Quality, testing and warranties

The use of biodiesel is expanding as a cleaner burning viable alternative to traditional petroleum diesel. This is creating a new market place and with it new opportunities for forward-looking individuals and companies who wish to become involved in the production of biofuels. There are a variety of feedstocks and production technologies and this is of major concern to the current fuel and automotive industry.

Standards play a vital role in ensuring that fuel will perform its primary task without any negative effects to the engine and the environment. Most importantly is that standards are designed to protect the end consumer from poor quality fuels and the potential harm that could be done to the vehicle.

However, as with every new emerging industry, there are those that have no desire to work within this legislative framework and money is their motivation. In order to produce biodiesel commercially there needs to be a substantial financial commitment.
If a small producer makes a 1000L batch, and he perhaps makes R1.00 a liter profit, then that would yield R1000.00 profit. To provide a sample of his biodiesel to a lab for testing could cost between R800 to R2500, depending what tests are to be performed.
It is quite obvious that it is not financially possible for these small-scale producers to perform regular if any type of recognized quality control.

There are 4 major fuel injection equipment (FIE) manufactures that supply to all the motor vehicle brands. Bosch, Denso, Stanadyne and Delphi have all recognized that biodiesel is coming of age. Together they have performed extensive tests and studies and have released a combined position statement that accepts biodiesel blending, but that also points out potential component failures that could occur if certain quality concerns are not addressed. (click here to view report)

In a recent statement, Paul Henderson, Quality systems manager of STANADYNE (USA) stated that results indicated the inclusion of a biodiesel blend would address the lubricity concerns with current mineral fuels. However they were concerned about the risks of using substandard biodiesel, either neat (B100) or as a blend. Of particular concern was the presence of the following

Their collective position was that “ fuel injection equipment manufactures would not accept legal liability or warranties for equipment failure that could be attributed to their equipment being used with fuel of substandard quality.” This statement also includes substandard mineral fuels. The various vehicle manufactures however cannot reach common consensus and despite more than 1.4 billion Liters of biodiesel being used per year in America, representing hundreds of millions of miles of engine and vehicle usage in a wide range of operating conditions, each manufacture has a different viewpoint. Even the US military with its strict fuel requirements has approved the use of B20 for their vehicles.

Here is a position summary of some of the vehicle manufactures regarding the use of biodiesel.

(Source: Biodiesel basics and beyond…William kemp)

The reason for manufactures not supporting the use of B100 and high blends is the fear that it might lend credibility to the small scale home brewers producing poor quality fuel and the resulting negative public relations and liability that may flood in. In terms of product liability and reliability perceptions it is simply not to their advantage to fully support high biodiesel blends, so they don’t.

The one thing that they do all agree on is that quality is of utmost importance.

Fuel Quality Testing

In South Africa all fuels sold must comply with a local standard that is set by the SABS. These standards are based upon the fuel requirements of the automotive industry so that their respective engines can perform and reach certain levels of emission control. There is ongoing collaboration between the mineral fuel companies and the vehicle manufactures to work towards these emission goals. These standards also ensure a high quality of fuel reaches the customer and that it will not cause undue damage, other that normal wear.

We all here rumors about the poor fuel quality of South African diesel, but in reality the fuel majors in South Africa produce some of the best quality diesel that meets or exceeds international standards. However there are cases where fuel becomes contaminated or tampered with once it leaves the refinery, which is beyond their control.

Like wise there is a standard for the production quality of biodiesel that has been established by SABS, this quality specification in known as the SANS 1935.This standard is a set of tests and set values that a product must achieve to be deemed fit for use. These tests examine the physical and chemical properties of the fuel sample. The tests use international test procedures to ensure the following

Table 1- Requirements for automotive biodiesel fuel- SANS 1935

What the tests mean and the impact upon the engine

DENSITY: The measurement of mass per unit volume at a set temperature. This test is more of interest to the biodiesel producer as it can indicate incomplete reactions.

KINEMATIC VISCOSITY: A measure of a liquids ability to flow. This is of great importance to the fuel pump and the injector nozzles. A fuel that is to thick will place strain on the fuel pump and may lead to premature failure. A thick fuel will also not form the correct atomization pattern once it is forced through the tiny holes of the injector and sprayed into the combustion chamber. This can lead to incomplete fuel burn, fuel dripping from the nozzle and causing hot spots on the piston head witch will eventually damage or burn a hole in the piston, or the unburnt fuel can seep past the piston and mix with the lubricating oil, contaminating the oil and stopping the oils ability to lubricate certain engine components. The unburnt fuel will also cause excessive exhaust smoke.

  
(Left image shows the idea stray pattern. The right image is of partially blocked injector showing poor spray pattern.)

