THE WORLD BANK MONTERREY S LANDFILL GAS TO ENERGY PROJECT BIOENERGIA DE NUEVO LÉON, S.A. DE C.V. Jorge Humberto Padilla Olvera & Jaime Luis Saldaña Méndez Washington, D.C., March 19 th, 2007 Waste type: Household & Industrial Source: World Bank Bid Doc. 1
Simeprode s Landfill Location Map Simeprode s Landfill Population served: 4 million Public operated. Year of start of operations: 1990 Year expected closure: 2020 Types of waste disposed: Household, Comercial & Industrial. Separation & classification 2
Waste Tonnage Yearly Profile 1,800,000 1,600,000 1,400,000 1,200,000 Tonnes 1,000,000 800,000 600,000 400,000 200,000 0 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 Source: Simeprode s Data Simeprode s Landfill Aerial Photo 3
Benlesa (Phase 2) Expansion Project Simeprode s Landfill Aerial Photo Benlesa (Phase 1) Benlesa (Facility) Landfill Engineering Engineering details (construction) Gas collection system background: None Leachate collection system background: Vertical pumping extraction. Operation Average depth: 20 mts. Area covered: 56 ha. Total tonnage with gas collection: 8.7 million tons. Compaction details: Mechanical compactor: 0.8 kg/m 3 Frequency of waste cover: Daily Type of cover: Clay 4
Landfill Gas Engineering Main responsible for LFG Engineering: Bioeléctrica de Monterrey, S.A. Modelling When LFG curve was modelled: 2000 Model used: EPA-PLUS Model Inputs: Model results: Gas Model Source: World Bank Bid Document 5
Pump testing Carried out or not: Carries out If carried out, systematics: When: 2000 & 2002 How many wells: 1 & 160 Location of wells: Middle of the landfill / All the surface. For how long: 7 days in 2000 & 90 days between 2002-2003. Pump testing results (average LFG composition, flow) WELL NO CH 4 % CO 2 % O 2 % N 2 % 1 54.90 40.53 0.81 3.53 2 ---- ---- ---- ---- 3 ---- ---- ---- ---- 4 ---- ---- ---- ----.. TOTAL 54.90 40.53 0.81 3.53 Gas Measurements for the landfill (1 st. trial report) Source: World Bank Bid Document 2 nd. Gas Proving Trial The purpose of gas proving trial was to determine if there was sufficient quantity and quality of landfill gas available from the existing, closed, 44 Ha area of the SIMEPRODESO sanitary landfill located at Salinas Victoria, Nuevo León, Mexico, sanitary landfill to satisfactorily operate the 7MW landfill gas plant. The required gas level was calculated as follows: a. Each Jenbacher 320 Engine requires 311m 3 methane per hour (including the stated 5% ISO allowance) at an electrical output of 1,060kW at Standard Temperature and Pressure (0 o C, 1013.25mBar). b. The desired methane concentration in the landfill gas is between 35% and 50%. c. The desired Oxygen concentration is less than 2%. d. A safety margin of 20% excess methane volumes, above that level required by the engines, to take account of seasonal variation in gas yield from the landfill. This level of safety margin is based on experience. As a result the required gas flow rate is; 2,612m 3 /hr methane for 7 Engines at full output Table 1 shows the proportion of samples that contained oxygen above 5%, and above 10%, on each of the occasions that measurements were taken. 6
Date Number of Measurements Number over 5% Number Over 10% % over 5% % over 10% 22nd Feb 154 43 32 28% 21% 26th Feb 76 32 23 42% 30% 28th Feb 84 37 20 44% 24% 5th March 167 81 56 49% 34% 11th March 173 83 59 48% 34% Table 1 Gas proportion for the wells at the SIMEPRODESO landfill site. (Source: Bioeléctrica de Monterrey S. A. de C. V.) Measurements of flow rate, gas quality, temperature and pressure were made at the gas pumps. These are shown in Table 2. Measurement Error Band Max 108.15 % Analyser Methane Error 3% Upper Max Lower Orifice Plate Error 5% 92.15% Excess Gas Requirement 20% Jenbacher 320 Methane Requirement 311 22nd 24th 26th 28th 4th 10th 14th Before Tuning Feb Feb Feb Feb March March March Oxygen 6.6 3.3 6.6 5.1 2 4.2 3.4 Methane 40 48.5 40 43.8 50.1 45.6 47 Gas Temperature (c ) 35 35 35 35 35 44 44 Gas Pressure (mb Rel) 43 43 43 43 43 43 45 Flowrate 4242 4100 4242 4242 4121 4131 4131 Corrected Flow Rate m 3 /hr 3920 3789 3920 3920 3808 3709 3716 Methane Flow Rate m 3 /hr 1568 1837 1568 1717 1908 1691 1746 Lower Estimated