1.1.1 Analysed Biofuels

In our study, we examined first and second generations of bioethanol and bio­diesel, hydrated vegetable oil (HVO) and BTL fuel as specific combinations of raw materials and conversion technologies (Fig. 1).

First-generation bioethanol is produced through fermentation of sugar — and starch-containing organic materials. The most common raw materials are starch — containing plants. In Europe and North America that is wheat or corn; in Brazil, it is sugar cane. While sugar-containing plants can be fermented directly, starch needs to be hydrolysed to sugars through specific enzymes. During fermentation, microorganisms, such as yeast, metabolise sugars to ethanol. Second-generation biofuels are made of the non-edible part of the plant which remains on the field

after the crops have been harvested (e. g. com stover). If this lignocellulosic material could also be utilised, bioethanol production could be increased signifi­cantly. Because the conversion of lignocellulose to ethanol is more complex than that of sugar and starch, to date no large-scale production of second-generation bioethanol exists. However, Kim and Dale (2004) estimate that lignocellulosic bio­mass offers potential for the production of 442 billion litres of bioethanol per year.

Biodiesel is produced from plant oils or animal fats and transesterification with methanol. The most commonly used raw material is rapeseed, which has an oil content of 40-45 %. However, biodiesel has major disadvantages. It has the poten­tial to clog filters inside the tank and to cause leaks, because it acts aggressively against some rubbers and plastic. Thus, rubber parts in the fuel system may cor­rode over time. Explain that most diesel cars have been licensed to use biodiesel blends of up to 5 %. However, the conversion of a conventional diesel engine for pure biodiesel is associated with significant costs. In Germany, for example, com­panies offer a conversion service for roughly Euro 1,500 per engine. In addition, engine oil changes need to be done more often.

Just like biodiesel, HVO can be produced from oil-containing raw materials. Hydrotreating of vegetable oils or animal fats is an alternative process to esteri­fication for producing bio-based diesel fuels (Mikkonen 2008; Hodge 2008). In the HVO production process, hydrogen is used to remove the oxygen from the tri­glyceride (vegetable oil) and integration to an existing oil refinery is preferred for small plants. In 2007, the first HVO plant at commercial levels started operations in Finland. It has the capacity to produce 170,000 tonnes of HVO per year. Today, oil companies and process technology suppliers across the globe are constructing numerous plants with scales of up to 800,000 tonnes per year per unit.

The BTL production process consists of a number of different process steps. A low-temperature gasifier breaks down biomass to coke — and a gas-containing tar. In a gasification reactor, a tar-free synthesis gas is produced and liquefied to fuel through a Fischer-Tropsch reaction thereafter. Depending on the octane number, BTL fuels can be used in conventional petrol — or diesel-powered cars. A modifica­tion of the engine is not necessary. The existing filling station infrastructure can be used without further investments. Fischer-Tropsch plants for the production of BTL fuels from biomass, such as wood and residues, are estimated to reach com­mercial scale in the next decade.

The first step in our analysis is the projection of future production scales for each type of biofuel, as a technology’s maturity has a decisive impact on produc­tion costs and some technologies are not expected to leave pilot or demonstration scale in the near future. We have defined comparable reference scenarios related to biofuel production for the years 2015 (scenario 2015) and 2020 (scenario 2020) based on the maturity of each biofuel technology (Fig. 2). In each scenario, we take the technology’s maturity status (pilot scale, demonstration scale or produc­tion scale) into account. Therefore, we assume that more mature technologies have larger scales than technologies which are in the process of being developed. This in return means that the use of more mature technologies offers significant cost advantages.