4. Biodiesel and Biodiesel Blends
4.1 Introduction
Biodiesel is a renewable fuel with properties similar to petroleum diesel. It is obtained by esterification of oils or fats derived from plants or animals. Esterification involves producing a reaction of a vegetable oil or an animal fat with an alcohol, such as ethanol or methanol, in the presence of a catalyst to yield mono-alkyl esters, and glycerine, which is removed. Biodiesel is a generic name for mono-alkyl esters.
New Zealand's biggest source of biodiesel is tallow, an animal fat by-product from the meat processing industry. Vegetable based oils, such as rapeseed, and suitably processed used cooking oil from restaurants can also be made into biodiesel. There are currently only small amounts of biodiesel being produced in New Zealand and these are not yet part of the retail fuel mix.
There are currently no regulated biodiesel specifications in New Zealand, only a voluntary biodiesel standard - Automotive Biodiesel: Specification for manufacture and blending (NZS 7500).
NZS 7500 specifies requirements and test methods for biodiesel manufacture and its use either as automotive fuel for compression ignition engines at 100% concentration or as a blend component. It was prepared by a committee consisting of representatives from biofuel manufacturing companies, oil companies, the motor vehicle industry, the New Zealand Refining Company and government agencies.
It is considered that biodiesel blends containing up to five per cent by volume may be used in any diesel engine without modification. There is also the potential for higher blends of biodiesel to be used, for example, to power bus and truck fleets and for use in the fishing industry. As for petroleum diesel, it is proposed that a distinction is made in the regulations between all biodiesel "supplied, or available or intended for supply" and biodiesel that is sold by retail.
The conventional nomenclature for describing biodiesel blends is BX where the X is the volume percent of biodiesel in the blend. For example, B100 is neat biodiesel and B5 is a blend of 5% biodiesel and 95% petroleum diesel.
The following section discusses the proposed specification for B100, retail biodiesel blends, and non-retail biodiesel blends, in that order.
4.2 Scope of Regulations
Rather than replicate the analysis undertaken to develop NZS 7500, the proposed regulations use this standard as a starting point. The proposals discussed reflect new knowledge and developments and changes necessary to incorporate biodiesel and biodiesel blends in the PPSR.
Biodiesel is predominately produced by methanol esterification of natural product fatty acids, thus known as fatty acid methyl esters (FAME). However, other alcohols could be used in the production process, such as ethanol which would produce a fatty acid ethyl ester (FAEE). Bioethanol is of interest as this is a renewable resource, rather than methanol which is usually derived from fossil fuels. At present the use of methanol is an economic decision, as this is the cheapest alcohol. In addition, reactions proceed faster with the use of methanol over ethanol. Many of the methods used to measure biodiesel quality are not necessarily appropriate to analyse ethyl rather than methyl esters.
NZS 7500, while based on FAME, does not exclusively specify this type of ester. The European and Japanese diesel fuel standards specify the allowable biodiesel component as FAME. It is proposed that the New Zealand biodiesel specifications likewise specify the biodiesel component as FAME. This will be reviewed in line with international developments.
NZS 7500 applies only to biodiesel for use as an automotive fuel for compression ignition engines. Petroleum diesel as regulated in the PPSR is not limited to automotive use. For consistency in approach, and to ensure that all biodiesel sold in New Zealand is of a suitable quality, it is proposed that the regulated biodiesel specification does not make a distinction between automotive and other use. Hence, all biodiesel supplied in New Zealand will need to meet the specifications set out in the regulations. Note however that the non-retail specification (discussed in Section 4.5) for biodiesel will provide some flexibility for non-vehicular use of biodiesel (e.g. heating purposes and powering machinery).
4.3 Specification for B100
4.3.1 Background
The regulated B100 specification will specify requirements and test methods for B100 supplied in New Zealand. B100 will mainly be sold as a blend with petroleum diesel. The proposed requirements for retail and non-retail biodiesel blends are discussed in Section 4.4 and 4.5 respectively. It is also proposed to allow B100 to be sold via a written contract (i.e. non-retail only). Comments are sought on this approach.
Effort is underway internationally to harmonise biodiesel specifications. However, currently the appearance of specifications varies substantially between countries (see Table 1) due to differences in regulatory approach, climate, feedstock and vehicle technology. The specifications in NZS 7500 were developed to be consistent with the European automotive biodiesel standard (EN 14214) but be performance based rather than feedstock specific. The relatively few differences between NZS 7500 and EN 14214 are shown in Table 2. The Japanese and Australian specifications likewise look to EN 14214.
The other major standard for biodiesel is the ASTM D 6751, which is less comprehensive than EN 14214, containing only 14 parameters compared to the 22 in EN 14214. Being less comprehensive, this standard gives more flexibility for feedstock. However, ASTM D 6751 is only applicable for biodiesel used for blending with petroleum diesel up to 20% by volume, not as a final fuel in itself.
It is proposed that the New Zealand regulations incorporate the B100 specification as set out in NZS 7500. These parameters are considered to give B100 of an appropriate quality, while ensuring that the costs of supplying compliant fuel are reasonable.
Table 1: International B100 Specifications
| Country |
B100 Specification |
Comments |
| Europe |
EN 14214 |
For final fuel and blending component. 22 different parameters specified, based predominantly on rapeseed oil feedstock. |
| United States |
ASTM D 6751 |
Applicable for biodiesel for blending in levels up to 20% by volume, not as a final fuel. Much less comprehensive than EN 14214, only 14 parameters specified. More flexibility in feedstock. |
| Japan |
JASO M 360 |
Voluntary, based on EN 14214 but with oxidation stability and cold flow performance being agreed between producer and distributor. |
| Australia |
Fuel Standard (Biodiesel) Determination 2003 |
For final fuel and blending component. Based on EN 14214 but not as comprehensive. Slightly tighter density requirement. |
| New Zealand |
NZS 7500 |
For final fuel and blending component. Based on EN 14214 but some differences. Issued 2005. |
Table 2: Comparison of EN 14214 and NZS 7500:
The differences between EN 14214 and NZS 7500 B100 standards are highlighted in grey below.
The term "%m/m" is used to represent the mass fraction.
