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Breathless tech reporters have discovered <i>farming</i>
During WW2 Germany was making edible fats/margarine out of coal. Similarly, the atmospheric CO2 can be a source of carbon, especially say on Mars.<p>(another thing back then in Germany - ramjet engine using coal in a metal basket as a fuel. The war does put minds to work - radars/computers/nukes on the Allies side also come to mind.)