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Understanding Emissions Data

OpenElectricity provides comprehensive emissions data for the Australian electricity grid, calculating CO₂ emissions from electricity generation using facility-specific emissions intensity factors. This guide explains how emissions are calculated, data sources, and how to access the data.

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What are Emissions?

Emissions in the electricity sector refer to greenhouse gases, primarily carbon dioxide (CO₂), released during electricity generation. Different generation technologies have vastly different emissions profiles:
  • Coal: High emissions (0.7-1.4 tCO₂/MWh)
  • Natural Gas: Moderate emissions (0.4-0.6 tCO₂/MWh)
  • Renewables: Zero operational emissions (solar, wind, hydro)
  • Biomass: Variable emissions depending on fuel source

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How OpenElectricity Calculates Emissions

OpenElectricity calculates emissions at the unit level using the following formula: Emissions=Energy Generated×Emissions Intensity Factor\text{Emissions} = \text{Energy Generated} \times \text{Emissions Intensity Factor} Where:
  • Emissions are measured in tonnes of CO₂ (tCO₂)
  • Energy Generated is measured in megawatt-hours (MWh)
  • Emissions Intensity Factor is measured in tCO₂/MWh

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Detailed Calculation

For each generation unit at each time interval: Eunit=Gunit×EFunitE_{unit} = G_{unit} \times EF_{unit} Where:
  • EunitE_{unit} = Emissions from the unit (tCO₂)
  • GunitG_{unit} = Energy generated by the unit (MWh)
  • EFunitEF_{unit} = Unit’s emissions factor (tCO₂/MWh)
Total emissions for a facility, region, or network are calculated by summing individual unit emissions: Etotal=∑i=1nEunit,iE_{total} = \sum_{i=1}^{n} E_{unit,i} The aggregate emissions intensity for a region or network is: EIaggregate=∑i=1nEunit,i∑i=1nGunit,iEI_{aggregate} = \frac{\sum_{i=1}^{n} E_{unit,i}}{\sum_{i=1}^{n} G_{unit,i}}

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Implementation Details

The emissions calculation is implemented in the facility aggregation pipeline (opennem/aggregates/facility_interval.py): 
-- Calculate emissions for each unit
CASE
    WHEN sum(fs.energy) > 0 THEN
        coalesce(round(sum(u.emissions_factor_co2 * fs.energy), 4), 0)
    ELSE 0
END as emissions,

-- Calculate emissions intensity
CASE
    WHEN sum(fs.energy) > 0 THEN
        coalesce(round(sum(u.emissions_factor_co2 * fs.energy) / sum(fs.energy), 4), 0)
    ELSE 0
END as emissions_intensity

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Data Sources

OpenElectricity sources emissions intensity factors from authoritative Australian government agencies:

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Primary Sources

  1. AEMO (Australian Energy Market Operator)
    • Provides emissions factors for NEM generators
    • Updated annually in the Integrated System Plan (ISP)
    • Includes technology-specific and unit-specific factors
  2. Clean Energy Regulator (CER)
    • National Greenhouse and Energy Reporting (NGER) scheme data
    • Facility-level emissions reporting
    • Verified emissions data for major generators
  3. State Environmental Agencies
    • WEM (Western Australia) emissions data
    • State-specific emissions reporting

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Data Quality

Emissions factors are assigned with source attribution:
  • aemo: Direct from AEMO publications
  • cer: From Clean Energy Regulator NGER data
  • opennem_estimated: Estimated based on fuel type and technology

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Available Metrics

OpenElectricity provides emissions data at multiple levels:

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Network Level

  • Total emissions by network (NEM, WEM)
  • Emissions intensity (tCO₂/MWh)
  • Historical trends and patterns

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Regional Level

  • Emissions by network region (NSW1, QLD1, VIC1, SA1, TAS1)
  • Regional emissions intensity
  • Inter-regional emissions flows

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Facility Level

  • Individual facility emissions
  • Unit-level emissions where available
  • Technology-specific emissions profiles

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Accessing Emissions Data

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Via the API

Emissions data is available through multiple API endpoints: Network Emissions: 
const response = await client.getNetworkData(
  "NEM",
  ["emissions", "emissions_intensity"],
  {
    interval: "1h",
    dateStart: "2024-01-01",
    dateEnd: "2024-01-31",
    primaryGrouping: "network_region"
  }
)
Facility Emissions: 
const response = await client.getFacilityData(
  "NEM",
  ["ERARING", "BAYSW1"],
  ["emissions"],
  {
    interval: "1d",
    dateStart: "2024-01-01"
  }
)

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Via the Website

Emissions data is displayed on:
  • Network pages: Total grid emissions and intensity
  • Facility pages: Individual facility emissions profiles
  • Technology pages: Emissions by generation technology

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Use Cases

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Carbon Accounting

Track the carbon intensity of electricity consumption for:
  • Corporate sustainability reporting
  • Scope 2 emissions calculations
  • Time-of-use optimization

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Grid Analysis

Understand emissions patterns:
  • Daily and seasonal variations
  • Impact of renewable generation
  • Regional differences

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Policy Analysis

Support decision-making with:
  • Emissions reduction tracking
  • Technology transition monitoring
  • Market mechanism evaluation

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Important Considerations

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Scope Limitations

  • OpenElectricity reports operational emissions only (Scope 1)
  • Does not include lifecycle emissions from construction or decommissioning
  • Does not include upstream fuel extraction emissions

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Time Resolution

  • 5-minute intervals: Instantaneous emissions rates
  • Hourly/Daily: Total emissions for the period
  • Use appropriate metrics for your analysis timeframe

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Interconnector Flows

  • Emissions can be “imported” or “exported” between regions
  • Regional emissions include local generation only
  • Consider interconnector flows for consumption-based accounting

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Future Enhancements

OpenElectricity continues to improve emissions data:
  • More granular unit-level factors
  • Lifecycle emissions estimates
  • Consumption-based emissions tracking
  • International emissions factors for comparison