## 3 Developed Biogas Upgrading Technologies
The selection of the upgrading technology must be site-specific and case-sensitive, depending on local circumstances and regulations [66]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Characteristics**} & \multicolumn{2}{c}{**Adsorption**} & \multicolumn{2}{c}{**Absorption**} & \multirow{2}{*}{**MS**} & \multirow{2}{*}{**CS**} \\ \cline{2-3} \cline{5-6}  & **PSA** & **WS** & **OPS** & **AS** & & \\ \hline Compounds & H\({}_{2}\)S and H\({}_{2}\)O & H\({}_{2}\)S (if the & H\({}_{2}\)S (recommended) & & H\({}_{2}\)S (if the & & \\ that must be & [51, 61, 63, 69] & concentration is & (recommended) & concentration is & H\({}_{2}\)S and & H\({}_{2}\)S and & H\({}_{2}\)S and \\ pre-removed & [51, 61, 63, 69] & high) [61, 63, 65] & [61, 63] & high) [61, 63] & H\({}_{2}\)O [61, 63] & H\({}_{2}\)O [61, 63] & H\({}_{2}\)O [52, 61] \\ \hline Technology & Yes & & & & & Partly separates & Possible if \\ separates N\({}_{2}\) & Yes & No [65, 66] & Yes [61] & No [65, 66] & No [65, 66] & O\({}_{2}\) but not & LBM is \\ and O\({}_{2}\) & [51, 54, 66] & & & & N\({}_{2}\)[65] & obtained [51, 55] \\ \hline Methane & 95–99 [54, 61, 63] & \multirow{3}{*}{\(>\)97 [52, 61]} & \multirow{3}{*}{\(>\)97 [52, 61]} & \multirow{3}{*}{99 [61]} & \multirow{3}{*}{92 [78]} & \multirow{3}{*}{98 [61]} \\ content in & \(>\)96 [69] & & 95–99 [63] & 98 [52] & 97–99 [66] & 98 [51, 65] & 97–99 [54, 66] \\ upgraded gas & 98 [52, 76] & & 95–98 [77] & 95–99 [63] & 98 [52, 63] & 99 [54] & \(>\)97 [52] \\ (\%vol CH\({}_{4}\)) & 96–98 [77] & & 95–98 [77] & 95–98 [77] & \(>\)98 [77] & 95–99 [63] & 99 [77] \\ \hline Water demand & & & & & & 90–99 [77] & \\ (dm\({}^{3}\)/Nm\({}^{3}\) & \multirow{3}{*}{0} & \multirow{3}{*}{0} & \multirow{3}{*}{0.4–4} & \multirow{3}{*}{0} & \multirow{3}{*}{0.03} & \multirow{3}{*}{0} \\ biogas) [65] & & & & & & \\ \hline Heat demand & & & & & & \\ (kWh/Nm\({}^{3}\) & 0 [65, 69, 78] & 0 [65, 69, 78] & \(<\)0.2 [78] & 0.55 [65] & & \\ biogas) & & & 0.10–0.15 [69] & 0.50–0.75 [78] & 0 [65, 69, 78] & 0 [69, 78] \\ \hline Electricity & 0.15–0.30 [65] & 0.20–0.30 & & & & & 0.20–0.28 \\ consumption & 0.23–0.30 [78] & [65, 69] & 0.20–0.29 [65] & 0.12–0.14 [65] & 0.20–0.30 [65] & [78] \\ (kWh/Nm\({}^{3}\) & 0.16–0.35 [69] & 0.3 [78] & 0.2–0.3 [78] & 0.10–0.15 [78] & 0.18–0.21 [78] & 0.72 [78] \\ biogas) & 0.16–0.43 [77] & \(<\)0.25 [78] & 0.23–0.33 [69] & 0.06–0.17 [69] & 0.18–0.35 & 1.05 [78] \\  & & 0.10–0.33 [77] & 0.10–0.33 [77] & 0.05–0.18 [77] & [69, 77] & 0.18–0.25 [69, 77] & 0.18–0.25 [69, 77] \\ \hline Other & & & Anti-foaming & Organic solvent & Anti-foaming & Membrane & \\ consumables & Lubricant oil & agents (in some & addition once a & a & age, up of & replacement (5–10 years) and & Lubricant oil \\ [65] & for compressors & cases) and lubricant oil for & lyberant oil for & amine, and & (5–10 years) and & for compressors \\  & & compressors & lubricant oil for & compressors & lubricant oil for & compressors & \\ \hline \multirow{4}{*}{Methane losses (\%)} & \(<\)2 [63, 65] & \(<\)2 [52, 54, 61, 77] & 1–4 [65] & \(<\)0.1 [52, 65, 69] & \(<\)0.5 [54, 65] & \(<\)1 [51, 61] \\  & 2–4 [66] & 3–5 [66] & \(<\)2 [51] & 0.04 [63] & 1–15 [69] & \(<\)2 \\ \cline{1-1}  & 10–12 [66] & 0.5–2 [69] & \(<\)1 [52] & \(<\)1 [52] & \(<\)1 [52] & [52, 65] \\ \cline{1-1}  & 1.5–10.0 [69] & 2 [63] & \(<\)4 & \(<\)0.5 [77] & 0.5–20 [63] & 0.1–2.0 [69] \\ \cline{1-1}  & \(<\)3 [77] & 1 [65] & [63, 66, 77] & \(<\)5 [77] & \(<\)0.1 [77] & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison of developed biogas upgrading technologies. Note: OPS data from [65] are valid only for Genosorb solvent.