diff --git a/config/config.default.yaml b/config/config.default.yaml
index eee27b2fb3..b2fdd17831 100644
--- a/config/config.default.yaml
+++ b/config/config.default.yaml
@@ -911,7 +911,9 @@ sector:
     - H2 pipeline
     - H2 pipeline retrofitted
     - gas pipeline
+    - gas pipeline new
     - electricity distribution grid
+    - CO2 pipeline
     DC:
       efficiency_static: 0.98
       efficiency_per_1000km: 0.977
@@ -924,8 +926,13 @@ sector:
     gas pipeline:
       efficiency_per_1000km: 1
       compression_per_1000km: 0.01
+    gas pipeline new:
+      efficiency_per_1000km: 1
+      compression_per_1000km: 0.01
     electricity distribution grid:
       efficiency_static: 0.97
+    CO2 pipeline:
+      efficiency_per_1000km: 1
   H2_network: true
   gas_network: true
   H2_retrofit: false
diff --git a/config/schema.default.json b/config/schema.default.json
index e03c0b0571..974bf24e67 100644
--- a/config/schema.default.json
+++ b/config/schema.default.json
@@ -4897,12 +4897,26 @@
               "description": "Gas pipeline transmission efficiency.",
               "type": "object"
             },
+            "gas pipeline new": {
+              "additionalProperties": {
+                "type": "number"
+              },
+              "description": "Gas pipeline new transmission efficiency.",
+              "type": "object"
+            },
             "electricity distribution grid": {
               "additionalProperties": {
                 "type": "number"
               },
               "description": "Electricity distribution grid efficiency.",
               "type": "object"
+            },
+            "CO2 pipeline": {
+              "additionalProperties": {
+                "type": "number"
+              },
+              "description": "CO2 pipeline transmission efficiency.",
+              "type": "object"
             }
           }
         },
@@ -8126,12 +8140,26 @@
           "description": "Gas pipeline transmission efficiency.",
           "type": "object"
         },
+        "gas pipeline new": {
+          "additionalProperties": {
+            "type": "number"
+          },
+          "description": "Gas pipeline new transmission efficiency.",
+          "type": "object"
+        },
         "electricity distribution grid": {
           "additionalProperties": {
             "type": "number"
           },
           "description": "Electricity distribution grid efficiency.",
           "type": "object"
+        },
+        "CO2 pipeline": {
+          "additionalProperties": {
+            "type": "number"
+          },
+          "description": "CO2 pipeline transmission efficiency.",
+          "type": "object"
         }
       }
     },
@@ -11365,12 +11393,26 @@
               "description": "Gas pipeline transmission efficiency.",
               "type": "object"
             },
+            "gas pipeline new": {
+              "additionalProperties": {
+                "type": "number"
+              },
+              "description": "Gas pipeline new transmission efficiency.",
+              "type": "object"
+            },
             "electricity distribution grid": {
               "additionalProperties": {
                 "type": "number"
               },
               "description": "Electricity distribution grid efficiency.",
               "type": "object"
+            },
+            "CO2 pipeline": {
+              "additionalProperties": {
+                "type": "number"
+              },
+              "description": "CO2 pipeline transmission efficiency.",
+              "type": "object"
             }
           }
         },
diff --git a/doc/release_notes.md b/doc/release_notes.md
index 101ab4a150..440860d058 100644
--- a/doc/release_notes.md
+++ b/doc/release_notes.md
@@ -5,6 +5,9 @@
 
 <!-- Upcoming Release -->
 <!-- ================= -->
+
+* Fix: Set transmission efficiencies for `gas pipeline new` and `CO2 pipeline` links by default, to ensure consistency with other link type carriers.
+
 * Security: SBOM security scan included in CI.
 
 * Security: Development dependencies (pre-commit, pylint, jupyter, etc.) moved to `dev` `pixi` environment.
diff --git a/scripts/lib/validation/config/sector.py b/scripts/lib/validation/config/sector.py
index 0ff3f482d5..4a8e028791 100644
--- a/scripts/lib/validation/config/sector.py
+++ b/scripts/lib/validation/config/sector.py
@@ -233,7 +233,9 @@ class _TransmissionEfficiencyConfig(BaseModel):
             "H2 pipeline",
             "H2 pipeline retrofitted",
             "gas pipeline",
+            "gas pipeline new",
             "electricity distribution grid",
+            "CO2 pipeline",
         ],
         description="Switch to select the carriers for which transmission efficiency is to be added. Carriers not listed assume lossless transmission.",
     )
@@ -268,11 +270,24 @@ class _TransmissionEfficiencyConfig(BaseModel):
         alias="gas pipeline",
         description="Gas pipeline transmission efficiency.",
     )
+    gas_pipeline_new: dict[str, float] = Field(
+        default_factory=lambda: {
+            "efficiency_per_1000km": 1,
+            "compression_per_1000km": 0.01,
+        },
+        alias="gas pipeline new",
+        description="Gas pipeline new transmission efficiency.",
+    )
     electricity_distribution_grid: dict[str, float] = Field(
         default_factory=lambda: {"efficiency_static": 0.97},
         alias="electricity distribution grid",
         description="Electricity distribution grid efficiency.",
     )
+    CO2_pipeline: dict[str, float] = Field(
+        default_factory=lambda: {"efficiency_per_1000km": 1},
+        alias="CO2 pipeline",
+        description="CO2 pipeline transmission efficiency.",
+    )
 
     model_config = ConfigDict(populate_by_name=True)