A system for producing synthetic fuels, in particular jet fuel (kerosene), petrol and/or diesel, comprising: a) a device for separately obtaining carbon dioxide and water from the ambient air, b) a synthesis gas producing device for producing a raw synthesis gas comprising carbon monoxide, hydrogen, carbon dioxide and water, the synthesis gas producing device having a supply line for carbon dioxide, coming from the device for separately obtaining carbon dioxide and water from the ambient air, a supply line for air, and a supply line for water, c) a separation device for separating carbon dioxide and water from the raw synthesis gas produced in the synthesis gas producing device, d) a Fischer-Tropsch device for producing hydrocarbons by a Fischer-Tropsch method from the synthesis gas from which carbon dioxide and water have been separated in the separation device, e) a refining device for refining the hydrocarbons produced in the Fischer-Tropsch device into synthetic fuels, f) a desalination device for desalinating water, wherein the desalination device has a water supply line from the device for separately obtaining carbon dioxide and water from the ambient air, as well as a water discharge line to the Fischer-Tropsch device, and g) a water purification device which comprises a water supply line coming from the Fischer-Tropsch device and intended for purifying water accumulating therein, wherein the system further has a pre-reformer for converting hydrocarbons accumulated in the Fischer-Tropsch device and in the refining device into methane, carbon oxide, water, and hydrogen, as well as i) a water vapor supply line leading from the water purification device to the pre-reformer, ii) a process gas supply line (54, 52) leading from the refining device into pre-reformer, and/or a return gas line (56, 52) leading from the Fischer-Tropsch device into the pre-reformer, and iii) a circulating line leading from the pre-reformer into the supply line for water connected to the synthesis gas producing device. a) a device for separately obtaining carbon dioxide and water from the ambient air, b) a synthesis gas producing device for producing a raw synthesis gas comprising carbon monoxide, hydrogen, carbon dioxide and water, the synthesis gas producing device having a supply line for carbon dioxide, coming from the device for separately obtaining carbon dioxide and water from the ambient air, a supply line for air, and a supply line for water, c) a separation device for separating carbon dioxide and water from the raw synthesis gas produced in the synthesis gas producing device, d) a Fischer-Tropsch device for producing hydrocarbons by a Fischer-Tropsch method from the synthesis gas from which carbon dioxide and water have been separated in the separation device, e) a refining device for refining the hydrocarbons produced in the Fischer-Tropsch device into synthetic fuels, f) a desalination device for desalinating water, wherein the desalination device has a water supply line from the device for separately obtaining carbon dioxide and water from the ambient air, as well as a water discharge line to the Fischer-Tropsch device, and g) a water purification device which comprises a water supply line coming from the Fischer-Tropsch device and intended for purifying water accumulating therein,