Chicken Litter and Sewage Sludge Power Generation in Greater ...

POWER GENERATION FROM
MUNICIPAL SOLID WASTE
Chicken Litter &
Sewage Sludge
GREATER GABORONE, Botswana
November 2010
Botsile Gubago
G4 Consulting Engineers

Waste Disposal in Greater Gaborone
• Greater Gaborone comprises;
– City of Gaborone : Pop. 200,000
– Mogoditshane : Pop. 60,000
– Tlokweng : Pop. 40,000
• Waste Generation Rate
– Municipal Solid Waste : 65,000tons/yr
– Chicken Litter : 64,000tons/yr
– Sewage Sludge : 2,500ton/yr

Municipal Solid Waste (MSW)
• Problem compounded by rapid growth in population
• In Gaborone land for land filling very limited
• Regional landfill opened 35 km outside City
• This has resulted in increased haulage cost, as well as
associated carbon footprint.
• Open dumping in vacant spaces common

Chicken Litter
• Chicken consumption has increased in Botswana, and so has
chicken production.
• A major chicken producer has 14 chicken production farms
within 30km of Gaborone, each with an average stock holding of
40,000 chicks per cycle.
• Total chicken litter production for this one producer is currently
60,000tons/year.
• Litter is disposed of semi dry at landfills, while a small portion is
taken by farmers as manure.
• Chicken producers are keen to have the litter disposed of
properly but do not have the means.

Sewage Sludge
• Rapid population growth and land requirements have resulted in
departure from sewage ponds to modern wastewater treatment
plant.
• The activated sludge sewage treatment plant has 40,000m³/day
capacity & serves City of Gaborone, Mogoditshane, Kgale and
Tlokweng.
• Expected sludge production is 16tons/day in 2015 and
20tons/day over the 15 year life span of proposed project.
• Another by-product of the sewage treatment plant is sludge gas
and 5,000,000 m³/year of it is available for power generation

Botswana Strategy for Waste Management
(Adopted 1998)
1.Waste Reduction
Can quantity of
waste produced be
minimised?
2. Reuse/ Recycling
Can waste be
reused/recycled?
3. Treatment
Does hazardous
nature of waste
need to be
reduced?
4. Safe Landfill
Disposal
Waste Management Hierarchy
5. Incineration
for Power
Generation

Power Generation from Waste
• Waste disposal problem presents opportunity
• Aim to address waste disposal in sustainable manner
• Incentives for the project are as follows;
– Revenue from electricity sales
– Revenue from tipping fees
– Carbon Credits
• Project Benefits
– Environmental protection
– Employment creation
– Reduction on Botswana’s carbon footprint

Credit
Period
Year
MSW POWER GENERATION POTENTIAL
Population
Growth
Waste after
recycling
Potential CH 4
Production
(CH 4 Avoided)
CERs (CH 4 )
Tons of CH 4
CERs
Potential kWh - Potential MSW
MSW Combustion Plant Size
Potential
MW to Grid
CO 2 eq
Avoidance
(tons/yr) (m 3 /yr) (tons/yr) (tons/ yr) (kWh/yr) (MW) (MW) (tons/yr)
1 2012 297,903 59,532 1,071,578 698 14,650 35,897,873 5.06 4.55 28,718
2 2013 301,746 60,300 1,085,402 707 14,839 36,360,956 5.12 4.61 29,089
3 2014 305,638 61,078 1,099,403 716 15,030 36,830,012 5.19 4.67 29,464
4 2015 309,581 61,866 1,113,586 725 15,224 37,305,119 5.26 4.73 29,844
5 2016 313,574 62,664 1,127,951 734 15,420 37,786,355 5.33 4.79 30,229
6 2017 317,620 63,472 1,142,501 744 15,619 38,273,799 5.39 4.85 30,619
7 2018 321,844 64,316 1,157,697 754 15,827 38,782,841 5.47 4.92 31,026
8 2019 326,124 65,172 1,173,094 764 16,037 39,298,652 5.54 4.98 31,439
9 2020 330,462 66,039 1,188,696 774 16,251 39,821,324 5.61 5.05 31,857
10 2021 334,857 66,917 1,204,506 784 16,467 40,350,948 5.69 5.12 32,281
11 2022 339,311 67,807 1,220,526 795 16,686 40,887,616 5.76 5.19 32,710
12 2023 343,688 68,682 1,236,271 805 16,901 41,415,066 5.84 5.25 33,132
13 2024 348,121 69,568 1,252,219 815 17,119 41,949,320 5.91 5.32 33,559
14 2025 352,612 70,465 1,268,372 826 17,340 42,490,467 5.99 5.39 33,992
15 2026 357,161 71,374 1,284,734 836 17,564 43,038,594 6.07 5.46 34,431

