Case study: Briggs
& Stratton’s first-of-its-kind power regeneration system cuts costs in
reliability lab. Global small engine maker captures wasted energy, expects to
save $50,000 per year, and modernizes data collection and control system.
October
8 -- Lawn mower and small engine parts manufacturer Briggs & Stratton was
spending over $1 million in fuel costs alone to run engine endurance tests in
its labs. To cut costs and realize the power wasted in heat from existing
dynamometers, Briggs & Stratton worked with an automation vendor to develop
a new power regeneration system. The new system helped Briggs & Stratton
win two honors for sustainability, and the 556,000 kWh expected output could
power 48 homes each year.
Daily,
around the clock, the buzz of small engines fills the reliability laboratory
inside Briggs & Stratton’s main plant near Milwaukee, Wis. Employees monitor
the prototype and modified engines to meet the exacting standards set by one of
the largest producers of lawn mowers, snowblowers, and other outdoor power
equipment.
“Our
task is to flush out failures in the lab, and prove the durability and safety
of the design before it’s sold to a customer,” explained Ray Matuszak, test
engineering manager, Briggs & Stratton. “Continuous, consistent, and
accurate measurement of test time and operating characteristics are vital to
establishing the engine’s long-term reliability.”
In
February 2011, Matuszak and his team began gleaning this critical information
from fully automated test stands that also provide a first-of-its-kind
benefit—regenerating power for the plant. These innovative technologies helped
Briggs & Stratton’s reliability lab become one of the most advanced in the
industry, and quickly earned the company awards for environmental
sustainability.
But
overcoming the many challenges associated with the project took four years of
effort and ingenuity.
The
reliability lab’s endless endurance tests are costly. Briggs & Stratton was
spending nearly $1 million in fuel cost alone to run engine endurance tests in
the labs.
Briggs
& Stratton engineers realized they could lower operating costs if they
could capture power that’s wasted in heat from the existing dynamometers. Their
goal was to harness that energy and convert it into electricity for the plant’s
consumption.
The
problem was this type of power regeneration system didn’t exist. And the cost
of creating it, engineers worried, might be too high to justify the investment.
Besides,
the reliability lab needed other advanced technology to meet its core goals.
First on the list: an automated supervisory control and data acquisition system
with customized visualization and historical tracking capabilities.
At
the time, clipboard-carrying technicians manually monitored each engine during
its life span in the lab, recording load, various operating temperatures and
other key metrics. This labor-intensive, information-gathering system was prone
to inconsistencies and human error.
As
engineers from both companies began brainstorming the custom requirements for
the project, they also focused on ways to achieve the best return on
investment. One potential opportunity: a “Focus on Energy” grant from
Wisconsin, which—like many states—had begun offering incentives to boost the
use of clean, renewable power.
The
engineers worked to compete for the state funding in 2008 and again in 2009. On
their third try, they won a grant to pay half the cost of a pilot project.
The
combined engineering team spent the next several months collaborating closely
on keeping the captured electricity within the plant while maintaining a smooth
and safe connection with the external power grid. Automation engineers worked
with the local utility company, We Energies, to accommodate both power flows.
On
the data-acquisition side, the biggest hurdle was establishing what information
needed to be captured by the automated system, and what controls and safeguards
would be included in the system. Then there were the discussions about control
details, how engine operating characteristics should be displayed, along with
understandable terms and data system custom features.
“For
technicians accustomed to recording information on a clipboard, an interactive
touchscreen presented a major mind shift,” said Richard Feustel, corporate
energy services manager, Briggs & Stratton.
The
automation vendor “walked a roomful of us through hours of whiteboarding,
explaining options on how to enter, acquire, and share data. Everybody who
would be affected by the conversion had an opportunity to contribute to the
planning, so we got exactly what we wanted. That also made the later transition
in the lab easier, because our folks had been part of the design process,”
Feustel said.
In
February 2011, the pilot program went online with 12 test stands designed for
use with various engine types and horsepower limits. Each test stand is run by
an alternating current (ac) motor using a variable frequency drive (VFD). The
drives run at fixed speeds to start a gasoline engine. Once the gasoline engine
is up to speed, the motor and drive load the engine to a torque level based on the
engine horsepower rating. Alternatively, the system is capable of controlling
complex duty cycles with varying loads and speeds as defined by the operator.
