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What is Biodiesel?

Biodiesel is a fuel made from vegetable-based oils, such as soybean oil, canola oil, or recycled restaurant fryer grease. Biodiesel can be substituted for diesel fuel in most applications, and can be blended with diesel fuel in any ratio. The major advantage of biodiesel as a fuel is that it is a sustainable resource. In other words, it is a resource made from feedstocks that can be readily regenerated in a short period, unlike petroleum that is sourced from depleting oil reserves that took millions of years to form. An important measure of the sustainability of a fuel is called the energy balance, this is a ratio of the energy a resource contains relative to the energy required to produce it. Biodiesel has a positive energy balance of approximately 3.2:1. Thus a gallon of biodiesel contains 3.2 times as much energy as was required to produce it. When biodiesel is made from recycled grease, it has an energy input of approximately 7:1. In addition, biodiesel has what is known as a negative carbon balance. In other words, the crops grown for biodiesel feedstocks absorb more carbon dioxide from the atmosphere than the CO2 that is created when the fuel is burned. Compare this with petroleum, which releases millions of years worth of absorbed carbon dioxide into our atmosphere at a rate at which threatens the stability of our climate.

So you’re telling me that basically any diesel engine can run on biodiesel? This must be some pretty cutting-edge technology! When was biodiesel invented?

Actually, biodiesel owes its origin to Rudolph Diesel, inventor of the diesel engine in the 1800’s. The engine which bears his name was originally designed to run on vegetable-based fuels, in order for farmers to be able to provide fuel for their own equipment from waste oils produced from crop production. This was quickly sidestepped by America’s love for petroleum once large oil reserves were discovered in the United States. Today we are seeing resurgence in biodiesel, as oil reserves become increasingly scarce and costly to produce. In addition, biodiesel offers greatly reduced emissions and superior lubricity relative to petroleum diesel. In fact, petroleum diesel has such poor lubricity, that manufacturers currently add sulfur as a lubricating agent. This sulfur is responsible for much of the sulfur dioxide emissions in our environment. There are laws in place to phase out sulfur usage, and all diesel fuels sold in California in 2006 must meet the new Ultra-Low-Sulfur Diesel (ULSD) specification.

How does biodiesel compare with other alternative fuels out there?

There are many emerging alternative fuel technologies these days, and to compare them, we must look at the following parameters: energy balance, carbon balance, pollution created, availability, and cost to consumer. Conventional petroleum fuels are also included for comparison


Energy balance: 0.74:1

Carbon balance: emits large quantities of sequestered carbon into our atmosphere. The rate at which the carbon is released is greater than our environment can handle. This threatens the stability of our climate.

Pollution created: carcinogenic in liquid form, creates carcinogenic compounds when burned

Availability: very common, infrastructure in place

Cost to consumer: Heavily subsidized industry. Most estimates put the actual taxpayer cost of gasoline to be approximately $15 per gallon. This includes subsidies to petroleum companies for exploration, drilling, production, as well as the cost for environmental remediation and health problems associated with gasoline.

Petroleum Diesel:

Energy balance: 0.83:1

Carbon balance: emits large quantities of carbon dioxide into our atmosphere

Pollution created: carcinogenic in liquid form, creates carcinogenic compounds when burned. Burns cleaner than gasoline, but emits more fine particulate matter

Availability: very common, infrastructure in place

Cost to consumer: Heavily subsidized in the same way as gasoline. More economical than gasoline, as diesel engines are much more efficient.


Energy balance: 3.2:1 – 7:1, depending on feedstock

Carbon balance: net negative, feedstock cultivation absorbs more CO2 than is produced in combustion of biodiesel

Pollution created: Greatly reduced emissions relative to diesel fuel, with the exception of nitrogen oxides (NOx), which are slightly increased. Technology is forthcoming to reduce NOx emissions, which will soon make biodiesel cleaner than petroleum diesel in all aspects

Availability: Not very common, yet. However, any vehicle using biodiesel can be filled with diesel fuel for the times when biodiesel is not available.

