opportunities for energy production from solid waste in the mexicali/imperial valley region kevin...
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Opportunities for Energy Production from Solid Waste in the
Mexicali/Imperial Valley Region
Kevin WhittyChristina Smith
The University of UtahSalt Lake City, Utah
Margarito QuinteroSara Ojeda Benitez
Universidad Autónoma de Baja CaliforniaMexicali, Mexico
SCERP Project HW-06-3
SCERP Annual Technical ConferenceSCERP Annual Technical ConferenceDecember 5-6, 2008December 5-6, 2008
Tempe, ArizonaTempe, Arizona
2
Outline
Background / Motivation
Project Objectives
Approach
Sampling and Analysis
Key Findings
Conclusions
3
Mexicali and the Imperial Valley
MexicaliMexicali
4
The Imperial Valley Region
5
Mexicali / Imperial Valley Region
Imperial Valley• Area 28,000 km2 • Population: 1.16 million
Mexicali Municipality• Area: 12,000 km2 • 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
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Yearly Electricity Consumption
50,000
100,000
150,000
200,000
250,000
300,000
1988 1990 1992 1994 1996 1998 2000 2002 2004
February
August
0
Co
nsu
mp
tion
, MW
h
Year
Total Monthly Consumption – Mexicali Residential Sector
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Monthly Electricity Consumption
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
50,000
100,000
150,000
200,000
250,000
0
Co
nsu
mp
tion
, MW
h
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
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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
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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
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Location of Sampling Colonies
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Waste Sampling
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25 1m
1m
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Result of Waste Survey
Roughly 678 tons of solid waste per year available for energy production
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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
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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
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Spring Waste Classification
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Classification of Waste Samples
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
High Med Low High Med Low High Med Low High Med Low
Com
posi
tion
(wei
ght%
)
Autumn Winter Spring Summer
Paper, cardboard, natural fibers
Wood, yard waste
Plastics
Other wastes
Non-combustible(metal, glass, etc.)
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Proximate Analysis
Volatile matter
Fixed carbon
Ash
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
High Med Low High Med Low High Med Low High Med Low
Wei
ght%
Autumn Winter Spring Summer
20
Ultimate Analysis
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
High Med Low High Med Low High Med Low High Med Low
Com
posi
tion
(wei
ght%
)
Autumn Winter Spring Summer
Nitrogen (N)
Sulfur (S)
Oxygen (O, diff)
Hydrogen (H)
Carbon (C)
Chlorine (Cl)
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Energy Value of Waste
0
2,000
4,000
6,000
8,000
10,000
12,000
High Med Low High Med Low High Med Low High Med Low
Hea
ting
valu
e (B
tu/lb
dry
)
Autumn Winter Spring Summer
Dry Basis
Average: 5,860 Btu/lb
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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. TemperatureLow Socioeconomic Stratum
0%
20%
40%
60%
80%
100%
0 200 400 600 800 1000Temperature, °C
We
igh
t, p
erc
en
t of i
niti
al
Winter
Autumn
Summer
Spring
24
Weight Loss vs. TemperatureMedium Socioeconomic Stratum
0%
20%
40%
60%
80%
100%
0 200 400 600 800 1000Temperature, °C
We
igh
t, p
erc
en
t of i
niti
al
Winter
Autumn
Summer
25
Weight Loss vs. TemperatureHigh Socioeconomic Stratum
0%
20%
40%
60%
80%
100%
0 200 400 600 800 1000Temperature, °C
We
igh
t, p
erc
en
t of i
niti
al
Autumn
Winter
Spring
Summer
26
Task 3: Energy Production Evaluation
Total thermal energy input (fuel input) approx. 77 MWth on continuous basis
Corresponding electrical output approx. 23 MWel 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)
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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
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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