* parameters to be discussed further in the following section.
| Property |
Unit |
EN 14214 |
NZS 7500 |
| Minimum |
Maximum |
Minimum |
Maximum |
| Ester content |
% m/m |
96.5 |
- |
96.5 |
- |
| Density at 15ºC |
kg/m³ |
860 |
900 |
860 |
900 |
| Viscosity at 40ºC* |
mm²/s |
3.5 |
5.0 |
2.0 |
6.0 |
| Flash point |
ºC |
120 |
- |
100 |
- |
| Sulphur content* |
mg/kg |
- |
10 |
|
50, 10 |
| Carbon Residue (on 10% distillation residue) |
% m/m |
- |
0.3 |
- |
0.3% m/m on 10% distillation or 0.05% m/m on 100% distillation1 |
| Cetane number |
|
51.0 |
- |
51.0 |
- |
| Sulfated ash content |
% m/m |
- |
0.02 |
- |
0.02 |
| Water content |
mg/kg |
- |
500 |
- |
500 |
| Total contamination |
mg/kg |
- |
24 |
- |
24 |
| Copper strip corrosion (3 h at 50ºC) |
rating |
|
class 1 |
|
class 1 |
| Oxidation stability, 110ºC |
hours |
6.0 |
- |
6.0 |
- |
| Acid value |
mg KOH/g |
- |
0.5 |
- |
0.50 |
| Iodine value* |
g iodine/100 g |
- |
120 |
- |
120 |
| Linolenic acid methyl ester |
% m/m |
- |
12.0 |
- |
12.0 |
| Polyunsaturated (>=4 double bonds) methyl esters* |
% m/m |
- |
1 |
- |
Not specified |
| Methanol content |
% m/m |
- |
0.20 |
- |
0.20 |
| Monoglyceride content |
% m/m |
- |
0.80 |
- |
0.80 |
| Diglyceride content* |
% m/m |
- |
0.20 |
- |
Not specified |
| Triglyceride content* |
% m/m |
- |
0.20 |
- |
Not specified |
| Free glycerol |
% m/m |
- |
0.02 |
- |
0.02 |
| Total glycerol |
% m/m |
- |
0.25 |
- |
0.24 |
| Group l metals (Na+K) |
mg/kg |
- |
5.0 |
- |
5.0 |
| Group ll metals (Ca+Mg) |
mg/kg |
- |
5.0 |
- |
5.0 |
| Phosphorus content |
mg/kg |
- |
10.0 |
- |
10.0 |
4.3.2 Discussion of specific parameters for B100 specification
4.3.2.1 Viscosity
Viscosity is a measure of a fuel's resistance to flow. High viscosity can cause poor injector spray atomisation leading to excessive coking and oil dilution. Low viscosity can cause increased wear of fuel system components, incomplete combustion and restart problems. These problems are associated with reduced engine life and increased emissions. The viscosity of biodiesel is typically higher than that of petroleum diesel, depending on feedstock.
EN 14214 and the Australian Biodiesel Determination set the limits of viscosity (at 40°C) to 3.5 – 5.0 mm²/s. The limits for viscosity in ASTM D 6751 are 1.9 – 6.0 mm²/s. NZS 7500 sets the limits of viscosity to 2.0 – 6.0 mm²/s, but this limit may be increased to 7.5 mm²/s if it is required to encompass a wider range of feedstocks or mono esters other than methyl esters.
The upper viscosity limit in NZS 7500 is set relatively high because at the time the standard was developed there was relatively little data on the viscosity of tallow based biodiesel. Another factor in this decision was that viscosity is also controlled in NZS 7500 at the B5 level (i.e. 2.0 – 4.5 mm²/s). NZS 7500 notes that the B100 viscosity limit would be reviewed once there is sufficient data on viscosity of biodiesel manufactured from locally produced tallow.
It is desirable that the biodiesel regulations are based on performance of the fuel, rather than feedstock characteristics. It has been suggested that good quality biodiesel, including that produced using tallow, should have a viscosity below 5.0 mm²/s.2
It is proposed that the B100 specification regulations limit viscosity (at 40ºC) to 3.5 – 5.0 mm²/s when measured by ASTM D 445 or ISO 3104. This seems appropriate for both biodiesel as a final fuel and as a blending component.
4.3.2.2 Cold Flow Performance
As diesel cools, paraffins start to form wax crystals which can lead to blockages of the fuel line and filters, leading to fuel supply interruption and problems with engine start-up. Hence, adequate cold flow performance is an important operability criteria.
The PPSR specifies two measurements of cold flow performance. The Cloud Point is the temperature at which wax crystals start to precipitate out and the fuel becomes cloudy. The Cloud Filter Plugging Point (CFPP) is the temperature at which the fuel crystallisation causes a fuel filter to plug.
Cold flow properties of biodiesel vary depending on the amount of saturated fatty acids in the feedstock. Generally, the amount of saturated fatty acids in a feedstock and cold flow performance have a negative correlation. Hence, biodiesel made from tallow tends to have poor cold flow properties.
Limits on cold flow properties in EN 14214 are dependent on climate, therefore differing between seasons and localities. The PPSR cold flow requirements for diesel are similar. NZS 7500 does not specify cold flow properties for B100, but notes that the CFPP will need to be measured and recorded so that diesel/biodiesel blends can be formulated to provide the required properties.
It is proposed that cold flow properties for New Zealand's B100 are as agreed between seller and purchaser to meet seasonal operability requirements. Accordingly, cold flow properties will not be included in the B100 specification regulations.
4.3.2.3 Sulphur
Sulphur limits are generally imposed for environmental reasons as combustion of fuel containing sulphur causes emissions of sulphur dioxide and particulate matter. In addition, sulphur in fuels can degrade the performance and durability of emissions control equipment.
Biodiesel produced from fresh vegetable oils should contain only traces of sulphur. There is limited data available on the sulphur content of biodiesel made from tallow, but it tends to be higher than that of vegetable oils due to the presence of protein and hair in the fats. Waste cooking oil may also have higher sulphur levels due to sulphur picked up during cooking. The limit for sulphur in NZS 7500 is aligned with the sulphur limits for petroleum diesel, i.e. presently 50 mg/kg, to be reduced to 10 mg/kg from January 2009.
