Waste to Energy Project in Ghana: Landfill Gas or Incineration
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This document compares landfill gas (LFG) and waste incineration technologies for power generation in Accra, Ghana using RETScreen software. LFG would generate 6 MW of electricity annually while waste incineration would generate 48 MW annually. LFG results in greater greenhouse gas reductions at 273,657 tons of CO2 per year compared to 41,413 tons for waste incineration. Financially, LFG has a higher net present value and benefit-cost ratio but a longer payback period. Both technologies provide environmental and economic benefits for Ghana as well as social impacts like job creation and improved sanitation. LFG is the preferred option due to its outstanding environmental performance though waste incineration may be better if
Waste to Energy Project in Ghana: Landfill Gas or Incineration
- 1. Comparison Between Landfill Gas and Waste Incineration for Power Generation in Accra, Ghana Serwaa ANAGLATE Syawalianto RAHMAPUTRO Carlos RUIZ Prof. Luis Rojas 1
- 2. Outline Accra Objective & Scope RETScreen Waste Characterization Landfill Gas Waste Incineration Results Social Impact Conclusions Outlook 2
- 3. Accra, Ghana 1,800 Daily Tons of Waste Open Dump Sites Insufficient Waste Collection Insufficient Power Capacity Source: www.atokd.com Source: http://raklak.wordpress.com 3
- 4. Objective & Scope Objective Assess and compare landfill gas and waste incineration Technical Environmental Economic Social Impact Scope Total Electricity Exported GHG Emissions Reduction Approximate Costs Financial Summary Pre-feasibility Level 4
- 5. RETScreen® Free Software Clean Energy Project Analysis Inexpensive Technical and Financial Feasibility Analysis Energy Model Cost Analysis GHG Analysis Financial Summary Sensitivity & Risk Analysis 5
- 6. Waste Characterization 3% 3% 3% 2% 6% 17% 66% Organic Inert Paper Plastic Glass Metal Textile & Leather 6
- 7. Landfill Gas Source: Affiliated Engineers, 2010 7
- 8. Landfill Gas Simulation Amount of Waste Input Parameter Value Waste Disposal Rate (mi) 270,000 t/yr Landfill Opening Year 2014 Landfill Closing Year 2044 Generation Constant (k) 0.06 yr-1 Generation Potential (Lo) Waste Composition 170 m3/t Climatic Conditions 6MW Assumptions: Constant Biodegradable Fraction in Waste 50% of CH4 by Volume 75% Collection Efficiency 8
- 9. Waste Incineration Electricity Generation Pretreatment Furnace - Waste Incinerator Flue Gas Treatment Drying in the receiving pit. Source: www.sick.com Moving grate furnace is the most Boiler robust. Energy Recovery - Low-pressure steam boiler is convenient when energy recovery is designed for electricity use only (Haukohl, J., Rand, T., & Marxen, R. ,1999) Energy Production - Rankine cycle with steam turbine, condenser, boiler, and pump for power generation. Flue Gas Treatment - For 600 ton to 900 ton/day: SNCR, semi-dry scrubber, activated carbon, and a bag house filter are usually used (Kuo, Lin, Chen, Tseng, & Wey, 2011). Grate Furnace Receiving Area Receiving Pit Source: www.valorena.fr 9
- 10. Waste Incineration Simulation Proximate AnalysisAsh Combustibles Moisture 14% Ash 31% 1 Waste Analysis WASTE INCINERATION Waste Feed Rate Dry Weight of Feed Waste 270,000 120,727.12 Feeding Rate Lower Heating Value Moisture 55% t/yr t/yr 13.78 t/hr 15.854 Ultimate Analysis 2 Fuel Potential POWER SYSTEM GJ/t Fuel Potential 218.49 Gj/hr Predefined: • Udomsri, Petrov, Martin, & Fransson, 2011 • Suggested values from RETScreen Simulation: Energy Model Combustibles 3 Power Generation Availability 8,401 hours Back Pressure 5.6 kPa Steam Temp. 380 °C Return Temp. 90 °C Steam Flow 68,600 kg/hr Operating Pressure 80 bar Turbine Efficiency 75 % Fuel Required 218 Gj/hr 10
- 11. Results – Energy and Environment Landfill Gas Technology Engine Power Capacity (kW) Electricity Exported (MWh/yr) Waste Incineration 6,000 16,505.24 48,000 138,658 Electricity Export Rate - $ 58.7 Source: www.engineeringnews .co.za Source: www.siemenspowergeneration.c om Technology Landfill Gas Waste Incineration Emission Factor (Kg/GJ) CO2 CH4 N 2O Annual GHG Reduction (tCO2) 0 0.0040 0.00010 273,657 29.43 0 0.00315 41,413.4 Energy Mix in Ghana: • Hydro Power 67.6% • Thermal Power 32.4% WI energy output > 8 times that of LFG GHG reductions are achieved in both technologies LFG GHG reductions > 6 times that of WI 11
- 12. Results - Financial 25,000,000 Cost Breakdown Accumulated Landfill Gas WI CashFinancial Flow 20,000,000 Cash Flow (USD) Engineering $ 3,743,026 $ 10,455,025 $ 7,512,749 Balance of System $ 3,630,152 $ 23,679,131 Total Initial Cost $ 15,135,177 $ 34,934,905 5,000,000 Results 8.1% 4.8% Payback Period $ 1,050,000 Power System 10,000,000 WI IRR Initial Cost 15,000,000 Landfill Gas 13.2 15.9 years Annual Income $2,817,600 $8,139,215 Net Present Value (NPV) Benefit-Cost Ratio $4,612,086 $826,358 1.61 1.05 Project Year 0 1 2 3 Annual Cost 0 -5,000,000 and Debt Payment 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 -10,000,000 O&M $ 1,531,000 $ 5,460,225 Debt Payment (10 yr) $ 1,028,193 $ 2,373,267 $ 2,559,193 $ 7,833,492 $ 2,817,600 $ 8,139,215 -15,000,000 Total Annual Cost LFG Waste Incineration -20,000,000 Annual Income Inflation Rate – 3% Debt Interest Rate – 6% Discount Gas rendered better profitability Electricity Export Escalation – 2% Landfill Rate – 4.5% Since Ghana is a developing country, affordability is important 12
- 13. Social Impact Job Creation Source: www.rvg-ghana.com Improvement of the City’s Image Improved Sanitation Source: Schah Fekri, 2011 Productivity Increase Source: Journalists for Human Rights, 2010 13
- 14. Conclusion & Outlook Both technologies are environmentally friendly and economically feasible. Any solution would represent a great improvement. LFG is preferred due to its outstanding environmental performance. WI is more suitable in case of limited space. Risk and sensitivity analysis are recommended. Inclusion of carbon credits should be considered. Further on-site tests should be carried out. 14
- 15. Thank you. Any Questions? Pictures in cover page courtesy of: •www.treehugger.com •Graham Turner (http://www.guardian.co.uk) •www.sick.com 15