Self-sufficiency of motor fuels on organic farms

The aim of the present work was to evaluate systems for making organic farms self-sufficient in bio-based fuels. The energy efficiency and environmental load for systems based on rape methyl ester (RME), ethanol and biogas produced by processing raw material from the farm in industrial-scale plants were evaluated using a life cycle perspective. Eventual constraints when implementing the systems in practice were also identified and the farmer’s costs for the systems estimated. The RME scenario showed some good characteristics; the energy efficiency and potential effects on global warming were favourable, the technology well known and no engine modifications were necessary. However, the high price of the organically produced rapeseed made the fuel expensive. The ethanol scenario provided fuel at a comparatively low cost, but the energy efficiency was low and existing engines would have to be modified. The biogas scenario was not as economically advantageous, due to high costs for storage and transport of the biogas and the extensive tractor modifications needed. The calculations further showed that systems based on so-called exchange of fuels, i.e. when the farm produces raw material for one type of biofuel, but instead uses another type of biofuel more suitable for its own tractors, were an economically favourable way of supplying the organic farms with ‘self-produced’ bio-based fuels. The exchange scenario based on delivery of organic wheat to a large-scale plant and use of RME at the farm was somewhat more expensive than scenarios based on production of biogas raw material at the farm. However, the wheat/RME system has the advantage of being possible to put into practice immediately, since industrial-scale wheat ethanol plants are in operation and RME fuel is available on the market.