Upgas università Firenze

25 Maggio 2012 – TERRAFUTURA- Firenze - Italy
Processi innovativi per l’upgrading del biogas – Innovative processes for biogas upgrading
1
UPGAS-LOWCO2
LIFE08/ENV/IT/000429
Ing. Lidia Lombardi
Dipartimento di Energetica
“Sergio Stecco”
Università degli Studi di Firenze

Economic analysis
Selected operative conditions AwR - BABIU
Reference size definition AwR - BABIU
Input and output flows AwR - BABIU
Sizing and capital costs AwR - BABIU
Operation costs AwR - BABIU
Upgrading specific cost AwR - BABIU
Conclusions and future developments
2

AwR: selected operative conditions
3
Low alkali
concentration in the
absorbing solution
(2,8 eq./l)
Solution/biogas
ratio:
12 l/Nm3
Regeneration
efficiency: 60-65%
Low alkali
concentration in the
absorbing solution
(3,8 eq./l)
Solution/biogas
ratio:
9 l/Nm3
Regeneration
efficiency: 50%

AwR: reference size
4
Biogas Nm3/h 50 100 150 200 250 300 350 400 450 500 1.000
APC kg/h 190 379 569 758 917 1.138 1.327 1.517 1.706 1.896 3.792
APC* t/year 1.368 2.729 4.097 5.458 6.826 8.194 9.554 10.922 12.283 13.651 27.302
*7.200 h/y
WtE  70.000 ÷ 140.000 t/y
APC ≈ 3%
APC  2.100 ÷ 4.200 t/y
2-3 WtE plants
km
CaO based
250 Nm3/h

AwR: schematic layout on industrial scale
5
BIOGAS
BIOMETHANE
WATER MAKE-UP
REACTANT MAKE-UP
WATER
APC
WATER
WASTE WATER
WASTE WATER
REGENERATED SOLUTION
PRE-WASHING TANK
POST-WASHING TANK
CARBONATION/
REGENERATION TANK
FILTER PRESS 1
FILTER PRESS 2
FILTER PRESS 3
APC
ABSORPTION
COLUMN
COMPRESSOR

AwR: input/output flows (alkali 3,8 eq./l)
6
Absorption
KOH NaOH
Entering biogas flow rate Nm3/h 250
CO2 % vol. 50
CH4 % vol. 50
Exiting biomethane flow rate Nm3/h 126
CO2 % vol. 98
CH4 % vol. 2
Solution flow rate l/h 2.250
KOH/NaOH content % w/w 18 13
Overall regeneration efficiency % 50 50
KOH/NaOH make up kg/h 235 167
Water make-up l/h 1.072 1.118
Regeneration
Required APC kg/h 917
Water for pre-washing l/h 4.587
Water for post-washing l/h 3.697
Waste water from pre-washing l/h 4.041
Waste water from post-washing l/h 3.688
Output APC kg/h 1.279
Captured CO2 kg/h 148-222

AwR: economic balance (alkali 3,8 eq./l)
7
Specific cost KOH NaOH
Capital cost 762.850
Annual amortization 103.647
Maintenance 26.700
Financial remuneration 26.700
Make-up reactants
1,2 €/kg 2.032.312 -
0,66 €/kg - 794.069
Pre-washing water 0,29 €/m3 9.446
Post-washing water 0,29 €/m3 7.614
Make-up water 0,29 €/m3 2.207
WWT pre-washing 52 €/m3 1.512.855
WWT post-washing 52 €/m3 1.380.855
Labour cost 50.000 €/person 125.000
Electricity 0,17 €/kWh 135.775
APC transport [50 km] 0,129 €/(t km) 59.381
APC final disposal 70 €/t 644.445
Income from entering APC 220 €/t -1.453.244
34-17%
25-32%
23-29%
11-14%

AwR: input and output APC
8
AwR
APC
hazardous waste
≈ 220 €/t
(income)
APC
non hazardous waste
≈ 70 €/t
(cost)
BIOGAS
BIOMETHANE

AwR: upgrading specific cost (alkali 3,8 eq./l)
9
KOH NaOH
€/Nm3 of entering biogas 2,56 1,88
€/Nm3 of biomethane 5,08 3,71
€/kWh of biomethane 0,53 0,39
WWT post-washing 52 €/m3 1.380.855
Make-up reactants
1,2 €/kg 2.032.312 -
0,66 €/kg - 794.069
32%
29%
To comply with non-hazardous limits
To remove Cl-
USP < 0,10
€/kWh

AwR: upgrading specific cost - improvement
10
Carbonation Post-washingPre-washing
WATER
WASTE WATER
Cl- ≈ 8.000 mg/l
WASTE WATER
Cl- ≈ 47.000 mg/l

AwR: upgrading specific cost - improvement
11
KOH NaOH
WWT post-washing - -
The possibility of selling the CO2 allowance within the CO2 emission trading mechanism was
considered. A basic allowance of 10 €/t of CO2 was assumed.
About 1.065-1.597 t of CO2 may be stored per year, meaning about 10.650-15.970 €/y, which,
unfortunately, do not affect considerably the overall balance.
Which price for CO2 allowance in the future?

