Andersen Closes the  Loop on  its Energy  Supply
                   with  Renewable  On-site  Generation and
                   Warm  Water  Recovery
Costs and Benefits of Andersen's
Steam and Warm Water Recovery
 $22 million for
 the project-
 large capital
 with multi-
 year payback
 period, (grant
 and rebates
 can offset some
 of the costs
 of renewable

 Working with
 regional and
 stakeholders to
 ensure support.
Savings and
Other Benefits
Reduces energy loss from
piping steam from an
external supplier.

Control over the efficiency
and reliability of facility
steam supply.
Closes the loop on Andersen's
wood waste stream-reduced
waste disposal cost.
WWRS uses free source of
waste heat from a nearby
power plant.
WWRS reduces the thermal
load of waste water flowing
into the St. Croix River.
        U.S. Environmental Protection Agency
             United States
             Environmental Protection
Andersen Corporation, Bayport, Minnesota

Alternate Goal: Increase renewable energy use from biomass
and recovered warm water

Inputs: Total Energy Used from Renewable Sources

Andersen Corporation's window and door manufacturing facility sits on a 65-acre site
along the St. Croix River in Bayport,  Minnesota. In 2007, the plant began operation of
its new on-site steam generating facility (SGF), which supplies steam for the production
of up to six million windows and doors per year.1 Built on the footprint of an older,
vacant Andersen building, the new SGF was designed to efficiently burn renewable
wood fuel and eliminate the facility's reliance on coal-based steam sourced  from a
neighboring power plant.
In 2005 when the SGF  project began, more than 60 percent of Andersen's steam was
being piped in from a neighboring power plant, with the remainder generated in-house
by the existing wood-fed boiler system. When the local supplier began phasing out its
steam generating capacity, Andersen decided to assume  greater control of its energy
supply by designing and installing its own steam generating facility at its Bayport site.
Based on environmental, cost, and performance measures, Andersen calculated that
a new on-site, biomass steam sourcing solution would meet its energy needs while
having the least impact on the surrounding community and environment. The boilers
are fed with wood byproduct—shavings, chips, or fines—from Andersen's own wood
milling operations. All of the material is processed through a grinder to produce a fine
powder, called wood flour, which is fed directly into the on-site renewable boilers. The
company set Environmental Management System (EMS) goals to increase the quantity
of renewable wood flour used to fuel the boilers for steam production, and to increase
the use of recovered condenser water from the neighboring  power plant to heat
portions of the facility during the winter months. Andersen also decommissioned its six
older wood-fired boilers as a result of this project.
The new SGF  installation includes a warm water recovery system (WWRS), which
uses existing pipes from the old steam infrastructure to transport warm discharge
water into the facility heating system. As part of Andersen's commitment to voluntary
environmental improvement,  its goal under the Performance Track program was to
increase the use of renewable biomass fuel and warm-water energy. Progress toward
                               2008 figure

increasing energy use from renewable sources is measured
in MMBtu.2 Currently, Andersen's SGF enables the facility to
produce more than 60 percent of its required steam and heat
from renewable energy and the warm water recovery loop.
Andersen intends to  continuously improve this percentage.

