H2 valleys docs

Author: cristobal-GC

docs/H2_valley_demands.rst

@@ -0,0 +1,74 @@
+..
+  SPDX-FileCopyrightText: 2019-2024 The PyPSA-Spain Authors
+
+  SPDX-License-Identifier: CC-BY-4.0
+
+
+####################################################################
+The model for H2 valley demands
+####################################################################
+
+
+PyPSA-Spain includes a functionality to model geolocalised annual hydrogen demands associated with so-called H2 valleys (clusters of industrial, mobility or sectoral H2 consumers planned at a given location). Each H2 valley represents a fixed annual amount of hydrogen consumed inside the Spanish system at a given geographical location, which the model then distributes as a constant load over the whole year.
+
+The required elements are added during the rule ``prepare_sector_network``, after the regular sector-coupled network has been built. The configuration relies on two groups of elements: a YAML file describing the H2 valleys, and a corresponding entry in the ``pypsa_spain`` module of the configuration file.
+
+
+Model components
+========================
+
+For each H2 valley, the following element is added to the network:
+
+- a **fixed H2 load** with carrier ``H2``, attached to the closest H2 bus of the Spanish network and consuming a constant power such that the total annual consumption equals the configured amount of hydrogen.
+
+The closest H2 bus is identified at runtime based on Euclidean distance between the H2 valley coordinates and the H2 buses in peninsular Spain.
+
+The annual hydrogen amount is converted to a constant power setpoint using:
+
+.. math::
+
+   p = \frac{\text{annual\_amount} \cdot 33.33 \times 10^6}{\sum_t w_t} \quad [\text{MW}]
+
+where :math:`33.33 \times 10^6` MWh is the lower heating value of one million tonnes of H2, and :math:`\sum_t w_t` is the total weight of the snapshots (equal to 8760 hours for full-year runs at any temporal resolution).
+
+The constant load is imposed by directly setting ``loads_t.p_set`` for the load.
+
+
+Configuration
+========================
+
+The functionality is enabled in the ``pypsa_spain`` module of ``config/config_ES.yaml``:
+
+.. code-block:: yaml
+
+   H2_valley_demands:
+     enable: true
+     file: data_ES/H2/H2_valley_demands.yaml
+
+The characteristics of each H2 valley are defined in the file referenced above. Each entry specifies the valley coordinates (``x``, ``y``) and the annual hydrogen demand in MtH2/year. The ``bus`` field of the load is left empty in the YAML file and assigned at runtime to the closest H2 bus on the Spanish network.
+
+.. note::
+
+   When this functionality is enabled, the electricity demand associated with H2 production should be removed from the regular electricity demand input to avoid double counting.
+
+
+The following figure shows the H2 valleys defined in the template file included in the repository. A more detailed description of these example valleys is provided in `PR #18 <https://github.com/cristobal-GC/pypsa-spain/pull/18>`__.
+
+.. figure:: img/H2_valley_demands.png
+  :width: 85%
+  :align: center
+  :alt: Map of H2 valley demands in PyPSA-Spain
+
+
+
+
+
+
+Modelling assumptions and limitations
+========================================
+
+The current implementation deliberately makes some simplifications:
+
+- The H2 demand of each valley is imposed as a **constant load** over all snapshots. Intra-annual variability of the demand is not represented.
+- Each valley is attached to a **single H2 bus**, identified as the closest one by Euclidean distance. The internal hydrogen distribution network within the valley is not modelled.
+- The annual amount is treated as **exogenous**: it is not co-optimised with the rest of the system.

docs/img/H2_valley_demands.png

@@ -37,6 +37,7 @@ Find the details of PyPSA-Spain v.0.0.0 in the `seminal paper <https://doi.org/1
    ISA_index
    interconnections
    regional_network_focus
+   H2_valley_demands
    H2_imports_exports
 
 .. toctree::