Retreive missing queries (#3224)

* Retrieve query for export of network gas

* Restoring network gas use for electricity and heat production queries

* Style fix for query

* Style fix for query

* Style fix for query

---------

Co-authored-by: Kas Kranenburg <[email protected]>

Author: mabijkerk

gqueries/general/import_export/export/export_of_network_gas.gql

@@ -0,0 +1,8 @@
+# Export of network gas
+
+- query =
+    SUM(
+      Q(export_of_natural_gas),
+      Q(export_of_greengas)
+    )
+- unit = PJ

gqueries/general/network_gas/demand_per_conversion/network_gas_use_for_collective_heat_production.gql

@@ -0,0 +1,16 @@
+# Network gas used for collective heat production.
+
+- query =
+    DIVIDE(
+      SUM(
+        V(
+          FILTER(
+            G(heat_production),
+            "steam_hot_water_output_conversion > 0.0 && electricity_output_conversion == 0.0"
+          ),
+          "input_of_network_gas"
+        )
+      ),
+      BILLIONS
+    )
+- unit = PJ

gqueries/general/network_gas/demand_per_conversion/network_gas_use_for_electricity_production.gql

@@ -0,0 +1,17 @@
+# Network gas used for electricity production
+
+- query =
+    DIVIDE(
+      SUM(
+        V(
+          G(electricity_production),
+          input_of_network_gas
+        ),
+        V(
+          energy_mixer_for_gas_power_fuel,
+          input_of_network_gas
+        )
+      ),
+      BILLIONS
+    )
+- unit = PJ