New Energy, Old Waste
A study of alternative energy from landfill methane gas
A research project submitted to the Urban Studies and Planning Program
Senior Sequence Class of 2010-2011
February 21, 2011
Caroline Lao
University of California, San Diego
Urban Studies & Planning Program
calao@ucsd.edu
Abstract
This research project examines the use of energy converted from methane gas at
the Miramar Landfill in San Diego. Developed nations currently hold a high
demand for fossil fuel energy, relying less on alternative energies such as methane
gas, which is released in landfills as trash decomposes. The existence of methane
gas in landfills raises two fundamental issues: the cost effectiveness of converting
methane gas, and harmful methane gas being released into the atmosphere, thus
damaging the environment. This project included a cost-benefit analysis of energy
from methane gas. The study found that the payoff of incorporating a methane gas
system for a landfill is worth the cost, though it is relative to the amount of
methane being generated from the landfill.
Keywords: methane gas, alternative energy, landfill
Introduction
In our world today, the industry that is essential to the livelihood of all developed nations
is the manufacturing of energy. Energy comes from a variety of fuel sources, which can be
grouped into fossil, renewable, and fissile. Fissile energy sources are largely uranium and
thorium; materials “capable of sustaining a chain reaction of nuclear fission” (Demirbas 2008:12). Fissile energy appears in nuclear power plants. The most common energy sources are from
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fossil fuels, consisting of petroleum, coal, and natural gas. As of 2008, fossil fuels were still
representative of “over 80% of total energy supplies in the world” (Demirbas 2008:3). Fossil
fuels are non-renewable sources because their consumption rate is much higher than their
production rate. The fossil fuel facing the highest risk of depletion is oil, of which the most
dominant source lies in the Middle East, “accounting for 63% of global reserves” (Demirbas
2008:3).
The use of fossil fuels in the developed world has gained attention as a negative method
of energy production. Instead, “sustainable” energy is becoming increasingly popular as the
preferred alternative to the use of fossil fuels. The most well-known alternative options of
renewable energy largely include energy generated by hydro-dams, wind turbines, or solar
panels. Another rising prospect in the world of renewable energy is that of biomass, which
includes energy from wood, waste, or plants, and from which biofuels may be produced.
Bioalcohols, or alcohol fuels, are a type of biofuel derived from biological sources rather than
petroleum. Methanol and ethanol are the most common bioalcohols used; they can be extracted
from both fossil fuels and biomass. Other forms of renewable energy include geothermal,
marine, and hydrogen (Demirbas 2008:2). Although renewable energy is “more evenly
distributed than fossil and nuclear sources” (Demirbas 2008:2), renewable forms of energy
remain a minority in contrast to the use of non-renewable energy forms.
In San Diego, methane gas is extracted from the Miramar Landfill and then converted to
energy, which is used to source the North City Water Reclamation Plant (City of San Diego). Is
energy from landfill methane gas a viable source of alternative energy? This study served to
determine the cost effectiveness of employing landfill methane gas. It considered the economic,
ecologic, and spatial dimensions of the landfill project. To further understanding of the cost
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effectiveness of using landfill methane gas, this study investigated the San Diego Miramar
Landfill and analyzed the costs and benefits of methane gas as a general source of alternative
energy.
For the City of San Diego, the Miramar Landfill is a demonstration of an effort for
independence in the world of energy consumption, encouraging reduction in environmental
disturbance. While energy generation is a necessity in the modern world, the use of methane is
an alternative to fossil fuels, and the methane gas from the landfill allows the city to tap into its
own source of alternative energy.
Background
Currently, the West Miramar Landfill serves the City of San Diego. The 1,500-acre
landfill accepts approximately 910,000 tons of waste per year. Previously, the South Miramar
Landfill operated for 14 years from 1959-1973, and the North Miramar Landfill following was
active for 10 years from 1973-1983. Now, the West Miramar Landfill is the only active landfill
in the City of San Diego, having opened in 1983 and remaining active for the past 27 years. A
landfill byproduct is the greenhouse gas methane. In the West Miramar Landfill, methane is
“captured and used to provide 90% of the fuel to power electrical generators at the Metropolitan
Biosolids Center and North City Water Reclamation Plant” (City of San Diego). Methane gas is
still being extracted from the South and North Landfills, and approximately 10 megawatts of
energy are generated to power the plant.
