What are the advantages of fuel ether blending compared to ethanol blending?
ETBE features very different and advantageous physical and chemical characteristics, compared to ethanol, when blended into petrol. These include
- significantly lower blending volatility,
- no significant distortion of the distillation curve,
- better tolerance of wet distribution systems,
- double the octane increase per "barrel" at equivalent ethanol content and narrower octane sensitivity,
- better material compatibility.
When ETBE is co-blended with ethanol in petrol, those characteristics entail a whole series of practical advantages, including:
- positive economic impact by mitigating the need to remove light components such as butanes/pentanes,
- reducing risk of phase separation when in presence of water,
- better compatibility with seals and gaskets,
- octane sensitivity in line with finished petrol specifications requirements.
Such a "co-blend", implying a reduced volume of alcohol movement and management at terminals, also allows significant logistic advantages, e.g.:
- reduced movements of ethanol to terminals,
- smaller tank size requirements,
- lower logistical complexity, lighter administrative burden.
Last but not least, ETBE provides a series of environmental benefits compared to ethanol used alone, such as lower VOCs emission, lower permeation losses in the vehicle, and additional CO2 emissions reduction due to less severe refinery operations.
Finally the combined used of ETBE and ethanol allow to maximise the O2 limit exploitation in the new European "Protection Grade” (E5) of gasoline defined in Directive 2009/30/EC and intended for use in older vehicles, since ethanol is limited to 5%v/v, while the 15%v/v for ETBE equated to some 6.42%v/v of ethanol.