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Configure Energy Share Requirements

Energy Share Requirements (ESR) are constraints that require a minimum fraction of load to be served by eligible resources. They are how PowerGenome models Renewable Portfolio Standards (RPS) and Clean Energy Standards (CES).

This guide walks through setting up ESR constraints and assigning resource eligibility.

Prerequisites

  • A working PowerGenome settings folder (see Getting Started)
  • An extra_inputs folder referenced by input_folder in settings

How ESR constraints work

An ESR constraint says: "At least X% of load in zone Z must be served by eligible resources for constraint N."

Two inputs define each constraint:

  1. emission_policies.csv — sets the minimum fraction per zone per constraint
  2. model_tag_values (ESR tags) — marks which resources are eligible for which constraint

PowerGenome writes these to Energy_share_requirement.csv (zone requirements) and Resource_energy_share_requirement.csv (resource eligibility) in the GenX output.

Step 1: Create the emission policies CSV

In your extra_inputs folder, create emission_policies.csv. The required columns are case_id, year, and region. Additional columns define policy constraints.

Column naming:

  • ESR_<N> — energy share requirement constraint N (fraction, e.g. 0.5 = 50%)
  • CO_2_Cap_Zone_<N> — marks zone as part of CO₂ cap constraint N (1 = included)
  • CO_2_Max_Mtons_<N> — CO₂ cap in million metric tons for constraint N

Single-region example (RPS applied to all zones equally)

case_id,year,region,ESR_1
all,2030,all,0.50
all,2040,all,0.70
all,2050,all,0.90

Using region = all applies the same policy fraction to every model region.

Multi-region example (different RPS per zone)

case_id,year,region,ESR_1,ESR_2
all,2030,CA_N,0.60,0.80
all,2030,CA_S,0.60,0.80
all,2030,AZ,0.15,0.00
all,2040,CA_N,0.80,0.90
all,2040,CA_S,0.80,0.90
all,2040,AZ,0.25,0.00

Multi-case example

Use case_id = all when the same policy applies to all scenario cases. Use a specific case_id to vary policies across scenarios:

case_id,year,region,ESR_1
all,2030,all,0.50
high_policy,2030,all,0.70
low_policy,2030,all,0.30

Copy policies from another case

Use copy_case_id to reuse another case's policies rather than duplicating rows:

case_id,year,region,copy_case_id,ESR_1
baseline,2030,all,,0.50
alternative,2030,all,baseline,

alternative will use the same ESR_1 value as baseline.

Step 2: Point settings to the file

# settings/policies.yml
input_folder: extra_inputs
emission_policies_fn: emission_policies.csv

Step 3: Define which resources are eligible

In model_tag_values in settings, add ESR tags. The tag names must match the column names in your CSV (ESR_1, ESR_2, etc.):

model_tag_names:
  - THERM
  - VRE
  - MUST_RUN
  - STOR
  - HYDRO
  - ESR_1    # RPS: renewable energy requirement
  - ESR_2    # CES: clean energy standard

model_tag_values:
  ESR_1:
    LandbasedWind: 1
    OffShoreWind: 1
    UtilityPV: 1
    ResPV: 1
    Hydroelectric: 1
    Geothermal: 1
    NaturalGas: 0
    Coal: 0
    Nuclear: 0

  ESR_2:
    LandbasedWind: 1    # Eligible for CES
    OffShoreWind: 1
    UtilityPV: 1
    Nuclear: 1          # Nuclear counts as clean
    NaturalGas_CCS: 1   # Gas with CCS may count as clean
    NaturalGas: 0
    Coal: 0

Only resources with tag value 1 count toward the corresponding constraint.

Tag names must be in model_tag_names

Any tag name you use in model_tag_values must also be listed in model_tag_names. If you add ESR_1 to model_tag_values but not model_tag_names, PowerGenome will raise an error.

Step 4: Clean Energy Standard (CES) credits

For a CES — where resources earn fractional credits based on their emission rate relative to coal — enable the ESR_CES_numerator option:

ESR_CES_numerator: true

When enabled, resources earn a credit equal to (1 - emission_rate / coal_emission_rate) instead of a binary 0/1 flag. A zero-emission resource earns a credit of 1.0; a resource emitting half of coal earns 0.5.

Verification

After running PowerGenome, check the output:

policies/Energy_share_requirement.csv — should have one row per zone and one ESR_<N> column with the fraction you specified.

resources/policy_assignments/Resource_energy_share_requirement.csv — should have one row per resource with ESR_<N> = 1 for eligible resources and 0 for others.

Cross-check that the technologies you expect to be eligible are marked 1.

Troubleshooting

ESR columns missing from output

Confirm emission_policies_fn is set in settings and the file is in input_folder. If the CSV has no ESR_* columns, no ESR output is produced.

Resources not marked as eligible

Check that the technology name in model_tag_values is a substring of the resource names in your output. Technology matching is case-insensitive. Use Generators_data.csv (or the equivalent resources CSV) to see actual resource names, then adjust tag key strings accordingly.

Wrong fraction applied to a region

If using region = all, the same value is applied everywhere. Switch to per-region rows if zones need different fractions.