At the Miramar Landfill, methane gas is extracted through wells and sent through a
pipeline to become energy. At the currently active West Landfill site, a liner at the bottom of the
landfill prevents seepage of gas into the groundwork, and a network of extraction wells installed
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in the waste allow the methane gas to be removed. There are over 250 wells, and each is
monitored to ensure proper maintenance of pressure and generation of methane. Off of the direct
landfill runs a wildlife corridor, which also has a series of off-site wells that measure dangerous
fumes, such as carbon dioxide or methane, which may have leaked off-site. The maintenance of
the off-site wells is a safe measure taken to ensure protection for the wildlife animals and
surrounding environment. At the finished North and South landfill sites, methane continues to be
extracted from the underground landfill, and the completed top layer has been re-vegetated with
native plants.
Just outside of the Miramar Landfill is a recycling center, and in addition to generic
waste, the landfill plot provides a location for food and yard waste. Inside the landfill is the
Miramar Greenery, at which citizens may deposit yard waste, and San Diego residents may take
up to two cubic yards of compost or mulch for free. Food waste comes from larger organizations
including Qualcomm Stadium, Petco, Point Loma Nazarene University, and the Marine Corps
Recruit Depot, and this is mixed in with mulch at the landfill to produce windrows, which are
rows of compost, baked naturally in the sun at approximately 160˚F to kill seeds and bacteria and
leave behind nutrient rich compost. Aside from compost and mulch, the city also produces wood
chips for sale.
Conceptual Framework
The conceptual issue of this study is whether or not the use of methane gas from landfills
is a viable source of alternative energy. In particular, this study will investigate the efficiency of
methane gas energy through a cost-benefit analysis; a comparison to ethanol; and the history and
potential future of methane gas from landfills. This research is relevant to other landfill projects
around the world that are working to capture and utilize methane gas. The study examined the
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advantages and disadvantages to the effort to utilize methane gas from landfills. It considered the
efficiency of such a process and questioned the need for it.
Literature Review
The use of renewable energies from solar or wind power can be dated back to the first
uses of the sun for heat, or the wind for sailing. The growing awareness of a need for renewable
energy to generate electricity might be traced back to the 1960s, linking a political movement to
the era of the hippies in the United States. In 1997, the Kyoto Protocol was created, amending
the international agreement of the United Nations Framework Convention on Climate Change
and signed by various countries as an agreement to reduce greenhouse gas emissions. However,
the United States did not sign. To date, fossil fuel emissions remain “the main cause of human
contributions to the increase of greenhouse gases in the atmosphere” (Smith 2008:76). The
change in consciousness of carbon footprints has evolved to more than just a movement; it has
become a sustainable way of life. Solar and wind energy may have been well-known from the
start of mankind, but it is biomass, organic matter, that is in fact the oldest form of renewable
energy, with its impressive ability to re-grow in a short time duration (Union of Concerned
Scientists, 2010).
Fossil fuels remain the most common form of generating energy. They are non-renewable
resources, formed over millions of years by natural resources and consisting most commonly of
coal, petroleum, and natural gas, all of which have high amounts of carbon. Fossil fuels are
burned to produce energy, and simultaneously release carbon dioxide into the air. This is
believed to contribute significantly to global warming, which raises the surface temperature of
the Earth. As a non-renewable resource, there is a limited supply of fossil fuels, leading to heavy
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competition for available sources and ultimately a quest for renewable forms of energy.
Currently, the “dominance of fossil fuels as an energy source reflects their convenience of use
and relative ease of production in comparison with other energy sources” (Lincoln 2005:622).
Fossil fuels are easy to process for public use. However, as the demand for energy increases, the
sources of fossil fuels are depleting. Production is expected to become more costly as the world’s
supply decreases.
