Use of alternate refrigerants in optimized cascade process

A method for liquefaction of natural gas comprising:

• a) providing at least one nonflammable refrigerant selected from the group consisting of:
• difluoromethane, pentafluoroethane, trifluoromethane, hexafluoroethane, tetrafluoroethane, pentafluorethane, trifluoroethane, pentafluoroethane, any derivative thereof, and any combination thereof;
• and
• b) cooling a natural gas stream in an LNG facility via indirect heat exchange with the nonflammable refrigerant.

A method for liquefaction of natural gas comprising:

• a) cooling a natural gas stream in a LNG facility via indirect heat exchange with a first nonflammable refrigerant selected from the group consisting of:
• difluoromethane, pentafluoroethane, trifluoromethane, hexafluoroethane, tetrafluoroethane, pentafluorethane, trifluoroethane, pentafluoroethane, any derivative thereof, and any combination thereof during a first refrigeration cycle;
• b) cooling the natural gas stream in the LNG facility via indirect heat exchange with a second refrigerant during a second refrigeration cycle;
• and
• c) cooling the natural gas stream in the LNG facility via indirect heat exchange with a third refrigerant during the third refrigeration cycle.