Organic rankine cycle decompression heat engine

A heat engine employing an organic Rankine cycle comprising:

• an organic refrigerant exhibiting a boiling point below −35 degrees Celsius;
• a hot water heat source having a temperature of less than 82 degrees Celsius;
• a heat sink;
• a sealed, closed-loop path for the organic refrigerant, the sealed, closed-loop path having both a high-pressure zone configured to absorb heat from the hot water heat source, and which contains a first portion of the organic refrigerant in at least a gaseous phase, and a low-pressure zone which transfers configured to transfer heat to the heat sink, and which contains a second portion of the organic refrigerant in at least a liquid phase;
• a positive-displacement decompressor configured to provide a pressure gradient through which the organic refrigerant in the gaseous phase is configured to flow continuously from the high-pressure zone to the low-pressure zone, the positive-displacement decompressor maintaining a pressure differential between the high-pressure zone and the low-pressure zone of between about 20 bar and about 42 bar, the positive-displacement decompressor extracting mechanical energy due to the pressure gradient;
• an electrical generator coupled to the positive-displacement decompressor configured to convert extracted mechanical energy to electrical energy;
• and
• a positive displacement hydraulic pump for providing continuous flow of the organic refrigerant in the liquid phase from the low-pressure zone to the high-pressure zone.