According to the Union of Concerned Scientists, a nonprofit organization of citizens and
scientists working for environmental solutions, the use of biomass can be beneficial not only by
providing energy, but also by reducing carbon emissions (UCS, 2010). Beneficial biomass
includes energy crops, or “power crops” that can be grown on farms; residues; and conversion to
energy. Trees, grasses, and other crops can be used for energy, though corn and oil crops such as
soybeans and sunflowers require “intensive management and may not be sustainable in the
longer term” (UCS, 2010). The potential of microalgae exists as a future option. As a whole,
biomass is widely available around the world, lacking the restraints of fossil fuels limited to
regional sources. While biomass combustion can emit carbon dioxide, it can also be a carbon
sink. “As long as [biomass] does not emit more carbon dioxide when used than it takes in while
growing, it essentially becomes a zero net emitter” (Smith 2008:19). Among other advantages of
biomass, it can be “cofired with fossil fuels” (Smith 2008:19) and therefore assist with the
transition from fossil fuels to clean energies.
Biomass residues can also produce energy. Biomass waste includes wood waste from the
forest; crop residues from farming; and urban waste from cities, coming in the form of
biodegradable garbage or captured methane from sewage. Environmental benefits include
reduction in air and water pollution and erosion, along with better soil quality and wildlife
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habitat. Burning can also reduce “pest pressure, weed competition, and… [improve] soil fertility,
texture, and moisture content” (McGrath, 1987:224). There are environmental risks to biopower;
poor management can lead to overharvest, damage to ecosystems, air pollution, excess water
consumption, and net greenhouse gas emissions (UCS, 2010). However, as with any risk, proper
management can utilize biomass production to its potential and minimize harm.
The use of solar energy is considered one of the top choices for alternative energy in San
Diego because of the sunny climate. Solar panels, called photovoltaic cells, convert sunlight into
electricity. In 2008, San Diego was ranked in 4th in “U.S. utilities for total solar-power capacity”
by the Solar Electric Power Association (Heiser, 2008). The reliance of photovoltaic cells on the
appearance of the sun makes the idea of solar power vulnerable and subject to failure. “Climate
is susceptible to a number of external influences” (Arnold, 2002:2788). San Diego is well known
for the amount of sunshine it receives, so it is reasonable to use photovoltaic cells. Solar power,
while expensive, is also quiet during operation, without the harmful side effect of emitting
greenhouse gases or other chemicals (Diesendorf, 2007:157).
Since the 1980s, there have been nine solar plants in the Mojave Desert, known as Solar
Energy Generating Systems, which generate enough electricity for roughly 500,000 people (Sun
Lab 1998). In 2007, the Nellis Solar Power Plant was opened, marking the largest solar
photovoltaic system on the continent. In April of 2009, a San Diego subsidiary of Sempra
Energy was reported to propose building the “largest solar energy plant in North America”
(Joyce 2009). However, it was not expected to power San Diego. Instead, the Nevada plant
would sell to a “southwest-based utility” (Joyce 2009). Other operations have been making
progress or intending it. Kyocera Solar, Inc. is a producer and supplier of solar energy products
providing solar electric systems and solutions. In March of 2010, Kyocera International
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announced plans to “start manufacturing solar modules in San Diego” (Joyce 2010). The city
was picked for the company’s first U.S. solar panel manufacturing site. In July of 2010, the
Canadian company Enbridge responsible for an oil spill in Michigan announced plans to
construct what they intend to be the largest photovoltaic solar energy facility on the continent.
(Kart 2010). These intentions reflect on the amount of support toward seeking alternative energy,
and show an increased awareness of the need.
Energy can also be harvested from the ocean. The movement of water can be used as
energy to create electricity. Ocean energy includes ocean thermal; tidal power; and wave power.
In an ocean thermal process, “warm water at the surface is used to heat a working fluid, which is
then vaporized, or to create steam directly from the sea water” (Berinstein 2001:113). The steam
is used to power a turbine, and cool water from below is used to recondense the vapor and repeat.
