Post on 03-Oct-2021
Carbon footprint and biosolids treatment
Dr Bill Barber
process generated
vs. supply chain
fossil fuel use vs.
process emissions
manufacture construction
vs. operating
Carbon footprint
Embodied
Operating
+
Indirect
Direct
+
Owned
Influenced
+
Power (kWhr) Fuel
N2O, CH4
CO2e / kWhr
Emissions
Processing
Indirect Carbon Footprint
Depends on power source
Wind 0.05 Solar 0.02 – 0.04 Nuclear 0.05 Biomass 0.02 – 0.08 Gas 0.20 Coal 0.80 – 1.20
4
0
0.2
0.4
0.6
0.8
1
1.2
1960 1970 1980 1990 2000 2010 2020 2030
UK
Po
we
r G
HG
em
issi
on
fac
tor
[kgC
O2
e/k
Wh
r]
Power Emission Factors depend on energy mix
Power Emission Factors depend on energy mix
0
0.2
0.4
0.6
0.8
1
1.2
1.4
NSW + ACT VIC QLD SA WA TAS NT UK
Car
bo
n f
oo
tpri
nt
[kg
CO
2/k
Wh
r]
Coal
Gas
Manufacture Transport
N2O, CH4
Fuel
CO2e CO2e CO2e
Emissions Power
Quantity
Design
Embodied Carbon Footprint
Aggre
gate
Sand
Soil
Asp
halt
Sto
ne
Pla
ster
Concre
te
Road
Soil-
cem
ent
Hig
h s
trength
Pre
-cast
Bricks
Cla
y
Mort
ar
Pla
sterb
oard
Cla
y p
ipe
Cla
y ti
le
Tim
ber
Bitum
en
Cem
ent
Gla
ss
Hard
board
Port
land …
Paper
Carb
on S
teel
Insu
latio
n
Pla
stic
s
Copper
Pain
t
Sta
inle
ss S
teel
Alu
min
ium
Em
bo
die
d C
arb
on
Fo
otp
rin
t
Embodied Carbon Footprint
Metals complex materials fertilizers
Natural materials
Processed Natural Materials
Sustainability – Carbon Footprint
Electricity, 77%
Process Emissions,
17%
Transport, 5%
Other, 1%
Pumping +
Aeration
• Biosolids influences all of these parameters
• UK Water industry > 5 million tonnes CO2e
• Only the power industry emits more carbon footprint
WwTW Transport
N2O, CH4
Biogas
-CO2e
Fuel
CO2e CO2e CO2e CO2e
Emissions Chemicals Power
Carbon Impacts in Biosolids Carbon Footprint of Biosolids
Land Application
Emissions
N2O, CH4
CO2e
Fertilizer Disp
-CO2e
(Sequestration)
-CO2e
Landfill
Emissions
CH4
CO2e
Biogas
-CO2e
+16 CO2e -532 kg CO2e
157 kg CH4
1000 kg
39
1 k
g
609 kg 589 kg
CHP
+168 kg CO2e
+380 kg CO2e
8 kg CH4
138.9
kg C
H4
18.1
kg C
H4
20
kg
8 k
g C
H4
Primary Digestion Open secondary Digestion
Dir
ect a
tmo
sp
he
ric
em
issio
n
Dir
ect a
tmo
sp
he
ric
em
issio
n 649 kWhr
-704 CO2e -893 kg CO2e
202 kg CH4
1000 kg
50
4 k
g
496 kg
CHP
+189 kg CO2e
193 k
g C
H4
9 k
g C
H4
Primary Digestion Secondary Digestion
Dir
ect a
tmo
sp
he
ric
em
issio
n 1089 kWhr
Pre-treatment
Para
sitic
Dem
and
Carb
on
Fo
otp
rin
t
Cla
ss A
lim
ing
Raw
Dry
ing
Lim
e +
su
pp
he
at
Ra
w I
ncin
era
tion
No digestion
Th
erm
al h
yd
roly
sis
+ M
AD
Se
rie
s a
cid
ph
ase
+ M
AD
TA
D-M
AD
ATA
D
Pre
-MA
D p
aste
uri
sa
tio
n
Dig
este
d D
ryin
g
Dig
este
d In
cin
era
tio
n
Ad
va
nce
d D
ige
ste
d In
c
With digestion
Carbon Footprint of Class A Biosolids treatment
Carbon footprint breakdown
Liming Composting TH + MAD
BH + MAD TAD + MAD ATAD
Key: ( Biosolids Transport); ( Land Emissions); ( Chemicals); ( Dewatering); ( Transport Other); ( Power); ( Gas); ( Process Emissions); ( Down Time)
Carbon footprint breakdown
Liq Past + MAD Raw Drying MAD + Drying
Lime + S H Raw Incineration
MAD + Incineration
Key: ( Biosolids Transport); ( Land Emissions); ( Chemicals); ( Dewatering); ( Transport Other); ( Power); ( Gas); ( Process Emissions); ( Down Time)
- Australian government reduction target of 5% of 2000 levels by 2020
• 357 million t/CO2 e year
- Currently being measured and reported
- Carbon tax will come in force 1 July 2012
• Will cover 500 worst polluters (approx 60% of the emissions)
• This will include all large water companies
• $ 23 AUD/t carbon dioxide
Rising 2.5% per year
- Will become trade scheme 1 July 2015
Australia
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
Hunter Water
Melbourne Water
SA Water SunWater Sydney Water
Water Corp.
