World has become interested in the development of new dean energy because of oil prices rise and global warming due to carbon dioxide emissions. This study evaluated the safety of the refueling infrastructure for hydrogen, CNG and HCNG(hydrogen blended natural gas) which recently take center stage as a clean fuel. The risk of fuel was evaluated by 3D computational fluid dynamics program for gas dispersion and explosion. Hydrogen is higher than the CNG explosion overpressure and shows rapid spread. On the other hand, CNG and 30% HCNG showed quite similar characteristics. HCNG slightly rises in risk than the CNG, but HCNG is safe compared to hydrogen.