Ocean thermal systems have been difficult to test because they require locations with high
surface temperatures but close to freezing depths, and have a variety of issues from “the need for
huge heat exchangers to the question of how to circulate massive amounts of water to problems
with corrosion and clinging sea gunk” (Berinstein 2001:113). Furthermore, the systems may
negatively impact ocean temperature, chemistry, and life. Tidal power is an ancient method of
harvesting energy, though it was previously on a small scale; mills in medieval England were
used to grind grain (Berinstein 2001:113). Tidal power is reliant on “water falling and passing
through a turbine,” and there are several different forms of technology dependant on the flow of
the tide. While tidal power is reliable, there is “difficulty in delivering even power during the two
daily tidal peaks” (Berinstein 2001:114), and the areas of greatest need may sometimes be too far
removed from the tidal sites for the benefit to outweigh the cost. The risk of environmental
damage is also great, as tidal power technology can block marine life, change fish migration, kill
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fish, and change tidal regime. The third form of ocean energy, wave power, is dependent on the
speed and breadth of winds blowing across the sea surface. Wave power “captures the
mechanical energy in waves” (Berenstein 2001:115), utilizing deep waves that can provide large
amounts of energy. This energy technology is still in research and development stage.
Research Design and Methodology
When organic waste decomposes, it produces methane gas, which can be harvested as an
energy source and used as fuel. The Miramar Landfill is divided into three sites: North, South,
and West. The North and South sites were previously open but have long since closed and are
currently inactive. At the landfill, a system is used to extract methane gas and convert it to
energy. One method of research involved in this project was to visit the Miramar Landfill site
and gather information regarding the landfill in order to understand how the methane gas
collection system works. This meant finding out how the landfill functioned, why it worked, and
what was involved on the landfill property aside from being merely a dumpster. In order to gain
understanding, I took a guided tour with José Ysea, the Public Information Officer at City of San
Diego, who led me around the landfill site and showed me the variety of ways in which the
landfill operated.
Another method of research used was to conduct an interview with one of the engineers
on the methane gas project. I spoke with Ray Purtee, a mechanical engineer and Environmental
Services Senior who helped to design the methane gas system in use at Miramar Landfill. I
questioned the use of methane gas at the landfill, its cost history, and opinion on the capacity for
use of inactive landfills. The interview questions may be found in the appendix. After receiving
this data from the site visit and the interview, I used them to conduct a cost-benefit analysis of
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the Miramar Landfill methane project. This investigated the cost for the installation of the system
that extracts and converts gas, along with the continued cost to utilize methanol as an energy
source. Other factors involved included the amount of energy generated and saved, and the
weight of the benefits of methanol production. I investigated where the sources of revenue are,
and whether the city is losing or making money through the methanol project. This was
dependent on who received the output; if the energy is generated back to a city development,
then it may be saving the city money, and there is no financial profit. I compared these costs with
the known benefits of capturing methane gas for use of energy.
Capturing the methane gas from landfills generates a series of benefits in an effort to
become environmentally aware. Methane, which is a greenhouse gas about 20 times more potent
than carbon dioxide, is used for human energy consumption instead of being released into the air
(EPA 2010). This benefits the environment by reducing the amount of greenhouse gas emissions
entering the atmosphere. By generating energy, this process reduces the need for non-renewable
energy, such as coal, oil, or natural gas. Incorporating a system of methane gas extraction further
creates jobs, revenues, and cost savings (EPA 2010). Pollution is reduced, and air quality is
improved.
My personal theory is that landfill methanol is a viable source of energy, because it is
utilizing a material that is already in existence without becoming wholly dependent on it. In a
way, it is similar to petroleum, because it is tapping into something that has been generated as a
result of decay. However, I feel a greater responsibility toward using methane from landfill gas
because, as a consumer, I have contributed to the waste in the landfill, and am part of the reason
behind the trash. The concept of extracting methane gas from the landfill is smart to me,
regardless of the financial cost. It is important because it is, in a way, removing from the earth a
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destructive matter that we created, and sending it a different direction in an attempt to be less
destructive. If the city is not profiting, they are still making an effort to be less harmful to the
environment by reducing the use of energy from petroleum. As there are pros and cons to every
method, I further investigated the costs and benefits regarding the use of landfill methane gas to
produce energy.
