Regional Carbon Intensity Forecast

This dataset contains regional carbon intensity forecast for the GB electricity system.The carbon intensity of electricity is a measure of how much CO2 emissions are produced per kilowatt hour of electricity consumed.<br/><br/>

Publicly Available 
 
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Authors: Dr Alasdair R. W. Bruce, Lyndon Ruffa, James Kelloway, Fraser MacMillan, Prof Alex Rogersb 
a St. Catherine’s Lodge, Wokingham, NESO, b Department of Computer Science, University of Oxford 
Issue: May 2024 
 
National Energy System Operator (NESO), in partnership with Environmental Defense 
Fund Europe and WWF, has developed a series of Regional Carbon Intensity forecasts for 
the GB electricity system, with weather data provided by the Met Office. 
Introduction 
NESO’s Carbon Intensity API has been extended 
to include forecasts for 17 geographical regions of 
the GB electricity system up to 48 hours ahead of 
real-time [1]. It provides programmatic and timely 
access to forecast carbon intensity. This report 
details the methodology behind the regional 
carbon intensity estimates. For more information 
about the Carbon Intensity API see here. 
What’s included in the forecast 
The Regional Carbon Intensity forecasts include 
CO2 emissions related to electricity generation 
only. The forecasts include CO2 emissions from all 
large metered power stations, interconnector 
imports, transmission and distribution losses, and 
accounts for regional electricity demand, and both 
regional embedded wind and solar generation.  
This approach considers the carbon intensity of 
electricity consumed in each region and uses peer 
reviewed carbon intensity factors of GB fuel types 
[2][3]. The carbon intensity factors used in this 
data service are based on the output-weighted 
average efficiency of generation in GB and 
DUKES CO2 emission factors for fuels [4]. GB 
regions are divided according to Distribution 
Network Operator (DNO) boundaries, see Figure 
1. 
 
 
Carbon Intensity 
Regional Forecast Methodology 
Figure 1: GB Regions and IDs for the API. 

 
 
 
 
Publicly Available 
 
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Methodology 
A reduced GB network model is used to calculate 
the CO2transfers between importing/exporting 
regions, which takes into account the impedance 
characteristics of the network, constraints, and 
system losses. See Figure 2. 
Estimating the carbon intensity of the electricity 
consumed in each region requires modelling the 
power flows between importing/exporting regions 
and the carbon intensity of those power flows. The 
estimated regional carbon intensity of generation 
uses metered data for each fuel type. 
Step 1: Forecasting ahead 
The demand (𝑃𝑖
𝑑𝑒𝑚), generation (𝑃𝑖
𝑔𝑒𝑛), and 
generation by fuel type for each region is forecast 
two days ahead at 30-min temporal resolution 
using an ensemble of state-of-the-art supervised 
Machine Learning (ML) algorithms. The forecasts 
are updated every 30 mins using a nowcasting 
technique to adjust the forecasts a short period 
ahead. 
Step 2: Calculating the generation and CO2 
emissions at each node 
The GB power system is divided into regions and 
represented as an N-bus network connected by 
lines. The power generation at bus is the sum of 
the generation in that region: 
𝑃𝑖
𝑔𝑒𝑛= ∑𝑃𝑖,𝑔
𝑔𝑒𝑛
𝐺
𝑔=1
 
The CO2 emissions of each generator is estimated 
to calculate the CO2 emissions from generation in 
each region:  
𝐸𝑖
𝑔𝑒𝑛= ∑𝑃𝑖,𝑔
𝑔𝑒𝑛
𝐺
𝑔=1
× 𝑐𝑔 
Where 𝑐𝑔is the carbon intensity of generator’s fuel 
type, see Table 1. Then, the carbon intensity of 
generation 𝐶𝑖
𝑔𝑒𝑛 is calculated at each node:  
𝐶𝑖
𝑔𝑒𝑛= 𝐸𝑖
𝑔𝑒𝑛
𝑃𝑖
𝑔𝑒𝑛 
Step 3: Calculate power imbalance between 
exporting and importing regions 
The power imbalance 𝑃𝑖 at bus 𝑖 is calculated by 
subtracting the regional power generation 𝑃𝑖
𝑔𝑒𝑛 
from the regional power demand 𝑃𝑖
𝑑𝑒𝑚: 
𝑃𝑖= 𝑃𝑖
𝑔𝑒𝑛−𝑃𝑖
𝑑𝑒𝑚 
A region is exporting power if 𝑃𝑖> 0 and importing 
power if 𝑃𝑖< 0. 
Step 4: Three-phase Newton Raphson AC power 
flow 
A network of 𝑁 buses and 𝐿 lines is described by 
an 𝐿 × 𝑁 incidence matrix 𝐴, such that 𝐴𝑙,𝑖= −1 if 
line 𝑙 ends at bus 𝑖, 𝐴𝑙,𝑗= −1 if line 𝑙 ends at bus 𝑗, 
and 𝐴𝑙,𝑘= 0 if 𝑘 ≠𝑖≠𝑗. The power equations for 
the AC power flow in polar form are: 
𝑃𝑖= |𝑉𝑖| ∑|𝑉𝑗|
𝑁
𝑗=1
|𝑌𝑖𝑗| cos(𝛿𝑖−𝛿𝑗−𝜃𝑖𝑗) 
𝑄𝑖= |𝑉𝑖| ∑|𝑉𝑗|
𝑁
𝑗=1
|𝑌𝑖𝑗| sin(𝛿𝑖−𝛿𝑗−𝜃𝑖𝑗) 
Figure 2: Electrical representation of reduced GB network. 

 
 
 
 
Publicly Available 
 
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Where |𝑌𝑖𝑗| is the admittance, |𝑉𝑖| and |𝑉𝑗| are the 
bus voltages, 𝛿𝑖 and 𝛿𝑗 are the phase angles at 
buses 𝑖 and 𝑗 respectively. 
A three phase Newton Raphson iteration is 
performed to calculate the active and reactive 
power flows between buses 𝑖 and 𝑗. 
Step 5: Calculate the carbon intensity of power 
flows 
Once the inter-regional power flows have been 
determined from the power flow analysis, it is 
possible to calculate the carbon intensity of power 
flows through every line. 
T

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