## 3 Results and Discussion  
In Tables 3-5, the amounts of carbon dioxide in the NCG are reported, representing carbon dioxide emission as the average CO\({}_{2}\) content in Italian geothermal fluids, with values ranging between 95 and 98%, calculated from boric acid production. Considering that H\({}_{3}\)BO\({}_{3}\) was extracted from highly emitting ponds ('lagoni') and fumaroles, the calculated amounts are under-estimated, neglecting the contribution of the non-industrially exploited ponds and other sources. Moreover, the availability of chemical composition of steam was started only in 1841 by [PERSON], who first measured (Figure 8) only the gas portion of the vented steam (CO\({}_{2}\) 57.30%, H\({}_{2}\)S 1.32%, N\({}_{2}\) 34.81%, O\({}_{2}\) 6.57%). Nevertheless, although some contamination of air is present in these first studies, the original data can be corrected by air contamination, leading to a composition of 97.7% CO\({}_{2}\) and 2.3%H\({}_{2}\)S. Data on boric acid concentration in steam and gas content are more recent. Even if the reported data are underestimated, they give an idea of the amount of carbon dioxide that progressively depleted at the surface with the development of the industrial use of steam for boric acid production and, since 1913, for electrical use. The emerging picture of steam and NCG emission calculated in the 1818-1867 period shows steam values continuously increasing during early geothermal development, starting at 6.6 t/h, and increasing to 215 t/h, and eventually reaching 236 t/h in 1867. The rates of NCG emission range between 0.47 t/h and 15.4 t/h up, reaching 17 t/h in 1867, with a ratio of about 7.2 tons of carbon dioxide (NCG) per 100 t/h of naturally emitted steam. These emissions from natural 'lagoni' have gradually depleted and are substituted by power plant emission. A comparison \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Plant Name**} & **Boric acid Daily** & **Boric Acid** & **Boric Acid** & **Steam** & **NCG Emission** & **Average** & **Average** \\  & **Production** & **Production** & **Production** & **Calculated** & **Calculated from** & **Steam Flow** & **NCG Flow** \\  & **(kg/d)** & **(kg/y)** & **(t/y)** & **from R\({}_{t}\) (t/y)** & **R\({}_{\text{NCG}}\) (t/y)** & **Rate (t/h)** & **Rate (t/h)** \\ \hline Larderello & 1740 & 634,841 & 635 & 732,111 & 52,618 & 83.6 & 6.0 \\ \hline Castelnuovo & 304 & 111,235 & 111 & 128,278 & 9220 & 14.6 & 1.1 \\ \hline Sasso & 710 & 259,267 & 259 & 298,992 & 21,489 & 34.1 & 2.5 \\ \hline Monterotondo & 317 & 115,524 & 116 & 133,225 & 9575 & 15.2 & 1.1 \\ \hline Lago- & & & & & & & \\ Collacchia, S. & 1180 & 430,931 & 431 & 496,958 & 35,717 & 56.7 & 4.1 \\ Edoardo, S. & & & & & & & \\ Federigo & & & & & & & \\ \hline Lustignano & 310 & 113,067 & 113 & 130,391 & 9371 & 14.9 & 1.1 \\ \hline Serrazzano & 348 & 127,389 & 127 & 146,908 & 10,558 & 16.8 & 1.2 \\ \hline Total & 4909 & 1,792,254 & 1792 & 2,066,863 & 148,548 & 236 & 17.0 \\ \hline \end{tabular}
\end{table} 
Table 5: Calculated NCG emission from data from boric acid production data according to ref. [37] and their distribution in factories in 1867.  
with current emission can be performed by considering an average performance of Italian Geothermal Power Plants currently running with turbine efficiencies of 7 to 8 tons of steam per MWh produced. The largest natural NCG emissions flux calculated in this work reaches 17 t/h, carried by 236 t/h of venting steam. This amount of steam is equivalent to about 30-34 MW of a standard geothermal power plant, representing a significant estimation of the degree of substitution of natural emission. Considering that in the Larderello area, a substantial depletion of gas content has been observed after the systematic application of condensate reinjection practice, by reducing the gas content in steam, in some cases to 2% or less, the same 17 t/h of ancient NCG emission would be equivalent to 850 t/h steam or about 106 to 121 MW power production.