Abstract. The pace of the transition to a low-carbon economy – especially in the fuels sector – is not high enough to achieve the 2 °C target limit for global warming by only cutting emissions. Most political roadmaps to tackle global warming implicitly rely on the timely availability of mature negative emission technologies, which actively invest energy to remove CO2 from the atmosphere and store it permanently. The models used as a basis for decarbonisation policies typically assume an implementation of such large-scale negative emission technologies starting around the year 2030, ramped up to cause net negative emissions in the second half of the century and balancing earlier CO2 release. On average, a contribution of −10 Gt CO2/year is expected by 2050.(Anderson and Peters, 2016) A viable approach for negative emissions should (i) rely on an unlimited source of energy (solar), (ii) result in a safely storable product (e.g. liquid or solid, not gaseous), (iii) be highly efficient in terms of water and energy use, to reduce the required land area and competition with water and food demands of a growing world population and (iv) be large-scale feasibility and affordability.