Electrical Energy kw 4924 5771 4924 5392 5992 5312 5485 Estimated Electrical Energy kw 5344 6263 5344 5852 6502 5764 5953 Upper Estimated Electrical Energy kw 5780 6773 5780 6329 7032 6234 6438 Number of Jenbachers at full ouput 5.04 5.91 5.04 5.52 6.13 5.44 5.62 % Above (below) safety margin -35% -24% -35% -29% -21% -30% -28% Table 2 Flow rate and temperature for measurements made on SIMEPRODESO s landfill site. (Source: Bioeléctrica de Monterrey S. A. de C. V.) 22nd Feb Air / Biogas Ratio 26th Feb 28th Feb 5th March 10th March 100% 0% 10% 20% 30% 40% 50% 60% 70% 80% Percentage Oxygen 10% 1% 0% Percentage Methane Gas Measurements for the landfill on different dates (2 nd Trial Report) (Source: Bioeléctrica de Monterrey S. A. de C. V.) 7
Table 1. indicates that 34% of the gas wells exhibit oxygen levels above 10%. On the assumption that all of these wells are upgraded, and that 60% of those seal upgrades are successful from the methane generation point of view, then the gas flow rate and consequently electrical output will be improved by 20.5%. The current lower estimated electrical energy (taking into account the required safety margins and measurement accuracy) is 5,485kW. An improvement of 20.5% on this level implies an estimate lower electrical output of 6,690kW, or the equivalent of 6.31 Jenbacher 320 Engines at full output. Comparison of this figure with the gas curve provided by the World Bank s consultants (Model), as part of the original bid documentation, shows broad agreement with the projected gas yield of the site. The projected figure is also in good agreement with the gas curve produced by Bioeléctrica de Monterrey (Pump Testing) at the outset of the project, which estimated a gas availability figure of 6,841kW for the year 2002. In order to operate the proposed seven engines at full output, and under the worst-case scenario basis, an improvement in gas yield of a minimum of 11% is required. As a result, the following conclusions and recommendations are made: 1) Current Energy Available is 1,609m 3 /hr Methane (Equivalent to 5,485kW electrical). 2) Estimated Energy Available after Well Upgrades is expected at 1,938m 3 /hr Methane (Equivalent to 6,609kW electrical), enough for the operation of the six engines not including the 20% safety margin. 3) The desired gas supply, including the safety margin is 2,612m 3 /hr for the total installed capacity of seven engines. Gas Curve Data provided by Simeprodeso as part of the Bid Documentation 9000 Model Gas Production Rate m3/hr / Energy Potential kw 8000 7000 6000 5000 4000 3000 2000 1000 7 MW 0 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 Time Vs 12000 m3/hour Energy Potential kw SIMEPRODESO 150m3/T Dom Eq, 70% collection Filled from 1991 to 1999 Total 7,698,057 T 10000 Pump testing 8000 6000 4000 2000 6 MW 0 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 Time m3/ hour Energy Potential kw 8
Landfill Gas Plant Plant recent photo: Cogeneration Company Framework: COGENERATION COMPANY SIMEPRODE (DECENTRALIZED PUBLIC ENTITY) - LANDFILL OWNER - LANDFILL OPERATOR BIOELECTRICA DE MONTERREY (PRIVATE CONSORTIUM) -SEISA 55% - GENTOR 45% DESIGN, CONSTRUCTION, COMMISSIONING, LONG TERM OPERATIONS & SERVICE CONTRACT (O&M) SPECIFIC PURPOSE COMPANY ELECTRICITY USERS- PARTNERS 7 MUNICIPALITIES Metrorrey (Subway), Nuevo Leon State Government, Water and Se werage State Company and Child and Family Assistance Public Entity 9
Engineering Who designed the plant: Bioeléctrica de Monterrey, S.A. Construction When: 2002-2003 Who built the plant : Bioeléctrica de Monterrey, S.A. Brief description of the plant: Type Quantity Unit Capacity Biogas Engines 7 1,060 kwe Transformers 7 1,250kVA Biogas pumps and filter unit 3 2,500 m³/h Elevated biogas flares 2 2,500 m³/h Dewatering pumps 2 28 m³/day Cooling equipment 1 420 m 3 /h Biogas Collection Piping: Polyethylene medium density pipe (315 mm Ø) Polyethylene medium density pipe (63 mm Ø) 4,232 m. 17,590 m. Manifolds 10 Extraction wells (63 mm Ø) 248 Main branches 18 Condensate separators 20 Water Tanks and Ancillaries 1 20 m³ Flow control system 1 Export / Import Meter Unit 2 Biogas measure device 1 Equipment: Equipment Engines Pumps & Flares Piping Transformers Manufacturer GE-Jenbacher Organics Repsa Prolec Origin Austria UK Mexico Mexico Operation: Bioeléctrica de Monterrey, S.A. Plant Start Date: May-2003 10