FLASH PIONT: A measure of the temperature required to ignite a fuel. It is used to determine the safe handling of a fuel and it’s potential risk to cause a fire while being stored. It will also determine how the fuel burns in the combustion cycle of an engine. Biodiesel has a high flash point and is a very safe fuel to use. Samples that fail this test may still have volatiles such as unrecovered methanol present and indicate poor production and process control. In the engine this may cause premature ignition of the fuel, resulting in inconsistent firing, irregular timing and excessive exhaust emissions.

SULFUR CONTENT: Sulfur is a common contaminant in mineral diesel. During the combustion process sulfur oxides are produced as an exhaust gas and can harm the environment. In the engine they form acids in the combustion cylinder that can lead to early metal fatigue, and they form in the crankcase where they attack the lubricating oil. This is why diesels traditionally have short intervals for oil changes. Some sulfur is needed in the fuel as it provides the lubrication for the fuel pump and injectors. Biodiesel is very low in sulfur, ranging between1 and 14 parts per million (ppm), mineral diesels range from the ultra low sulfur diesel (50ppm) to the standard grade diesel with 500 ppm. This makes biodiesel an ideal additive as it is low in sulfur and has outstanding lubrication properties. The sulfur content in biodiesel is generally dependent upon the feedstock and is not determined by the producer.

CARBON RESIDUE: This is an indication of the amount of carbon residue that will be deposited in the engine as the result of fuel combustion. The most common cause of excess carbon when using Biodiesel is a high level of glycerine. This carbon can cause scuffing on metal surfaces and a build up of carbon around the injector tips could interfere with the spray pattern and amount of fuel delivered. To the producer it can point to an incomplete reaction and to a poor wash/ filtration cleansing system.

These valves come from two VW 1.9TDI engines. Both vehicles have done 15 000km under similar conditions. The one on the left ran with standard mineral diesel and the valve on the right ran with B100. The valve on the left clearly shows the build up of carbon left by the combustion of mineral diesel, compared to the relatively clean biodiesel valve on the right. Carbon build up can eventually form deposits around the edge of the valve, preventing proper sealing of the valve in the closed position.

CETANE NUMBER: This is an index used to determine a fuels ignition time delay. Biodiesel contains 10-11%oxygen by weight, which encourages a more complete combustion than mineral diesel. Biodiesel cetane numbers depend upon the feedstock used for its production, and are superior to those of mineral diesel. Mineral diesels often require a cetane booster additive at refinery level. A cetane that is to low will cause hard starting, rough and unsteady idling, engine clatter and increased exhaust smoke. Fuels with to high a cetane will burn before there has been a mix between the fuel and air, and will result in smoking.

SULFATED ASH: This is a measure of the amount of trace metals such as zinc, magnesium, tin, potassium, calcium, barium and sodium that are found in the fuel. Due to biodiesels organic nature these levels are normally very low. However potassium and sodium are commonally used as catalysts in the biodiesel reaction. Ash forming materials can be found in 3 forms- 1) abrasive solids 2) residual catalyst 3) soluble metallic soaps. Abrasive solids and unrecoverd catalyst may contribute to wear of the fuel pump, injectors and the piston and rings. The soluble soaps have no affect on wear, but may cause deposits and filter blocking. For the biodiesel producer it will point to a poor method of final washing and filtration.

WATER CONTENT: Fuels can contain dissolved water that cannot be visibly seen.
Water is a major cause of most engine failures and can be present in the fuel due to leaking underground fuel storage tanks, poor production and the engines own cooling system may be leaking radiator coolant internally. Water in the fuel will cause the following. Shorter component life due to rust and corrosion, hydrogen embrittlement of certain parts, oxidation of bearing Babbitt, water etching, erosion and vaporous cavitations and excessive wear caused by loss of lubricating oil film and hard water deposits such as calcium scaling. The build up of scale can also cause blockages in fuel delivery pipes. Water contamination will over time cause catastrophic engine failure. If water is present in the fuel there is also a chance of microbial growth, and this algae may accumulate in the fuel tank where it can lead to blocked fuel lines and some loss of power. Both mineral and biodiesel can have fungicides added to them at refinery level to prevent this, however the major concern is leaking of ground water into underground storage tanks at petrol stations. Some biodiesel processors use water to clean impurities from the finished fuel, and then need to remove it later. There is also a small amount of water that is made during the chemical reaction of transesterification. Testing for water is critical to the biodiesel producer and gives an idea of how his technology is operating.

TOTAL CONTAMINATION: This is a test for other non-specific contaminants that may be suspended in a set volume of fuel.
These are items such as waxes that could lead to filter blocking if found in excessive levels.

COPPER STRIP CORROSION:  This is a basic test used on all fuels to test for acids and other corrosive materials that may be present. Certain engine components may consist of copper or bronze or other materials that might be aggressively attacked by acids. Generally though it tests for sulfur compounds which may convert to corrosive agents when heated. Again biodiesel is generally low in sulfurs, but biodiesel producers can cause contamination with other acids that are used in their process. The effect on the engine can be chemical etching on metal surfaces and a break down in the fuels lubricity function. There can also be corrosive damage to O-rings and seals in the fuel delivery system.

