diff --git a/Snakefile b/Snakefile
index c24bd250..49c9fd5f 100644
--- a/Snakefile
+++ b/Snakefile
@@ -7,7 +7,7 @@ wildcard_constraints:
     simpl="[a-zA-Z0-9]*|all",
     clusters="[0-9]+m?|all",
     sectors="[+a-zA-Z0-9]+",
-    opts="[-+a-zA-Z0-9]*"
+    opts="[-+a-zA-Z0-9\.]*"
 
 rule cluster_all_elec_networks:
     input:
diff --git a/config.yaml b/config.yaml
index 9d54e0f3..70e48fab 100644
--- a/config.yaml
+++ b/config.yaml
@@ -27,6 +27,7 @@ enable:
 electricity:
   voltages: [220., 300., 380.]
   co2limit: 7.75e+7 # 0.05 * 3.1e9*0.5
+  co2base: 3.1e+9 # 1 * 3.1e9*0.5
 
   extendable_carriers:
     Generator: [OCGT]
diff --git a/scripts/prepare_network.py b/scripts/prepare_network.py
index b44effaa..4516378f 100644
--- a/scripts/prepare_network.py
+++ b/scripts/prepare_network.py
@@ -16,10 +16,16 @@ import geopandas as gpd
 import pypsa
 from add_electricity import load_costs, update_transmission_costs
 
-def add_co2limit(n, Nyears=1.):
+def add_co2limit(n, Nyears=1., factor=None):
+
+    if factor:
+        annual_emissions = factor*snakemake.config['electricity']['co2base']
+    else:
+        annual_emissions = snakemake.config['electricity']['co2limit']
+
     n.add("GlobalConstraint", "CO2Limit",
           carrier_attribute="co2_emissions", sense="<=",
-          constant=snakemake.config['electricity']['co2limit'] * Nyears)
+          constant=annual_emissions * Nyears)
 
 def add_emission_prices(n, emission_prices=None, exclude_co2=False):
     assert False, "Needs to be fixed, adds NAN"
@@ -151,9 +157,13 @@ if __name__ == "__main__":
     else:
         logger.info("No resampling")
 
-    if 'Co2L' in opts:
-        add_co2limit(n, Nyears)
-        # add_emission_prices(n, exclude_co2=True)
+    for o in opts:
+        if "Co2L" in o:
+            m = re.findall("[0-9]*\.?[0-9]+$", o)
+            if len(m) > 0:
+                add_co2limit(n, Nyears, float(m[0]))
+            else:
+                add_co2limit(n, Nyears)
 
     # if 'Ep' in opts:
     #     add_emission_prices(n)