Findings & Analysis
After a tour of the landfill and interviews with engineer Ray Purtee and Deputy Director
Stephen Grealy, engineer Ray Purtee, and Senior Mechanical Engineer Tom Alspaugh, I was
able to gather information regarding the costs and benefits of extracting methane gas from the
San Diego Miramar Landfill. Monetary costs to the City came from a variety of sources. What is
notable is that the initial start-up cost of installing the gas collection system was paid for by the
private cogeneration firm, Fortistar, which continues to own and operate the systems, saving the
City the $6.4 million cost. According to Stephen Grealy, the Deputy Director of the Waste
Reduction and Disposal Division at the Environmental Services Department, “the City had to
install gas collection systems anyway to satisfy air pollution regulations.” The agreement with
the private firm Fortistar thus saved the City a significant cost. Grealy stated that fines were
“denominal, very small” (Grealy 2011). According to Alspaugh, any fines are usually protests,
which take time to resolve. Ultimately, I was unable to garner precisely how much the City had
collected in fines for the landfill, and consequently could not add them to the sum of costs. The
data also does not include the costs of hiring and maintaining employees.
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Costs of Landfill
Costs to City
Monetary cost of maintenance per year:
Non-monetary cost of time to recuperate: 6
years
Total cost to City since installation in 1997
(2011-1997 = 14 years)
Value
$250,000
$250,000(6) = $1,500,000
$250,000(14) = $3,500,000 (monetary)
$3,000,000 + $250,000 = $3,250,000
The installation of the methane gas collection wells has also enabled the City of San
Diego to save money. It is estimated that the City saves $2 million per year on utility bills
because of the energy plants, which lowers electricity and hot water costs (Grealy 2011).
Savings to City
Start-up cost of installation of gas collection
system, paid for by private firm:
Utility bills per year:
Total savings to City in 14 years since 1997:
$6,400,000
$2,000,000
$2,000,000(14) + $6,400,000 = $34,400,000
While taking a tour of the landfill with Public Information Officer José Ysea, I was
impressed to learn of the amount of production occurring at the site. Aside from being a
dumpster for the trash of the city, the landfill holds a recycling center, a nursery, a greenery, and
also has an area for food compost from larger organizations. There is a Goodwill Drop-off
Center for donations of clothing, furniture, household goods, and jewelry. There is also a wildlife
corridor just off the immediate landfill site. All these are additional services or products of the
landfill site that have an unknown monetary value, and could be classified as benefits to the City
by reducing the amount of waste allocated to the landfill.
In order for a landfill to be a candidate for methane extraction, it must be generating
methane; some landfills are simply too old to produce enough methane for an extraction network
to be of beneficial use. To begin with, there is a network of extraction wells installed in the waste
across all three sites of the Miramar Landfill (North, South, and West) that extract methane gas
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and send it through a pipe, where it ultimately combines with gas from the Cogeneration Plant
and produces energy for the North City Water Reclamation Plant. The wells have valves to
regulate gas flow, and each has a sampling port to measure the pressure, gas generation, and
composition (Agency for Toxic Substances and Disease Registry 2001). Each well also has a
vacuum port, which sucks the gas from the waste. There are over 250 wells on the landfill
property, producing up to 10 megawatts of electricity (Purtee). The energy is used to power the
North City Water Reclamation Plant and the Metro Biosolids Center. This saves the City power
that would otherwise need to be sourced alternately. Leftover energy is sold back to San Diego
Gas & Electric. The use of methane gas also offsets the need for non-renewable resources, being
“coal, natural gas, and oil” (EPA 2010). This reduction in power reduces a toll on the
community. Methane waste that would otherwise be released into the atmosphere or burned in a
flaring process is instead converted to energy, improving air quality as local air pollution
decreases.
Just off-site of the immediate landfill is a wildlife corridor, a habitat for wildlife running
from East Santee to the coast. In this habitat, there are additional wells that monitor the amount
of dangerous fumes leaking off-site, including carbon dioxide and methane. The city contracts to
a private company to maintain the methane quality and keep it marketable. The company may
shut down a well on-site if there is something wrong with it or the trash underground is not
decamping quickly enough to produce enough methane; the shut-off allows pressure to build up
or repair the well if necessary. This, in turn, may cause an issue by increasing the amount of
methane being generated off-site; the levels must be monitored and if they are too high, the onsite well would need to be turned back on. Results are sent to the State Board, who also does
surprise inspections (Ysea 2011). If too many greenhouse gases are being produced, they are
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burned off in flares to prevent pipe explosions and avoid having methane enter the environment
as methane. As a whole, the methane levels on and off-site are very controlled and thoroughly
maintained to ensure safety to the public. The production of energy through the methane gas
extraction system destroys most “non-methane organic compounds that are present at low
concentrations,” and can also reduce “explosion hazards from gas accumulation in structures on
or near the landfill” (EPA 2010). This is beneficial because the system reduces health risks.
