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Petrol And Diesel – Delivering Quality

The rules governing the quality and safety of the fuel New Zealanders put in their cars are to be reviewed Associate Minister of Energy Paul Swain announced today.

The Ministry of Economic Development will be leading the 'Petroleum Products Specifications Regulations Review' with the assistance of the Ministry of Consumer Affairs, Ministry for the Environment, Ministry of Health, and Ministry of Transport.

“The review will consider consumer, industry, health, safety, environmental, and quality issues in developing recommendations for petrol and diesel that are appropriate for New Zealand,” Paul Swain said.

“The goal of the review is to ensure that consumers have access to petrol and diesel that comply with accepted and up-to-date quality, safety, and environmental standards.

"At the same time, we recognise that these products need to be available at a reasonable cost,” he said.

“The present fuel standards were set in 1988 and reflected the nature of New Zealand’s motor vehicle fleet and the technologies of the day.

“Since then amendments have seen lead-free petrol introduced from 1996 and a limit placed on the amount of aromatics used in petrol to increase the octane rating.

“Developments in fuel and engine technologies, improvements in international petroleum standards, and innovations in refining and blending petrol and diesel are changing the automotive fuel industry.

“At the same time, the health, safety, and environmental impacts of fuel components are better understood, and New Zealand’s minimum fuel standards need to reflect these changes and concerns," he said.

The rules, known as the Petroleum Products Specifications Regulations, specify a number of properties and limits for both premium grade and regular grade petrol and for diesel. They include, for example, minimum requirements for octane number and maximum limits for such components as sulphur and benzene.

The review complements work being done by the Ministry of Transport on vehicle emissions standards and the Ministries of Health and Environment on air quality issues.

The Ministry of Economic Development plans to release a public discussion document on petrol and diesel quality later this year as part of the review. The public will be invited to make submissions on the paper at that time. Final decisions on any changes to the fuel standards would then be made, taking into account all the views expressed.


1. What do the regulations cover?
The Petroleum Products Specifications Regulations specify a number of properties and limits for both premium grade and regular grade petrol and for diesel. They include, for example, minimum requirements for octane number and maximum limits for such components as sulphur and benzene.

2. Are there any current concerns with the quality of petrol and diesel currently sold on the New Zealand market?
No. Fuel quality is monitored by the Energy Safety Service, a branch of the Ministry of Consumer Affairs, which regularly tests petrol and diesel from service stations around the country to ensure that the fuel meets established quality, health, and environmental standards. These tests show that New Zealand’s fuel quality is good.

3. Why are the specifications being reviewed now?
The Petroleum Products Specifications Regulations were first issued in 1988 and have changed very little since then (aside from the elimination of lead in petrol in 1996). However, during that period, there have been developments in engine technologies, innovations in refining petrol and diesel, and changes in international petroleum standards. As well, there have been increased concerns about the environmental and health effects of petrol and diesel. After 12 years, the review is a good way to check if the regulations are the best possible for New Zealand’s situation, or if they need to be changed in some way to incorporate technological advances and to address health and environmental issues.

4. Will the review lead to increased costs for consumers?
Not necessarily. If the petrol and diesel specifications are changed, fuel prices may also change. However, any potential increase in the cost of fuel as a result of the review would need to be balanced by increased benefits to consumers in the form of enhanced fuel performance or increased health and environmental protection.

5. Will the review have an impact on the oil industry?
The potential impact on the oil industry as a result of changes to the regulations will be examined as part of the review. Aspects to be considered in this part of the review include the capacity and productivity of the New Zealand refinery and the quality of petrol and diesel available for import from other refineries in the Asia-Pacific region, such as those in Australia and Singapore.

6. How do New Zealand’s current specifications compare with those of other countries?
Worldwide, there is a movement to eliminate lead from petrol – a step that New Zealand made in 1996. Lead is a highly toxic substance and a proven health hazard. New Zealand’s current regulations for unleaded petrol and diesel are similar to those of Australia, Japan and a number of other countries. Some countries are also changing to fuel that contains less of certain components such as sulphur and benzene. One of the objectives of this review is to determine if lowering levels of these components would also be appropriate for New Zealand, based on an analysis of the costs and benefits of such a change.

7. Does New Zealand have any choice but to adopt the standards of other countries?
The review will look at the issue of fuel specifications from the perspective of New Zealand – what are the costs and benefits to New Zealand’s consumers, its economy, its environment? What fuel specifications would best suit the cars New Zealanders are driving and are likely to drive in the future? Of course, we don’t live in isolation from the rest of the world, so worldwide fuel specifications will also be taken into consideration.

8. What are the environmental issues? Will changing our specifications help us meet any of our international environmental obligations (e.g., the Kyoto protocol)?
One of the issues to be looked at is how the petroleum specifications relate to climate change issues.

9. Will business be consulted during the review?
Businesses, consumer groups, oil companies, refineries, other stakeholders, and the general public will be consulted in the course of the review.

