Environmental Engineering Reference
In-Depth Information
Table 1 GB electricity generation mix as of 2012 [
29
]; Contracted Background
TEC (MW)
a
MPP stations
Thermal eff.
Availability
Coal
0.360
0.75
27,571
22
Natural Gas
0.477
0.95
33,769
79
Nuclear
0.398
0.77
10,561
10
Wind
6,910
71
Hydro
1,626
79
Pumped Storage
6,380
4
a
'
Transmission entry capacity
'
(TEC) is a Connection and Use of System Code term that de
nes a
generator
'
s maximum allowed export capacity onto the transmission system. All companies whose
prime purpose is the generation of electricity are included under the heading
'
Major power
producers
(MPPs); they account for more than 90 % of total electricity generation. Large scale
hydro, large scale wind, and some biofuels fall within this category. Most generators of electricity
from renewable sources are
'
because of their comparatively small size, even
though their main activity is electricity generation
“
Other generators
”
Regarding load, UK of
cial statistics take
'
Electricity available
'
as the starting
point for sales of electricity to consumers. This amount re
ects the contribution
from all stations including pumped storage
P
. Electricity available in 2012
amounted to 336.96 TWh. After subtracting transmission and distribution losses
alongside theft, sales to consumers reached 308.41 TWh.
7
Value is sacri
ced
whenever load is lost. We assume VOLL = 2,500
₤
/MWh interrupted [
30
], or
2,904.44
€
/MWh.
As for the generation capacity, the second column of Table
1
shows the gen-
eration mix by fuel source as of 2012. Based on UK DECC [
35
], coal-
red stations
reach a thermal ef
ciency of 36 %, combined cycle gas turbines reach 47.7 %, and
nuclear stations 39.8 %.
“
Wind
”
denotes both offshore and onshore wind.
“
Hydro
”
stands for
owing water
through turbines from sources naturally replenished through rainfall.
“
Other renewables
”
; hydro stations generate electricity by
“
Pumped
storage
; the latter stations use off-peak electricity to
pump water to a reservoir. They then release water to generate electricity at times of
peak demand (they are not considered to be renewable sources; UK DECC [
36
]).
The next column shows the number of power stations owned or operated by Major
Power Producers classi
”
denotes
“
Other (Oil/Pumped)
”
eet of identical
average plants for each technology every year. The number and type of power
stations is expected to change signi
ed by type of fuel. Our model assumes a
cantly in the years ahead.
Maintenance and other works make plants unavailable from time to time. We
assume that natural gas plants are available 95 % of the time; nuclear plants 77 %;
and coal plants 75 %. As for renewable sources, all the stations are active in
principle but are intermittent. The time series of their metered output accounts for
their active/inactive state and load factor in a uni
ed form. We use these data to
7
UK Department of Energy and Climate Change [
35
], Table 5.5, support MC Excel spreadsheet.
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