Diesel
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The current New Zealand diesel fuel standard as prescribed in the Regulations differs from the fuel specifications required for Euro 6 and Euro VI[4] in two respects:
- The maximum diesel density specification; and
- The maximum polycyclic aromatic hydrocarbon (PAH) limit.
If New Zealand diesel fuel standards are not aligned with the European standards, these differences will affect the emissions performance of Euro 6 vehicles.
Maximum density
What is maximum density?
Generally, higher quality diesel is lower in density. The process to remove sulphur to improve diesel’s quality also saturates the carbon chains making the diesel more paraffinic (lighter). New Zealand diesel contains low amounts of sulphur (less than 10ppm), so it tends to be lower density.
A maximum density specification is included in the specification to avoid longer chain (heavier) components being retained in the diesel blend. These longer chain components can create more particulate matter (which is harmful to human health) when combusted.
Current Regulations
The New Zealand specification currently has a maximum diesel density specification of 850 kg/m³, which can be relaxed to a 854 kg/m³ maximum when blended with a maximum of 7% fatty acid methyl esters (FAME). The reasoning behind relaxing the standard with a FAME blend is based on a worst-case of a maximum density diesel (850 kg/m³) being blended with a worst-case FAME (900 kg/m³) at 7%.
By contrast, the Euro 6 specification (EN:590) has a maximum specification of 845 kg/m³, with no allowance to be relaxed when blended with FAME.
Specifications for Euro 6 and Schedule 2 of the Regulations all have the same minimum specification for diesel of 820 kg/m³.
While our maximum permitted diesel density is higher than the Euro 6 standard, in practice, our diesel would meet the European standard. Our 2022-23 Fuel Quality Monitoring Report[5] shows that all density results for diesel were between 830 and 840 kg/m³.
Proposal and rationale
We propose to reduce the maximum allowable density specification for both neat diesel and diesel/FAME blends to 845 kg/m³, in line with Euro 6 quality. This would ensure that the emissions reduction benefits from meeting the maximum allowable diesel specification required by Euro 6 would be achieved.
As New Zealand’s diesel already meets this lower specification, we do not anticipate any fuel price impacts.
Questions for consultation
13. Should the maximum allowable diesel density be reduced to 845 kg/m³? If not, why not?
14. For FAME blends, should the density relaxation be removed (845kg/m³) or reduced in line with the proposed maximum density change for diesel (849kg/m³)? If not, why not?
Limiting Polycyclic Aromatic Hydrocarbons
What are PAHs?
Polycyclic Aromatic Hydrocarbons (PAHs) are hydrocarbons that can be found in natural sources, such as crude oil and bitumen, or produced from combustion processes.
The presence of PAHs in exhaust fumes can irritate eyes and breathing passages. Several PAHs, and some specific mixtures of PAHs, are considered to be cancer-causing chemicals.[6] PAHs can contribute to harmful particulate matter being formed, as PAHs can bind with air to form small particles.
Current Regulations
PAHs are regulated on human health grounds. New Zealand's current specification for PAH is set at a maximum of 11%. This is higher than the equivalent Euro 6 standard for PAH of 8%.
However, MBIE’s Fuel Quality Monitoring Programme test results from 2017 to 2022 found that PAH content in diesel was routinely below four%. Of the 210 PAH results in the 2022-23 Fuel Quality Monitoring Report[7], only four results had PAH levels of up to 4.3%.
For markets with “more stringent requirements for emission control” the WWFC recommends that the maximum limit for PAH be 3%.[8] For markets with “advanced requirements for emission control” the WWFC suggests a PAH maximum limit of 2%.[9] However, we understand that 2% would be difficult for many refineries to meet.
Proposal and rationale
We propose to reduce the PAH maximum in diesel from 11% to 8% in line with Euro 6. This would reduce the risk to human health from PAHs. As the PAH in our diesel is routinely below 4%, we do not anticipate any fuel price impacts.
Questions for consultation
15. Do you agree with lowering the maximum PAH percentage from 11% to 8%? If not, why not?
Filter blocking tendency
What is filter blocking tendency?
The fuel filter screens out any contamination from fuel. If the filter is clogged, it can prevent proper circulation, and cause serious engine operation problems. Fuel with a high filter blocking tendency (FBT) is more likely to block filters in engines.
FBT is a relative figure from 1 to 4 (or higher), with a figure of 1 being a perfectly clean fuel/filtering, and that of 3 and above starting to cause serious operating issues for diesel engines.
Current Regulations
The current New Zealand diesel specification has a Filter Blocking Tendency specification with a maximum of 2.5 with a general statement regarding its fitness for use. This is less stringent than the 2.0 maximum standard applied in Australia.
