Biofuels
As explained above, fuel ethers are already an alternative component which makes the production of modern, cleaner-burning gasoline possible. High octane, easy-to-blend and cost-effective they are essentially drop-in blending components for the refiner. There are a few other non-aromatic octane options such as alkylates, isomerates and ethanol, but they are limited in terms of both octane contribution and supply availability. In addition, they provide fewer air quality benefits.
The net octane contribution of a blending component is related to both its octane number and the amount of the component used in petrol. Since the content of aromatics in petrol is being reduced by another 7% in Europe, their octane contribution must be replaced to maintain the quality of the petrol.
Fuel ethers and ethanol are more effective octane components since they deliver higher octane numbers than aromatics and therefore require less volume to deliver the same amount of octane. However, ethanol cannot be utilised without difficulties by the refiners in petrol because of its high water solubility, which effectively prevents its use in the distribution system for petrol. Ethanol has also a high, non-ideal blending vapour pressure which tends to knock off some other, light, low-boiling hydrocarbons from the gasoline blend in order to meet the volatility regulations. Technically, and because of its higher cost, ethanol is not really a viable alternative.
In 2003, the European Union adopted directive 2003/30, which aims at promoting the use of biofuels or other renewable fuels to replace diesel or petrol for transport purposes in each Member State, with a view to contributing to objectives such as meeting climate change commitments, environmentally friendly security of supply and promoting renewable energy sources. Allowed biofuels include alcohols such as bio-ethanol and ethers such as bio-ETBE and bio-MTBE. The directive sets no obligation, but indicates that Member States should set national indicative targets for a minimum proportion of biofuels and other renewable fuels to be placed on their markets, these targets being 2 % in 2005 and 5.75 % in 2010 in terms of energy content. A review was carried out in 2006 based on progress reports by each individual Member State in EU 25. As part of this review, the Commission has issued the Renewable Energy Package that contains a proposed 10% mandate for biofuels, which is currently subject to a lot of scrutiny.
Today, the high cost of production of biofuels requires that they benefit from fiscal incentives to become economically viable. Directive 2003/30 has therefore been implemented by Directive 2003/96 on the taxation of energy products, which allows Member States to apply a total or partial tax exemption to biofuels. As the various Member States prepare their national plans to implement the biofuels directive, specific care should be taken to ensure that the implementation of the fiscal directive does not hinder the free movement of products or creates distortions in the market.
Due to their relatively low octane numbers, alkylates and isomerates are much less effective suppliers of octane, which means that larger amount must be used to deliver the same amount of octane. However, the future supply available for these two components is very low due to the limited amounts of feedstocks available in the refinery. The cost of their octane is also much higher than that of fuel ethers.
For these reasons, fuel ethers have the potential to replace all octane loss from aromatic reductions in petrol.
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