On the lack of a unique relation between CO2 partial pressure and temperature in geothermal system. Comment on “Geothermal mineral equilibria” by W. F. Giggenbach

Giggenbach (1981) has proposed a relation of van't Hoff form, log₁₀P_CO2 = A ? B/(t + 273), between temperature and CO₂ partial pressure in deep liquid in geothermal systems. The proposed values for the coefficients are A = 15.26, B = 7850.The proposal is not supported by pressure-temperature data used by Giggenbach, and a survey of different fields indicates that the proposal is not valid.