Car
bo
n f
oo
tpri
nt
[t C
O2
/yr]
SCOPE 2
SCOPE 1
Carbon Footprint of Australian Water Industry
Data plot using Australian Government NGER 2009/10 data
0
100,000
200,000
300,000
400,000
500,000
600,000
700,000
Hunter Water
Melbourne Water
SA Water SunWater Sydney Water
Water Corp.
Car
bo
n f
oo
tpri
nt
[t C
O2
/yr]
SCOPE 2
SCOPE 1
Carbon Footprint of Australian Water Industry
Data plot using Australian Government NGER 2009/10 data
Carbon Footprint of Australian Water Industry
Normalised (to UK) Carbon Footprint of Australian
Water Industry
Tightening Legislation
Tightening Legislation
Tightening Legislation
Case Study – New advanced digestion facility
Option 1 – New raw sludge incineration plant
Main Inputs/Outputs impacting Carbon
Contributing
Sites Dewatering Conveying
Sludge Transport
Power Chemicals
Power Chemicals Start-up Gas Combustion Air
Pre-drying Air provision Waste Heat Recovery Dust Removal Acid gas clean-up Scrubber Effluent Treatment
Power Generation
Waste Sludge Flue gas Ash Transport
Incinerator Plant
Option 2 – Advanced Digestion with existing incineration
Contributing Sites
Digestion Centre
Dewatering Conveying
Sludge Transport
Power Chemicals
Re-liquification Thickening Thermal Hydrolysis Anaerobic Digestion Liquor Treatment Dewatering Conveying CHP Plant
Power Chemicals Natural Gas
Renewable Energy Generation
Liquid Sludge Pumping
Power Chemicals Start-up Gas Combustion Air
Pre-drying Air provision Waste Heat Recovery Dust Removal Acid gas clean-up Scrubber Effluent Treatment
Power Generation
Waste Sludge
Sludge cake Export
Flue gas Ash Transport
Existing Incinerator Plant
Weight of Construction Materials
Raw Incinerator Advanced
Digestion
Weig
ht of
Co
nstr
uction
mate
rial
Steel
Concrete
Embodied Carbon
Raw Incinerator Advanced
Digestion
Em
bo
die
d C
arb
on
(C
O2e
)
Total Concrete (CO2e)
Total Steel (CO2e)
Factors Contributing to Increasing Operating Carbon
Raw
Incinerator
Advanced
Digestion
Bre
akdow
n o
f carb
on f
ootp
rint
Dewatering at DH
Land Application
Additional pumping to SG
Incinerator chemicals
Incinerator power demand
Ash transport
Downtime
Incinerator emissions
Sludge transport
Dewatering (inc liquor treatment)
Impacts and benefits on operating carbon
Raw Incinerator Advanced
Digestion
Opera
ting C
arb
on f
ootp
rint
Total
Total Benefits
Biogas production
Energy generation at
incinerator
Fertilizer displacement
Carbon sequestration
Whole Life Carbon Impact
0 10 20 30 40 50
Cu
mu
lative C
arb
on
Fo
otp
rint
Years in operation
Liming
Raw Incineration
AD
AD delay 5
AD Delay 10
Summary
- Everything we do has a carbon impact and that also includes biosolids production and processing
- Carbon footprint is made up of:
• embodied and operating
• Indirect and Direct
• Owned and influenced emissions
- Choice of technology has large impact on carbon footprint of biosolids options
- Anaerobic digestion is very influential
• Renewable energy generation
• Reduces biosolids for further processing
• Can improve dewatering so reducing transport
Thank You
bill.barber@aecom.com
44,8
70 (
Raw
Incin
era
tion)
52,230
Transport
8,640
Fuel
CO2e
Incineration
37,370
CO2e
Pow
er
Chem
icals
M
anufa
ctu
re
Em
issio
ns
N2O
Dow
ntim
e
CH
4 +
N2O
Ash
T
ransport
Gas
Dewatering
CO2e
Poly
mer
Pow
er
Manufa
ctu
re
6,220
Power Generation
CO2e
Avoided Power
7,360
29,3
00 (
Option 1
– E
xis
ting)
Dewatering
CO2e
Poly
mer
Po
we
r
Manufa
ctu
re
6,500
Lime Addition
Lime Manufacture
CO2e
CO
2
Pow
er
5,600
Transport
Fuel
CO2e
11,300
Field Application
GHG Emissions
CO2e
N2O
CH
4
16,800
Fertiliser Manufacture
CO2e
Avoided Power
10,850
40,200 29,3
00 (
Option 1
– E
xis
ting)
Advanced Digestion Carbon Footprint
1. Impact on existing digestion plant
2. Impact at existing incineration facility processing additional sludge
3. Recycling of additional Class A biosolids
4. Additional transport (double-handling)
652 (Existing Digestion)
–26,282 (New Digestion) –
26,934 (Reduction at Existing Digestion) =
SBAP – Impact at Davyhulme Impact on existing digestion plant
10,778 (Contributory land application)
1,969 (Beneficial land application) –
8,809 (Additional land application) =
Additional land application emissions
10,778 (Contributory incineration)
1,969 (Beneficial incineration) –
8,809 (Additional Incineration) =
Impact on existing incineration plant
-26,934 (Reduction at existing digestion)
3,829 (Additional land application) +
8,809 (Additional Incineration) +
–2,888 (Advanced Digestion Total) =
11,408 (Additional Transport) +
Total for Advanced Digestion Option