Cost to consumer: Currently commands a premium over petroleum diesel, but emerging industry is expected to reduce the cost to the same as petroleum diesel or less in the next few years


Energy balance: 1.2:1

Carbon balance: net negative

Pollution created: Creates less pollution than the gasoline it displaces

Availability: Ethanol is typically blended with gasoline, at ratios up to 85% (E85). It is blended in small amounts into gasoline in California, replacing MTBE, a known groundwater-polluting agent. E85 is rather uncommon in most markets

Cost to consumer: Currently commands a premium for high-ethanol blends


Energy balance: Derived from petroleum, not sustainable

Carbon balance: Produces no carbon when burned, however, processing of petroleum products into hydrogen releases carbon into the environment

Pollution created: Hydrogen is very clean burning, however, processing of petroleum into hydrogen is energy intensive and creates pollution.

Availability: Hydrogen is rather uncommon, as the industry has not developed a practical, safe way to store it

Cost to consumer: To be determined, expected to be the most expensive of all alternative fuel solutions

When we compare all the fuels above, only biodiesel stands out as a renewable, clean burning resource that is available today.

What about hybrid vehicles? Are they better than biodiesel?

The new hybrid vehicles such as the Toyota Prius and Honda Insight generate a lot of press these days, mostly due to the fact that they are different technology, and get good mileage. However, these are powered by gasoline engines, and mileage is generally comparable or only slightly better than a modern diesel non-hybrid vehicle. Considering the fact that the gasoline hybrids are still using a non-renewable fuel, biodiesel is the most logical choice. There are many companies working on diesel hybrid technologies, that promise to offer us the best of both worlds in the near future. These cars are expected to get 100 mpg on renewable fuel. Now that’s technology to get excited about!

I’ve heard biodiesel called B20 and B100, what does that mean?

The designation ‘B’ followed by a number indicates the amount of biodiesel used in a biodiesel/petroleum diesel blend. So B20 would be 20% biodiesel/80% petrodiesel. B100 is the term used for 100% biodiesel. B5 and B20 blends are commonly used as they greatly reduce the emissions relative to pure petroleum diesel, and also may be useful in very cold climates. So technically only B100 should actually be called ‘biodiesel’, but many people in the industry use the term to describe a diesel blend with any amount of biodiesel in it.

What sort of emissions reductions can I expect by using biodiesel?

Most emissions are reduced with increased biodiesel blend use:



Carbon Monoxide (CO)



Nitrogen Oxides (NOx)






Particulate Matter



What about the increase in NOx? Isn’t that bad for the environment?

While the increase in NOx with biodiesel use is widely reported, it is of little concern for several reasons. NOx is only considered a component of smog formation when large amounts of hydrocarbons are present. The overall reduction of emissions from use of biodiesel makes the very small NOx increase irrelevant. There are ways to eliminate this increase such as retarding injection timing. Also, there are several promising technologies on the horizon that can potentially make biodiesel a NOx-neutral or NOx-negative fuel.

So I can use biodiesel in my diesel vehicle today? What are the differences relative to using petroleum diesel?

Any diesel engine can use biodiesel, but there are some specific instances where B100 is not recommended. All diesel fuels tend to solidify (‘wax’) at cold temperatures. For this reason, petroleum diesel is often ‘winterized’ by blending in kerosene or other additives. Typically, unwinterized diesel is usable down to about 20°F. Winterized diesel can be good down to 0°F or below. Biodiesel tends to solidify at a slightly higher temperature, typically 20-40°F. For this reason, B100 is not recommended for use in very cold climates.

So I can’t use biodiesel because it gets below 40°F here in the winter, what can I do?

In cold climates, biodiesel either needs to be winterized or blended with petroleum diesel. Typically, B20-B50 blends work well in climates where the temperature does not go below 20°F for extended periods.

So what modifications are required to use biodiesel in my diesel vehicle?

