diff --git a/process/models/physics/current_drive.py b/process/models/physics/current_drive.py
index 29987c96aa..386ab6b70d 100644
--- a/process/models/physics/current_drive.py
+++ b/process/models/physics/current_drive.py
@@ -1908,11 +1908,10 @@ def current_drive(self):
             # Calculate the dimensionless current drive efficiency for
             # the primary heating method (ζ)
             self.data.current_drive.eta_cd_dimensionless_hcd_primary = self.calculate_dimensionless_current_drive_efficiency(  # noqa: E501
+                eta_cd_hcd=self.data.current_drive.eta_cd_hcd_primary,
                 nd_plasma_electrons_vol_avg=self.data.physics.nd_plasma_electrons_vol_avg,
                 rmajor=self.data.physics.rmajor,
                 temp_plasma_electron_vol_avg_kev=self.data.physics.temp_plasma_electron_vol_avg_kev,
-                c_hcd_driven=self.data.current_drive.c_hcd_primary_driven,
-                p_hcd_injected=self.data.current_drive.p_hcd_primary_injected_mw * 1.0e6,
             )
 
             if self.data.current_drive.p_hcd_secondary_injected_mw > 0.0:
@@ -1922,9 +1921,7 @@ def current_drive(self):
                     nd_plasma_electrons_vol_avg=self.data.physics.nd_plasma_electrons_vol_avg,
                     rmajor=self.data.physics.rmajor,
                     temp_plasma_electron_vol_avg_kev=self.data.physics.temp_plasma_electron_vol_avg_kev,
-                    c_hcd_driven=self.data.current_drive.c_hcd_secondary_driven,
-                    p_hcd_injected=self.data.current_drive.p_hcd_secondary_injected_mw
-                    * 1.0e6,
+                    eta_cd_hcd=self.data.current_drive.eta_cd_hcd_secondary,
                 )
 
             # ===========================================================
@@ -2383,11 +2380,10 @@ def calculate_normalised_current_drive_efficiency(
 
     @staticmethod
     def calculate_dimensionless_current_drive_efficiency(
+        eta_cd_hcd: float,
         nd_plasma_electrons_vol_avg: float,
         rmajor: float,
         temp_plasma_electron_vol_avg_kev: float,
-        c_hcd_driven: float,
-        p_hcd_injected: float,
     ) -> float:
         """Calculate the dimensionless current drive efficiency, ζ.
 
@@ -2402,10 +2398,8 @@ def calculate_dimensionless_current_drive_efficiency(
             Major radius of the plasma in meters.
         temp_plasma_electron_vol_avg_kev:
             Volume averaged electron temperature in keV.
-        c_hcd_driven:
-            Current driven by the heating and current drive system.
-        p_hcd_injected:
-            Power injected by the heating and current drive system.
+        eta_cd_hcd
+            Absolute current drive efficiency in A/W.
 
         Returns
         -------
@@ -2428,7 +2422,7 @@ def calculate_dimensionless_current_drive_efficiency(
                 (nd_plasma_electrons_vol_avg * rmajor)
                 / (temp_plasma_electron_vol_avg_kev * constants.KILOELECTRON_VOLT)
             )
-            * (c_hcd_driven / p_hcd_injected)
+            * eta_cd_hcd
         )
 
     def output(self):
diff --git a/tests/unit/models/physics/test_current_drive.py b/tests/unit/models/physics/test_current_drive.py
index dd543fb7e1..47bbf07642 100644
--- a/tests/unit/models/physics/test_current_drive.py
+++ b/tests/unit/models/physics/test_current_drive.py
@@ -315,38 +315,36 @@ def test_current_drive_primary_electron_bernstein(current_drive):
 
 @pytest.mark.parametrize(
     (
+        "eta_cd_hcd",
         "nd_plasma_electrons_vol_avg",
         "rmajor",
         "temp_plasma_electron_vol_avg_kev",
-        "c_hcd_driven",
-        "p_hcd_injected",
     ),
     [
-        (1e20, 1.0, 1.0, 1.0, 1.0),
+        (0.05, 1e20, 1.0, 1.0),
     ],
 )
 def test_calculate_dimensionless_current_drive_efficiency_simple(
+    eta_cd_hcd,
     nd_plasma_electrons_vol_avg,
     rmajor,
     temp_plasma_electron_vol_avg_kev,
-    c_hcd_driven,
-    p_hcd_injected,
     current_drive,
 ):
-    cd = current_drive
     expected = (
         (constants.ELECTRON_CHARGE**3 / constants.EPSILON0**2)
         * (
             (nd_plasma_electrons_vol_avg * rmajor)
             / (temp_plasma_electron_vol_avg_kev * constants.KILOELECTRON_VOLT)
         )
-        * (c_hcd_driven / p_hcd_injected)
+        * eta_cd_hcd
     )
-    result = cd.calculate_dimensionless_current_drive_efficiency(
-        nd_plasma_electrons_vol_avg,
-        rmajor,
-        temp_plasma_electron_vol_avg_kev,
-        c_hcd_driven,
-        p_hcd_injected,
+
+    result = current_drive.calculate_dimensionless_current_drive_efficiency(
+        eta_cd_hcd=eta_cd_hcd,
+        nd_plasma_electrons_vol_avg=nd_plasma_electrons_vol_avg,
+        rmajor=rmajor,
+        temp_plasma_electron_vol_avg_kev=temp_plasma_electron_vol_avg_kev,
     )
+
     assert result == pytest.approx(expected, rel=1e-12)