F U T U R E LFG Extracted x Precipitation 35,000 2500 30,000 2000 25,000 1,000 m3 20,000 15,000 1500 1000 mm 10,000 500 5,000 0 2003 2004 2005 2006 0 LFG Extracted Precipitation 11
Landfill Gas Plant Comparison: model/engineering vs actual project: Original engineering: 160 extraction wells in 44 ha. Actual project: 248 extraction wells in 58 ha. 12
Extracted x Estimated 40,000 30,000 1,000 m3 20,000 10,000 0 2003 2004 2005 2006 LFG Extracted LFG Estimated Benlesa Methane Extraction 1,200 2003 2004 2005 2006 1,000 Metric Tons 800 600 400 200 0 Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. Jan. Apr. Jul. Oct. 13
Explanation for differences: The comparison of the figure with the gas curve provided by the World Bank s consultants (model curve), as part of the original bid documentation, shows broad agreement with the projected gas yield of the site. The projected figure is also in good agreement with the gas curve produced by Bioelectrica de Monterrey at the outset of the project, which estimated a gas availablity figure of 6.8 MW for the year 2002. For this reason in order to ensure the enough gas for the planned capacity (7 MW) the decision was to drill 88 more wells in an additional area to provide at least a 20% margin of safety in the amount of gas avaliable as a reserve for the plant operation. Landfill operation x LFG Plant operation/performance: 7000 Performance Results 2003 2004 2005 2006 100.0 Mwh 6000 5000 4000 3000 2000 1000 0 Abr. May. Jun. Jul. Ago. Sep. Oct. Nov. Dic. Ene Feb. Mzo. Abr. May. Jun. Jul. Ago. Sep. Oct. Nov. Dic Ene Feb Mzo. Abr. May. Jun. Jul. Ago. Sep. Oct. Nov. Dic. Ene. Feb. Mzo. Abr. May. Jun. Jul. Ago. Sep. Oct. Nov. Dic. 90.0 80.0 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 % Energy produced Plant Avaliavility Tendency Tendency 14
REAL TIME OPERATIONS DISPLAY Main Issues Background on main issues faced during project design/construction/operation: No local experience in this type of projects (LFG to energy). Initial gas estimation: Future projects should seek more certainty on the amount of available gas in order to avoid additional cost once the plant is set up. Field measurements and conservative mathematical model to estimate the gas amount will help in that regard. Mexico s permits complexity. Siloxanes presence in the gas. Background on how issues were tackled - Development of local support, as driller company, piping supplier, etc (adviced by an expert) reducing implementation time. - Uses an extra area of the landfill to assure the amount of gas required for the operation of the plant. - SEISA s knowledge and implementation capacity. - Providing maintenance more often. 15
Solutions under implementation/to be implemented: In order to improve the performance of the gas field, and to take account of the drying effect of the high temperature of the landfill gas, and perhaps drier than expected conditions in certain areas of the site, we installed an extra Bentonite seals on a number of wells and irrigation system to increase the moisture of the seal. In the second phase (88 additional boreholes) the Bentonite seals were relocated at 9 meters under the top of the landfill, reducing the amount of oxygen introduced in the gas collection system. Final Remarks To which factors is the plant underperformance attributed: Too optimistic model. Use estimate values for L o & k of the model. The first cells at Simeprode s landfill has industrial waste. Extreme weather condition in Monterrey (high temperatures in spring and summer) reduce the LFG volume. 16
Application of lessons learned 7,000 Estimated Electricity & Landfill Gas Generation Monterrey II (Celdas 99,00,01,02,03,04 y 05) 6,000 5,000 Estimated kwe 4,000 3,000 5.3 MW 4.2 MW 2,000 3.2 MW 1,000 2.1 MW - 1995 1998 2001 2004 2007 2010 2013 2016 2019 2022 2025 2028 2031 2034 2037 2040 2043 2046 2049 2052 Year kwe (m3/hr) Monterrey II Expansion Project Model Input Values: Lo= 80, k=0.050 vs Monterrey I Project Model Input Values: Lo= 95.4, k=0.066 THANK YOU! 17