The Hillsborough County, Florida, energy-from-waste
facility—operated by Covanta Energy—currently produces 30 MW and
is undergoing an expansion that will see it produce approximately
47 MW. (The post-expansion facility is pictured.) Photo courtesy
of CDM.
Energy From Waste
Rising landfill costs—as well as increases in energy
prices—are fueling renewed interest in energy-from-waste, and
Covanta Energy stands ready to expand its well-established network
of facilities, which currently produce 7,800 gigawatts of renewable
energy.
By Diane Mettler
Each year thousands of acres of land are lost to
landfills in the United States. That figure will only continue to
rise as the country’s population grows.
Unfortunately, the bad news doesn’t stop there.
Methane produced from decomposing waste is a potent greenhouse
gas—over 20 times more powerful than CO2. And the costs associated
with using a landfill are rising as cities and counties truck their
waste ever farther away—sometimes over state lines.
Reasons like these, and others, are causing
municipalities to re-evaluate the benefits of energy-from-waste (EFW)
facilities. Some municipalities are considering new facilities and
others are looking at expanding the ones they have.
Covanta Energy of New Jersey is well aware of the
growing interest. A leader in the industry, the company runs 31 EFW
facilities in the U.S., processing about 15 million tons of
municipal solid waste annually and producing 7,800 gigawatts of
renewable energy (enough to power all the homes in Philadelphia).
Recently, the company has responded to two proposals for new
facilities, has expanded a facility in Lee County, Florida and is
currently expanding another one in Hillsborough County, Florida.
"One of the last greenfield projects that was put
into operation was our Montgomery County, Maryland facility, which
came on line in 1995," says Derek Porter, the company’s director of
corporate communications. "Essentially, there were no new facilities
built over a 10-year-period—until our two expansions in Florida."
The municipalities foresee numerous benefits to
expanding or building an EFW facility, including:
• Controlled Costs and Long-term Disposal Options:
Land-filling in densely populated areas, particularly Florida, is
very costly, and there’s no way to know what the price will be
three, five, or 10 years from now.
"Even if the municipality owns its own landfills,
they don’t want to fill them up quickly with raw municipal solid
waste," says Porter. "With EFW facilities, counties can extend the
remaining disposal capacity in their existing landfill by as much as
20 times, and can also retain control of their long-term solid waste
disposal options and create predictable disposal rates."
• Revenue from Energy: With renewable, alternative
energy at the forefront, people are looking for ways to provide
significant energy from non-fossil fuel sources. EFW facilities,
like Covanta’s, can produce about 80 MW and run 24/7, providing a
reliable source of renewable energy. Approximately 10 percent of
energy produced is used to power the facility; the remainder is then
available for sale to utility companies or on the free market.
• Elimination of Greenhouse Gases: No methane is
produced at an EFW facility. "Although, no new facilities today have
been built to offset greenhouse gases, the subject is in the
forefront, and people are starting to recognize EFW facilities as an
excellent way of mitigating harmful GHG emissions," says Porter.
• Expansion without Rate Hikes: Many facilities were
built in the late 1980s or early 1990s, and often financed with
public money in the form of 20-year bonds. As the bonds are paid
off, municipalities can now choose to either lower the solid waste
disposal rates they’ve charged customers or use the bonding capacity
that has been freed up to expand their EFW facilities while keeping
customers’ rates the same.
"It’s a great incentive," says Joseph Treshler,
vice-president of business development for Covanta. "It’s exciting
to see our clients, local government staff, be able to go to their
governing board and say: ‘We can expand the capacity of our solid
waste management system and cover our needs for another 15 to 20
years. And by the way, we don’t have to increase the disposal rates
to our ratepayers.’ It’s a great position to be in for county staff
or board of county commissioners."
• Expansion Ready: Many of the original EFW
facilities were designed with growing populations and future
capacity expansion in mind.
• Easy Urban Interface: Unlike landfills, EFW
facilities cause no odor and don’t attract rodents or birds. They
also have a very small footprint.
Porter reinforces this last point. "I’m actually
working at one of our facilities in Alexandria, Virginia, which is
across the street from a Washington D.C. metro station. There are
some very expensive townhomes on the other side of this facility and
we don’t receive any complaints."
Condenser fans on the roof of a Covanta energy-from-waste (EFW)
facility. Covanta is a leader in the industry, running 31 EFW
facilities in the U.S., processing about 15 million tons of
municipal solid waste annually and producing 7,800 gigawatts of
renewable energy.
But maybe one of the best reasons to consider an EFW
facility is that municipalities across the nation have been
successfully operating them for over 20 years. The process is proven
and fairly straightforward.
Municipal solid waste is deposited into a refuse pit
and an industrial crane feeds the waste into specially designed
combustion units equipped with integral boilers.
Each combustion system has a unique grate system to
help burn/combust/process the waste efficiently. "Most of them
employ the German-made Martin GMBH grate system," says Porter.
