Option to extend solid biomass potentials by imports

config/config.default.yaml

@@ -628,6 +628,11 @@ sector:
     max_boost: 0.25
     var_cf: true
     sustainability_factor: 0.0025
+  solid_biomass_import:
+    enable: false
+    price: 54 #EUR/MWh
+    max_amount: 5 #EJ
+    upstream_emissions_factor: .1 #share of solid biomass CO2 emissions at full combustion
 
 # docs in https://pypsa-eur.readthedocs.io/en/latest/configuration.html#industry
 industry:
@@ -1017,6 +1022,7 @@ plotting:
     biogas: '#e3d37d'
     biomass: '#baa741'
     solid biomass: '#baa741'
+    solid biomass import: '#d5ca8d'
     solid biomass transport: '#baa741'
     solid biomass for industry: '#7a6d26'
     solid biomass for industry CC: '#47411c'

scripts/prepare_sector_network.py

@@ -2285,6 +2285,59 @@ def add_biomass(n, costs):
         e_initial=solid_biomass_potentials_spatial,
     )
 
+    if options["solid_biomass_import"].get("enable", False):
+        biomass_import_price = options["solid_biomass_import"]["price"]
+        biomass_import_max_amount = round(
+            options["solid_biomass_import"]["max_amount"] * 1e9 / 3.6, 0
+        )  # EJ --> MWh
+        biomass_import_upstream_emissions = round(
+            options["solid_biomass_import"]["upstream_emissions_factor"]
+            * costs.at["solid biomass", "CO2 intensity"],
+            4,
+        )
+
+        print(
+            "Adding biomass import with cost",
+            biomass_import_price,
+            "EUR/MWh, a limit of",
+            options["solid_biomass_import"]["max_amount"],
+            "EJ, and embedded emissions of",
+            options["solid_biomass_import"]["upstream_emissions_factor"] * 100,
+            "%",
+        )
+
+        n.add("Carrier", "solid biomass import")
+
+        n.madd(
+            "Bus",
+            ["EU solid biomass import"],
+            location="EU",
+            carrier="solid biomass import",
+        )
+
+        n.madd(
+            "Store",
+            ["solid biomass import"],
+            bus=["EU solid biomass import"],
+            carrier="solid biomass import",
+            e_nom=biomass_import_max_amount,
+            marginal_cost=biomass_import_price,
+            e_initial=biomass_import_max_amount,
+        )
+
+        n.madd(
+            "Link",
+            spatial.biomass.nodes,
+            suffix=" solid biomass import",
+            bus0=["EU solid biomass import"],
+            bus1=spatial.biomass.nodes,
+            bus2="co2 atmosphere",
+            carrier="solid biomass import",
+            efficiency=1.0,
+            efficiency2=biomass_import_upstream_emissions,
+            p_nom_extendable=True,
+        )
+
     n.madd(
         "Link",
         spatial.gas.biogas_to_gas,