diff --git a/doc/release_notes.rst b/doc/release_notes.rst
index d395f035..0f8e122f 100644
--- a/doc/release_notes.rst
+++ b/doc/release_notes.rst
@@ -13,6 +13,7 @@ Upcoming Release
 * Individual commits are now tested against pre-commit hooks. This includes black style formatting, sorting of package imports, Snakefile formatting and others. Installation instructions can for the pre-commit can be found `here <https://pre-commit.com/>`_.
 * Pre-commit CI is now part of the repository's CI.
 * The heuristic distribution of today's renewable installations is now enable per default.
+* Marginal costs of conventional generators are now taking the plant-specific efficiency into account.
 
 PyPSA-Eur 0.6.0 (10th September 2022)
 =====================================
diff --git a/envs/environment.yaml b/envs/environment.yaml
index 3de2e373..16d6f374 100644
--- a/envs/environment.yaml
+++ b/envs/environment.yaml
@@ -46,7 +46,7 @@ dependencies:
   # GIS dependencies:
 - cartopy
 - descartes
-- rasterio<=1.2.9    # 1.2.10 creates error https://github.com/PyPSA/atlite/issues/238
+- rasterio!=1.2.10
 
   # PyPSA-Eur-Sec Dependencies
 - geopy
diff --git a/scripts/add_electricity.py b/scripts/add_electricity.py
index 64f18d45..3d9babfd 100755
--- a/scripts/add_electricity.py
+++ b/scripts/add_electricity.py
@@ -369,6 +369,9 @@ def attach_conventional_generators(
         .rename(index=lambda s: "C" + str(s))
     )
     ppl["efficiency"] = ppl.efficiency.fillna(ppl.efficiency_r)
+    ppl["marginal_cost"] = (
+        ppl.carrier.map(costs.VOM) + ppl.carrier.map(costs.fuel) / ppl.efficiency
+    )
 
     logger.info(
         "Adding {} generators with capacities [GW] \n{}".format(