It is proposed that the regulated B100 specification limits sulphur to 50 mg/kg maximum initially, to be reduced to 10 mg/kg from January 2009. This is considered appropriate due to the low levels of sulphur that should be in biodiesel and the necessity for biodiesel to be absorbed by the market as a blending component with "sulphur-free" petroleum diesel.
4.3.2.4 Iodine Value
The iodine value is a measure of the degree of unsaturation in biodiesel. It is reported in terms of the grams of iodine that will react with 100 grams of fat or oil under specified conditions. Unsaturated fatty acids tend to polymerise when exposed to heat and pressure conditions leading to the formation of engine deposits or to deterioration of the lubricating oil.
Thus iodine value is a rough indicator of fuel stability, with highly unsaturated fuels (a high number of double bonds and therefore a high iodine value) having relatively poor oxidation stability. It is recognised, however, that fuel stability is better measured by parameters such as oxidation stability, linolenic acid methyl ester and polyunsaturated alkyl esters. A predominant reason for this is that polymerisation reactions appear to a significant extent only in fatty acid esters containing three or more double bonds3 and the iodine value does not take into account the positions of the double bonds. However, it is also recognised that the current oxidation stability tests are seen by some as relatively weak, and there is as yet no test to measure polyunsaturated alkyl esters (as discussed below). Effort is underway internationally to develop these tests further.
Biodiesel of a suitable quality from feedstocks with a high degree of unsaturation, e.g. soybean which has an average iodine value of 117 – 143, might be unable to meet biodiesel specifications because of the iodine value requirements. The iodine value is limited to 120 maximum in NZS 7500 and EN 14214 (as the iodine value of rapeseed is generally less than 120). In Spain, the standards for biodiesel require a maximum iodine value of 140 to facilitate the use of soybean oil in the production of biodiesel. A number of other countries, for example Brazil and South Korea, have not specified an iodine value limit when adopting a biodiesel specification similar to EN 14214 to allow flexibility in feedstocks. Neither ASTM D 6751 nor the Australian Biodiesel Determination set a limit for iodine value.
It is proposed that the regulated B100 specification limit iodine value to 140 maximum, when measured by the test method EN 14111. This will allow for more flexibility in feedstocks, whilst still controlling the degradation performance of the biodiesel.
4.3.2.5 Polyunsaturated Alkyl Esters
As discussed above, unsaturated fatty acids tend to polymerise when exposed to the heat and pressure conditions within a compression ignition engine. This can lead to the formation of engine deposits or to deterioration of the lubricating oil, which can affect engine operability.
EN 14214 limits polyunsaturated methyl esters with four or more double bonds to 1% mass maximum, noting that a suitable test method is to be developed. NZS 7500 notes that polyunsaturated alkyl esters should be limited to 1% mass maximum but that an appropriate limit will be considered once a suitable test method is available. At the time of writing this document a suitable test method for polyunsaturated alkyl esters was still under development. Polyunsaturated alkyl esters are not specified in ASTM D 6751 or the Australian Biodiesel Determination.
It is proposed that the regulated B100 specification does not limit polyunsaturated methyl esters. This property will be reconsidered when a test method is available.
4.3.2.6 Diglycerides and Triglycerides
Diglycerides and triclycerides (and monoglycerides) are present in the biodiesel feedstock and small quantities can remain in the final product if the conversion reaction is incomplete. Thus, low concentrations of glycerides can be achieved by selecting optimum reaction conditions and/or distillation of the final ester product. Glycerides may adversely affect cold weather operability and can cause formation of deposits on injector nozzles, pistons and valves.
EN 14214 specifies a separate content limit for each of monoglycerides, diglycerides, triglycerides, free glycerol and total glycerol. NZS 7500 only specifies limits for monoglycerides, free glycerol and total glycerol. Total glycerol is the sum of the concentrations of free glycerol and glycerol bound in the form of monoglycerides, diglycerides and triglycerides. When NZS 7500 was developed, having a limit on total glycerol and monoglycerides content, rather than control on individual glyceride levels, was considered to give effective control of these properties. In addition, high glyceride contents in biodiesel have a positive correlation with values for viscosity and carbon residue. The NZ 7500 sets limits for both viscosity and carbon residue.
ASTM D 6751 and the Australian Biodiesel Determination both do not specify limits for diglycerides and triglycerides (or monoglycerides).
It is proposed that the B100 specification does not include a limit for diglycerides and triglycerides. Limiting total glycerol (which will indirectly measure diglycerides and triglycerides through the glycerol they contain) and monoglycerides is considered to give effective control for ensuring that the glyceride products of incomplete reaction are minimised.
4.3.3 Test Methods
While the test methods in NZS 7500 are being used as a starting point, where possible it is desirable to specify the same test methods for B100 as are currently in the PPSR.
NZS 7500 specifies ASTM, EN and ISO test methods for B100. In many cases, two or more test methods are specified for a single property. It is proposed to not specify some of the additional test methods which are similar or equivalent to those ASTM methods routinely used by the testing laboratories in New Zealand.
Table 3 below includes the proposed test methods for the B100 specification regulations. Comments are sought on the appropriateness of these test methods.
There are current international efforts to align ASTM and CEN test methods for describing biodiesel product. The New Zealand regulations will be updated as necessary to reflect international developments in this area.
4.3.4 Proposed B100 Specification
Table 3 below shows the proposed B100 specification.
For the proposed B100 specification, please provide comment on the following:
a) Do you agree with the proposed requirements?
b) If not, what is an appropriate requirement (i.e. limit and test method)? Please provide an explanation of how this impacts on vehicle operability and / or biodiesel manufacturing.
