It's an unsightly spectacle that's all-too familiar – trash
bins overflowing with rubbish, littering the landscape from city streets to
local beaches with mountains of plastic bottles, newspapers, Styrofoam take-out
containers and everything in between.
Yet amid the mounting piles of garbage, a group of engineers
saw opportunity. After learning that garbage trucks are one of the most costly
vehicles to operate – they consume over 1 billion gallons of diesel fuel each
year in the United States alone and limp along getting an average of 2.8 miles to
the gallon – the team formed a company in 2003 to take on the growing waste
management problem and design a new kind of trash receptacle.
BigBelly Solar
had a few very specific design goals: The trash compactor had to be around the
size of a normal receptacle so it could easily fit street-side; the unit had to
process larger quantities of trash to reduce the frequency of garbage pickup,
and it had to be standalone so it could derive power from an alternative energy
source. Wind was quickly ruled out because the energy source wasn't constant
and it was too dangerous to have wind turbines lined up across city streets.
"When you're aiming for the street corner, there are a lot
of limitations as to what you can use for power," says Jeff Satwicz,
BigBelly product manager and one of the original engineers behind the company.
"In order to run an electrical line to a standard outlet, you're talking about
thousands of dollars of investment for each location just to provide power
there. (As a result), the whole value proposition of cost savings around not
collecting trash goes out the window because you're paying so much to install
the unit."
None of that was the case with solar power. While there were
no major breakthroughs in solar panel technology that led to BigBelly Solar's
decision, the timing pointed to solar energy as the natural path to choose.
Other solar, so-called off-grid applications were being introduced, including solar-powered
parking meters and solar-powered
traffic signals, which underscored the effectiveness of this power source
for BigBelly's trash compactor application.
"Solar applications are becoming more acceptable everyday
technology," Satwicz says. "There are solar panels on calculators and walkway
lights – it's something people are starting to see more and more on things other
than rooftops."
Back to the Drawing Board
While the timing was right, BigBelly's original design
concept – a simple refashioning of an existing trash compactor into a solar
unit – was not. Existing trash compactor designs zeroed in on cost efficiencies
or ruggedness, but none took into account energy consumption, which was so
critical to the solar-powered design. Because BigBelly was committed to
delivering the compactor as a smaller, self-contained unit, it needed to
rethink the design for a fresh approach that demanded less energy. "If we
didn't take steps to minimize energy consumption, the whole idea of a
solar-powered trash compactor would be a total failure," Satwicz says. "The
size of the panel we'd need to power the system would be the size of a wall and
that would defeat the whole purpose of having one self-contained unit."
Armed with 3-D CAD and simulation tools from SolidWorks, the BigBelly engineering team
went back to the drawing board to rethink its design in a way that would
best leverage solar power. Drawing inspiration from the simplicity of a bicycle
chain, the BigBelly team created a drive chain mechanism to propel the
compaction system, which in turn uses no hydraulic fluids and consumes minimal
energy. As a result, the BigBelly trash compactor is powered by a 30W solar
panel, which measures 18 inches by 22 inches – just the right footprint to
accommodate the design goal of creating a self-powered, self-contained unit.
The next step was to optimize every component choice and all
materials for efficient energy consumption. The BigBelly receptacle features a monitoring
system comprised of a microprocessor, circuit board and infrared emitter and
sensor, which determines when the trash needs to be compacted and collected.
The design also calls for a multicrystalline solar photovoltaic module used to
collect the sun's energy for subsequent storage in a 12V battery. That's where
the chain mechanism and gear motor kick in. They leverage the stored energy and
transform it into compaction power, Satwicz says.
The choice of materials was also a major design challenge. When the
price of steel went up early in the design process, the BigBelly team and its
outsourced partners embarked on a major effort to remodel the early prototype
to reduce the amount of steel parts, both to make the unit more price
competitive and in keeping with an eco-design focus. Using SolidWorks' sheet metal
features and the finite element analysis features of COSMOSxpress, the BigBelly
unit was rearchitected with 30 percent fewer steel parts, Satwicz says.
Other materials choices included a Lexan polycarbonate cover to protect
the solar panels on the top of the trash barrel. While the polycarbonate blocks
out minimal amounts of the solar radiation, it was a better design tradeoff
than leaving the panels exposed to the elements, according to Satwicz.
SolidWorks' eDrawings
email-enabled viewing and communications tool also played a key role in the
on-going development effort. Using eDrawings, the BigBelly team was able to
send 2-D drawings and 3-D models back and forth with both its outsourced design
and manufacturing partners, a process which kept everyone on the same page and
speaking the same language when it came to the product's evolving design.
The ability to send lightweight 3-D models back and forth with the
eDrawings tool really helped BigBelly and its manufacturing partner, Mack Molding Co. meet the company's tight
production and launch deadlines, according to Chris Glaski, sheet metal
manufacturing engineer at Mack. Rather than the time-consuming process of
sending memory-intensive CAD files over the Internet, the teams were able to
share smaller eDrawings files in a timely fashion, which aided in identifying
and modifying potential areas of interference. That was especially the case
with some of the initial sheet metal designs, which proved not to work properly
with Mack's press break tooling. "It's
one thing to design a sheet metal assembly in SolidWorks; it's another thing to
manufacture it," Glaski says.
Today, there are over 1,700 BigBelly solar trash compactors spread
across the U.S.
and the world, including a couple of high-profile units at Boston's
Fenway Park and the Portland Oregon Zoo. At 300 lb and about the same
height and width of an average receptacle, BigBelly compresses the equivalent
of five trash cans into a single receptacle, which helps companies and
municipalities avoid four out of five garbage collection trips, on average,
Satwicz says.
The newest iteration of BigBelly launched last year and the company is
planning new designs, including a dumpster-sized system and adding new
technology that communicates information wirelessly back and forth between the
unit and its owner. In this way, customers can get a sense of when a BigBelly
unit is full and arrange trash pickup accordingly.
All of these innovations
wouldn't be possible without 3-D models driving the iterative process. Says
Satwicz: "Given that we're a mature product now, if we didn't have CAD to try
out new ideas and see how they fit with our robust design, we wouldn't be able
to make any changes."
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