10. How can a motorist, car importer, oil company, environmentalist, or consumer advocate have a say in this process?
The first step in the review process is the preparation of a discussion document by the Ministry of Economic Development that will address the many issues related to fuel specifications. After the document is released, the public will be invited to provide comments on it during a submission period.

11. Who is conducting the review?
The Ministry of Economic Development is co-ordinating the review. It is being assisted by an advisory group with representation from the Ministry for the Environment, Ministry of Transport, Ministry of Health, and the Energy Safety Service branch of the Ministry of Consumer Affairs (also part of the Ministry of Economic Development). URS New Zealand, an independent consulting firm, is undertaking research for the Ministry of Economic Development related to the preparation of the discussion document. URS brings to the project environmental and technical expertise as well as strong international experience.

12. What is petrol and how is it made?
Petrol is a blend of different components found in crude petroleum oil.
Crude oil is a mixture of many different substances. Most of these substances are hydrocarbons, which are molecules composed of carbon and hydrogen atoms. Generally, the more carbon atoms a hydrocarbon contains, the higher its boiling point. A refinery uses the differences in boiling point of the hydrocarbons to separate them by distillation. This process yields products that range from very light components like propane, which has a boiling point of less than 20◦C, to very heavy products with boiling point ranges over 400◦C. A subset of these distillation products with relatively low boiling point ranges (20◦C to 200◦C) is used to blend petrol. Distillation products with higher boiling point ranges may undergo further heat or chemical processing to transform them into substances with lower boiling points that can be used as petrol components. Oil companies blend different petrol components together depending on the octane number, vapour pressure, and other properties required for a particular petrol product.

13. What does the octane number mean?
Octane number measures whether a petrol is likely to cause knock in an engine. Knocking or pinking is caused by self-ignition in the engine’s cylinders, which happens when the petrol/air vapour mixture in the cylinder ignites before the spark is passed by the spark plug. This premature ignition pushes against the crankshaft instead of with it, producing a knocking or pinging sound. Knocking causes the engine to overheat and lose power, and it can damage the engine in the long run.

The way to avoid knocking is to use petrol with a sufficiently high octane number. The higher the octane number, the more resistant the petrol is to the self-ignition that causes knocking.

14. Why is vapour pressure important?
Vapour pressure is a measure of how easily a liquid vaporises, or changes into a gas. Petrol is supplied in liquid form, but at least part of it must be vapour to ignite in an engine combustion chamber. This means that on a cold day in a cold engine, enough petrol must vaporise to enable ignition. On the other hand, on a hot day in a completely warmed-up engine, it is also important that the petrol does not vaporise and expand so much that it does not allow any air to be mixed with it in the cylinder. Oil companies balance these two extremes when blending petrol, taking into account the climate and the season where the petrol will be sold.

15. Why was lead ever added to petrol and why was its use disallowed in 1996?
Adding certain lead compounds to petrol was an effective and cost-efficient way to increase the petrol’s octane number. Lead is known to be toxic to humans, and its use in petrol is being phased out on a worldwide basis. New Zealand banned lead from petrol in 1996.

16. How is the octane number of petrol increased today?
The petrol that you buy at a service station is actually a mixture of different petroleum components. Each component has its own properties, including octane number. By blending carefully, the oil companies can come up with a formula that has the properties they require for a given type of fuel, including octane.

17. What is diesel and how is it different from petrol?
Like petrol, diesel fuel is blended from various petroleum components produced in a refinery. However, diesel contains components that have a boiling point range of approximately 200◦C to 350◦C. Vapour pressure is not an important consideration in the production of diesel, since the fuel does not need to change to a gas in a diesel engine. Diesel engines inject liquid fuel into the cylinder, unlike petrol-powered engines with carburettors. However, temperature can have an effect on the operation of diesel fuel in an engine. At low temperatures, diesel fuel may thicken and restrict the flow of fuel to the cylinder. Oil companies produce diesel blends that are formulated for specific climates and times of the year to prevent problems in cold weather.

18. Does diesel have an octane number?
No. Diesel engines do not have spark plugs and depend on the fuel igniting itself by compression, unlike petrol engines. The measure of a diesel fuel’s ignition quality is called the cetane number, which indicates the readiness of a diesel fuel to ignite spontaneously under the temperature and pressure conditions in the combustion chamber of an engine. The higher the number, the shorter the delay between fuel injection and ignition.

19. Why is there sulphur in petrol and diesel?
Sulphur is present to a greater or lesser extent in all crude oils. When crude oil is distilled into petrol and diesel fuel blending components, some sulphur finds its way into those components. The amount of sulphur allowed in petrol and diesel is limited because of the undesirable effects it causes during combustion, such as its odour, its corrosiveness, and its tendency to produce acidic by-products. In addition, advanced technologies that are used to meet stringent emissions limits generally require very low levels of sulphur in order to operate effectively.

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