Fuel monitoring data shows that the FBT of diesel supplied in New Zealand is typically below the established maximum limit. Most test results for FBT in New Zealand fall within the range 1.00 to 1.05, which means almost perfect filtering.[10]
Proposal and rationale
We propose that the maximum FBT specification should be reduced from 2.5 to 2.0 for New Zealand diesel, to align with Australia’s maximum level. As the internal acceptance limits for fuel importers is generally between 1.4-1.8, we do not anticipate that this change will affect current practice or impact on prices. Based on MBIE’s fuel monitoring data, the diesel currently used in New Zealand easily meets the tighter specification.
Questions for consultation
16. Do you agree with reducing the filter blocking tendency limit from 2.5 to 2.0? If not, why not?
Renewable diesel (HVO) specification
What is renewable diesel?
Renewable diesel (or HVO / hydrotreated vegetable oil) is a biofuel made from fats and oils, such as used cooking oils, tallow, or vegetable oils, that is processed to be chemically the same as (or very similar to) petroleum diesel.
Because it is so chemically similar to petroleum diesel, renewable diesel is referred to as a ‘drop-in’ fuel, since it can be used instead of fossil diesel. This is different to other types of biofuels that may need to be blended with fossil fuels to be combusted in internal combustion engine vehicles. Renewable diesel tends to have a very good cetane number.[11] As well as this, “the majority of the available literature… agrees that using renewable diesel reduces carbon monoxide, hydrocarbons and particulate matter emissions when compared to regular diesel”.[12]
In theory, as renewable diesel is so similar to petroleum diesel, we should not need a special specification. However, there are some ways in which renewable diesel does not meet the current New Zealand diesel specification (set out in Table 3 below). For instance, since renewable diesel is paraffinic, it is much less dense than petroleum diesel. This means that, if it were to be sold in unblended form, renewable diesel may not meet the minimum density specification for diesel in the Regulations.
Table 3: Renewable diesel (HVO) property comparison with NZ diesel and FAME[13]
| Property | Unit measure | NZ Diesel | FAME | HVO |
|---|---|---|---|---|
| Oxygen | Wt% | 0 | 11 | 0 |
| Specific gravity | 0.835 | 0.88 | 0.78 | |
| Sulphur | Ppm | <10 | <1 | <1 |
| HHV[14] | MJ/kg | ~45 | 38 | 44 |
| HHV | MJ/l | 37.6 | 33.4 | 34.3 |
| Cloud point | oC | -2 to -8 | -5 to +15 | -10 to +20 |
| Distillation | oC | 180-360 | 320-380 | 200-320 |
| Cetane number | 51 minimum | 51-65 | 70-90 | |
| Stability | good | marginal | good |
Current Regulations
New Zealand has a specification for biodiesel and a blend percentage allowable in the regulated diesel grade (7%). However, there is no specification for renewable diesel. As renewable diesel does not fit the definition of diesel under the Regulations (as neither a petroleum distillate nor a biodiesel) it is not regulated in New Zealand. This risks substandard renewable diesel being sold in New Zealand and creates uncertainty for fuel importers.
In some instances, fuel companies can sell diesel or diesel blends according to a slightly different specification, via non-retail sale to commercial customers (regulations 15-17 of the Engine Fuel Specification Regulations 2011). However, the Regulations are not clear about how these slightly relaxed requirements for non-retail sale of diesel (in certain instances) would apply to renewable diesel. This may be creating confusion for commercial customers (such as trucking businesses), who might wish to use a 100% renewable diesel fuel.
Proposal and rationale
The European Union has developed a specific specification (EN 15940) for renewable diesel. We propose to use EN15940 as the basis for a New Zealand specification covering renewable diesel / HVO and other paraffinic diesels.
Since renewable diesel is so chemically similar to petroleum diesel, we do not propose to impose a blending limit on diesel/renewable diesel blends or labelling requirements for diesel/renewable diesel blends. Due to its renewable source (and higher expected cost), we anticipate that suppliers will want to highlight it for the consumer.
We propose that, for retail sale of renewable diesel, the diesel/renewable diesel blends must meet the density specification for diesel. This would ensure that consumers purchasing fuel from retailers would obtain similar levels of energy (and tailpipe-specific CO2 emissions) from diesel/HVO blends and petroleum diesel. The density specification would also allow for retailers to blend renewable diesel to a reasonably high level, up to 25%, with current technology.
For non-retail sale of renewable diesel, we propose that renewable diesel can be sold in neat form, without any need to meet the diesel density specification. This would also allow fuel wholesalers and their customers to negotiate commercial agreements to procure blends with very high renewable diesel content.
Questions for consultation
17. Do you agree that EN15940 should be used as the basis for a New Zealand specification covering renewable diesel (HVO) and other paraffinic diesels? If not, why not?
18. Do you agree that the Regulations do not need to prescribe the blending limit on diesel / renewable diesel blends? If not, why not?
