Switching to unleaded gasoline

By Kardono

JAKARTA (JP): The use of leaded petroleum is gradually being phased out worldwide, because of increasing recognition of health risks of lead exposure and the introduction of catalytic converters, which require unleaded petroleum. However, as each country considers the issues of leaded petroleum, the same questions are revisited concerning health risks, technical feasibility and costs.

Unleaded petroleum, that grand scheme to help us all breathe easier, is getting more attention. Some countries have replaced leaded petroleum with the unleaded type whereas others, including Indonesia, have still kept lead in petroleum as a main octane booster.

Indonesia planned to phase out lead in petroleum in 1993 but the plan was stalled due to the economic crisis. Reports say unleaded petroleum may be implemented as soon as July 2001 in Jakarta, to be followed by other cities.

In general, the transition to unleaded petroleum will require refinery improvements and perhaps the use of other additives, such as methyl tertiary-butyl ether (MTBE).

The basic refinery options to produce unleaded petroleum include catalytic reforming, which results in higher octane aromatics (such as benzene, xylene, and toluene) and isoparaffins; and isomerization, which transforms normal paraffins into higher-octane isoparaffins.

Whereas, MTBE, one of the petroleum additives, is a chemical compound manufactured by the chemical reaction of methanol and isobutylene -- a liquefied petroleum gas. It is among a group of chemicals commonly known as "oxygenates" because they raise the oxygen content of petroleum.

Most refiners have chosen MTBE over other oxygenates as a lead substitute primarily for its blending characteristics and for economic reasons.

MTBE has been used in petroleum to replace lead as an octane enhancing material, which helps prevent the engine from "knocking". Oxygen helps petroleum burn more completely and therefore reduce harmful tailpipe emissions from motor vehicles. In one respect, the oxygen dilutes or displaces petroleum components such as aromatics (e.g., benzene) and sulfur. In another, oxygen optimizes the oxidation during combustion.

The Balongan refinery of the state oil firm Pertamina has chosen catalytic reforming in the production of its unleaded petroleum. The government's choice of the next type of unleaded petroleum is still unclear. Thailand for example, is making the transition from leaded petroleum with 0.45 gram per liter to unleaded petroleum using both refinery improvements and MTBE.

In Malaysia, the production of unleaded petroleum is similar to that in Thailand. In the European Union, unleaded petroleum is mostly carried out by blending oxygenate additive of MTBE into petroleum.

In the United States, the unleaded petroleum program has been implemented through the Clean Air Act Amendments of 1990 (CAAA). The Act contained two primary requirements for cleaner petroleum. The first, known as the oxygenated fuels program, began during the winter of 1992-1993 and required all petroleum sold in 39 carbon monoxide (CO) nonattainment areas to contain 2.7 percent oxygen. Nonattainment areas in the United States are areas which have failed to comply with ambient air quality standards, due to their very high levels of emissions.

The higher oxygen content helps to reduce CO emissions, especially during the winter months when most CO violations occur. The other fuel program, known as the reformulated gasoline (RFG) program which requires cleaner-burning reformulated petroleum, has been sold in the nine worst ozone nonattainment areas since Jan. 1, 1995.

About 40 other cities have voluntarily adopted the RFG program. Among requirements of the program are that the reformulated gasoline must have an oxygen content weight of 2 percent, a maximum benzene content of 1 percent, and no heavy metals.

RFG is also subject to a performance standard; among others it should lead to a 15 percent reduction of volatile organic carbon and toxic air emissions from baseline levels between 1995 and 2000.

Ambient monitoring data from the first year of the RFG program in 1995 showed strong signs that RFG was working. For example, detection of benzene (one of the air toxins controlled by RFG, and a known human carcinogen) declined dramatically, with a median reduction of 38 percent from the previous year.

Actually, neither the Clean Air Act nor the Environmental Protection Agency (EPA) requires the use of MTBE in reformulated gasoline. The 1990 Clean Air Act Amendment did not specify which oxygenate to use. However, both MTBE and ethanol are, in fact, used successfully in the current RFG program with the MTBE more dominantly used by some 80 percent fuel providers.

Despite air quality improvement aspects of oxygenates in RFG, there is growing concern about contamination of drinking water by MTBE in some areas. EPA is also concerned about detected MTBE in drinking water, as well as ground and surface waters.

As of June 1999, MTBE was detected in 3.7 percent of samples of water from California's drinking water systems. It was reported that about 3 percent of ground water wells in RFG program areas were detected to contain MTBE at or above five parts per billion. This was primarily a result of leaking underground fuel storage tanks, and possibly from spills from distribution facilities.

Some users do not accept the RFG program based on complaints of MTBE contributing to negative health effects, increased fuel prices, and lower engine performance. Reported health effects include headaches, dizziness, nausea, sore eyes and throats, and respiratory irritation.

Research about MTBE health effects has been inconclusive, however, most studies have failed to find acute health effects. RFG is expected to benefit health by helping areas achieve cleaner air. On average, RFG has decreased the use of fuel by two miles to three miles per gallon because oxygenates have lower energy content than petroleum. There are reports of much more savings of fuel for some vehicles. There are also reports that small engines do not perform well using RFG.

There is now a growing debate concerning environmental and health effects of MTBE. No doubt unleaded petrol using MTBE additive has resulted in cleaner air quality. However some researchers have revealed indications of MTBE contaminating water, and community members have also reported on its suspected effects on health.

Thus, the change from leaded to MTBE-unleaded petrol may lead to a shift from the issue of improving air quality to water quality problems. The states of California and Maine have ordered the phasing out of MTBE in their respective RFG programs. Several congressional hearings have been held to seek a solution.

The lesson for us here is how to find the best available technology in producing unleaded petrol. The decision is urgent given growing concern about air quality due to leaded gasoline. There is no such thing as a clean technology for eternity because the clean technology that we might choose today may be no longer clean in the future.

Thus decisions on such an important matter must include all related parties -- the government and the people, based on comprehensive assessment.

The writer, who holds a Phd. in air pollution, works for the Agency for the Assessment and Application of Technology (BPPT).