If God had wanted us to have nearly unlimited clean energy, He would have placed a fusion reactor into the sky.
(europe.pub)
china already have a supercritical carbon dioxide system integrated into a functioning powergrid and operating commercially. The system exploits an exotic phase of co2 which expands to fill a volume like gas, but moves frictionlessly through tubes as a liquid. There are concerns about lifespan because of how caustic the system is, but apparently some new materials are being trialled which negate this.