Because the landfill site is located on the base of a Marine Corps Air Station, there are
multiple regulations that must be followed to comply with the necessities of the air base. Though
these requirements are met for the sake of military safety, they are also beneficial to the public
health. Obstructions to military aircrafts, for instance, are not permitted and can come in the form
of dust or birds. At the landfill site, water tanks come in to trek down the dirt and prevent dust
from rising and disrupting military practices. While this measure is a necessity for the military, it
also contributes to better air quality. Another issue is the forbidden presence of seagulls. While a
few crows were spotted during my tour to the site, they did not fly high enough and were not
large enough to be considered a hazard to the military aircrafts. Seagulls, on the other hand, pose
a threat when they get caught and blow up the flight engines. At the landfill, a Bird Control
Program is in place to discourage seagulls from appearing. The landfill takes 1.4 million tons of
trash per year, and while gulls can normally be found where there is trash, they are nonexistent at
the San Diego Landfill. Biologists hired by the city developed a bioacoustics method of using
gull distress calls; they combined the calls with a dead gull on site, making it move artificially,
and created a warning to live gulls to stay away. Although the landfill is permitted to kill 20 gulls
a year, they resort instead to shooting off firecrackers from a shotgun and have not killed any in
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at least the past three years (Ysea 2011). These safety measures are part of what allows the
landfill to continue its business.
The State of California requires landfills to cover their trash every night for safety, to
prevent gas escapes and keep animals out of the trash. Most landfills set an alternate daily cover,
or ADC, sending mulch and dirt over the trash. At the Miramar Landfill, dirt is regularly added
to the trash and consists of 5-10% of the hole. Instead of adding more mulch every other night,
the city is permitted to cover the trash with a large white tarp. The bottom-most layer of the trash
is a lining, preventing seepage of the waste. While the landfill life expectancy was initially
expected to last until 1995, recycling and less consumption has extended the lifespan to 2019.
Additionally, the city was granted a height extension from the military to increase another 20 feet
(Ysea 2011). An extended lifespan is a benefit to the City of San Diego, as it gives more time to
find the next method of waste disposal. This also shows that consumers may be more conscious
of the environment, thus reducing inorganic waste and contributing to a greater awareness.
Another demonstration of increasing consciousness of environmental waste at the landfill
is the greenery, which allows the production of mulch, compost, and wood chips. These are all
sold for profit. Citizens can bring their yard waste to the greenery, and San Diego residents may
take up to two cubic yards of mulch or compost for free. There is also a location for food waste,
which comes from organizations including Qualcomm Stadium; Petco; Point Loma Nazarene
University; San Diego State University; the University of California, San Diego; the Convention
Center; and the Marine Corps Recruit Depot. The food waste is mixed in with mulch to produce
compost, which is arranged into windrows, or rows of compost or mulch. Every two weeks, the
windrows are turned inside-out. There are no issues with weeds. The windrows bake at close to
160˚F, cooking the mulch and killing seeds or bacteria while leaving nutrient-rich soil behind
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(Ysea 2011). The ability of the landfill to support the greenery project is a beneficial to the City
because consumers are encouraged to reduce waste, and the greenery utilizes organic waste by
reusing it in different forms.
Revegetation is another facet of the San Diego Miramar Landfill that occurs on site.
