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• Estimated cost of solar fuels via supercritical water gasification of algae is 2.5 USD/L. • Fast-ramping Fischer–Tropsch units will be critical for solar-driven gas-to-liquids. • A predictive dispatch scheduler for the FT unit brings cost savings of 19%. This paper evaluates the annual dynamic performance and techno-economic feasibility of a solar fuels process driven by concentrated solar power (CSP). The process integrates solar supercritical water gasification (SCWG) of microalgae, syngas storage, and downstream Fischer–Tropsch (FT) synthesis, to produce renewable drop-in liquid transport fuels. Performance curves for key components, derived from design-point and off-design simulations in steady-state flowsheet models established in the previous work of the authors, are incorporated into a dynamic energy-based model of the overall plant in OpenModelica. Control units are implemented to model the high-level state transitions of the plant relating to ramp-up and ramp-down of solar-SCWG and FT units as well as syngas storage and dispatch. There is significant uncertainty about the achievable ramping time for FT plant, owing to the dynamics of the synthesis of long-chain hydrocarbons in the FT reactor, so this is modelled as a variable-duration ramp-up with no useful product output. A perfect one-day-ahead forecast scheduler is developed to regulate the supply of solar syngas to the FT unit to minimise these ramp-up events. The levelised cost of fuel (LCOF) for the plant is minimised using a genetic algorithm to adjust the solar multiple and syngas storage capacity of the plant, with weather data and location of Geraldton in Western Australia. The optimal configuration has a solar multiple of ∼4 and syngas storage of ∼20 h, and achieves an LCOF of ∼3.5 AUD/L (∼2.5 USD/L) and capacity factor of ∼72%. Sensitivity analysis shows that the price of the farmed microalgae feedstock has the strongest influence on the LCOF. The one-day-ahead syngas dispatch scheduler contributes an LCOF reduction of 19% compared to an immediate dispatch strategy. The importance of the FT ramping time in these simulations suggests that fast-ramping FT reactors (e.g. microchannel reactors) will be essential for the techno-economic success of solar-gasified FT fuels, and motivates further research and development on this topic. [ABSTRACT FROM AUTHOR]

Abstract: Black carbon-rich chert dikes are common features of early Archean terranes and are especially prominent on the Pilbara Craton of Western Australia. The dikes cut across the local stratigraphy before truncating abruptly at specific stratigraphic horizons where they can be seen to interfinger with the stratigraphic succession. These uniquely Archean dike complexes are enigmatic and raise significant questions about the source of the carbon they contain—is it biogenic, and therefore indicative of the early biosphere, or abiotic, and perhaps indicative of prebiotic conditions that led to the appearance of the first life on Earth? The Strelley Pool Chert, which is exposed on the Pilbara Craton of Western Australia, forms part of the Warrawoona Group and rests unconformably on older ultramafic volcanics. The formation, which is generally less than 30m thick, consists of a relatively consistent lithologic succession found over a wide area. Locally, a basal transgressive sandstone is overlain by a sequence of carbonate, barite?, black and white laminated chert and grey–green chert which is locally stained blue green by weathered fuchsite. The formation is intersected by normal faults about which the depositional successions thickens and thins. The mineralogy and geochemistry (including stable isotope data) of the underlying dike complex closely parallels that of the lithologies preserved in the Strelley Pool Chert. Similarly, the depositional sequence of minerals in voids within the dike complex parallels that of the depositional sequence above. This new data from the Strelley Pool Chert and its associated dike complex show that the black chert dikes are an integral part of a hydrothermal mineralogical complex. The complex accumulated around vents fed by growth-fault-controlled dikes that extended to a depth of more than 2km below the Archean paleo-seafloor. The mineralogy of the sedimentary succession reflects deposition during the declining temperature regime of an evolving hydrothermal system driven by an intruding granitoid complex below. The fault system and associated hydrothermal complex evolved in the tensional environment developed during doming above the intermittently intruding granitoid complex that forms the framework of the Pilbara Protocontinent. Carbonaceous compounds contained within the black chert dikes could have been generated abiotically by a process similar to Fischer–Tropsch synthesis at elevated temperatures (200–300°C) and pressures (500bar) at a paleo-depth of 2km within the hydrothermal system. The “primordial medium” in which life first evolved may thus have been a silica-rich slurry with a low pH and a high CO2 content which contained basic abiotic organic building blocks fundamental to the origins of life. The abiotic organic output from these hydrothermal systems may overwhelm any early biospheric geochemical signal and may therefore be the most difficult environment in which to recognise the early biospheric record. [Copyright &y& Elsevier]