diff --git a/scripts/prepare_sector_network.py b/scripts/prepare_sector_network.py
index b6c052be..540b3f23 100644
--- a/scripts/prepare_sector_network.py
+++ b/scripts/prepare_sector_network.py
@@ -1874,10 +1874,12 @@ def add_biomass(n, costs):
         bus0=spatial.gas.biogas,
         bus1=spatial.gas.nodes,
         bus2="co2 atmosphere",
+        bus3="co2 stored",
         carrier="biogas to gas",
         capital_cost=costs.loc["biogas upgrading", "fixed"],
         marginal_cost=costs.loc["biogas upgrading", "VOM"],
         efficiency2=-costs.at['gas', 'CO2 intensity'],
+        efficiency3=costs.at["biogas", "CO2 stored"],
         p_nom_extendable=True
     )