While the North and South plots are closed and inactive, they continue to produce methane and
contribute to the amount of methane gas extracted from the pipes. At the landfill nursery, native
plants are grown and replanted over the completed landfill sites in an effort to bring the once
open area close to its original state. As part of the City’s contract with the Marine Corps, they
must “revegetate the land upon completion of its use” (City of San Diego). The goal of the City
staff is to revegetate 50 acres of land per year, and the greenhouse grow and house 30,000 plants
at a time. The landfill does not introduce any non-native plants to the sites, leaving that to the
natural system of animals as seed transporters. In addition to the vegetation of the land, boulders
were brought in to provide habitat elements for snakes and birds. Revegetating the landfill plot
encourages wildlife existence, leading down the food chain to the decomposition of trash. As
part of the contract with the military, the City must comply and simultaneously creates a more
habitat that will be more attractive to any future outdoor use than if it the land were left alone
and barren.
My interview with Ray Purtee, Mechanical Engineer for the City of San Diego, answered
questions regarding more detailed information about the San Diego Miramar Landfill. From my
interaction with Purtee, I learned that the criteria necessary for a landfill to extract their methane
gas largely involves age. Some landfills are too old to generate methane and be financially
viable. Another factor is the size. According to Purtee, “larger landfills are more viable for
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methane utilization,” as they can produce a greater output from the installation of methane
extraction wells.
At the Miramar Landfill, the initial cost to install the collection systems and flare system
was $6.4 million. A private company paid for the initial gas installation system and generators,
so there was no capital input from the city. Purtee estimates maintenance fees to be close to
$250,000 per year. According to Purtee, the system generates 10 megawatts of electricity a year,
saving the City $1 million a year in energy costs. Grealy estimates a higher sum of $2 million per
year. It took approximately 6 years to “recoop the initial factor in investment” (Purtee 2011),
before the amount of revenue surpassed the cost. The extraction of methane gas was done for
both financial profit and ecological purposes, as there are state regulations requiring the control
of landfill gases, in addition to a financial incentive of having a private entity install the system
(Purtee 2011). Aside from cost savings, the extraction system has financially benefited the city
by stimulating the economy, creating jobs and revenues (EPA 2010). Extra gas can be sold for
revenue, and jobs are created for design, construction, and operation of the system.
Purtee agrees that the system of methane extraction could easily be done elsewhere.
However, what is essential to recognize is the question of what the financial factors are, and what
the payback is in years. Physically, it can be done; he simply questions “whether it would be
done because of the financial consideration.” For the two inactive San Diego landfills, Purtee
offers input on ongoing efforts from the city to utilize the land:
“We’ve been trying for many years to get private industry interest in these two sites that
we have in the city for energy utilization and we’ve not been successful because the
economics don’t play out. The sites are just too small to give payback—we haven’t
stopped trying… there is some beneficial use possible… One could do a small project
that only uses a fraction of the gas available; that would keep your capital initial cost
down. If you go in with a larger project, expending higher capital… you may not get a
payback” (Purtee 2011).
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For inactive landfills in general, Purtee mentions that some landfills have golf courses on
them. Additionally, landfills could be used as sports fields, hiking trails, or anything that is “lowintensive, where the community could have access to the site.” There is an inactive site in Balboa
Park, where there are trails and people can walk their dogs, go jogging, or mountain biking.
The costs and benefits of the methane gas extraction system at Miramar landfill can be
appraised accordingly, but the benefits do not have monetary values the way the costs do. Of the
benefits of the methane gas extraction project at the landfill, air quality, reduced health risks, the
economy, and access to renewable energy contribute to a series of benefits that cannot be priced.
The values of these benefits vary by their importance to people of differing opinions.
Conclusion
There are a variety of advantages and disadvantages to the use of methane gas from the
San Diego Miramar Landfill. While there are heavy financial costs and ecological benefits, there
is also financial revenue and ecological losses. As a project, the extraction system provides an
important alternative to allowing the methane gas in the landfill to enter the atmosphere as a
toxin. However, a solid conclusion requires further investigation of the success of the system and
the amount of regulations that have been broken during its lifespan. Without further research, I
cannot offer a condemnation or approval of the project.
