Environmental thermal energy conversion

A method of electricity production using water thermal energy, the method comprising:

• pressurizing an enclosed working fluid to cause the enclosed working fluid to ascend from a first depth of a body of water to a second depth of the body of water and subsequently descend to the first depth in a closed loop, the water at the second depth having a greater temperature than the water at the first depth such that the enclosed working fluid transitions to a liquid phase in a condenser portion of the closed loop at the first depth and to a vapor phase in a boiler portion of the closed loop at the second depth, the pressurizing done by a pump using power from a battery;
• and
• expanding the enclosed working fluid through a turbine at the second depth to generate electricity to charge the battery,
• wherein the closed loop is entirely submerged in the body of water during said pressurizing and said expanding.

A method of electricity production using water thermal energy, the method comprising:

• pressurizing an enclosed working fluid to cause the enclosed working fluid to ascend from a first depth of a body of water to a second depth of the body of water and subsequently descend to the first depth in a closed loop, the water at the second depth having a greater temperature than the water at the first depth such that the enclosed working fluid transitions to a liquid phase in a condenser portion of the closed loop at the first depth and to a vapor phase in a boiler portion of the closed loop at the second depth, the pressurizing done by a pump using power from a battery;
• expanding the enclosed working fluid through a turbine at the second depth to generate electricity to charge the battery;
• and
• fully submerging an apparatus housing the closed loop, the pump, and the turbine in the body of water.