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Page count: 92

Biofuels are a renewable alternative for reducing the climate impact of transport.Due to the versatility of biomass and complexity of economics and impacts, biofuels arepart of a complex system, which is here analysed from a systems perspective. Severalmodels are developed in order to assess the competitiveness of various crop based biofueloptions as part of a system, using different economic and environmental functional units.The scope is set to Germany until 2050.The capital and feedstock costs were revised to higher levels compared to common assumptions.The different functional units result in different merit orders for the biofuel options.Currently used biofuels, rape seed based biodiesel and starch crop based bioethanol, werefound not to be competitive when considering differentiated and increasing feedstock costs.Advanced liquid fuels were only competitive at extreme assumptions, contrary to commonexpectations. Instead, sugar beet based ethanol dominated for most of the time spanwhen comparing energetic cost, whereas Synthetic Natural Gas (SNG) was competitiveon a greenhouse gas abatement (GHG) cost basis, especially at a rapid decarbonisationof the power mix. With a land use GHG abatement functional unit, silage maize basedbiomethane was the best, with SNG converging only at very high renewables shares of thebackground systems.Switching from current practise to higher yielding biofuel options can treble the abatementper land area for the present day, and potentially increase it by a factor five in the future.A focus on GHG abatement per area of arable land results in the land passenger transportsector to be of the highest priority due to the suitability of higher yielding biofuel options,followed by land goods transport, shipping and finally aviation. If gaseous fuels are notpossible to introduce on a large scale, sectors where liquefied gaseous fuels are suitablebecome the priority, i.e. goods transport and shipping. The current practise of applyingadmixture quotas to sub-sectors of land transport renders a significantly lower climatebenefit compared to an overall optimal usage, and a large societal transition is requiredbefore aviation biofuels become the climate optimal biomass usage.The direct importance of land use has thus far not received enough attention in terms ofthe economics of biofuels from dedicated crops, as well as for the greenhouse gas emissionspolicy. Biofuels produced from arable land can provide a strong GHG benefit if an expansionof arable land is hindered through redirecting land use, which requires a holistic policyapproach.