Products P and Q have life cycle phases of material extraction, production, use, and end of life disposal. CH$_4$, CO$_2$ emissions and mass used per functional unit (f.u.) from the different phases of the products are given in the following tables.
Product P
\[
\begin{array}{|c|c|c|c|}
\hline
\text{Phase} & \text{CO$_2$ emissions (kg/tonne)} & \text{CH$_4$ emissions (kg/tonne)} & \text{Mass (tonne/f.u.)} \\
\hline
\text{Material Extraction} & 1.0 & 0.75 & 4.0 \\
\text{Production} & 1.5 & 1.0 & 2.0 \\
\text{Use} & 0.5 & 0.0 & 1.0 \\
\text{End of life disposal} & 1.0 & 0.25 & 1.0 \\
\hline
\end{array}
\]
Product Q
\[
\begin{array}{|c|c|c|c|}
\hline
\text{Phase} & \text{CO$_2$ emissions (kg/tonne)} & \text{CH$_4$ emissions (kg/tonne)} & \text{Mass (tonne/f.u.)} \\
\hline
\text{Material Extraction} & 0.75 & 0.75 & 3.0 \\
\text{Production} & 0.25 & 1.0 & 2.5 \\
\text{Use} & 0.0 & 0.5 & 0.75 \\
\text{End of life disposal} & 2.0 & 0.0 & 0.75 \\
\hline
\end{array}
\]
Given: Global warming potential (GWP) of CH$_4$ = 23 kg CO$_2$ equivalent per kg of CH$_4$.