AwR: upgrading specific cost (alkali 2,8 eq./l)
12
KOH NaOH
KOH NaOH
2,56 1,88
5,08 3,71
0,53 0,39
KOH NaOH
KOH NaOH
1,79 1,10
3,55 2,19
0,37 0,23

BABIU: selected operative conditions
13
2 Nm3/(h·t)
Duration:
6 hours
CH4 > 98% vol.

BABIU: reference size
14
* 300 d/y
Biogas Nm3/h 50 100 150 200 250 500 1.000
BA t/d 100 200 300 400 500 1.000 2.000
BA t/year 30.000 60.000 90.000 120.000 150.000 300.000 600.000
WtE  70.000 ÷ 140.000 t/y
BA ≈ 20%
BA  14.000 ÷ 28.000 t/y
2-4 WtE plants
km
100 Nm3/h 720.000 Nm3/y

BABIU: schematic layout on industrial scale
15
Discontinous operation (6 h/day)
BIOGAS
COMPRESSOR
BIOGAS STORAGE
CARBONATION TANK 1
CARBONATION TANK 2
CRUSHER
ENTERING BA
CARBONATED BA
≈150 m3
4 ≈ 2X2X7 m
100 Nm3/h x 24 h
400 Nm3/h x 6 h
400Nm3/h
/ 2 Nm3/(ht)
≈200 t
N2 STORAGE
N2
BIOMETHANE
BIOMETHANE

BABIU: economic balance
16
Specific cost Amount
Capital cost 926.349
Annual amortization 125.861
Maintenance 32.422
Financial remuneration 32.422
Fuel 1,29 €/l 34.621 l/y 44.662
Nitrogen 0,4 €/l 74.201 l/y 29.480
Labour cost 50.000 €/person 2 person 100.000
Electricity 0,17 €/kWh 67.500 kWh/y 11.475
BA transport [50 km] 0,129 €/t·km 60.000 t/y 387.000
BA final disposal 70 €/t 60.000 t/y 4.200.000
Income from entering BA 70 €/t 60.000 t/y 4.200.000

BABIU: input and output BA
17
BABIU
BA
non hazardous waste
(cost)BIOGAS
BIOMETHANEBA
non hazardous waste
(income)

BABIU: upgrading specific cost
18
€/Nm3
of entering biogas 1,06
€/Nm3
of biomethane 1,90
€/kWh of biomethane 0,20

19
BABIU
BA
non hazardous waste
60 €/t
(cost)
BIOGAS
BIOMETHANE
BA
non hazardous waste
73 €/t
(income)
€/Nm3
of entering biogas -
€/Nm3
of biomethane -
€/kWh of biomethane -
∆€ ≈ 13

20
BABIU
BA
0 €/t (cost)
civil work material
??? €/t (income)
BIOGAS
BIOMETHANE
BA
non hazardous waste
73 €/t
(income)
€/Nm3
of entering biogas - 5,56
€/Nm3
of biomethane - 9,99
€/kWh of biomethane - 1,03
Landfill gas/
upgrading/
BA to landfill

Conclusions & …
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• AwR process is more complex but allows higher CO2
up-take (about 0,2÷0,3 kg/kgAPC) so it requires lower
amount of entering solid residues; drawback: costs are
high
• BABIU process is more simple but allows lower CO2 up-
take (about 0,01-0,02 kg/kgBA) so it requires large
amounts of entering solid residues; advantages: costs
are low, effective also for H2S; limit: availability of BA at
d < 150 km

Conclusions & …
22
• For both AwR and BABIU application is limited by the
available amounts locally (100-250-500? Nm3/h)
• The use of solid residues from WtE for landfill or AD
biogas treatment is a good example of industrial
symbiosis and may offer favorable opportunities when
the different involved types of plants are located in the
same site or are not too far one from the other

…future
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• Better investigate the operative conditions which allows for declassing the
waste
• Improve operative conditions for AwR to reduce costs
• Put the two processes in series (1° BABIU + 2° AwR)
• Investigate different types of alkaline industrial solid residues for both AwR
(pre- and post-washing may be not required) and BABIU (higher up-take)
• Propose different way of solid/gas contact; different ways of realizing
carbonation
• Investigate the application of BABIU for low-CH4 biogas
• Associate the H2S removal to CO2 in BABIU

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