Supplying gaseous fuel from a liquid state to an engine

A method for supplying gaseous fuel from a liquid state to an internal combustion engine, the method comprising:

• employing a second internal combustion engine as a source of energy;
• pumping said gaseous fuel in said liquid state by transforming energy from said source of energy into mechanical work for said pumping;
• exchanging waste heat from said second internal combustion engine in a first heat exchange fluid circulating through said second internal combustion engine to a second heat exchange fluid circulating in a heat exchange loop separate from said internal combustion engine;
• vaporizing said gaseous fuel pumped from said liquid state with heat from said second heat exchange fluid;
• and
• delivering said gaseous fuel vaporized from said liquid state to said internal combustion engine;
• whereby a pressure of said gaseous fuel delivered to said internal combustion engine is maintained within a predetermined range of tolerance by said pumping.