Merge pull request #227 from iiasa/costs/reduction-year

Change decay to reach cost reduction specified by 2100 (instead of 2110) `tools.costs`

doc/whatsnew.rst

@@ -17,6 +17,7 @@ Next release
   - Replace solar and wind technologies with new ones (:pull:`206`).
   - Reorganize input files and incorporate `first_year.csv` data into `tech_map.csv` (:pull:`221`).
   - Reconfigure use and implementation of technology variants/modules to be more agnostic (:pull:`221`).
+  - Change cost decay to reach reduction percentage specified on the year 2100 (:pull:`227`).
 - Improve and extend :doc:`/material/index` (:pull:`218`).
 
   - Release of MESSAGEix-Materials 1.1.0 (:doc:`/material/v1.1.0`).

message_ix_models/tools/costs/decay.py

@@ -278,6 +278,12 @@ def project_ref_region_inv_costs_using_reduction_rates(
     This function uses the cost reduction rates for each technology under each scenario
     to project the capital costs for each technology in the reference region.
 
+    The changing of costs is projected until the year 2100
+    (hard-coded in this function), which might not be the same
+    as :attr:`.Config.final_year` (:attr:`.Config.final_year` represents the final
+    projection year instead). 2100 is hard coded because the cost reduction values are
+    assumed to be reached by 2100.
+
     The returned data have the list of periods given by :attr:`.Config.seq_years`.
 
     Parameters
@@ -323,7 +329,7 @@ def project_ref_region_inv_costs_using_reduction_rates(
             cost_region_2100=lambda x: x.reg_cost_base_year
             - (x.reg_cost_base_year * x.cost_reduction),
             b=lambda x: (1 - config.pre_last_year_rate) * x.cost_region_2100,
-            r=lambda x: (1 / (config.final_year - config.base_year))
+            r=lambda x: (1 / (2100 - config.base_year))
             * np.log((x.cost_region_2100 - x.b) / (x.reg_cost_base_year - x.b)),
             reference_region=config.ref_region,
         )