Petroleum products and the environment

In 1977, I visited a major Asian city, which was congested and you can smell the gasoline and diesel fuel and the fumes of combustion in every street.

Twenty-one years later I visited the same city, which was even more congested due to a dramatic increase in the number of vehicles on its streets.

Surprisingly, I found the atmosphere cleaner and the air quality improved. This result was achieved by improved fuel quality, the use of catalytic converters to clean the exhaust and the use of much more efficient engines to reduce fuel use per distance travelled.

The oil industry whether by its own initiative or under the pressure of the public has made great strides to improve fuel quality and reduce harmful emissions.

Refineries got very complicated in order to be able to meet fuel standards and to provide the fuels demanded by the market. There is however, a long way to go especially in developing countries where the lack of capital has not allowed them to catch up with the industrial countries.

While it is important to recognise the different nature of markets around the world and allow for different sets of fuel standards, we must be aware that eventually the convergence of fuel specifications around the world is on its way and though this will take time, it could be much quicker than one might have thought before.

Gasoline specification

The general direction of gasoline specification is to move away from blending with lead to increase octane number because of the impact of lead in gasoline on human health.

Only few countries now still use lead and the desire to move away from that is only unfulfilled by the lack of capital for investment.

Other gasoline qualities are moving in the direction of reducing benzene content to not more than one part per million due to the fact that benzene is known to be cancer causing.

Similarly, aromatic contents have to be reduced to induce lower emissions of carbon monoxide, which causes smog especially in cold climate.

Sulphur content will be reduced drastically to about 10 parts per million because sulphur is very harmful to every fuel due to its damaging effects on engine parts and the emissions of sulphur and nitrogen oxides to the atmosphere cause breathing problems and acid rain.

Finally, the addition of some oxygenates to the gasoline improves its overall octane number and combustion qualities. The most important oxygenates is MTBE, which has been used successfully since 1973.

Storage tanks

However, this product has come under pressure in the United States due to its discovery in some underground water wells from leaking storage tanks.

The debate continues at the national level in the US for many years now and it is a foregone conclusion that the product will be banned.

The rest of the world and especially in Europe and Asia is increasingly relying on MTBE to produce cleaner and higher octane gasoline.

With the increase of the number of diesel driven vehicles, diesel fuels started to receive the same attention as that of gasoline. It is probably easier to produce cleaner diesel than cleaner gasoline.

Many years ago the 0.5 per cent sulphur level in diesel fuel was quite acceptable and still is in some countries. This level has been reduced gradually over the years to 150 parts per million and is heading for further reductions to reach the 10 parts per million, like gasoline.

The refineries have to use modern hydro-treating units with improved and more active catalysts.

In the Arab countries petroleum products specification vary but they are generally much less stringent that those of the United States or Europe and even some of the Asian countries.

Lead is still being used for increasing octane in most Arab countries. However, there is a major move towards lead-free gasoline where total gasoline is lead-free in the UAE, Qatar, Kuwait and Saudi Arabia will soon follow.

The writer is the former head of the Energy Studies Department at the Opec Secretariat and is currently working as an adviser.