The document summarizes a workshop on estimating the carbon intensity of electricity grids. It discusses how carbon intensity is used to measure technology performance but is based on assumptions that may not be valid for all assessments. It questions commonly used average grid carbon intensity values and whether they accurately reflect the electricity being used. The document suggests carbon intensity likely varies over time and location and that increasing electrification may impact future grid carbon intensity.

1. ICARB workshop: Grid
Carbon Intensity
How much carbon is in a kWh?
Dr David Jenkins
Urban Energy Research Group

2. Itinerary
14.30 Coffee and welcome
15:00 Introduction to topic , Dr David Jenkins, Heriot-Watt University
15:10 Estimating Marginal Emissions Rates for Electricity Systems
Progress and Challenges, Dr Adam Hawkes, Imperial
College/AEA Tech.
15:30 Carbon intensity of electricity: towards more realistic numbers,
Prof Gareth Harrison, University of Edinburgh
15:50 Discussion point 1
16:10 Discussion point 2 Workshop discussion
16:30 Discussion point 3
16:50-17:00 Closing remarks

3. Introduction to topic
 “Carbon” is now used as a metric for a range of
technology performances
 Buildings
 Transport
 Industry
 Energy use (kWh) can be measured but carbon
is estimated based on series of assumptions
 But how valid are these assumptions?
 Are they fit-for-purpose for all carbon assessments?

4. Grid Carbon Intensity
 National averages are often used for grid carbon
intensity
 kgCO2/kWh
 These figures are generally trusted without too
much interrogation but:
 0.422 kgCO2/kWh (SAP, 2005)
 0.568 kgCO2/kWh (SAP, 2005, grid-displaced)
 0.52 kgCO2/kWh (DEFRA, 2007)
 0.43 kgCO2/kWh (DECC, 2008)
 0.517 kgCO2/kWh (SAP, 2009)
 0.529 kgCO2/kWh (SAP, 2009, grid-displaced)

5. Grid Carbon Intensity
1.2
Grid carbon intensity (kgCO2/kWh)
1
0.8
0.6
2009
0.4
2005
0.2
0
1965 1970 1975 1980 1985 1990 1995 2000 2005 2010
Year

6. Technology performance - GSHP
100
80
Annual CO2 savings c.f. gas boiler (%)
60
40
35degC
45degC
55degC
20
0
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
-20 DEFRA 2007 = 0.52
"Displaced from grid"
SAP 2005 = 0.43 = 0.568
-40
Grid CO2 intensity (kgCO2/kWh)

7. Is our understanding sufficient?
 Are the official annual average grid carbon intensities
indicative of the electrical energy that we use? Why, in
previous years, have these figures varied so much?
 Do we need to think about how carbon intensity
varies over the year, and throughout a given day, to
understand the carbon impact of specific technologies?
 As we electrify both transport and energy use in
buildings, what impact will this have on the electrical
infrastructure of the UK and, in turn, the carbon
intensity of electricity generation?