By Liam Mitchell
The federal government's promised tax on leaded petrol (super) came into effect on February 1. Launched with a lot of rhetoric about reducing lead levels in the atmosphere, the tax raises the prices of leaded fuel by 2 cents per litre and unleaded petrol (ULP) by one cent per litre.
A media campaign is also being waged to promote the increased tax as a way of helping to save the environment. Entitled "Take the step. No lead. No worries.", the campaign is aimed at getting people to use unleaded petrol in their car instead of leaded if they can.
The government and vehicle manufacturers have produced a booklet listing pre-1986 cars — mainly smaller Japanese or European cars built in the early 1980s — that can be run on unleaded petrol. However, a number of inconsistencies are raised, with some vehicle manufacturers recommending that a tank of leaded petrol be used after every 3-5 tanks of unleaded.
There is certainly an obvious necessity to reduce the atmospheric content of lead. Excessive amounts of lead in the blood have been linked to impaired intellectual development as well as disorders in the kidneys and reproductive organs.
Approximately 55% of petrol consumption in Australia is from leaded fuel, which releases 4000 tonnes of lead into the air annually. Australian lead levels in petrol are between 0.3 and 0.8 grams per litre, the highest in the industrialised world (it's 0.15 grams per litre in many European countries).
Lead in petrol has a twofold use. It serves as a lubricant for the valves and upper cylinder, and it increases the octane rating, or anti-knocking characteristics, of the fuel. (ULP has an octane rating of 91-93 whereas leaded petrol's rating is 97.)
When a fuel of a low octane is used in an engine not designed for that fuel, the air/fuel mixture can tend to detonate or knock (a small explosion of the mixture due, not to ignition by the spark plug, but to the heat in the combustion chamber). In severe cases, knocking causes engine damage.
The factors affecting the octane rating of the fuel needed by an engine are the compression ratio (the amount the air/fuel mixture is compressed), the valve timing, the combustion chamber design — all fixed properties of an engine — and, to a lesser extent, the degree of advance of the ignition timing. Other factors are what emission controls are fitted and whether they are functioning correctly.
While it is true that some car owners will be able to switch to using unleaded petrol without adversely affecting their vehicle, older cars, and even some early 1980s vehicles (particularly those with cast iron cylinder heads), will not be able to take the change in fuel without some modification.
Older vehicles tend to run with higher combustion temperatures, increasing the tendency for the fuel to detonate, as well as possibly having emission controls that are either not functioning correctly or are disconnected. Use of ULP in these circumstances is likely to increase the tendency for detonation to occur.
Vehicles that are not able to merely switch to using ULP would have to undergo some modification, ranging from a simple retune and cross-the-fingers approach (hoping that engine damage will not occur) to overhauling the cylinder head and replacing the valves and valve seats. Most would also need to change the thermostat to run the engine at lower temperatures.
The cost of a major modification would make it absurd. Some suggested simpler and cheaper modifications have not been proven in practice. So many vehicle owners may be forced to use ULP hoping that the engine can take the fuel without compromising performance and economy.
However, this raises the question of who should pay to protect the environment. With oil companies making record profits from selling leaded petrol and the government cashing in through increasing taxation, the consumer is being asked to shoulder the financial burden.
An estimated capital expenditure of $350 million to further refine raw fuel instead of adding octane agents would enable oil companies to produce a 97 octane fuel that does not contain lead. Such a fuel could immediately replace leaded petrol at no cost to the consumer and reduce the effect of super-grade petrol on the environment and community health.
However, this alone would be only one step along the way to reducing the impact of motor vehicles on the environment. In fact, cars manufactured before 1986 that run on ULP will produce more toxic emissions than later vehicles designed for ULP and fitted with a catalytic converter. And it is probable that pre-'86 vehicles using ULP will produce more (non-leaded) toxic emissions than they would with leaded fuel due to inefficiencies in using the new fuel.
"The government is claiming that it is doing something to reduce emission from cars", Environmental Youth Alliance national coordinator Sam Wainwright told Green Left Weekly. "In reality, it is simply promoting the use of more highly polluting private vehicles instead of investing in an efficient public transport system that would provide an alternative to private motor vehicles.
"The increase in the tax on unleaded petrol as well as leaded fuel shows this initiative up for what it is — a revenue-raising grab, making the people pay for a trivial gain in the fight to save our planet."