Table 3: Proposed B100 Specification:
Note that the Bold text in this table indicates differences from NZS 7500.
| Property |
Unit |
Minimum |
Maximum |
Test Method |
| Ester content |
% m/m |
96.54 |
- |
EN 14103 |
| Density at 15ºC |
kg/m³ |
860 |
900 |
ASTM D 1298 |
| Viscosity at 40ºC |
mm²/s |
3.5 |
5.00 |
ASTM D 445 |
| Flash point |
ºC |
100 |
- |
ASTM D 93 |
| Sulphur content |
mg/kg |
- |
505 |
IP 4976 or ASTM D 5453 |
Carbon residue (on 100% distillation residue) or
Carbon residue (on 10% distillation residue)7 |
% m/m |
-
- |
0.050
0.30 |
ASTM D 4530
ISO 10370 |
| Cetane number |
|
51.0 |
- |
ASTM D 613 |
| Sulfated ash content |
% m/m |
- |
0.02 |
ASTM D 874 |
| Water content |
mg/kg |
- |
500 |
ASTM D 6304 |
| Total contamination |
mg/kg |
- |
24 |
EN 12662 |
| Copper strip corrosion (3 h at 50ºC) |
rating |
class 1 |
ASTM D 1306 |
| Oxidation stability, 110ºC |
hours |
6.0 |
- |
EN 14112 |
| Acid value |
mg KOH/g |
- |
0.5 |
ASTM D 664 |
| Iodine Value |
g iodine/100 g |
- |
140 |
EN 14111 |
| Linolenic acid methyl ester |
% m/m |
- |
12.0 |
EN 14103 |
| Methanol content |
% m/m |
- |
0.20 |
EN 14110 |
| Monoglyceride content |
% m/m |
- |
0.80 |
ASTM D 6584 |
| Free glycerol |
% m/m |
- |
0.02 |
ASTM D 6584 |
| Total glycerol |
% m/m |
- |
0.24 |
ASTM D 6584 |
| Group l metals (Na+K) |
mg/kg |
- |
5.0 |
EN 14108 and EN 14109 |
Group ll metals (Ca+Mg) |
mg/kg |
- |
5.0 |
EN 14538 |
| Phosphorus content |
mg/kg |
- |
10.0 |
ASTM D 4951 |
4.4 Retail Biodiesel Blends
4.4.1 Background
There are currently no retail biodiesel blends being sold in New Zealand. NZS 7500 includes a specification for B5 biodiesel for retail sale which is largely the same as the diesel requirements in the PPSR. Internationally, it is common that low biodiesel blends are required to meet the relevant petroleum diesel specification. This is consistent with low level biodiesel blends being seen as totally fungible with petroleum diesel. A technical investigation was undertaken by Hale & Twomey8 in 2006 to determine whether waivers were necessary for B5 blends to meet the density, viscosity and cold flow properties of the PPSR. The report concluded that no waivers to these properties are needed at this time.
In NZS 7500 the biodiesel component is required to meet the B100 specification in NZS 7500 and the petroleum diesel component the specification in the PPSR. As noted above this requirement is also common internationally. For example, B5 blend fuel in CEN member countries needs to meet the same standard as petroleum diesel (EN 590), with the biodiesel component meeting EN 14214 and the diesel component meeting EN 590. The United States does not currently have standards for biodiesel blends for use as automotive fuels but there are continued efforts to incorporate B5 into the diesel fuel standard (ASTM D 975).
There is currently no maximum blending limit set for biodiesel in Australia. Up to 100% by volume biodiesel can be marketed in Australia, but all blends must meet the Diesel Determination. Work is underway in Australia to standardise biodiesel blends, which includes the option of amending the Diesel Determination to allow for up to 5% by volume of biodiesel, subject to the biodiesel component of the blend meeting the Biodiesel Determination.
Japan has a mandatory standard for low biodiesel blends specified in the "Law on the Quality Control of Gasoline and Other Fuels" (Quality Assurance Law: JIS K 2204). JIS K 2204 allows up to 5% biodiesel blends but in contrast to the standards of Europe and New Zealand, the blends are required to meet a number of additional properties on top of those properties mandated for petroleum diesel, these being triglycerides, methanol, total acid number and individual acids (Formic, Acetic and Propionic acids).
These additional properties are considered necessary for controlling the quality of B5 blends as the Japanese B100 Standard is only voluntary and fuel quality is only tested by the relevant Government authority at the pump (i.e. as B5 blends). In contrast, New Zealand will have a mandatory B100 specification that all biodiesel must comply with before being blended with petroleum diesel. Thus, methanol, total acid number and glycerides will be controlled at the B100 level. Individual acids are discussed in Section 4.4.3.5.
Table 4: International Diesel and Low Level Biodiesel Blend Specifications
| Country |
Diesel Specification |
Low Level Biodiesel Blends Specification |
Comments |
| Europe |
EN 590 |
EN 590 (maximum 5% by volume FAME) |
|
| United States |
ASTM D 975 |
Under development |
|
| Japan |
JIS K 2204 |
JIS K 2204 (maximum 5% by volume FAME) |
B5 blends are required to meet a number of additional properties. |
| Australia |
Fuel Standard (Diesel) Determination 2001 |
Under development |
|
| New Zealand |
PPSR – Schedule 3 |
NZS 7500 (maximum 5% by volume FAME) |
NZS 7500 is very similar to both EN 590 and the PPSR. |
It is proposed that in New Zealand regulations, low level biodiesel blends intended for retail sale be required to meet the petroleum diesel specification in Schedule 3 of the PPSR, with each of the blend components meeting their respective neat specifications.
4.4.2 Maximum blend limit
NZS 7500 requires that biodiesel blends for retail sale contain no more than 5% biodiesel by volume. A 5% limit applies for biodiesel blends for retail sale in Europe and Japan, and is under consideration in the United States and Australia. The World-Wide Fuel Charter recommendations for diesel fuel include 5% maximum FAME for category 1 to 3 vehicles. The New Zealand vehicle fleet could be considered as predominately a mix of category 2 and category 3.
At blend levels of above 5% there are concerns around vehicle compatibility and the potential for increased harmful (NOx) emissions. Many engine, vehicle manufacturers and fuel injection equipment suppliers do not support biodiesel blends in excess of 5% biodiesel.
It is proposed that Schedule 3 of the PPSR be amended to allow up to 5% FAME by volume. It is recognised that higher level blends are being considered overseas for inclusion in petroleum diesel specifications e.g. CEN are currently considering increasing the allowable biodiesel component in EN 590 from 5% to 10%. The limit in Schedule 3 of the PPSR, along with other relevant property limits, will likely be reconsidered in future based on developments internationally. It is proposed that blends of over 5% by volume biodiesel be allowed, but only via written contract. The requirements for these blends are discussed in Section 4.5.