OXIDATION STABILITY: This is a test for how long a product can be stored before the fuel starts to chemically react with oxygen molecules to form peroxides. These peroxides then undergo a complex series of chemical reactions resulting in polymerization of the base fuel. All fuels have a shelf life after which they start to degenerate. Fuels should generally be able to be stored for six months before this process starts, and both mineral diesel and biodiesel can have anti oxidants added to them to improve the fuels stability. Again smaller producers don’t purchase and blend these anti oxidants, but it may not always be necessary if the fuel is to be consumed shortly after production. The process is accelerated if the product is stored for long periods in hot conditions, or in vessels that may contain rust. Long-term storage should remove the air/ fuel interface by using nitrogen blanketing and airtight tanks. The result on the engine can be the formation of sludge like deposits in the fuel filter and fuel delivery system and the formation of hard deposits and lacquers on parts that are present in the combustion process.

ACID VALUE: This is a measure of the acidic groupings in a product. These acids emanate from two sources, acids that are utilized in the production process that have not been removed, and acids that are in the free fatty acids that are caused by oxidative degradation. High acid values have been shown to increase fueling system deposits and may increase the potential for corrosion. For the producer it may indicate poorly refined product or poor process control when converting the feedstock oils into biodiesel. In the engine the fuel can display a strong solvency effect on rubber seals and hoses, deposits and potential filter clogging which may lead to a drop in fuel delivery pressure and a loss of power.

IODINE VALUE: A basic measure of the number of double bonds in an oil or biodiesel. This is of importance to the producer to choose feedstocks. The higher an iodine value (more double bonds) the lower the cetane number, reducing engine performance, but also the fuel will be more prone to oxidative stability damage.

LINOLENIC ACID METHYLE ESTER:
POLYUNSATURATED:  These two tests are an indication to the producer for the completeness of the reaction of converting oils into biodiesel, Biodiesel is chemically called Fatty Acid Methyl Ester (FAME). This test is designed to provide a profile of fatty acids for a given biodiesel sample.

METHANOL CONTENT: This represents unreacted methanol remaining after trans methylation, and will affect the flash point test.

MONOGLYCERIDE, DIGLYCERIDE and TRIGLYCERIDE CONTENTS: This is a measure of any un-reacted material in the biodiesel. This is used by the producer to examine the efficiency of his process and as a measure of how good his crack has been. The key re-action in biodiesel is called transesterification and involves chemically breaking the glycerin bonds within the oil molecule and converting to a methyl ester. The glycerine becomes a byproduct and can be separated from the remaining biodiesel. Essentially a monoglyceride is an uncompleted reaction where only two of the three glycerine bonds have been broken and one remains bonded. The resultant fuel will contain glycerine that will be a major cause of carbon deposits left behind after the combustion process.

(Left injector showing carbon build-up and potential blocking of nozzle holes. )

FREE GLYCERINE: This is a measure of glycerine that was successfully converted and is no longer bonded to an ester. In theory this can now be separated from the biodiesel, but some processors do not adequately remove these impurities. Glycerine eventually settles out to the bottom of the storage or vehicles fuel tank, but will cause blockages in the fuel pump, or the strain of the fuel pump to move this thick sludge may cause premature pump failure. The most common result will be the blockage of the filter before it even reaches vital components such as the fuel pump. In small quantities it may contribute to dirty injectors and poor atomization of the fuel, in which case there will be white exhaust smoke.

Where to test

BIOSERVICES cc
Bioservices is a Honeydew based independent test laboratory that specializes in the testing of biodiesel. Although there are other labs we have found Bioservices to have a better understanding and more experience of the biofuels industry, and are thus able to provide more meaningful feed back that is essential to understanding how to control your product quality. Peter Finnegan also has extensive history of involvement within the petroleum fuels industry.

The lab is run by Dr Irene Finnegan who received her honours degree in Biochemistry from the university of Kent in 1979, and her doctorate from the university of Manchester in 1980. Her specialist subject was the study of the chemical and physical properties of lipids in biological membranes and how they influenced trans membrane hormone signaling systems. Dr Finnegan has worked at South African Medical Research and has also held a senior lecture post in the department of chemistry and biochemistry at the university of Johannesburg.

Dr Irene Finnegan discussing with Mark Glock of GC Biofuels some of the recent test results

We strongly recommend to other Biodiesel producers that they make use of the professional services of Dr Finnegan. Bioservices have just made a substantial commitment to the biodiesel industry by purchasing a Fourier Transform Infrared  (FTIR) spectrum analyzer that will reduce the cost of testing samples, ensuring that costs should no longer be a barrier for small-scale producers to testing their product.