The JTEC harvests thermal energy to create electricity
A schematic of the JTEC device is shown above. In the device, there is a hot side (right) and a cool side (left). Each side contains a Membrane Electrode Assembly (MEA) stack consisting of a proton-conducting membrane and porous electrodes on the top and bottom. The proton-conducting membranes separate regions that contain hydrogen (H2) gas with different pressures, and they are permeable to protons (H+) but are largely impermeable to H2 gas. The bottom region contains high pressure and the top region contains low pressure.
During operation, H2 gas on the hot (right) side of the device is oxidized in the high-pressure region, and the resulting H+ ions travel through the membrane and are reduced to H2 at the low- pressure region. This is a spontaneous process driven by the pressure gradient. Simultaneously, the reaction is driven in reverse at the low-temperature (left) side: the H2 gas is oxidized in the low-pressure region, and the resulting H+ ions travel through the membrane and are reduced to H2 at the high-pressure region. This process is not spontaneous, but some of the voltage produced on the hot side is used to drive this process at the cold side. The reason this device is able to operate is because the open-circuit voltage (Voc) produced at the high-temperature side is greater than that required to drive the reaction in reverse at the low-temperature side. Thus, the device operates by continuously moving the hydrogen gas from high to low pressure and back again, while the excess electrical energy produced during this process can be used to do useful work. The device uses highly reversible electrochemical reactions and a temperature differential to pressurize gas, which can result in efficient conversion of thermal to electrical energy.
When used in reverse - it uses electrical energy for highly efficient air conditioning and refrigeration applications.
The device uses electrochemical reactions at different temperatures and pressures to create a potential difference, which can be harnessed to drive electrical current. It has the potential to generate electricity more efficiently than any device in use today.
The JTEC operates in a closed, sealed environment; it does not need fuel added. It is scalable; it can be made small enough to harness body heat and power a wearable device, or large enough to capture waste heat from an industrial factory and convert it to usable electricity.
It has distinct advantages over other devices:
The JTEC has no moving parts, making it easier and less expensive to maintain than traditional Stirling engines.
Uses Electrochemical Reactions
It uses electrochemical reactions to move and pressurize hydrogen. Other electrochemical converters, such as alkali- metal thermo electrochemical converters, employ similar concepts but use liquid sodium or potassium metal, which are highly corrosive.
Operates in a Wide Temperature Range
It operates in greater temperature ranges than traditional liquid-based electrochemical converters.
The January 2020 issue of Applied Energy Materials features a closer look at the JTEC technology:
Fei Huang, Andrew T. Pingitore, Tedric Campbell, Andrew Knight, David Johnson,
Lonnie G. Johnson, and Brian C. Benicewicz. A Thermoelectrochemical Converter Using High-Temperature Polybenzimidazole (PBI) Membranes for Harvesting Heat Energy. ACS Applied Energy Materials 2020 3 (1), 614-624. DOI: 10.1021/acsaem.9b01830
A Thermoelectrochemical Converter Using High-Temperature Polybenzimidazole (PBI) Membranes for Harvesting Heat Energy
To meet the rising energy demand and efficiently utilize a larger amount of waste heat energy from various devices and systems, here we report an innovative hermoelectrochemical converter which utilizes the electrochemical potential of a hydrogen pressure differential applied across a proton conductive membrane. The amount of energy available to the external load is the difference in electrical potential between that generated during a high-temperature expansion stage and that required during a low-temperature compression stage.
In this work, various phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes, DiOH-PBI, para-PBI, and m/p-PBI, are prepared via the poly(phosphoric acid) (PPA) process and investigated to understand how the membrane chemistry affected device performance. When operating a laboratory scale device at 20 °C/200 °C and a pressure ratio of 770, DiOH-PBI exhibited the best performance (maximum current density of 43 mA/cm2, peak power density of 0.52 mW/cm2, and net efficiency of 17.1%) as compared with the other two PBIs due to its high proton conductivity. Further increases in temperature or pressure differentials are expected to significantly improve the device output.
All the reported results are consistent with the Nernst equation and thus further confirm the working principle of the thermoelectric conversion technique. This transformational approach may allow for efficient generation of electricity from many diverse forms of waste heat.
JTEC Energy has worked with partners in Government, Education and Business.