Ethyl Tertiary Butyl Ether (ETBE) is produced from ethanol and isobutylene in a catalytic reaction. Blending with ETBE, improves the combustion characteristics of petrol, and ETBE is also more compatible with pipelines and engines than ethanol.
Although ETBE can be produced from bioethanol (Bio-ETBE), isobutylene is currentl derived from fossil sources (as a bioproduct of refining or from natural gas).
ETBE can provide improvements in air quality when blended into conventional gasoline. The EU blending level for ETBE this level is scheduled to be up to 22% in gasoline (the current level is 15%).
Bio-ETBE is extensively used in the EU in conventional vehicles and fuel distribution systems. This requires minimal investment in distribution system infrastructure, Bio-ETBE currently accounts for the vast majority of bioethanol destined for the EU gasoline market.
Tert-Amyl Ethyl Ether (TAEE) can also be derived from ethanol. Bioethers may also be produced from methanol (MTBE, TAME).
Further informaiton on ETBE and bioethers is available from the European Fuel Oxygenates Association