Upon entering this research project, I expected to find that the methane gas system was
used only on what is considered the “active” landfill, and had little to do with the inactive
landfills. I had thought that the payoff would be too small for inactive landfills and the process
too expensive for them to be financially worth the cost. However, the inactive landfills at
Miramar are in fact still producing methane that is being utilized as energy. They remain
18
productive. I essentially expected the inactive landfills to be plots of waste, discarded and
useless. However, the inactive sites at Miramar are revegetated, given encouragement to
reproduce native plants and species, and thus provide a habitat for the existing wildlife there. At
this particular landfill, the City is doing its utmost to develop its territory into more than just an
empty wasteland; it a business, working from the disposals to provide compost, mulch, wood
chips, a location to recycle clothes or unwanted goods for the public, and a place for trash as a
last resort.
The West Miramar Landfill is the last landfill owned by the City of San Diego. It is
expected to reach capacity around the year 2019. The air base last granted at 20-feet height
increase, but the city will have to wait approximately another 10 years for additional increase.
According to the San Diego County Greenhouse Gas Inventory Waste Report from September of
2008, the amount of waste disposed in San Diego has been steadily climbing since the 1950s (see
Appendix C). Space is running out, which means new ideas are needed to dispose of waste we
cannot recycle and will likely continue to produce. About 4-5 different pilot programs are in
progress for future solutions, ranging from the idea to sell the land and privatize it to the idea of
returning to the North Landfill and mining it. Because the North Landfill’s lifespan was from
1973-1983, recycling was a less prominent concept, and the landfill is full of trash that could be
removed and recycled, thus freeing up more space. A trial run revealed pieces of recyclable
items left intact, including newspaper. Unfortunately, this concept would also suggest that within
the landfill there would also be toxic waste, and uncovering such a territory would create a
significant health hazard (Ysea 2010).
In our developed nation, our consumption inevitably leads to a large amount of waste.
Landfills, then, are a necessary evil, so it is not reasonable to dismiss them altogether or to
19
suggest that we should stop using them. The concept of harvesting the methane gas produced
during the decomposition of metric tons of waste seems a practical idea to utilize the materials
we have. While we still have petroleum sources available, however limited, some might believe
that it is unnecessary to seek alternative forms of energy. Oil, natural gas, and coal are nonrenewable forms of energy. Petroleum is a limited resource that can provide much-needed fuel
for cars, but for as long as people do not see the boundaries of their resource, it is infinitely
available, and they may well deny the concept of an end. Unfortunately, landfills, much like
crude oil or natural gas, are currently a necessity, as is the need for energy. Equally similar to the
source of oil, landfills are a limited source of space, and there will come a time when the lack of
space will force an alternate path. Until landfills become obsolete, it seems only perfunctory to
capture the gas created by the decay of man-made products and use it for energy.
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Appendix A
Interview Questions
1. We have an abundance of landfills, so why is it that we cannot simply extract
methane from all of them? What criteria does a landfill need to meet in order to be a
candidate for methane extraction?
2. Exactly what happens at the Miramar Landfill? How is the methane gas extracted,
and where does it go?
3. How much did it cost to get to this process started? What about maintenance?
4. When did methane extraction first begin at this landfill?
5. What other costs are there to the city for the methane gas system? How much does the
city reap in fines?
6. What was the time span for the revenue to break even and surpass the cost? Is there
financial profit, or is this process done for ecological purposes?
7. Do you believe this system of extracting and converting methane gas to methanol
could be easily applied elsewhere? What conditions might be necessary?
8. What ideas or suggestions might you have for the use of inactive landfills? There are
two in San Diego. Do they have any potential for future use?
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Appendix B
Costs and Benefits
Monetary Costs
Start-up cost of installation of collections and
flare systems:
Maintenance per year:
Non-Monetary Costs to the City
Time to recuperate: 6 years
Total Cost to City After 6 Years:
Total Cost to City Since Project Birth:
Savings to City
Start-up cost of installation of gas collection
system, paid for by private firm:
Utility bills per year:
Total savings to City in 14 years since 1997:
Value
$6,500,000 (paid for by private company
Fortistar)
$250,000
$250,000(6) = $1,500,000
$0
$3,250,000
$6,400,000
$2,000,000
$2,000,000(14) + $6,400,000 = $34,400,000
Benefits to City
Air quality improved
Renewable energy option
Reduced health risks
Job opportunities
Revenues
Cost savings
Recycling of goods
Source for yard waste, compost, mulch, wood chips
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Appendix C
San Diego Waste Disposal
23
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