Grid Emissions Factors

We have recently been asked several questions about Grid Emissions Factors. Of which, the most popular question is “Why are there differences between eTool default Grid Emissions Factors and National Grid figures?”. This support post sheds some lights into where default eTool Grid Emissions Factors come from, what goes into the calculations for Grid Emissions Factors and why these number are different from figures published by Governments. 

Jump to the following sections in this post:


Grid Emissions Factors data sources

eTool Grid Emissions Factors data is provided by Life Cycle Strategies and Ecoinvent. For more information, please refer to this post: What LCI Data Sources Does eTool Use

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Reasons behind the discrepancy between eTool default Grid Emissions Factors and National Grid figures

GHG Protocol was originally designed immediately after Kyoto. There was some emphasis to ensure it was fit for nations to quantify emissions for their whole economy.  It had to meet the aims of Kyoto being for each nation to measure and report and ultimately reduce national emissions. As such, the standard needed to ensure that accounting at a corporate level allowed national inventory to avoid double counting.  Hence, the introduction of Scope 1, 2 and 3.  

LCA is very different, the intent is to quantify impacts within the chosen scope and system boundary such that any strategy to reduce the impacts may be considered. In that respect, LCA has no “Scope 1, 2, 3” boundaries. This affects the electricity factors in several ways. The example below demonstrates the electricity factors that are considered in the grid emissions calculation between National Greenhouse and Energy Reporting Scheme (NGERS) and LCA.

  1. Combustion of fuels: NGERS Scope 2 and LCA (Note that boundaries, assumptions, methods of the assessment can be different)
  2. Upstream impact of fuels (e.g. gas field fugitive emissions): NGERS* Scope 3 and LCA
  3. Distribution and Transmission Losses: NGERS* Scope 3 and LCA
  4. Embodied Impacts of Distribution and Transmission Infrastructure: LCA only

*If reported in Appendix “Electricity emission factors for end users” Table 46: Scope 2 and 3 emissions factors – consumption of purchased electricity by end users

For the eTool default grid emissions factors, there are emissions factors for ‘Energy Sources’ (e.g. combustion of black coal for electricity, wind for electricity, etc.,) and for ‘Energy Source Infrastructure’. The Energy Source Infrastructure is the embodied impacts of the grid. The way the grid emissions are determined is by adding up the impacts of the energy sources in the proportions of the grid mix (e.g. 40% black coal, 25% gas, 15% wind, 10% solar…) along with the infrastructure impacts. Therefore, the emission factors are not aligned with National Grid figures as they do not account for transmission and distribution losses, or inclusion of grid network embodied impacts.

In eTool, our grids take into account transmission and distribution losses, grid mixes and the embodied emissions of the infrastructure for energy generation & distribution such as cables, power station buildings, generators, hydro, PV, wind turbines etc.

It is important to note that even though the Grid Emission Factors are calculated based on ‘Energy Sources’ and ‘Energy Source Infrastructure’, the figures are not simply generated by adding these two. Other factors such as the proportions of the grid mix, transmission and distribution losses, etc. are also taken into account.

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How to investigate eTool default Emissions Factors for different Grids

If you wish to investigate eTool default Emission Factors for different Grids, you can do this by following the steps below:

1. Make sure you are using the latest LCI Source dataset in the Project Level.

 

2. Change the Predicted Service Life of your study to 1 year. For more information on service life, refer to this support post.


3. Click into the ‘Operational Energy’ category in your design and click the green ‘+Add Operational Energy‘ button at the top right corner.


4. Enter the inputs for 1000kWh/year of electricity using the grid that you want to find out the emissions factor for.

5. Click ‘Save’.

6. The GWP impact is your emissions factor in kgCO2e/GWh (or divide by 1000 to get kgCO2e/kWh).

 

NOTE:

  • You can even compare different grids by adding different inputs with different grids, however for a comparison with IMPACT dataset you will need to create a whole new project that uses the IMPACT dataset. Please read this link for why.
  • The emissions factor will vary between different LCI versions of the dataset even if it’s the same grid. Please use the latest version of the dataset for the most accurate figures.
  • Decarbonised grids (i.e. SAP 10 etc) will not have a fixed emissions factor since this assumes a carbon intensity that decreases over time and is not static. Therefore, please do not use decarbonised grids to compare emissions factors with other non-decarbonised grids.

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