In general, this depends on two factors: the percentage of biodiesel you would like to use, and the age of your vehicle. For B20 blends, no modifications are necessary in most cases. For B100 usage, most vehicles newer than 1994 require no modifications. Many vehicles older than 1994 use natural rubber fuel lines, which are not compatible with B100. In this case, both the fuel line from the tank, and return lines to the tank should be replaced with newer Viton lines. The only other effect of biodiesel occurs due to the strong solvent properties of the fuel. Petroleum diesel sold in America is generally very crude, dirty fuel, and tends to deposit varnish throughout the fuel system. Biodiesel dissolves this varnish, and many users find that they need to change their fuel filter after the first few tanks of B100. After changing the fuel filter once, in most cases no additional maintenance is required.

I’ve heard of people running their vehicles on unrefined fryer grease, is this biodiesel?

Although biodiesel can be made from fryer grease, the grease alone as it comes out of the fryer is not biodiesel. While diesel engines can burn straight vegetable oil (or SVO as it is commonly called), there are many limitations that prevent it from being used as a fuel replacement. SVO is much thicker than refined fuel, and can only be used as diesel fuel when it is pre-heated prior to being fed to the engine. Simple systems exist that use heat from the cooling system to heat the incoming fuel prior to injection into the engine. But in this case, the engine must be started up and shut down on regular diesel fuel or biodiesel, then switched to SVO while the engine is running. For this reason, SVO isn’t as user-friendly as biodiesel, and isn’t recommended for most people.

I’ve heard it is really easy to make biodiesel, so why shouldn’t I make my own?

While production of biodiesel is a relatively simple chemical process, producers of biodiesel use rigorous testing procedures to insure that the fuel meets the standards of the American Society of Testing and Materials (ASTM). The majority of these tests are cost-prohibitive for most home-brewers. While it is possible to home-brew ASTM-quality biodiesel, production involves some very flammable liquids that shouldn’t be undertaken lightly by just anyone.

Can biodiesel damage my engine?

There as never been (as far as we know) any engine damage attributable to ASTM-grade biodiesel. That said, off-spec biodiesel (or off-spec petroleum diesel for that matter) could harm your fuel delivery system. That is why it is important to purchase your biodiesel from a reputable company that you trust.

Will biodiesel void my warranty?

Although there have been conflicting reports on this subject, the reality is that engine manufacturers warranty engines, and do not warranty fuel used in engines. Fuel is warranted by the fuel manufacturers. All reputable manufacturers sell ASTM-quality biodiesel, which will not harm an engine. In fact there is a law known as the Magnusson-Moss act that specifically prohibits vehicle manufacturers from denying warranty service to a user of alternative fuels.

Will biodiesel affect my mileage and performance?

Biodiesel has slightly different properties than diesel fuel, mostly with respect to the cetane number and energy density. For this reason, it offers slightly less performance, and slightly less mileage. In most cases, the differences are less than 5% and are not verynoticeable. We have found that biodiesel is basically indistinguishable from petroleum diesel in our Jetta, we are still getting about 44 MPG, and it has power to spare. The only major difference we notice is that our exhaust smells a lot better!

Is the handling of biodiesel dangerous?

The flammability of a liquid is expressed as flash point, which is defined as the temperature at which the material can sustain a flame on its surface. From a hazard perspective, diesel fuels in general are considered to be much safer than other petroleum fuels, due to their high flash point. Within diesel fuels, biodiesel is much less flammable than petroleum diesel. To get an idea of the relative flammability of biodiesel, lets compare the flash points of several well-known fuels1:

Fuel Flash Point (°F)

Propane -100 to –150

Gasoline -45

Charcoal lighter fluid 160

Petroleum diesel 160

Biodiesel 321

From the data above, it is evident that the only reason to classify biodiesel as a ‘fuel’, is the fact that it can substitute well for petroleum diesel. From a flammability perspective, it is closer to the vegetable oil from which it is derived.

In a study performed by the University of Idaho, Biodiesel in water was found to degrade 95% in 28 days. During the same time period, petroleum diesel fuel degraded only 40%. In another study performed in an aquatic environment, Biodiesel was found to have similar biodegradable characteristics as dextrose (sugar). A standard aquatic toxicity test using bluegill determined that biodiesel is an ‘insignificant’ risk to marine life.

