GHG Accounting

model/ch4calcs.py

@@ -1,6 +1,6 @@
 """CH4 Calcs module.
 
-Computes reductions in CO2-equivalent emissions.
+Computes reductions for methane in individual gas units and CO2-equivalent emissions.
 """
 
 from functools import lru_cache
@@ -9,6 +9,9 @@
 
 from model.data_handler import DataHandler
 from model.decorators import data_func
+from model import emissionsfactors
+
+
 
 class CH4Calcs(DataHandler):
     """CH4 Calcs module.
@@ -26,67 +29,128 @@ def __init__(self, ac, soln_net_annual_funits_adopted,
         self.soln_pds_direct_ch4_co2_emissions_saved = soln_pds_direct_ch4_co2_emissions_saved
 
 
+
     @lru_cache()
     @data_func
-    def ch4_tons_reduced(self):
-        """CH4 reduced, in tons.
-           replace gas_ch4_step = `gas_tons_ch4' * `e'^(-(time_from_present - `n')/12)
-           SolarPVUtil 'CH4 Calcs'!A10:K56
+    def ch4_co2eq_tons_reduced(self):
+        """CH4 reduced, in tons of CO2eq per year.
         """
         if self.ac.ch4_is_co2eq:
             result = self.soln_net_annual_funits_adopted * 0
         else:
             result = self.soln_net_annual_funits_adopted * self.ac.ch4_co2_per_funit
         result.loc[:self.ac.report_start_year - 1] = 0.0
         result.loc[self.ac.report_end_year + 1:] = 0.0
+        result.name = "ch4_co2eq_tons_reduced"
+        return result
+
+    @lru_cache()
+    def ch4_tons_reduced(self):
+        """CH4 reduced from the RRS model, in tons CH4 per year.
+        """
+        if self.ac.ch4_is_co2eq:
+            ef = emissionsfactors.CO2Equiv(self.ac.co2eq_conversion_source)
+            result = (self.soln_net_annual_funits_adopted * self.ac.ch4_co2_per_funit)/ef.CH4multiplier
+        else:
+            result = self.soln_net_annual_funits_adopted * self.ac.ch4_co2_per_funit
+        result.loc[:self.ac.report_start_year - 1] = 0.0
+        result.loc[self.ac.report_end_year + 1:] = 0.0
         result.name = "ch4_tons_reduced"
         return result
+
 
 
     @lru_cache()
-    def avoided_direct_emissions_ch4_land(self):
-        """CH4 emissions avoided, in tons
-           replace gas_ch4_step = `gas_tons_ch4' * `e'^(-(time_from_present - `n')/12)
-           Improved Rice 'CH4 Calcs'!A12:K58
+    def avoided_direct_emissions_ch4_co2eq_land(self):
+        """CH4 emissions avoided from the land model, in tons of CO2eq per year
         """
         result = self.soln_pds_direct_ch4_co2_emissions_saved.copy(deep=True)
         result.loc[:self.ac.report_start_year - 1] = 0.0
         result.loc[self.ac.report_end_year + 1:] = 0.0
+        result.name = "avoided_direct_emissions_ch4_co2eq_land"
+        return result
+
+
+
+    @lru_cache()
+    def avoided_direct_emissions_ch4_land(self):
+        """CH4 direct emissions avoided, in tons per year
+        """
+        ef = emissionsfactors.CO2Equiv(self.ac.co2eq_conversion_source)
+        result = self.soln_pds_direct_ch4_co2_emissions_saved.copy(deep=True) / ef.CH4multiplier
+        result.loc[:self.ac.report_start_year - 1] = 0.0
+        result.loc[self.ac.report_end_year + 1:] = 0.0
         result.name = "avoided_direct_emissions_ch4_land"
         return result
+
+
+
+    @lru_cache()
+    def ch4_megatons_avoided_or_reduced(self):
+        """CH4 emissions avoided or reduced, in megatons per year (units needed for the FaIR model). A key result!
+        """
+        if self.soln_pds_direct_ch4_co2_emissions_saved is not None:
+            ch4_tons = self.avoided_direct_emissions_ch4_land()
+        else:
+            ch4_tons = self.ch4_tons_reduced()
+        result = ch4_tons * 0.000001
+        result.name = "ch4_megatons_avoided_or_reduced"
+        return result
+
 
 
     @lru_cache()
-    def ch4_ppb_calculator(self):
+    def ch4_ppb_calculator_avoided_or_reduced(self):
         """Parts Per Billion reduction calculator for CH4.
-
            Each yearly reduction in CH4 (in metric tons) is modeled as a discrete avoided pulse.
            A Simplified atmospheric lifetime function for CH4 is taken from Myhrvald and Caldeira
            (2012). Atmospheric tons of CH4 are converted to parts per billion CH4 based on the
            molar mass of CH4 and the moles of atmosphere.
-
-           SolarPVUtil 'CH4 Calcs'!A64:AW110
         """
         if self.soln_pds_direct_ch4_co2_emissions_saved is not None:
             ch4_tons = self.avoided_direct_emissions_ch4_land()
         else:
             ch4_tons = self.ch4_tons_reduced()
-
         col_years = np.arange(2015, 2061)
         index_years = ch4_tons.index.values
-
         deltas = index_years.reshape(-1, 1) - col_years.reshape(1, -1) + 1
-
         vals = np.exp( - deltas / 12) * ch4_tons.loc[col_years, "World"].values.reshape(1, -1)
         vals[deltas < 1] = 0 # Overwrite values for negative deltas
-
         total = vals.sum(axis=1).reshape(-1, 1)
         ppb = total / (16.04 * 1.8 * 10 ** 5)
+        ppb_calculator = pd.DataFrame(np.concatenate([ppb, total, vals], axis=1),
+                                    columns=["PPB", "Total"] + list(col_years),
+                                    index=ch4_tons.index.copy(),
+                                    dtype=np.float64
+                                    )
+        ppb_calculator.name = "ch4_ppb_calculator_avoided_or_reduced"
+        return ppb_calculator
 
+
+
+    @lru_cache()
+    def ch4_ppb_calculator(self):
+        """Parts Per Billion reduction calculator for CH4 using CO2eq.
+            This is the original way drawdown was calculating the concentration of methane 
+            in the atmosphere. This way is incorrect since the equation taken from Myhrvald and Caldeira (2012) 
+            assumes metric tons are converted to ppb, NOT CO2eq tons of methane (like it is done here).
+        """
+        if self.soln_pds_direct_ch4_co2_emissions_saved is not None:
+            ch4_tons = self.avoided_direct_emissions_ch4_co2eq_land()
+        else:
+            ch4_tons = self.ch4_co2eq_tons_reduced()
+        col_years = np.arange(2015, 2061)
+        index_years = ch4_tons.index.values
+        deltas = index_years.reshape(-1, 1) - col_years.reshape(1, -1) + 1
+        vals = np.exp( - deltas / 12) * ch4_tons.loc[col_years, "World"].values.reshape(1, -1)
+        vals[deltas < 1] = 0 # Overwrite values for negative deltas
+        total = vals.sum(axis=1).reshape(-1, 1)
+        ppb = total / (16.04 * 1.8 * 10 ** 5)
         ppb_calculator = pd.DataFrame(np.concatenate([ppb, total, vals], axis=1),
                                     columns=["PPB", "Total"] + list(col_years),
                                     index=ch4_tons.index.copy(),
                                     dtype=np.float64
                                     )
-        ppb_calculator.name = "ch4_ppb_calculator"
+        ppb_calculator.name = "ch4_ppb_calculator_co2eq"
         return ppb_calculator
+