<p>The fuel tank has an outer wall, an inner wall and an intermediate hollow space. The hollow space (4) is filled with a super-insulating aerogel (9), which is provided with an opacity medium against heat radiation. The pore width of the aerogel and the residual gas pressure in the hollow space are so matched that a heat conduction through air molecules contained in the hollow space does not take place. The pore width of the aerogel is approximately 50 nm and the residual gas pressure in the hollow space is approximately 10 power -2 to 10 power -3. The aerogel comprises an over-critical precipitated silicate.</p>
