Figure 1 shows a flow battery comprised of tanks 1 and 2. Tanks 1 contains liquid 4 and tank 2 contains liquid 6. These liquids 4 and 6 in tanks 1 and 2 are pumped past a membrane 5 held between two electrodes 8 and 10 in a reaction chamber 7. An ion exchange providing a flow of electric current occurs through the membrane 5 while both liquids 4 and 6 are circulating in their respective space as shown in figure 1. The flow battery can be recharged by flowing electricity through the battery.

If the liquids 1 and 2 are heated, the flow battery will produce more electrical energy. If the liquids 1 and 2 are cooled, the flow battery will use less energy to charge.

Figure 2 shows two reaction chambers 10 and 20. Reaction chamber 10 is heated or the liquids 12 and 14 flowing into reaction chamber 10 are heated. The reaction chamber 20 is cooled or the liquids 12 and 14 flowing into reaction chamber 20 are cooled. Reaction chamber 10 has electrodes 16 and 18 at each end. Through its center is a membrane 22 which divide reaction chamber 10 into two sections 24 and 26. Pump 28 pumps liquid 12 from tank 32 to section 24 of reaction chamber 10. Pump 34 pumps the liquid 14 from tank 36 to section 26 of reaction chamber 10. Ions move between section 24 and 26 through membrane 22. When electrode 16 and 18 are attached through a load, electricity will flow through the load.

In figure 3 the liquids 12 and 14 move out of reaction chamber 10 and into reaction chamber 12. Reaction chamber 12 has electrodes 40 and 42 and membrane 48. Reaction chamber 12 is divided into two sections 44 and 46. Liquid 12 flow from section 24 of reaction chamber 10 into section 44 of reaction chamber 12 and liquid 14 flow from section 26 into section 46 of reaction chamber 12. Electrodes 40 and 42 are charged, and electricity flows through the reaction chamber 12 to charge the liquid 12 and 14. Since reaction chamber 10 is warmer than reaction chamber 20 more electric will be produced by the discharge of liquids 12 and 14 than will be used to charge liquids 12 and 14.

Figure 2 also shows heat exchangers 50 and 52. Heat exchanger 50 takes the heat from liquid 12 flowing to reaction chamber 20 and heats the liquid 12 flowing to reaction chamber 10. Heat exchanger 52 takes the heat from liquid 14 flowing to reaction chamber 20 and heats the liquid 14 flowing to reaction chamber 10.

The flow battery engine is ideal for solar system and industrial waste heat recovery. During the day when the sun shines, and the industry runs, the flow battery engine could produce electrical energy. At night the flow battery engine could be recharged with cheaper energy and the cool ambient air.