Post on 05-Jan-2016
The infuriating inconsistency of network electricity carbon
intensity
Andrew Peacock
Heriot Watt University
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
BM – Build Margin emission rate
Assumes that the electricity reduction measure will reduce the need for future capacity
A proportion of the reduction is then assigned to the deferment of this added capacity
FIRST CONFUSION
What new plant is planned in the UK?
Installed Plant in the UK (2007/8)
0
5
10
15
20
25
30
35
40
45
Coal CCGT Nuclear Interconnector Wind
Ins
talle
d C
ap
ac
ity
(G
W)
Source: National Grid 7 year statement, 2007
Planned new plant (2013/14)
0
5
10
15
20
25
30
35
40
45
Coal CCGT Nuclear Interconnector Wind
Ins
talle
d C
ap
ac
ity
(G
W)
Source: National Grid 7 year statement, 2007
Planned new plant (to 2020)
However
Coal – 14.2 GW of new coal plant is in various stages of development
Build Margin emission rate for;
Coal (45% efficient plant) 0.776kgCO2/kWh
CCGT (50% efficient plant) 0.412kgCO2/kWh
Will coal be resurgent? Principal uncertainty – 3rd Revision of the EU Emission trading scheme
DEFRA Guidance 2007 – Build Margin Rate = 0.43kgCO2/kWh (Assumed for a CCGT Plant)
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
Operating Margin Emission Factor
Assumes that the electricity reduction measure will reduce demand
SECOND CONFUSION
What carbon intensity do we assign to the negawatts?
0.41
0.43
0.45
0.47
0.49
0.51
0.53
0.55
0.57
1994 1996 1998 2000 2002 2004 2006 2008Av
era
ge
an
nu
al c
arb
on
inte
ns
ity
(k
gC
O2/k
Wh
)System Average Carbon Intensity
0.41
0.43
0.45
0.47
0.49
0.51
0.53
0.55
0.57
1994 1996 1998 2000 2002 2004 2006 2008Av
era
ge
an
nu
al c
arb
on
inte
ns
ity
(k
gC
O2/k
Wh
)System Average Carbon Intensity
DEFRA Guidance – 5 Year rolling average – 0.523kgCO2/kWh
Not all plant will respond
If we exclude nuclear – approximate “load following”
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
1994 1996 1998 2000 2002 2004 2006 2008
Ca
rbo
n in
ten
sit
y (
kg
CO
2/k
Wh
)
5 year rolling average = 0.671kgCO2/kWh
Different Carbon intensities that could be used
Factor Description Carbon Intensity (kgCO2/kWh)
BM Efficient Coal Plant 0.776
Efficient CCGT Plant 0.412
DEFRA (CCGT plant) 0.430
OM System average 0.523
Annual “Load following” 0.671
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
World Resources Institute recommend that the grid electricity emission reduction factor should be calculated thus:
ERbaseline = ω.BM + (1-ω).OM
CO2 Emissions Saving Methodology
Third Confusion Weighting factor,
GuidanceWeighting Factor,
CFL Lighting Solar Panel – 1.5kW
DEFRA 0 0.5
World Resource Institute
0.92 0
Third Confusion Weighting factor,
Approx 2.9GW of maximum system peak demand is due to domestic lighting.
This will fall to approx 1.45GW with banning of incandescent bulbs in 2010
-200
0
200
400
600
800
1000
1200
0 4 8 12 16 20 24
Time of day (h)
An
nu
al e
ne
rgy
de
ma
nd
(k
Wh
)
Import Export Demand
No effect on system capacity
GuidanceWeighting Factor,
CFL Lighting Solar Panel – 1.5kW
DEFRA 0 0.5
World Resource Institute
0.92 0
Effect on savings from CFL Lighting and Solar-PV
0
100
200
300
400
500
600
700
800
900
CFL Lighting Solar PV
CO
2 s
av
ing
s p
er
ins
talla
tio
n
(kg
CO
2 p
a)
Using DEFRA Guidance
Effect on savings from CFL Lighting and Solar-PV
0
100
200
300
400
500
600
700
800
900
CFL Lighting Solar PV
CO
2 s
av
ing
s p
er
ins
talla
tio
n
(kg
CO
2 p
a)
Can be 76%
higher
Can be 53%
higher
Spread of possible BM and OM figures
Conclusions
Deriving a simple number for Carbon intensity of network electricity that suits all technologies is impractical and will mislead
The recognised international metric discussed here could be employed
One approach might be to assign factors to technologies based on this standard procedure
This has been a talk largely about the present – the future is more difficult still
Further Complication Time variant nature of carbon intensity
0
10
20
30
40
50
60
Time of day
De
ma
nd
(G
W)
nuclear coal ccgt gas turbine chp Interconnector oil pumped storage
Wednesday 26th January 2005
0.50
0.52
0.54
0.56
0.58
0.60
0.62
0 4 8 12 16 20 24
Time of day (h)
Ca
rbo
n in
ten
sit
y (
kg
CO
2/k
Wh
)
0
10
20
30
40
50
60
De
ma
nd
(G
W)
Time variant nature of carbon intensity
Wednesday 26th January 2005
Demand side response to reduce gradient change has the capacity to alter operating protocols that could yield reductions in CO2 intensity of network electricity
Time variant nature of carbon intensity