19. Do you agree that the Regulations do not need to prescribe labelling requirements for diesel / renewable diesel blends? If not, why not?
20. Do you agree that, for retail sale of HVO, the diesel/HVO blends should be required to meet the proposed density specification for diesel (820-845 kg/m³)? If not, why not?
21. Do you agree that, for non-retail sale, renewable diesel should be able to be sold in neat form?
22. Do you agree that, for non-retail sale, any diesel / renewable diesel blends would be exempt from the diesel density specification that would otherwise apply to the retail sale of renewable diesel? If not, why not?
23. If we clarify the regulations for renewable diesel, would you expect to see more renewable diesel on the market?
Miscellaneous technical amendments for diesel specifications
We also propose the following technical amendments for diesel specifications. We do not anticipate any impacts on fuel prices and emissions as a result of these proposals.
Table 4: Miscellaneous technical amendments for diesel specifications
| Proposed change | Reason |
|---|---|
| Replace the maximum limit for diesel’s total contamination[15] of 24 milligram per kilogram (mg/kg) with 20 milligram per litre (mg/l) in Schedule 2. | Correction of the unit of measurement in the test method for total contamination for diesel, in line with international standard ASTM D6217. The proposed level for the specification maximum in mg/l is 20 and this is consistent with the current specification on 24 mg/kg. |
| For the purpose of estimating the presence of suspended free water and solid particulate contamination in diesel, remove the colour test (ASTM D1500) and add an appearance test using ASTM D4176 with the requirement of “clear and bright, free from visible sediment and water”. | For consistency with the latest international standards, such as the WWFC and EN590 (Europe). |
| For the purpose of estimating the presence of suspended free water and solid particulate contamination in biodiesel (FAME), add appearance test by using ASTM D4176. | For consistency with the latest international standards, such as the WWFC and EN590 (Europe). |
| Revise regulation 5 to reflect a biodiesel blending limit of up to 7%, instead of 5%. | European Standard ‘EN 590’ has been included in the list of ‘Generally applicable requirements and test methods for automotive diesel fuel’ since 2013. EN 590 allows that diesel fuel may contain up to 7% volume of fatty acid methyl ester (FAME), complying with EN 14214. |
| Clarify the distinction between Regulation 15 (‘Requirements relating to diesel sold by non-retail sale’) and Regulation 17A (‘Requirements relating to marine fuel oil sold by non-retail sale’). | Introducing Regulation 17A (‘Requirements relating to marine fuel oil sold by non-retail sale’), creates ambiguity in how to interpret Regulation 15, especially, 15(1) (‘Requirements relating to diesel sold by non-retail sale’). Marine fuel oil is defined by the Regulations as “any engine fuel other than petrol delivered to a ship, and intended for combustion purposes for propulsion or operation on board a ship.” We need to clarify the distinction between 15 and 17A. |
Questions for consultation
24. Do you support these miscellaneous technical amendments for diesel specifications? If not, why not?
[4] Note that Euro VI is the standard for heavy vehicles (vehicles with a gross vehicle mass over 3.5 tonnes) and Euro 6 is the standard for light vehicles
[5] Fuel Quality Monitoring 2022-23 Annual Report(external link) — Trading Standards
[6] Human health effects of polycyclic aromatic hydrocarbons as ambient air pollutants - Report of the Working Group on Polycyclic Aromatic Hydrocarbons of the Joint Task Force on the Health Aspects of Air Pollution(external link) — World Health Organization
[7] Fuel Quality Monitoring 2022-23 Annual Report(external link) — Trading Standards
[8] Worldwide Fuel Charter 2013(external link) — ACEA European Automobile Manufacturers' Association
[9] Worldwide Fuel Charter 2013(external link) — ACEA European Automobile Manufacturers' Association
[10] Fuel Quality Monitoring 2022-23 Annual Report(external link) — Trading Standards
[11] Cetane rating, also known as cetane number, is a measurement of the quality or performance of diesel fuel.
[12] S d’Ambrosio, A Mancarella, A Manelli (2022) Utilization of Hydrotreated Vegetable Oil (HV)) in a Euro 6 Dual-Loop EGR Diesel Engine: Behavior as a Drop-In Fuel and Potentialities along Calibration Parameter Sweeps, Energies, 15(19), 7202
[13] This table was originally sourced a journal publication, and has been updated to include values for NZ fuel: New developments in renewable fuels offer more choices - Vegetable oil-based diesel can offer better integration within crude-oil refineries for fuels blending(external link) — ResearchGate
[14] Higher heating value. Also referred to as the energy or calorific value of a substance. It is the amount of heat released during the combustion of a specified amount of fuel.
[15] Contaminants may enter the fuel in many ways both intentionally and unintentionally, and many of these contaminants can cause significant harm the powertrain, fuel, exhaust or emission control systems.
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