Chicken Litter Power Generation Potential
Credit
Period
Year
Litter
Production
Potential kWh
from Combustion
Annual CH 4
Emission
CH 4
Avoidance
Potential
Plant Size
Potential
Power to Grid
Tons CO 2 e
Avoidance
(tons/yr) (kWh/yr @ 90% cf) (tons/yr) CERS/yr (MW) (MW) tons/yr
1 2012 65,908 81,066,941 4,284 89,965 10.28 9.25 64,854
2 2013 66,758 82,112,705 4,339 91,125 10.42 9.37 65,690
3 2014 67,619 83,171,959 4,395 92,301 10.55 9.49 66,538
4 2015 68,492 84,244,877 4,452 93,491 10.69 9.62 67,396
5 2016 69,375 85,331,636 4,509 94,697 10.82 9.74 68,265
6 2017 70,270 86,432,414 4,568 95,919 10.96 9.87 69,146
7 2018 71,205 87,581,965 4,628 97,195 11.11 10.00 70,066
8 2019 72,152 88,746,805 4,690 98,487 11.26 10.13 70,997
9 2020 73,111 89,927,138 4,752 99,797 11.41 10.27 71,942
10 2021 74,084 91,123,168 4,815 101,124 11.56 10.40 72,899
11 2022 75,069 92,335,107 4,879 102,469 11.71 10.54 73,868
12 2023 76,038 93,526,229 4,942 103,791 11.86 10.68 74,821
13 2024 77,018 94,732,718 5,006 105,130 12.02 10.81 75,786
14 2025 78,012 95,954,770 5,071 106,486 12.17 10.95 76,764
15 2026 79,018 97,192,586 5,136 107,860 12.33 11.10 77,754

Sewage Sludge Power Generation Potential
Credit
Period
Year
Estimated
Cake Prod.
Sewage Sludge Cake Sewage Gas Total Benefits
Potential
kWh/year
Generation
Potential
Plant
Size
Potential
CO 2
Displacem
ent
Excess
Sewage
Gas
Potential
Gas Plant
Size
Potential
CO 2
Plant Capacity
Displacement
Potential
Power to
Grid
CO 2
Displacement
(tons/yr) kWh/year (MW) (tons/yr) (m³/yr) (MW) (tons/year) (MW) (MW) (tons/yr)
1 2012 3,212 3,436,840 0.436 2,749 1,162,595 0.634 3,999 1.070 0.963 6,749
2 2013 3,504 3,749,280 0.476 2,999 1,219,995 0.665 4,197 1.141 1.027 7,196
3 2014 3,833 4,101,310 0.520 3,281 1,575,610 0.859 5,420 1.380 1.242 8,701
4 2015 5,840 6,248,800 0.793 4,999 1,929,555 1.052 6,638 1.845 1.660 11,637
5 2016 5,915 6,329,410 0.803 5,064 2,283,500 1.245 7,855 2.048 1.843 12,919
6 2017 5,992 6,411,059 0.813 5,129 2,637,445 1.438 9,073 2.252 2.026 14,202
7 2018 6,071 6,496,326 0.824 5,197 2,991,390 1.086 6,850 1.910 1.719 12,047
8 2019 6,152 6,582,727 0.835 5,266 3,345,335 1.825 11,508 2.660 2.394 16,774
9 2020 6,234 6,670,277 0.846 5,336 3,699,280 2.018 12,726 2.864 2.577 18,062
10 2021 6,317 6,758,992 0.857 5,407 4,053,225 2.211 13,943 3.068 2.761 19,350
11 2022 6,401 6,848,887 0.869 5,479 4,407,170 2.404 15,161 3.272 2.945 20,640
12 2023 6,486 6,939,977 0.880 5,552 4,761,115 2.597 16,378 3.477 3.129 21,930
13 2024 6,570 7,029,503 0.892 5,624 5,115,060 3.335 21,036 4.227 3.804 26,659
14 2025 6,654 7,120,183 0.903 5,696 5,469,004 2.983 18,813 3.886 3.497 24,510
15 2026 6,740 7,212,034 0.915 5,770 5,822,949 3.176 20,031 4.091 3.682 25,801

