on making homebrew biodiesel here. Buying biodiesel or a biodiesel blend at the pump generally costs a few cents more than regular diesel.
Ultimately, buying biodiesel at the pump costs more, but is far more convenient than homebrewing. Commercially available biodiesel also must meet standards including: complete reaction of chemicals, removal of catalyst, glycerin, alcohol, and free fatty acids. There are currently no state or federal rules that I am aware of that regulate its taxation if made in small quantities for your own consumption. There are a few laws coming up that do allow for small scale home production and consumption but you must stay under a certain amount produced/year. If you make your own biodiesel from used grease, its cost can be anywhere from 25cents/gallon to $1/gallon. Please note that biodiesel and/or biodiesel related material and activities may be regulated by fire codes and may be considered a fire hazard, always comply with any local, state, or federal regulations regarding your biodiesel making materials, storage, equipment, methods, production, or biodiesel use.
The infrastructure of distributing biodiesel already exists, so the cost of
supplementing petrol diesel with biodiesel is almost nothing compared to
hydrogen, hydrogen fuel cell, or other alternative fuel sources. The
overall price of supplementing diesel with biodiesel is even less than that of
adding ethanol to gasoline, since all diesel cars can run biodiesel, but few US
gasoline cars can run ethanol. For older gasoline cars, running even small
amounts of ethanol may cause corrosion in engines and fuel system components
such as fuel injectors.
Biodiesel is also not only better for the environment, it is also better for a
diesel engine. It provides better lubricity than diesel fuel which helps
lubricate the engine's various parts, and also has a cleansing effect.
Lubricity can increase by as much as 65% with just a 1% biodiesel blend, so it
is very valuable even as a fuel additive. However, when
people first use a high percentage biodiesel blend or full biodiesel on high mileage cars, they often think the
biodiesel is causing a problem because they see smoke or have
stumbling/stalling related to a clogged fuel filter. Biodiesel actually cleans
out the gunk and residue deposited from years of diesel use, causing it to get
burned and create smoke. If the build up is too severe, the sudden release
of gunk can actually clog the fuel
filter, stalling the engine. Low mileage cars should not have significant
build up, and should not be as susceptible to these problems. Its viscosity depends on the
source of grease and the quality of the maker.
Note that older cars that have used biodiesel for a long time may develop
fuel leaks if you go back to petrol diesel. Due to age/use and the switch
to ultra low sulfur diesel, USLD, stopping biodiesel use can result in fuel
leaks from the injection pump. The pump may just leak due to age/use as
well. Replacing the seals on the pump will stop any fuel leak. The
2009 Jetta diesel is new to the US and there is no record of long term biodiesel
use. Because of the lack of records and the fact that VW has never
approved biodiesel greater than 5% or B5, I do not suggest using biodiesel in
the 2009 Jetta yet.
Lastly, it provides a geopolitically more stable fuel and increases national
security. Since it is usually produced entirely from domestically grown plants or waste
grease, the supply of fuel is not interrupted by foreign conflict or hostile
governments. However, critics of hybrid, biodiesel, hydrogen, ethanol, and
electric cars, state that any one fuel source or technology cannot replace the
nation's addiction to oil and they are right. But I would say that those critics
are missing the point: much like gambling or playing the stock market, you do
not invest all your resources in one spot. Would you say that since all
cancer will not be cured with X cancer treatment, that you should not pursue any
further research of cancer treatment? No! By diversifying fuel sources into
biodiesel, hydrogen, ethanol, and electric, a secure and economically efficient
future will include cars with a variety of fuels and technologies. As the
current electric-gas hybrid craze proves, if automakers make green cars that
make sense, people will buy them. In the future, until the market sorts
this emerging technology out, expect to see a return to
the technologies of the early days of the automobile - pure electric cars,
diesel cars, gasoline cars, hybrids, and maybe even steam cars!
For more information on biodiesel and how to homebrew it, follow this link to
1000 answered questions: introduction to making biodiesel at home
Biodiesel vs. waste vegetable oil
First, it is my personal opinion that using biodiesel as a fuel, and not WVO is better for most people, so this article does have a bias toward biodiesel. I have included links at the bottom for those who want to see examples of WVO conversions or want to learn more. Here is a quick list of pros and cons comparing biodiesel and WVO and why I believe that biodiesel is a superior fuel to WVO. Please note that the pros and cons are specific to the VW TDI only! The cons of WVO used in a light duty VW TDI are not the same as WVO used in a rotary pump Mercedes Benz or older Dodge cummins Ram. It is possible to use WVO in a VW TDI successfully for many years, but the odds and the experiences of others strongly suggest that biodiesel is a better choice than WVO.
Biodiesel Pros:
Biodiesel Cons:
WVO Pros:
WVO Cons (some specific to the VW TDI)
As you can see, the only major advantage that WVO has over biodiesel is that you don't have to process it with chemicals. It still has to be collected, filtered, and settled. In my opinion, a much better option is to process the WVO into biodiesel because it is better for the engine, turbo, and fuel pump due to viscosity and temperature, better for emissions, better for the engine oil, and requires no modification to the car. Again, it is possible to successfully use WVO and not have a problem but the odds of successfully using biodiesel are much, much higher. WVO supporters would say that in the early days of automobiles, a diesel engine was demonstrated to run on peanut oil. Today, high pressure direct fuel injection, higher combustion pressures, and expectations of cars running 100,000 without a major failure, in my opinion, make WVO a poor choice for modern turbodiesels.
Further information on WVO: http://en.wikipedia.org/wiki/Waste_vegetable_oil
back to www.myturbodiesel.com home