Bioethanol can be used in different blends to fuel vehicles. In the BEST project we have used E85, ethanol bus fuel, lowblends in petrol (E5, E10 and HE15) and in diesel (E-Diesel and ED-diesel).
Bioethanol used for fuel is predominantly produced from sugar or starchy crops such as sugar cane, wheat, corn and sugar beets. In the USA, corn is also an important feedstock.
Bioethanol can be produced in a number of ways. If produced under socially and environmentally sustainable conditions, bioethanol can be a viable transport fuel and will reduce emissions of fossil carbon dioxide (CO2). Bioethanol is biodegradable and less toxic and explosive than petrol. A range of fuel blends can be produced from bioethanol, and BEST demonstrated, tested and assessed several different blends.
High bioethanol blends require dedicated vehicles, whereas low bioethanol blends do not. High blends contain a high proportion of bioethanol and effectively substitute fossil fuels. High blends can substantially reduce greenhouse gas emissions, depending on how they are produced. Due to the difference in properties between fossil fuels and bioethanol, high blends require some modifications to the vehicle engine and a dedicated fuelling infrastructure.
In BEST, these high blends were reviewed:
E85 – 85 % anhydrous bioethanol, 12% gasoline. It also containes MTBE, (2%) and small quantities of isobutanol. E85 It is intended for flexi-fuel vehicles that can run on pure ethanol, pure petrol, or a blend of these. The petrol component is needed only to allow cold starts during the winter months. E85 can be fuelled in a rapidly increasing net of fueling stations.
Ethanol bus fuel - The bioethanol bus fuel is a liquid homogeneous and stable fuel, which is developed for heavy-duty, ethanol compression-ignition engines. It is commercial and fulfils the ethanol fuel standard given by Scania. The trade name of the fuel is Etamax D and the ethanol used originates from renewable sources only. The fuel is produced by SEKAB and delivered directly to each ethanol bus depot. Etamax D has following composition (percentage by volume), 93,5 % bioethanol (hydrous 95 %), 3,6 % ignition improver, 3,0 % denaturants, Corrosion inhibitor.
The use of the ignition enhancer in the busfuel is patented. Ethanol bus fuel is available at bus depots where ethanolbuses are in operation.
E100 – 100 % hydrous bioethanol – used in modified petrol buses in Nanyang and (outside BEST) in petrol cars in Brazil.
ED95 – 96.5 % hydrous bioethanol, 3.5 % additives – used in bioethanol buses, converted diesel vehicles and dedicated heavy diesel vehicles, such as
waste collection trucks.
Low blends represent a quick way of introducing large volumes of biofuel into road transport fuels without making any alterations to fuel supply infrastructure or vehicles. Low blends are seen as a relatively cost-effective way of reducing fossil fuel consumption. Low blends using biofuels such as bioethanol and biodiesel have been used in Europe since the early 1900s. The 2009 Fuel Quality Directive approved the use of blends including up to 10 % bioethanol in petrol in the EU. This means that blends such as E5 and E10 can be marketed and sold as petrol in the EU. In BEST, several low blends were demonstrated:
E5 – 5 % anhydrous bioethanol, 95 % petrol – used in existing petrol cars and pumps.
E10 – 10 % anhydrous bioethanol, 90 % petrol – used in existing petrol cars and pumps.
HE15 – 15 % hydrous bioethanol, 85 % petrol – used in conventional petrol cars. Not recognised as petrol by the Fuel Quality Directive, but can be sold
under the specific name HE15.
E25 – 25 % anhydrous bioethanol, 75 % petrol – normal minimum blend used in Brazil.
E-diesel – 7.7 % anhydrous bioethanol, 0.62 % additives and diesel – tested in a bench cell. More flammable than diesel and must be handled as petrol.
ED-diesel – 10 % bioethanol derivative (not pure bioethanol) blended in diesel – used in two city buses and handled as diesel.
Hydrous and anhydrous bioethanol
There are two types of fuel bioethanol – hydrous and anhydrous. Hydrous bioethanol means water-containing ethanol (usually 2 %–7 % water). This ethanol is used in neat ethanol engines (engines adapted to use 100 % ethanol) like buses, and in some special fuels like HE15 tested in the Netherlands.
Anhydrous bioethanol is the product remaining when hydrous bioethanol is dehydrated, enabling it to be mixed in low blends with petrol and diesel. This fuel contains very small volumes of water – in Brazil a maximum water content of 0.7 % is permitted. This is the ethanol used in E85.