4.4.3 Discussion of specific parameters for Schedule 3 of the PPSR
4.4.3.1 Total Contamination
Total contamination is the insoluble material retained after filtration of a fuel sample. Impurities in biodiesel mostly result from the transesterification process. Contaminants include suspended catalyst residue and soaps, dirt, rust and scale. Soaps are formed from free fatty acids during the transesterification reaction and can be removed during ester washing, along with catalyst residue. Dirt, rust and scale can be removed by filtration.
Schedule 3 of the PPSR specifies particulates at 24 mg/L maximum using the test method ASTM D 6217. The B5 (and the B100) specification in NZS 7500 limit total contamination to 24 mg/kg using the test method EN 12662. The ASTM D 6217 test method is only applicable to petroleum diesel, whereas EN 12662 is applicable to petroleum diesel, biodiesel and biodiesel blends. Thus EN 12662 is the specified test method for total contamination in both EN 14214 and EN 590.
It is desirable to align the test methods specified for petroleum diesel and low level biodiesel blends wherever possible. This will help minimise compliance costs. Thus, it is proposed that Schedule 3 of the PPSR is amended from particulates at 24 mg/L maximum using test method ASTM D 6217, to total contamination at 24 mg/kg maximum using test method EN 12662.
It is recognised that ASTM D 6217 and EN 12662 are not considered as equivalent test methods. EN 12662 is less sensitive, using a smaller sample and weighing the filter to a lower level of precision. The lower precision of the EN 12662 test method is considered acceptable as insolubles are not an issue for petroleum diesel in New Zealand.
4.4.3.2 Cold Flow Properties
The cold flow requirements in the PPSR for petroleum diesel, although differing between winter and summer, are the same for all regions in New Zealand. The current requirements for cold flow properties are as follows:
- Winter (15th April to 14th October): cloud point +2ºC, CFPP -6ºC
- Summer (15th October to 14th April): cloud point +4ºC
B5 blends and petroleum diesel will be required to meet the same cold flow property limits specified in Schedule 3 of the PPSR. The requirements are considered by some as unnecessarily severe in Auckland/Northland9 given the temperature range in these low lying coastal regions. The coldest ever temperature recorded in Auckland/Northland is -2.5ºC. The minimum summer temperature in these regions is 10ºC.10 The more stringent the cold flow properties, the higher the costs are to produce diesel fuels that meet these requirements.
The oil companies have voluntary specifications to ensure "fit for common purpose" requirements are met given New Zealand's climatic conditions. These include a tighter CFPP specification than those in the PPSR for all regions except Auckland/Northland during the coldest winter months.11
Having slightly less stringent cold flow properties in Auckland/Northland would also facilitate the introduction of B5 blends in these regions. It was identified in the technical investigation by Hale & Twomey of fuel specification waivers for biofuel blends (2006) that based on current average petroleum diesel stock, a large number of theoretical B5 blends would fail the cold flow specification in the PPSR, particularly in Auckland/Northland. In reality, oil companies would manage their petroleum diesel stock to ensure cold flow requirements are met, but sourcing diesel with more stringent cold flow properties has cost implications. This report noted that a waiver for cold flow properties in the Auckland/Northland regions may be appropriate.
However, due to the geography of New Zealand, there are no guarantees that customers who purchase fuel in Auckland/Northland will consume it entirely in these warmer climates. The cold flow properties thus need to be suitable for a customer who for example refuels a tank in Auckland/Northland, and then travels to the cooler climate of the central volcanic region. The cost per litre of managing the cold flow properties of petroleum diesel in Auckland/Northland to meet the current specification are considered small. The report from Hale & Twomey estimated that assuming a requirement to produce diesel with cold flow properties 2 ºC lower, the cost for oil companies would be about NZ 0.2c/l. It is uncertain whether customers will benefit in terms of cheaper diesel if the specification is relaxed.
Your comment is sought on whether cold flow properties should be relaxed in Schedule 3 of the PPSR for the Auckland/Northland regions. The limits in Schedule 3 would apply to both petroleum diesel and B5 blends. Also note that the cold flow properties of these fuels, as with all other properties, are required to be "fit for common purposes".
c) Should the cold flow properties for Auckland/Northland be relaxed in Schedule 3 of the PPSR?
d) If so, what should the limits be for cloud point in winter and summer, and CFPP in winter?
4.4.3.3 Filter Blocking Tendency
The Filter Blocking Tendency (FBT) test measures the filterability of diesel in order to ascertain what affect a fuel will have on a fuel filter's life. The FBT test was introduced into the PPSR in 2002 to provide additional protection for consumers against operating problems associated with diesel that has poor filterability. The regulations require retail diesel to meet a maximum FBT of 2.5 when tested by IP 387 or ASTM D 2068, and the fuel to be of acceptable filterability so that it is fit for common purposes. The 2.5 maximum at this time was "indicative for monitoring purposes". The indicative nature of this limit was removed in late 2006 by the Petroleum Products Specifications Amendment Regulations 2006.
In following the PPSR, NZS 7500 also requires that B5 blends "be of acceptable filterability so that it is fit for common purposes". However, as NZS 7500 was developed before the 2006 PPSR amendments, the FBT maximum limit for B5 blends in NZS 7500 is still indicative, i.e. "acceptable filterability can be expected if the result of the FBT test is less than 2.5".
Some recent testing of New Zealand B5 blends has shown the unexpected formation of aggregates at room temperature. Thus these aggregates are separate from the flow problems that occur at cold temperatures, and are causing some sample B5 blends to fail the FBT test.
There is a paucity of information internationally relating to the FBT of biodiesel blends. Outside of New Zealand, Australia is the only other known jurisdiction that specifies a FBT limit in petroleum diesel standards. Biodiesel blend specifications are still under development in Australia.
Research into the filter blocking problems of soybean based B20 in the United States suggests that one possible root cause of the aggregate formation at temperatures above cloud point is the presence of sterol glucosides in biodiesel. Sterol glucosides are naturally occurring compounds found in vegetable oils and fats. It is unknown if sterol glucosides have a role in the filterability of biodiesel produced from animal fats.
