New Concepts in Waste Disposal
Complementing
WTE
By: Walling Whittaker, MSc
A Proposal to Implement Recycling and Remediate the GT Landfill
Presentation Outline
• A brief look at the GTLF – Issues and
challenges
• Innovation in Landfilling - Energy from Wastes
– Solar Landfill
– Sustainable Landfill
• Potential for energy recovery at the GTLF
Addressing the Problem
Closing and Capping GTLF
Engineered Containment
Rainfall
Cover System
Groundwater
Waste
Leachate
Leakage
Gas
Lining System
Demerits of Mining the Existing Landfill
According to GBB, it will take
19 years to mine the landfill
and reduce it to grade
During this period there will
be a continuous release of
landfill gas and odors over
George Town
Continuous risk of
Explosions, Sparks
causing fires
Workers will be
continuously exposed to
hazardous materials injury
and loss of life
A Typical Landfill Cap
Is A Renewable Energy Cap the Remedy?
A Solar Cap
provides a
protective barrier
while
generating energy to
run equipment or
produce revenue
Need for topsoil
and
vegetation is
eliminated. In
areas
where water is
limited
this saves
money in
O&M phase of
project.
Need for additional fill
material (and associated
heavy equipment and
manpower) is
eliminated while the
remedy is equally
protective.
Solar Energy Landfill Caps
An Innovative Alternative to Traditional
Landfill Capping
Advantages of Solar Energy Landfill Cap
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Transforms a liability into a revenue
Potential to reduce post-closure care costs
Sale of renewable power
Carbon cap and trade credits
Innovative end-use for closed landfill
Positive public image
Solar Energy Landfill Caps
• A great way to protect the
environment and provide
clean, renewable energy
• Landfill Design Benefits:
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–
Promotes positive drainage
Minimizes infiltration
Reduced maintenance
Accommodates settlement
Produces high quality
stormwater runoff
Two Types of Solar Caps
Flexible solar panels
Rigid panels
Low power production
efficiency ca. 6%
Higher power production
efficiency > 13%
Light
Heavier (steel frame, glass)
Flexible, unbreakable
Stiff frame
Works well with diffuse
light
Less efficient with diffuse light
Works well with
temperatures above 40°C
Less efficient with
temperatures above 40°C
Rigid Panels
Flexible Panels
Placement of Rigid Panels
Project Opportunities for Flexible Solar
Caps:
• Closed or ‘inactive’ landfills
• Sites located near transmission lines
• Sites adjacent to large electricity load/demand
Existing Solar Landfill Projects
• Malagrotta, Italy: 998 kW from
PV in landfill cap
• Brockton, Massachusetts 460 kW
“Brightfield” with ground
mounted panels
• Nellis Air Force Base, Nevada 15
MW from tracking panels on old
landfill
• Republic Services, San Antonio,
TX – solar demonstration project
to incorporate PV membranes in
landfill cap
• FPL’s 250 kW solar panel array on
closed Bee Ridge Landfill in
Sarasota, FL
• New Jersey Meadowlands Comm.
Proposal for 5 MW solar project
on Erie Landfill
• FLS Energy to build and operate 1
MW PV array on closed landfill in
North Carolina
• Epuron PV array adjacent to
G.R.O.W. Landfill owned by Waste
Management in Bucks Co. PA
Solar Integrated Technologies, Malagrotta Italy
Flexible
Panel
1 Megawatt Landfill Application.
Tessman Rd. Landfill, Houston Tx
Winner of the
2010 SWANA
Gold
Excellence
Award for
Landfill
Secondary
Use
Hickory Ridge Landfill Atlanta, Georgia
• 48 acres
• 7,000+ solar panels to
produce over 1 MW of
renewable energy over
a 10-acre south slope
• Construction completed
in July 2011
If this can be done in
other countries…why
not in Cayman?
A Solar Farm at GTLF
• Solar radiation in Cayman
reaches 6.6 Kwh/m2/day,
from March to September
• Can be designed using
either flexible panels or
rigid panels, ground
mounted at 15 degrees
angle.
• With the price of energy
averaging US$0.37/Kwh
• Has the potential to
produce 2.2Mw electricity
A Solar Farm at GTLF
• A small section ( 10 acres ) of the GTLF could
accommodate 9,300 rigid panels of 235 watts,
each.
• Based on climate data (10 years average), it
has a potential capacity of 2.18 Mwp, on just
40,950 square meters of the site.
• Enough electricity to power about 300 homes
A Solar Farm at GTLF
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Total Investment: US$ 6.1 MM
Installed Capacity :2.18Mwp
Average production/yr:3.9MMKwh
Project life:25 yrs
Pay Back Years - 8
Internal Rate of Return - 18%
NPV - US$8.9MM (6%)
Sustainable Landfills
What is a Sustainable Landfill?
• An engineered landfill in which the cells are designed
to operate as ‘bioreactors’ so that they can be reused
again and again
• Create conditions for waste degrading organisms to
thrive
• Most typically performed by increasing moisture
content
– Leachate recirculation
– Air Injection
• A large scale composting operation
Gas Production
Bioreactor Landfill
Conventional Landfill
0
10
20
Time (Years)
30
40
The Sustainable Landfill
Air
Landfill Cover
Leachate Collection System
Leachate
Economic Benefits of Sustainable Landfills
• Reduces the need to
build new landfills
• Enhanced gas
production
• Recovered space
• Reduced env. impact
• Reduced post-closure
care
Existing Projects
• 10 field-scale demonstration projects in the
US and Canada
– Waste solids decomposition
– Nitrogen cycling and management
– Liquid distribution
– Gas production modelling
– Liquid waste bioassay development
– Methane oxidation and emissions measurement
• 8 patents issued 6 applications pending
• Existing projects in Florida
New River Regional Landfill
• Lined Landfill
• Manages waste from
several North Florida
Counties
(approximately 800 tons
per day)
Gas is converted to “green” energy
Landfill Engineering is Becoming Innovative
Topsoil
Sand
Clay
Garbage
Probes to
detect
methane
leaks
When landfill is full,
layers of soil and clay
seal in trash
Methane
storage
and
compressor
building
Methane gas
recovery well
Better Engineered Landfills
Electricity
generator
building
Pipes collect explosive
methane for use as fuel
to generate electricity
Leachate
storage
tank
Compacted
solid waste
Garbage
Sand
Synthetic
liner
Sand
Clay
Subsoil
Leachate
treatment system
Leachate
pipes
Leachate pumped
up to storage tank
for safe disposal
Clay and plastic lining
to prevent leaks; pipes
collect leachate from
bottom of landfill
Groundwater
Groundwater
monitoring
well
Leachate
monitoring
well
Questions