Because of concerns about global climate change, possible global oil depletion, and because of potential benefits for both urban air pollution and rural employment and industry, many countries both in and out of the Organization for Economic Cooperation and Development (OECD), are promoting liquid biofuels as a replacement for oil-based transport fuels, and global output is rising steadily. In fact, bioenergy use in general is promoted, and is expected to play a major role in climate change mitigation. But bioenergy use in general faces competition for resources such as land, water and fertiliser from the two other general biomass uses, food production and biomaterials. Ethically, food production should take precedence over the other two uses (and at present all bioliquids are made from foodstuffs), and using biomass for biomaterials will in many situations reduce greenhouse gas emissions more than using the same amount of biomass for energy. Where a given amount of biomass is available for transport energy use, it will usually produce more greenhouse gas reductions per vehicle-km if used to produce electricity rather than liquid biofuels. Finally, there is signs that internal combustion engine vehicles could be phased out in the coming decades. If so, liquid biofuels will be phased out along with existing oil-based transport fuels. In conclusion, except for specialist uses, liquid biofuels do not appear to have a long-term future.

© 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC-BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/).