diff --git a/config.default.yaml b/config.default.yaml
index 66a9f299..14a6cc0a 100644
--- a/config.default.yaml
+++ b/config.default.yaml
@@ -467,6 +467,7 @@ plotting:
     hot water storage: '#BBBBBB'
     hot water charging: '#BBBBBB'
     hot water discharging: '#999999'
+    CO2 pipeline: '#999999'
     CHP: r
     CHP heat: r
     CHP electric: r