From bf79b4a817b33c8909121ff58ee405f629d676e0 Mon Sep 17 00:00:00 2001
From: LukasFrankenQ <lukas.franken@ed.ac.uk>
Date: Sun, 12 Nov 2023 20:14:04 +0000
Subject: [PATCH] added flexible operation

---
 config/config.default.yaml        |  2 ++
 scripts/prepare_sector_network.py | 22 ++++++++++++++++++++++
 scripts/solve_network.py          | 19 +++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/config/config.default.yaml b/config/config.default.yaml
index c00c6e25..7bb75c40 100644
--- a/config/config.default.yaml
+++ b/config/config.default.yaml
@@ -513,6 +513,8 @@ sector:
   enhanced_geothermal_performant: true # if true, adds only the cheapest patch of EGS potential to each region
   enhanced_geothermal_flexible: true # if true, adds a storage unit simulating flexible operation of EGS, see Ricks et al. 2023
   enhanced_geothermal_var_cf: true # if true, adds time-dependent capacity factor to EGS, see Ricks et al. 2023
+  enhanced_geothermal_reservoir_max_hours: 240 # relavant for flexible EGS, see Ricks et al. 2023
+  enhanced_geothermal_reservoir_max_boost: 0.25 # share of generation that can be added by flexible EGS, see Ricks et al. 2023
 
 # docs in https://pypsa-eur.readthedocs.io/en/latest/configuration.html#industry
 industry:
diff --git a/scripts/prepare_sector_network.py b/scripts/prepare_sector_network.py
index 68374785..2017e9d6 100644
--- a/scripts/prepare_sector_network.py
+++ b/scripts/prepare_sector_network.py
@@ -3468,6 +3468,28 @@ def add_enhanced_geothermal(
                 efficiency=efficiency_dh * 2.,
                 p_nom_extendable=True,
             )
+        else:
+            n.links.at[bus + " geothermal organic rankine cycle", "efficiency"] = efficiency_orc
+
+        if snakemake.params.sector["enhanced_geothermal_flexible"]:
+            
+            # this StorageUnit represents flexible operation using the geothermal reservoir.
+            # Hence, it is intuitively wrong to install it at the surface bus,
+            # this is however the more lean and computationally efficient solution.
+            
+            max_hours = snakemake.params.sector["enhanced_geothermal_reservoir_max_hours"]
+            boost = snakemake.params.sector["enhanced_geothermal_reservoir_max_boost"]
+
+            max_hours = max_hours * boost
+            n.add(
+                "StorageUnit",
+                bus + ' geothermal reservoir',
+                bus=f"geothermal heat surface {bus}",
+                carrier="geothermal heat",
+                p_nom_extendable=True,
+                p_min_pu=-1. - boost, 
+                max_hours=max_hours,
+            )
 
 
 
diff --git a/scripts/solve_network.py b/scripts/solve_network.py
index bdd75532..c299a0f1 100644
--- a/scripts/solve_network.py
+++ b/scripts/solve_network.py
@@ -777,6 +777,23 @@ def add_geothermal_chp_constraint(n):
     )
 
 
+def add_flexible_egs_constraint(n):
+    well_index = n.links.loc[n.links.carrier == 'geothermal heat'].index
+    storage_index = n.storage_units.loc[n.storage_units.carrier == 'geothermal heat  '].index
+
+    p_nom_rhs = (
+        n.model["Link-p_nom"].loc[well_index]
+	)
+    p_nom_lhs = (
+        n.model["StorageUnit-p_nom"].loc[storage_index]
+	)
+
+    n.model.add_constraints(
+        p_nom_lhs <= p_nom_rhs,
+        name="Upper bounds the charging capacity of the storage unit",
+    )
+
+
 def extra_functionality(n, snapshots):
     """
     Collects supplementary constraints which will be passed to
@@ -808,6 +825,8 @@ def extra_functionality(n, snapshots):
         add_retrofit_gas_boiler_constraint(n, snapshots)
     if "geothermal district heat" in n.links.carrier:
         add_geothermal_chp_constraint(n)
+    if config["sector"]["enhanced_geothermal_flexible"]:
+        add_flexible_egs_constraint(n)
 
 
 def solve_network(n, config, solving, opts="", **kwargs):