Opportunities for Energy Production from Solid Waste in the Mexicali/Imperial Valley Region Kevin Whitty Christina Smith The University of Utah Salt Lake City, Utah Margarito Quintero Sara Ojeda Benitez Universidad Autónoma de Baja California Mexicali, Mexico SCERP Project HW-06-3 SCERP Annual Technical Conference December 5-6, 2008 Tempe, Arizona

2 Outline  Background / Motivation  Project Objectives  Approach  Sampling and Analysis  Key Findings  Conclusions

3 Mexicali and the Imperial Valley Mexicali

4 The Imperial Valley Region

5 Mexicali / Imperial Valley Region  Imperial Valley Area 28,000 km 2 Population: 1.16 million  Mexicali Municipality Area: 12,000 km 2 Population (2008): 1,000,010 Population expected to double by 2035  Approx. 700 tons solid waste produced per day  Approx. 100 to 400 MW power consumed Varies by season Primarily natural gas based

6 Yearly Electricity Consumption 50, , , , , , February August 0 Consumption, MWh Year Total Monthly Consumption – Mexicali Residential Sector

7 Monthly Electricity Consumption JanFebMarAprMayJunJulAugSepOctNov Dec 50, , , , ,000 0 Consumption, MWh Year 2000 – Residential Sector

8 Waste Management Scheme

9 Project Objectives  Assess potential for converting non-hazardous solid waste to electrical power Consider entire Imperial Valley region Consider residential, commercial, industrial waste  Evaluate waste production Quantity of waste Quality of waste from a fuel perspective  Consider several possible technologies Incineration Gasification Landfill methane capture

10 Approach / Methodology  Task 1: Survey of solid waste  Task 2: Characterization of solid waste Gross characterization Chemical characterization Thermochemical characterization  Task 3: Evaluation of energy production technologies Technical feasibility (feedstock quantity, quality) Maturity of the technology Cost

11 Task 1: Waste Survey  Split into three demographic groups Low Medium High  Consider all four seasons of the year  Challenges… Lack of cooperation from private contractors responsible for commercial and industrial waste Lack of cooperation from U.S. side of the border  Focus primarily on residential waste

12 Location of Sampling Colonies

13 Waste Sampling

14 Result of Waste Survey  Roughly 678 tons of solid waste per year available for energy production

15 Task 2: Characterization of Waste  Gross characterization (metal, plastic, paper, etc.) Effort to obtain representative samples Three socioeconomic strata over 4 seasons  Chemical characterization Homogenization of sample Analysis performed by external lab Proximate, ultimate, energy value analysis  Thermochemical characterization Determine volatility of sample versus temperature  Challenge to obtain representative, homogeneous samples

16 Waste Classification Categories  Cotton  Cardboard  Fine waste  Cardboard packaging  Synthetic fiber  Bone  Rubber  Aluminum cans  China and ceramic  Wood  Building and demolition material  Iron material  Tin cans (Iron material)  Non iron metals  Paper  Disposable diapers  Sanitary waste  Plastic film  Rigid plastic  PET  Polyurethane  Extended polystyrene  Polyethylene foam  Food waste  Yard trimmings  Fabrics  Colored glass  Clear glass  Electric batteries  Others

17 Spring Waste Classification

18 Classification of Waste Samples Paper, cardboard, natural fibers Wood, yard waste Plastics Other wastes Non-combustible (metal, glass, etc.)

19 Proximate Analysis Volatile matter Fixed carbon Ash

20 Ultimate Analysis Nitrogen (N) Sulfur (S) Oxygen (O, diff) Hydrogen (H) Carbon (C) Chlorine (Cl)

21 Energy Value of Waste Dry Basis Average: 5,860 Btu/lb

22 Thermochemical Characterization  Thermogravimetric analysis to track mass loss as a function of temperature  Indication of volatility (reactivity) of fuel  Required that samples were homogenized to a fine powder

23 Weight Loss vs. Temperature Low Socioeconomic Stratum

24 Weight Loss vs. Temperature Medium Socioeconomic Stratum

25 Weight Loss vs. Temperature High Socioeconomic Stratum

26 Task 3: Energy Production Evaluation  Total thermal energy input (fuel input) approx. 77 MW th on continuous basis  Corresponding electrical output approx. 23 MW el on continuous basis  Actual output can be adjusted for time of day and season to correspond to demand

27 Energy Production Alternatives  Incineration Sufficient waste production to support at least one incinerator Best technology option –Mature technology –Costs are reasonable at this scale Consider removal of non-combustible components to produce higher energy value "refuse-derived fuel" (RDF)

28 Energy Production Alternatives (cont.)  Gasification Fluidized bed gasification best approach Amount of available waste too little to justify cost and complexity Technology not currently mature enough to recommend  Landfill methane capture Requires waste in existing landfill Relatively little electricity generation (< 5 MW) New landfill recently opened Possibly use on old landfill

29 Conclusions  Approx. 680 tons solid waste/year available for energy production in Mexicali region  Waste composition and quality varies significantly with season and source  Average energy content approx. 6,000 Btu/lb  Sufficient waste to support one incineration- based system  Potential to dramatically reduce quantity of waste sent to landfill  Additional study recommended

30 Acknowledgements  Co-authors  SCERP  Department of Chemical Engineering  Institute for Clean and Secure Energy