The combustion process reduces the volume by over 90
percent. The energy produced is used to power the facility and the
remainder is sold. The remaining ash, which represents less than 10
percent of the original waste volume, is commonly used as landfill
cover or landfilled.
Covanta has added an extra step prior to landfilling—pulling
out all the ferrous metals. "Essentially the ash is passed by a big
magnet that pulls out these magnetic metals," says Porter. And
Covanta pulls out a sizable amount. "We recycle about 360,000 tons
of ferrous metal a year, enough to make approximately 270,000 cars.
That’s metal that would have sat in a landfill if it hadn’t come to
one of our facilities."
Several facilities have also added non-ferrous metal
recovery to capture the aluminum, brass, copper and other
non-magnetic metals that have escaped the communities’ recycling
efforts.
Covanta doesn’t see itself as a recycling
competitor, but as a recycling promoter. "Communities that have EFW
facilities have a higher recycling rate on average compared to
communities that don’t," Porter says. "In the U.S., communities that
have EFW average 33 percent recycling rates compared to the national
average of 28 percent."
Despite EFW’s wide use, there hasn’t been much new
technology centered on EFW since the Clean Air Act was enacted in
the 1990s, when facilities installed advanced air pollution
equipment. But the lack of advancements may be because EFW was ahead
of its time. "We’ve always been heavily regulated," says Porter,
"And we have been far advanced and out in front of other combustion
industries, like coal-fired electric power plants, with the
technology we currently have in operation."
The control room of a Covanta energy-from-waste facility. EFW
facilities like Covanta’s can produce about 80 MW and run 24/7,
providing a reliable source of renewable energy
But that doesn’t mean there haven’t been any
breakthroughs. Covanta announced in February that it had developed
two new technologies that represent major advances in controlling
nitrogen oxide (NOx) emissions and improving energy efficiency. Both
technologies are tested and ready for full-scale commercial
application.
In short, the technology will allow existing EFW
facilities to cut NOx emission well below U.S. EPA requirements. And
when coupled with selective non-catalytic reduction (SNCR) systems,
will drop NOx emissions to approximately half of current regulatory
limits.
"This is particularly important in the heavily
populated areas of California and on the east coast of the U.S.
where these oxides of nitrogen are a precursor to ozone and this
low-lying ozone causes smog," says Porter.
Whether municipalities incorporate their new NOx
control technology or not, Covanta sees expansions as the wave of
the future. The current Hillsborough County, Florida, expansion may
turn out to be typical of what’s to come.
Hillsborough County’s EFW facility was originally
designed by Covanta to handle 1,200 tons of municipal solid waste
per day. The County is currently having Covanta expand the facility
to process 1,800 tons a day, by adding a single, 600 ton-a-day
combustion unit.
"There was space laid out in the original
footprint," says Covanta’s Joseph Treshler. "Originally the County
had envisioned a future 400 ton-a-day expansion. But they decided to
put in the largest unit they could fit into the confines of the
design and take advantage of economies of scale."
The Hillsborough EFW facility currently produces 30
MW and after the expansion will produce approximately 47 MW. About 5
MW will be used to meet the internal needs of the facility with the
remaining available for sale to Tampa Electric.
Covanta originally built the facility in 1987 and
was granted a 20-year operating agreement. In 2007, it’s somewhat of
a repeat—Covanta will handle the expansion and the County granted
Covanta a second 20-year operating agreement.
"We’re on a 28-month construction schedule," says
Treshler. "We started driving pilings in June and the expansion is
scheduled to be completed in April 2009."
The facility will only need a small addition to its
existing operating staff to cover the operation of the new expansion
unit, but the construction staff is expected to peak somewhere
around 250 people, which should give the community a positive boost.
As expected, many contractors will be involved. The
major ones include: Sauer Inc. as general contractor; the boiler and
erector supplier is Babcock Power; and the air pollution control
system supplier is Alstom Environmental System. The turbine
generator is manufactured by Siemens and the architect engineer on
the project is DMJM & Harris.
Despite all the work, the end product will be hard
to spot. "The way the facility was originally laid out, the
combustion unit fits into a slot in the back of the building. Others
things that you wouldn’t be able to notice are an additional cell on
the cooling tower and a side-by-side switchyard to tie into the new
generator. From the outside, people won’t even notice anything has
changed," says Treshler.
Porter believes that expansions like these will be
the first wave, and will be followed by new greenfield
infrastructure, partly because so many of the EFW facilities were
built with expansion in mind and it makes financial sense to add to
those first.
"The new EFW facilities will probably be centered
along the East Coast or where the population densities are the
highest. Just recently we heard that Los Angeles County, California
is looking at EFW options," says Porter. "Even Hawaii has a new EFW
proposal planned. I think we’re right on the verge here.
Municipalities are going to start really looking at their overall
long-term integrated waste programs again."
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