The acute oral lethal dose for Biodiesel has been found to be at 17.4 g/Kg of body weight. In comparison, ordinary table salt is lethal at 1.75 g/Kg of body weight, making salt almost ten times more toxic than Biodiesel. So for an average male who might weigh 175 pounds, the lethal dose of salt would be about 4.5 ounces and for Biodiesel almost 3 pounds, which translates to almost 1.5 quarts of Biodiesel that would have to be ingested.

In twenty-four hour patch tests on humans, 100% Biodiesel produced only mild irritations, which in comparison was much less than that produced by a 4% aqueous soap solution.2

So to summarize, biodiesel is safer to store and handle than petroleum diesel

Can I use biodiesel in my gasoline-powered car?

Unfortunately, biodiesel can only be used in diesel engines. A diesel engine is a completely different animal compared to a gasoline engine.

Why should I use biodiesel?

In addition to the increase in fuel economy offered by diesel engines over gasoline engines, biodiesel offers many benefits over conventional petroleum diesel:

· Burns much cleaner, great reduction in carcinogenic compounds

· Reduces greenhouse gases via its negative carbon cycle

· Increases national security by promoting American-grown fuel over imported foreign oil. The use of biodiesel keeps money in our own economy, creating jobs for

· Is available as an alternative fuel today

· Runs in most vehicles with little or no modification

· Offers superior lubricity and cleaner fuel system compared to petroleum diesel

Aren’t diesel vehicles hard to find?

While diesel vehicles are a lot less common in the United States relative to Europe, there are still many options available for those who want a diesel vehicle. New diesel passenger cars are currently being sold in the US by Volkswagen and Mercedes. For those people who don’t want to buy a new car, there are plenty of used VW and Mercedes on the market. Considering the longenity of the diesel engines in these cars (several hundred thousand miles is typical), there are diesel options available at all price ranges. When it comes to trucks, there is a wide selection of vehicles available, generally in the heavier trucks (3/4 ton and up). As consumer demand for new diesel vehicles continues to increase, American automakers are sure to respond with new models. There are many more models available for sale in Europe, where diesels are much more popular. We are starting to see this shift occur in the U.S., for a long time there were no mid-size SUVs with diesel engines, but Jeep will be offering a diesel version of their Liberty model in 2005. It appears that once the new low-sulfur diesel regulations go into effect in 2007, that there will be even more options available.

Are there any other applications where biodiesel can be used?

Biodiesel can substitute for practically any application that uses diesel fuel or fuel oil. It is being increasing used to replace home heating oil, thus further reducing our dependence on foreign oil. It is also widely used in generator and marine applications. Regardless of the specific application, the benefits of using biodiesel are realized.

I’d like to try biodiesel in my equipment, but I don’t have the time to do the extra maintenance and education of my employees. Where can I get help with these issues?

We offer a full range of support services to our customers. Everything from initial assessment to vehicle modifications to follow-up support is available. We believe in our product and we realize that a loyal customer base is critical to our success. An educated consumer is a happy consumer! With a little education, it can be a drop-in replacement that works as easily as petroleum diesel for most folks.

Sounds great, so where can I get it?

Currently, availability of biodiesel is limited in the Sierras. There are currently no local pumps in the Sierras carrying any blends over B5. There are plans for a B100 pump in both the Reno/Sparks area and in the greater Sacramento area in the near future. In the meantime, some people may find it more convenient to have biodiesel delivered to their home or business. Please contact us if interested, we have a variety of delivery and storage options available.


Properties of Fuels [pdf - http://afdc.nrel.gov/pdfs/fueltable.pdf], National Renewable Energy Labs (NREL), May 25, 2003.
National Biodiesel Board Website, http://www.biodiesel.org/pdf_files/Envi&Safetyinfo.PDF, 2004

Copyright 2004 Simple Fuels, LLC. This information may be duplicated and distributed for non-commercial information purposes. For the latest version of this FAQ, please visit us at www.simplefuels.com

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