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| What would be the consequences for air quality if fuel ethers were not used any more ? |
Without fuel ethers, real world air quality could easily worsen. High olefins concentration is just one example. To produce ETBE and MTBE, refiners convert C4 olefins, making good environmental use of these reactive components, which would otherwise have to be converted to isomerates or alkylates before being blended in the gasoline pool.
In California, ethanol started to replace MTBE in 2003 in anticipation to the MTBE-ban beginning January 2004. Measurements have shown an increase in air pollution caused by traffic, especially ozone, which seems to correlate with the MTBE replacement.
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Gasoline does not belong in the soil or in the groundwater: it belongs in storage tanks or in the tanks of cars. If gasoline is found in the soil or groundwater, it is because tanks, pipelines or equipment are leaking. The oxygenated fuel industry is very much concerned about leaks and spills, and recognises the need for dealing with this matter.
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| What is the state of underground storage tanks (UST) and what should be done about it ? |
A study conducted in March 2001 by A.D. Little (“MTBE and the Requirements for Underground Storage Tank Construction and Operation in Member States”) for the European Commission confirmed that contamination of groundwater by MTBE is unlikely if standards governing the construction and operation of underground storage tanks at service stations are robustly enforced.
The EU Risk Assessment on MTBE, published in 2000, concludes that as far as human health is concerned, risk for consumers are not expected and risk reduction measures already being applied are considered sufficient. It does recommend however, as part of the Risk Reduction Strategy, that the best available techniques be widely applied for the construction and operation of petrol underground storage and distribution facilities at service stations, and that harmonised technical standards for the construction and operation of the storage tanks be developed at a European level by the European Committee for Standardisation (CEN).
In the USA, federal UST regulation introduced in 1998 aimed at upgrading gasoline storage tanks and a whole range of state laws complimented/exceeded it. However compliance was notably poor. In 2003 the government enacted the Underground Storage Tank Compliance Act, making it illegal to deliver or accept fuel into a UST that has been "red-tagged" as not complying with the 1998 UST regulation, and introducing regular tank inspections.
According to the US EPA, at the end of fiscal year 2003, the compliance rates for release prevention were 79%, and for release detection the compliance rates were 72%.
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In certain conditions depending on water and rock formation, MTBE moves faster through the soil than other gasoline components. However, every compound in gasoline can end up in drinking water supplies, if tanks leak. Not using MTBE does not solve the problem of leaking tanks, and of other compounds that also risk ending up in drinking water supplies.
In some ways, the mobility of MTBE can be seen as an advantage. MTBE's strong, unpleasant taste and odour are easily detectable. Even in minute quantities, its presence will deter people from drinking water contaminated with gasoline, thus acting as an early warning signal. When MTBE is not used, gasoline could enter the drinking water system unnoticed for some time.
MTBE does degrade slowly in natural conditions but eventually forms carbon dioxide and water and the process can be speeded up by relatively simple remedial measures.
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There are no reasons to phase out this very useful substance.
MTBE has been demonstrated to improve air quality. It has undergone a full EU risk assessment study for both health and environmental effects. After considering all the available scientific information, the EU concluded that exposure to MTBE was not expected to have any harmful impact on human health, the atmosphere or the environment.
Phasing out MTBE would not solve the problem of leaking tanks. There is no justification for attributing the issue of leakage solely to MTBE, while ignoring other gasoline components.
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It is often alleged that MTBE is a persistent substance in soil and groundwater, yet research has demonstrated that decomposition occurs in natural conditions when air is present. Without air, decomposition of MTBE is slower, but in many cases the situation can be readily improved by simple measures, such as providing oxygen into the soil.
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Yes, MTBE contamination can be cleaned up in the soil and water by using well-proven remediation technologies such as air stripping, granular activated carbon (GAC), advanced oxidation, and soil vapour extraction (SVE).
Traditional "pump and treat" technologies available for water plants have been proven effective in remediation of gasoline-contaminated water, even if it contains MTBE. In the event of a contamination incident, activated carbon cartridges installed at the tap could be utilised as a temporary solution. These household filters have been commonly used for many years by private consumers to remove off-taste and odour from drinking water, and the devices work well for gasoline components, including MTBE. No matter what method is used, the key issue in groundwater remediation is immediate action to eliminate the contamination source, usually a piece of leaking equipment or contaminated soil.
Again, the problem of MTBE in groundwater is not inherent to the product itself, but has arisen from the way the product has been handled.
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| Bio-ETBE appears to be the best solution to further increase ethanol consumption, but its processing requires an extra CO2 output. Please explain. |
The energy needed to produce bio-ETBE is limited and only represents a small percentage of the energy needed from well to wheel, from the field to the final consumption. In terms of CO2 emissions this energy increase is offset by:
-- a potential benefit in the refinery process linked to a better balance of the production unit
-- the impact of distribution constraints: ethanol blends cannot use pipelines for security reasons and are made in specially equipped depots causing more transportation, while bio-ETBE blends follow the existing logistics without any change.
Bio-ETBE appears to be the best solution to further increase ethanol consumption but its processing requires an extra CO2 output. Please explain.