Combined Power Generation Potential
Credit
Period
Year
Sewage
Gas
Potential
Gas Plant
Size
MSW
Wastes Generated
Sewage
Sludge
Chicken
Litter
Total
Potential Power Generation
Potential Plant
Size
Power to Grid
(90%)
(m³/yr) (MW) (tons/yr) (tons/yr) (tons/yr) (tons/yr) (MW) (MW)
1 2012 1,162,595 0.634 79,376 3,212 65,908 148,496 16.41 14.77
2 2013 1,219,995 0.665 80,400 3,504 66,758 150,662 16.68 15.01
3 2014 1,575,610 0.859 81,437 3,833 67,619 152,889 17.12 15.41
4 2015 1,929,555 1.052 82,488 5,840 68,492 156,820 17.80 16.02
5 2016 2,283,500 1.245 83,552 5,915 69,375 158,842 18.20 16.38
6 2017 2,637,445 1.438 84,630 5,992 70,270 160,892 18.60 16.74
7 2018 2,991,390 1.086 85,755 6,071 71,205 163,031 18.49 16.64
8 2019 3,345,335 1.825 86,896 6,152 72,152 165,200 19.46 17.51
9 2020 3,699,280 2.018 88,052 6,234 73,111 167,397 19.88 17.90
10 2021 4,053,225 2.211 89,223 6,317 74,084 169,624 20.32 18.29
11 2022 4,407,170 2.404 90,409 6,401 75,069 171,879 20.74 18.67
12 2023 4,761,115 2.597 91,576 6,486 76,038 174,100 21.18 19.06
13 2024 5,115,060 3.335 92,757 6,570 77,018 176,345 22.16 19.94
14 2025 5,469,004 2.983 93,953 6,654 78,012 178,619 22.05 19.84
15 2026 5,822,949 3.176 95,165 6,740 79,018 180,923 22.49 20.24

Waste-to-Energy Technology Options
Landfill with Gas Recovery
• Oldest and widely used with lower initial capital costs
• But due to high land requirement not suitable for Gaborone
Anaerobic Digestion/Gasification/Pyrolysis
• Requires waste segregation to produce useful gases
• Landfilling required for what’s unsuitable hence not suitable
Mass Burn/Incineration
• Can burn almost anything and requires little sorting
• Maximum volume reduction for final waste disposal
• Suitable for co-firing with other Waste forms

Plant Configuration Proposal
Phase I 2012 – 2026 Phase II 2027 – 2042
Total Plant Capacity
1800tpd
Additional
500tpd
BOILER No.1
900 tpd
24 MW Nominal
BOILER No.2
900 tpd
24 MW Nominal
BOILER No.3
500tpd
15MW Nominal

Plant Configuration Proposal
Phase I 2012 – 2026 Phase II 2027 – 2042
Total Plant Capacity
140,000tons/yr
Additional
50,000tons/yr
BOILER No.1
20 MW
Nominal
BOILER No.2
5 -10MW
Nominal

PROJECT COSTS & BENEFITS (Phase I)
Unit Price for Electricity – 0.0401U$/kWh (0.281Pula/kWhr)
Unit Price for Carbon Credit – 11.00U$/CER
1 Plant Capacity MW 21.6
2 Net Power to Grid MW 20.0
3 Capital Costs US$(M) 49.3
4 Operating Costs/yr US$(M) 4.8
5 Revenue/yr
5.1 Electricity US$(M) 7.6
5.2 Methane Avoidance US$(M) 1.4
5.3 Carbon Dioxide Avoidance US$(M) 1.5
5.4 Tipping Fee (MSW) US$(M) 0.8
6 Total Revenue US$(M) 11.3
7 Gross Profit US$(M) 6.5

Project Schedule
• Pre Feasibility Study Completed – October 2009
• Submit Application for Reclamation Rights – September 2010
• Commence Plant Design & EIA – 1 st Quarter 2011
• Complete Bankable Feasibility Study – 3 rd Quarter 2011
• Funding Negotiations – 4 th Quarter 2011
• Commence Construction – 1 st Quarter 2012
• Plant Operation – 3 rd Quarter 2013

Government Support
Ministry of Local Government
Ministry of Environment

THANK
YOU