To ensure vehicle operability, it is proposed that B5 blends be required to meet the same FBT requirements as petroleum diesel, i.e. filter blocking tendency of 2.5 maximum when tested by IP 387 or ASTM 2068, and the fuel to be of acceptable filterability so that it is fit for common purposes. It is recognised that neither of these test methods are particularly representative of the filters used in motor vehicles as the test method filter is much more sensitive, but also that a more suitable international test method does not presently exist. The suitability of the FBT limit and test will be reconsidered when more information is available.
4.4.3.4 Oxidation Stability
Oxidation stability is a measure of a fuel's resistance to degradation by oxidation. Oxidation of diesel can result in the formation of insoluble sediments and gums that are associated with fuel filter plugging and formation of deposits in fuel injection systems and combustion chambers. Oxidation of biodiesel increases fuel acidity which has shown to increase fuel system deposits and may increase the likelihood for corrosion in the fuel system and engine. The PPSR and NZS 7500 specify limits on oxidation stability for diesel, and biodiesel and biodiesel blends respectively.
The methods for testing oxidation stability vary between petroleum diesel and biodiesel based on suitability, and between countries. An oxidation stability test method that measures acidity measures the stability of the biodiesel component. Whereas an oxidation stability test that measures insolubles measures the stability of the petroleum diesel component. The limits for these tests are not directly comparable as suggested by the different analytical approaches.
The main oxidation stability test methods are as follows:
- EN 14112 (Rancimat procedure): accelerated oxidation stability test method that measures acidity of B100. This is expressed in hours, known as the induction period. Test temperature is 110ºC.
- ASTM D 2274: accelerated oxidation stability test method that determines the concentration of insolubles expressed in g/m³. Test temperature is 95ºC, for 16 hours. Not suitable for biodiesel or biodiesel blends.
- ISO 12205: accelerated oxidation stability test that determines the concentration of insolubles expressed in g/m³. Test temperature is 95ºC, for 16 hours. Not suitable for biodiesel or biodiesel blends.
NZS 7500 specifies the Rancimat procedure as the test method for B100, with a limit of 6 hours minimum. NZS 7500 and the PPSR specify ASTM D 2274 as the test method for B5 and petroleum diesel respectively, with a maximum of 25 g/m³.
There are concerns by some that for biodiesel blends, even when the B100 has sufficient oxidation stability properties (i.e. induction period is >6 hours), the base diesel can impact on the stability of the biodiesel component. If B5 blends are only subject to a test method that measures insolubles, the growth in fuel acidity will not be controlled by the standard. Some research also suggests that such problems may be exacerbated when biodiesel is blended with ultra-low sulphur diesel fuels.
Thus to ensure that B5 blends have appropriate oxidation stability properties they could be required to meet an oxidation stability test that measures acidity. The unmodified Rancimat procedure, however, is not appropriate for biodiesel blends at this stage. Recent work in other jurisdictions has focussed on the modification of the Rancimat procedure and ISO 12205 / ASTM D 2274.
Due to concerns with oxidation stability, Japan has developed a test method for B5 blends that measures acidity. This test method was prepared with reference to ISO 12205, but requires a test temperature of 115ºC compared with 95ºC, and measures acidity instead of insolubles using JIS K 2501. This test method, which is equivalent to ASTM D 664, is based on the amount of potassium hydroxide required to neutralise 1g of FAME and measures the acid value growth. Hence the oxidation stability limit is expressed in mg KOH, i.e. 0.12 mg KOH/g maximum acid value growth. At the time of writing this document, the Japanese test method for oxidation stability was still in draft form. The summary of the test method is as follows:
"A test fuel filtered beforehand is oxidatively degraded by injecting oxygen at 115ºC for 16 hours. The acid values before and after this oxidation stability test are determined by the acid value-potentiometric titration method according to JIS K 2501."
The Japan Automobile Manufacturers Association (JAMA) have indicated that they consider an acceptable alternative to the B5 Japanese oxidation stability test detailed above to be a requirement that the B100 component of the blend meets an induction period of >10 hours (instead of >6 hours), as measured by the Rancimat test method.
Recent research by the National Renewable Energy Laboratory in the United States suggests that B100 stability is an excellent predictor of stability in B5 blends, i.e. if B100 meets the requirements of the Rancimat test in EN 14214 (induction period of >6 hours) then B5 blends will have good oxidation stability properties (induction period of >12 hours). Thus, acidity is not considered an issue for B5 blends and an induction period of below 6 hours may be suitable for B100. A final report on these findings has not yet been published.
There are several options available for oxidation stability requirements in Schedule 3 of the PPSR. Your comment is sought on which of the following is the most appropriate for New Zealand's regulations:
- Petroleum diesel and B5 blends are both required to have oxidation stability properties of 25 g/m³ maximum when measured by ASTM D 2274. The oxidation stability requirements for B5 blends will be reconsidered when the issue of the test method is settled by regulatory authorities in other jurisdictions.
- Petroleum diesel to meet 25 g/m³ maximum when measured by ASTM D 2274 and B5 blends to meet a limit of 0.12 mg KOH/g maximum acid value growth when tested by the Japanese oxidation stability test method described above (16 hours at 115ºC). This requirement would be reviewed when other jurisdictions land on this issue (indicative 2009).
- Petroleum diesel to meet 25 g/m³ maximum when measured by ASTM D 2274 and the B100 component of B5 blends to meet a minimum of 10 hours when tested by the Rancimat (EN 14112) procedure. To be reviewed indicative 2009.
- Petroleum diesel to meet 25 g/m³ maximum when measured by ASTM D 2274 and B5 blends to meet the modified Rancimat procedure (EN 14112) or modified ASTM D 2274. To be reviewed indicative 2009.
e) In regards to oxidation stability for B5 blends, do you prefer option i, ii, iii or iv above? Please provide an explanation of why this is appropriate for New Zealand's regulations.
4.4.3.5 Formic, Acetic and Propionic Acids
Formic, Acetic and Propionic acids are organic volatile acids produced during biodiesel oxidation, and are associated with increased corrosion of fuel injection systems. As discussed above, oxidative degradation of biodiesel has also shown to increase fuel system deposits.