The
regeneration system captures the power output of the gasoline engines and
creates electricity with that power. All 12 ac motors and drives convert to a
common direct current (dc) bus supply. The dc bus supply then converts the dc
to ac, and synchronizes to the ac line, where all the power is directed back to
the internal grid—reducing the need for electricity from the outside utility.
Six
local enclosures provide two functions: local control of the drives for setup
and up to six thermocouples per engine. Data used to monitor engine health and
diagnose potential failures—including test run-time, multiple temperatures,
alternator voltage, and engine speed and torque—goes to a programmable
automation controller (PAC) via an Ethernet network.
With
human-machine interface software, engineers and technicians can view critical,
real-time information on engine load, speed, temperature, test-run time,
oil-use rates, and other critical variables on any industrial computer in the
lab. Historian software automatically captures that real-time data for analysis
using Microsoft Excel, and technicians can identify any trending for use by
reliability engineers.
Briggs
& Stratton also invested in industrial energy management software, a
comprehensive Web-based application that logs and analyzes energy-use data
within one plant or from multiple, related sites. The energy management team at
Briggs & Stratton uses the software to gather information about electrical,
gas, and steam usage from power monitoring devices installed around the
Milwaukee campus. Energy managers can access that information in the industrial
energy management software and create reports about energy-use trends to share
with the various departments in the plant. This information helps identify
top-priority power issues.
It
made perfect sense to invest the energy management software “so we could benchmark
our power use and track our savings,” Feustel said. “Before, the only
information we had about our energy use came in our electrical bills.”
Results
Briggs
& Stratton engines are tested and regenerate electricity for use within
the plant via regeneration stations. Courtesy: Rockwell AutomationBriggs &
Stratton quickly achieved a range of benefits, some expected and others that
pleasantly surprised the company.
The
reliability lab is on track to generate as much as 556,000 kWh annually—equal
to the amount needed to power 48 homes every year. That captured electricity is
fed back to the plant’s internal grid, which the company hopes will save an
estimated $50,000 a year.
Another
environmental plus: the electricity generated by the 12 test stands alone
reduces the plant’s greenhouse gases by 442 tons annually.
The
regeneration project was a major reason Briggs & Stratton received two
prestigious honors for sustainability in 2011. The Environmental Innovation
Award from the Wisconsin Manufacturers and Commerce, and the Galaxy Star of
Energy Efficiency Award from the Alliance to Save Energy were presented in
Washington, D.C., to Briggs & Stratton’s Chairman, President and CEO Todd
Teske by Wisconsin U.S. Senator Herb Kohl.
In
accepting the Environmental Innovation Award, Briggs & Stratton thanked its
automation vendor for its role in creating the regeneration system.
Matuszak
acknowledges the importance of the regeneration system itself, but contends the
new automated data-acquisition and control capabilities are equally valuable.
“Certainly
without the payback derived from power regeneration, this project would not
have gone forward,” Matuszak said. “But automated data acquisition and control
has a lot of positive effects on the bottom line. The most important benefit is
improved test fidelity—we have streamlined data collection versus the crude
traditional methods. We can tell instantly when an engine is not operating
normally or when a test is set up incorrectly. The new system also increases
productivity and efficiency by freeing technicians for other tasks.” Feustel
and Matuszak agreed they’d like to eventually expand the project, but first
they must harvest all the insights from the initial phase.
“The
variety and volume of information is outstanding,” Feustel said. “We’re still
learning how to best utilize the data we’re getting from the 12 test stands.”
However, Briggs & Stratton is quickly expanding its use of industrial
energy management software, and its ability to track, analyze, and visualize
energy-use data from multiple locations. The company has installed a dozen
power monitors in its Milwaukee facility that feed information into the
software. Soon, Briggs & Stratton plans to put five monitors in its plant
in Murray, Ky., and within five years expects to place them in the company’s 10
other manufacturing facilities worldwide.
“With
the Web-based system, we can view other plants’ metrics and track our energy
usage and spending across the enterprise,” Feustel explained. “Adding onto this
global dashboard...is so easy, it simplifies the process of becoming even more
sustainable.”
Return
on investment details
Project
cost: $216,800
Project
savings: $48,031/year (533,678 kWh regenerated from expected engine testing at
$0.088/kWh)
Simple
payback: 4.5 yr (2.0 years with FoE Grant)
Focus
on Energy Grant: $118,600
Completion
date: 02/28/2011
Award:
The building received the Wisconsin Green Building Alliance Sustainability and
Energy Efficiency (SE2) Award Special Citation.
