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There has been growing concern about the way cultivating biomass for the production of agro-biofuels competes with food production. To avoid this competition biomass production for biofuels will, in the long term, have to be completely decoupled from food production. This is where microalgae have enormous potential. Here we propose a novel process based on microalgae cultivation using dilute fossil CO 2 emissions and the conversion of the algal biomass through a catalytic hydrothermal process. The resulting products are methane as a clean fuel and concentrated CO 2 for sequestration. The proposed gasification process mineralizes nutrient-bearing organics completely. Here we show that complete gasification of microalgae (Spirulina platensis) to a methane-rich gas is now possible in supercritical water using ruthenium catalysts. 60-70% of the heating value contained in the algal biomass would be recovered as methane. Such an efficient algae-to-methane process opens up an elegant way to tackle both climate change and dependence on fossil natural gas without competing with food production.

Production of synthetic natural gas (SNG) from wood by a catalytic hydrothermal process was studied in a laboratory batch reactor suitable for high feed concentrations (10-30 wt %) at 300-410 °C and 12-34 MPa with Raney nickel as the catalyst. A maximum methane yield of 0.33 (g of CH 4 )/(g of wood) was obtained, corresponding to the thermodynamic equilibrium yield. The carbon gasification efficiency was a function of the reaction time, and for reaction times long enough (∼90 min), complete gasification was achieved. At supercritical conditions, the remaining liquid phase always was tar-free, was colorless, and contained less than 2 wt % of the feed carbon. Analysis of the spent catalyst revealed a slight increase of carbonaceous deposits on the surface (15 atom % vs 10 atom % for the fresh catalyst).

Fuel cell powered electric cars using on-board methanol reforming to produce a hydrogen-rich gas represent a low-emissions alternative to gasoline internal combustion engines (ICE). In order to exceed the well-to-wheel efficiencies of 17% for the gasoline ICE, high-efficiency fuel cells and methanol reformers must be developed. Catalytic autothermal reforming of methanol o †ers advantages over endothermic steam-reforming and exothermic partial oxidation. Microreactor testing of copper-containing catalysts was carried out in the temperature range between 250 and 330 ¡C showing nearly complete methanol conversion at 85% hydrogen yield. For the overall process a simpliÐed model of the reaction network, consisting of the total oxidation of methanol, the reverse water-gas shift reaction, and the steam-reforming of methanol, is proposed. Individual kinetic measurements for the latter two reactions on a commercial catalyst are presented. Cu/ZnO/Al 2 O 3

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This paper presents a process model for the polygeneration of Synthetic Natural Gas (SNG), power and heat by catalytic hydrothermal gasification of biomass and biomass wastes in supercritical water. Following a systematic process design methodology, thermodynamic property models and thermoeconomic process models for hydrolysis, salt separation, gasification and the separation of CH 4 , CO 2 , H 2 and H 2 O at high pressure are developed and validated with experimental data. Different strategies for an integrated separation of the crude product, heat supply and energy recovery are elaborated and assembled in a general superstructure. The influence of the process design on the performance is discussed for some representative scenarios that highlight the key aspects of the design. Based on this work, a thermo-economic optimisation will allow for determining the most promising options for the polygeneration of fuel and power depending on the available technology, catalyst lifetime, substrate type and plant scale.