While the regulations will require B5 blends to meet an oxidation stability limit (refer Section 4.4.3.4), the percentage of formic, acetic and propionic acids in biodiesel could also be directly measured as another control on oxidation stability. The only example of these individual acids being mandated for B5 blends is in JIS K 2204. The limit in JIS K 2204 is 0.003% (in total) mass maximum when measured by the ion chromatography method. At the time of writing this document, the test method was still in draft form. The test method summary is as follows:
"A sample is mixed with water and shaken to extract formic, acetic and propionic acids into the water. The separated aqueous phase is injected into an ion chromatograph to separate and elute each component, of which a chromatogram corresponding to each acid ion is recorded. The concentration of each acid component is determined by comparing with a pre-determined calibration curve."
There are two possible options in regards to these individual acids:
- The regulations do not require B5 blends in New Zealand to meet a specific individual acid limit. This would be reconsidered if a test for individual acids is adopted internationally.
The regulations require B5 blends in New Zealand to meet a limit of 0.003% (in total) mass maximum Formic, Acetic and Propionic acids, when tested by ion chromatography (to the test outlined above).
f) In regards to individual acids in B5 blends, do you prefer option i or ii above? Please provide an explanation of why this is appropriate for New Zealand's regulations.
4.4.3.6 Carbon Residue (on 10% distillation residue)
Carbon residue is an indicator of the tendency of the fuel to form carbon deposits in an engine. Deposit formation can lead to increased engine wear and impact on engine life, as well as reducing fuel efficiency and increasing particulate emissions.
The carbon residue for diesel was recently amended from 0.25% mass maximum to 0.2% mass maximum in the PPSR. This was for consistency with the ASTM D4530 requirements of reporting carbon residue to the nearest 0.1% mass only. NZS 7500 B5 specification limits carbon residue (on 10% distillation residue) to 0.25% mass maximum.
It is proposed that B5 blends meet the carbon residue (on 10% distillation residue) requirement of 0.2% mass maximum, as specified for petroleum diesel in Schedule 3 of the PPSR.
4.4.4 Test Methods
The B5 requirements in NZS 7500 specify a number of additional test methods to those in the diesel specification in Schedule 3 of the PPSR. Most of the additional test methods in NZS 7500 are ISO developed and are similar or equivalent to the ASTM test method already specified.
It is proposed to not specify in Schedule 3 some of these additional test methods which are similar or equivalent to those ASTM methods routinely used by the testing laboratories in New Zealand. In the event of a dispute where more than one method is specified, the first method in the appropriate table will take precedence. Table 5 includes the proposed test methods for petroleum diesel and B5 blends.
4.4.5 Proposed Schedule 3 of the PPSR
Table 5 below shows the proposed Schedule 3 of the PPSR. The grey shaded rows are those properties discussed in the previous section where comments are specifically being sought. Note that the Bold text in this table indicates differences from the current PPSR.
For Schedule 3 of the PPSR, please provide comment on the following:
g) Do you agree with the proposed requirements?
h) If not, what is an appropriate requirement (i.e. limit and test method) for New Zealand's B5 specifications? Please provide an explanation of how this impacts on vehicle operability and / or biodiesel manufacturing.
i) Are there any other amendments that need to be made to Schedule 3 of the PPSR to incorporate B5 blends within the diesel specification?
Table 5: Proposed Schedule 3 of the PPSR
| Property |
Unit |
Minimum |
Maximum |
Test Method |
| Density at 15ºC |
kg/m³ |
820 |
850 |
ASTM D 129812 |
| Distillation – 95% volume recovered at (ºC) (T95) |
ºC |
- |
360 |
ASTM D86 |
| Cetane13 |
|
51 minimum cetane index or 51 minimum cetane number and 47 minimum cetane index |
- |
Cetane number: ASTM D 613
Cetane index: ASTM D 976 |
| Water content |
mg/kg |
- |
200 |
ASTM D 6304 |
| Total contamination |
mg/kg |
- |
24 |
EN 12662 |
| Colour (ASTM colour) |
|
- |
3.0 |
ASTM D 1500 |
| Cloud point14 |
ºC |
- |
Summer: +4 Winter: +2 |
ASTM D 5773 |
| Cold Filter Plugging Point14 |
ºC |
- |
Winter: -6 |
IP 309 |
| Sulphur15 |
mg/kg |
- |
5016 |
IP 497 or ASTM D 5453 |
| Polycyclic aromatic hydrocarbons |
% m/m |
- |
11 |
IP 391 |
| Filter blocking tendency |
- |
- |
2.5; fuel must be of an acceptable filterability so that it is fit for common purposes. |
IP 387 or ASTM D 2068 |
| Lubricity – HFRR wear scar diameter at 60ºC |
µm |
- |
460 |
IP 450 |
| Viscosity at 40ºC |
mm²/s |
2.0 |
4.5 |
ASTM D 445 |
| Oxidation stability |
g/m³ |
- |
25 |
ASTM D 2274 |
| Carbon residue (on 10% distillation residue) |
% m/m |
- |
0.2 |
ASTM D 4530 |
| Copper strip corrosion (3 hours at 50ºC) |
rating |
|
class 1 |
ASTM D 130 |
| Ash content |
% m/m |
- |
0.01 |
ASTM D 482 |
| Flash point |
ºC |
61 |
- |
ASTM D 93 |
| FAME content17 |
% m/m |
- |
5.0 |
EN 14078 |
4.5 Non-Retail Biodiesel Blends
4.5.1 Background
As discussed already, the PPSR distinguishes between all fuel "supplied, or available or intended for supply" and fuel that is sold by retail. The requirements relating to all diesel fuel (as opposed to diesel for retail sale) in the PPSR are that it must meet the property limits specified for sulphur and polycyclic aromatic hydrocarbons.
NZS 7500 includes a non-retail specification for biodiesel blends but, in contrast to the two required properties for petroleum diesel in the PPSR, eleven properties are specified. This, in part, recognises that blending two on-specification fuels does not guarantee the fuel quality of the resultant blend. Post-blending quality testing provides greater certainty to the market. In NZS 7500, blends for non-retail sale must also have a diesel component that meets the non-retail requirements in the PPSR and a biodiesel component that meets the B100 specification.
