The effect of thermal gradient for the energy protometabolism at early hydrothermal systems. Thermal gradients are known to exist in modern cellular systems, besides that is still under debate how crucial they are or their exact function for life. There is the example of mitochondrial membrane where a 10˚C-gradient was detected. Under interface conditions, the thermal gradient results in electrochemical potential, the well-known Seebeck effect/voltage. The potential generated from that effect is usually considered irrelevant, as it generally ranges from μV to hundredths of mV per Kelvin. On the other hand, thermodynamic and kinetic parameters of chemical reactions hosted in an interface region may be also considerably affected by temperature gradients. In the vent-ocean interface as modeled in the SAVT and evidenced by experimental works, there are reactions that are coupled on both sides of that interface and those can be independently affected by the local temperature on each side of the interface. The two reactions are represented below: 𝑘 𝐶𝑂 (𝑎𝑞) + 𝑛(𝐻 + 𝑒 ) ⇄ 𝑃 + 𝑚 𝐻 𝑂 (𝑙) {P= HCOOH, CH3COOH, HCHO} 𝐻 (𝑎𝑞) + 2 𝑂𝐻 (𝑎𝑞) ⇄ 2 𝐻 𝑂 (𝑙) + 2 𝑒 In the early vent-ocean interface, both reactions are coupled and mediated by an inorganic electron-conductive [Ni-]FeS mineral. Figure shows the result of an analytical model inspired by the works of Herschy et al. and Ooka et al. adapted to the context of the early vent-ocean interface. Based on that result, it is clear that thermodynamics becomes more favorable when there is a higher temperature gradient, as it increases the potential of both coupled reactions. and the natural radioactive environment in Witwatersrand basin, T=227°C for the Okinawa Trough hydrothermal field, and T=375°C for the Rainbow hydrothermal vent. The potential required for reduction of CO2 to HCOOH is shown (dashed line) by varying the pH and at the temperature of 5.5ºC, based on the work of Kortlever et al. The model that resulted in figure illustrates the overall thermodynamic advantage that the thermal gradient may promote. On the other hand, there is evidence of the vent-ocean interface kinetics from the results of the all-cool and all-hot experiments. While, under low temperatures, H2 and CO2 gases are expected to be more soluble and the high concentration can increase the thermodynamic parameters, however, it can also decrease the reaction rates. Nevertheless, the reaction rates are expected to increase at higher temperatures, although the gas concentrations decrease. Thus, the organic formation detected under the all-hot conditions in higher concentration even compared to the experiments under thermal-gradient conditions and the fact that there were no organics under "all-cool" Outcomes for the emergence of life model in early AHV systems. Modern hydrothermal systems show natural electrical current and local reducing condition on its surface that also shows different potential and current at different regions. Models of early alkaline hydrothermal systems also showed how electrochemical parameters might be sensitive to the early ocean local composition and consequently to the mineral barrier composition. Here, we demonstrated how the Ni-FeS mineral formation condition in the alkaline hydrothermal systems results in a mixture of phases that cannot be easily identified. Under different surface potentials, [Ni-]FeS minerals can also change their prevailing phases, as shown in recent experimental works, which may promote the formation of a metal phase. The gradient-rich along with the diversity of phases in the vent-ocean interface may be a key factor that makes the AHV scenario into a hatchery for life on early Earth, as envisioned in several works. As concluded from the discovery of lamellar distribution of minerals in black smokers, with the inner layer dominated with chalcopyrite contacting hydrothermal fluid while the outside layer dominated with Pyrite (FeS2) and sphalerite (Zn, Fe)S, and contacting the sea water. Inside that structure, the mineral layers are composed of pyrrhotite (FeS), pyrite and sphalerite. Such example of gradient structure is expected to affect the catalytic property at that submarine vent scenario. As shown here, after a period of hours, both formic acid and acetic acid are present in detectable concentrations under ventocean interface conditions. This indicates the possibility that at least two protometabolic steps could occur in the early ventocean interface, as illustrated in Figure . The variation of electrochemical conditions expected to exist on early hydrothermal systems, summed with the variation of Ni-FeS mineral phases does not compromise the occurrence of those protometabolic steps, but seems to only affect the accumulation of formic acid, probably due to the kinetics of the first step.