Blend concentrations greater than 5% by volume may be used in compression ignition engines designed or subsequently adapted to run on such blends. B20 dominates the international supply of biodiesel blends over 5% by volume biodiesel.
At present, biodiesel blends are being produced in New Zealand for the contracted market, albeit in relatively small volumes. In the main, these blends are manufactured to meet the requirements of NZS 7500 and range from 5% to 100% by volume biodiesel. These biodiesel blends are being supplied to a large variety of end users, including bus fleets, trucking and earthmoving companies and the agriculture and forestry sector.
There are very limited examples of biodiesel blend specific fuel quality standards in the world. ASTM and the Australian regulatory authorities have been working on B20 standards. The United States military, a major user of biodiesel, have developed their own B20 specification. The United States Engine Manufacturers Association (EMA) has also proposed a specification for biodiesel blends up to B20.
It is considered prudent to have a greater level of regulation for non-retail biodiesel blends than exists for non-retail petroleum diesel in the PPSR. There is limited information available for higher blend levels made from tallow based biodiesel. Particularly in the early stages of a biofuels market in New Zealand, it is vital to build and maintain consumer confidence and to protect the reputation of the industry as a whole. Hence the regulations for non-retail biodiesel blends should include vehicle operability and safety parameters, as well as environmental parameters.
4.5.2 Proposed non-retail biodiesel blend specification
As is the case with NZS 7500, it is proposed that the regulations allow non-retail biodiesel blends to consist of petroleum diesel and biodiesel in any proportion as agreed between seller and purchaser, from less than 5% up to and including B100. This gives greater flexibility for supply by the biodiesel industry and use by consumers with contractual agreements. The supply of biodiesel blends above B20 is currently subject to ERMA approval.
As in NZS 7500, the regulations will require blends for non-retail sale to have a diesel component that at least meets the non-retail requirements in the PPSR, and a biodiesel component that meets the B100 specification. The resultant blend must then meet the proposed regulated requirements for non-retail biodiesel blends at the point of sale to the user.
It is proposed that the regulated specification for non-retail biodiesel blends incorporate the requirements of NZS 7500. These requirements are as follows (refer Table 6):
- Non-retail biodiesel blends must meet the requirements from Schedule 3 of the PPSR for cetane number, colour, sulphur content, lubricity and viscosity.
- In addition, non-retail biodiesel blends must meet the following requirements:
- acid value of 0.1 + X / 250 (where X is the percentage of biodiesel in the blend);
- total glycerol of 0.05 + X / 500 (where X is the percentage of biodiesel in the blend); and,
- water and sediment limit of 0.015% volume maximum when measured by ASTM D 2709.
- Cold flow properties (cloud point and cold filter plugging point) are to be as agreed between seller and purchaser to meet seasonal operability requirements.18
It is proposed that the test methods in NZS 7500 for non-retail biodiesel blends are incorporated in the regulations. The exception to this is where a test method differs unnecessarily from those for B100, B5 and petroleum diesel. In addition some test methods are not proposed to be referenced where a similar or equivalent test method is already specified. Table 6 shows the proposed test methods for non-retail biodiesel blends. Comments are sought on the suitability of these.
4.5.3 Discussion of specific parameters for non-retail biodiesel blends
4.5.3.1 Filter Blocking Tendency
Filter blocking tendency is currently specified in NZS 7500 for non-retail blends as follows, "fuel shall be of acceptable filterability so that it is fit for common purposes". In the PPSR the "fit for common purposes" requirement only applies to fuel for retail sale. This is consistent with allowing for flexibility in fuel sold via a written contract or supply agreement. The suitability of the fuel (for any intended purpose) needs to be agreed between the seller and purchaser. Thus, it is proposed that filter blocking tendency is not specified for non-retail biodiesel blends.
4.5.3.2 Flash Point
Flash point is the lowest temperature at which contact with an ignition source causes the vapour of the fuel specimen to ignite. Hence, flash point is an important parameter for assessing hazards throughout the fuel distribution system.
Diesel is much more flammable than biodiesel, with the flash point for biodiesel being approximately twice that of diesel depending on the feedstock and processing. Typical values for biodiesel manufactured from feedstocks available in New Zealand are expected to be greater than 120°C. A limit of 100ºC is specified in NZS 7500 for B100. The PPSR requires the flash point of diesel to be more than 61ºC.
Flash point does not blend linearly and usually tends to the value of the lowest component, hence that of petroleum diesel. There is a risk that alcohol is added to biodiesel blends to assist homogenising the blend, especially in cold weather, which would reduce the flash point of the biodiesel blend further.
It is proposed that non-retail biodiesel blends are required to also meet the flash point minimum of petroleum diesel as specified in the PPSR (61ºC), because of the importance of this parameter for health and safety.
Table 6: Proposed Non-Retail Biodiesel Blend Specification:
Note that the Bold text in this table indicates differences from NZS 7500.
| Property |
Unit |
Minimum |
Maximum |
Test Method |
| Cetane Number |
|
51 |
- |
ASTM D 613 |
| Water and Sediment |
% vol |
- |
0.015 |
ASTM D 2709 |
| Colour (ASTM colour) |
|
- |
3.0 |
ASTM D 1500 |
| Sulphur19 |
mg/kg |
- |
5020 |
IP 497 or ASTM D 5453 |
| Lubricity – HFRR wear scar diameter at 60ºC |
µm |
- |
460 |
IP 450 |
| Viscosity at 40ºC |
mm²/s |
2.0 |
4.5 |
ASTM D 445 |
| Flash point |
ºC |
61 |
- |
ASTM D 93 |
| Acid value |
mg KOH/g |
- |
0.1 + X / 250 |
ASTM D 664 |
| Total glycerol |
% m/m |
- |
0.05 + X / 500 |
ASTM D 6584 |
For non-retail biodiesel blends specifications regulations, please provide comment on the following:
j) Do you agree with the proposed requirements?
k) If not, what are the appropriate requirements (i.e. limit and test method) for New Zealand's non-retail biodiesel blend specification? Please provide an explanation of how this impacts on vehicle operability or other non-automotive uses of biodiesel and / or biodiesel manufacturing.
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