The Andersen team worked closely with its design, engineering,
and construction contractors to ensure that the design and
implementation of the SGF followed the project's four guiding
* Partnership
* Innovative Design
* Environmental Responsibility
* Community Sensitivity
The design/build package consisted of a $22 million steam-
generating facility to be entirely owned by Andersen and
featuring all-new, state-of-the-art equipment. By owning and
operating the SGF on-site, Andersen directly manages the
day-to-day operation and efficiency of its boilers and maintains
control over the quality and  supply of the steam produced. This
also prevents energy loss when steam  is transported from an
off-site supplier.
To minimize environmental and visual impacts, the SGF was built
on the footprint of an existing storage building adjacent to the
manufacturing buildings.  Steel for the SGF structure was salvaged
from used railway lines from  the older demolished building. To
manage runoff and reduce sedimentation, an industrial rain
garden was added that reduces the  amount of stormwater
entering the adjacent St.  Croix River scenic waterway. In addition,
the structure itself was designed to  minimize noise and visual
impact; all noise-generating devices were located inside the
building and a casing pipe surrounds the two boiler stacks so that
only a single stack is  visible from the outside of the SGF.
The new boilers in the SGF have been designed to burn wood
byproduct from Andersen's manufacturing operations. Wood
was chosen as the primary boiler fuel because it  is a renewable
resource and an ample supply is generated from Andersen's
operations.  Different waste wood streams result  in differently
sized wood  particles  such as  shavings, chips, or fines. All of the
material is processed through a grinder to produce a fine powder.
The wood flour is then conveyed from a storage silo, weighed on
a belt scale, and delivered to a small live bottom  bin that feeds
burners firing two boilers, each capable of producing 40,000
pounds of steam per hour.
The wood fuel preparation process assures efficient combustion
and minimal ash generation.  The ash byproduct from the boilers
is sold to area farmers to  amend deficient soil, so Andersen is
2  MMBtu = 1 million Btu. The British thermal unit is a traditional
unit of energy used in the power, steam generation, heating, and
air conditioning industries.
                   n  or
Andersen's on-site Steam Generating Facility uses renewable sources
by combining wood-fired boilers with the heat recovery resulting
from a Warm Water Recovery System.

able to divert the majority of its SGF waste stream from the local
landfill and create an additional revenue stream for the company.
While the neighboring power plant no longer supplies steam
to Andersen, its thermal facility continued to release warm
water—up to 65 degrees Fahrenheit—from its turbines into the
St. Croix River. Part of the engineering contractor's design for
Andersen's new energy infrastructure included a customized
warm water recovery system (WWRS) that uses this warm water
to run through four large makeup air-handling units each capable
of ingesting 750 gallons of temperate water per minute for a
total of 3,000 gallons per minute. This warm water recovery loop
uses the old steam lines and new pumps to move water into
the facility heating and air circulation system, so less energy is
required to heat the plant.

Andersen worked closely with its community advisory boards and
welcomed feedback on the design and construction of its SGF.
The Andersen Community Advisory Committee (CAC) has been
a stakeholder in Andersen's environmental performance for more
than 10 years, and input from the CAC influenced many of the
low-impact features of the SGF—including the rain garden, the
one-stack exterior structure,  and the noise buffers.
TKDA, an engineering, architecture, and planning firm, was
involved throughout the entire SGF project from design to
implementation and construction. The project was led by a
team composed of staff from Andersen and TKDA. The design/
build team managed the construction phase of the project and
included energy, construction, and electrical contractors. The
team worked closely with Andersen to develop a customized
system to process and transport wood waste to the new SGF.
The wood-fired boilers are also equipped with low-nitrogen-
oxide natural gas burners as a backup heat source to the wood
burners. Flue gas is used to preheat make-up water to further
conserve energy. Andersen facility staff manage the maintenance
and operation of the SGF, which provides the facility with full
control over the system.

When Andersen committed to using recovered warm water and
renewable biomass fuel to meet its energy needs, it dramatically
reduced its reliance on steam purchased from coal-based,
non-renewable energy sources. By recovering warm water,
the Bayport facility currently offsets about one-eighth of the
total  energy needed to produce all of its steam requirements.
Andersen plans to continually increase this amount. Heating with
recovered warm water has the added benefit of reducing the
thermal load to the St. Croix River from the nearby power plant.
Because Andersen's boilers are extremely efficient at burning
wood flour to produce steam energy, they produce little ash.
This significantly reduces the facility's ash handling costs. The
Bayport plant's energy costs are now significantly lower and
the facility is in a position to meet  its energy needs without
depending on external sources. The award-winning Andersen
SGF has been  a clear success, helping the Bayport  plant to
improve its environmental performance while meeting its
energy needs in a sustainable, community-sensitive manner.3

* EPA's Clean  Energy site [
   index.html]  provides a gateway to resources on renewable
   energy technology and efficiency best practices.
* Andersen's Sustainability page [http://www.andersenwindows.
   communicates the  company's environmental initiatives and
   includes information on the Bayport plant's renewable energy
   steam facility.
3 TKDA's work on the Andersen SGF project was recognized
by the American Council of Engineering Companies as a
2009 Engineering Excellence Award Winner, which recognizes
excellence in engineering and new technologies that enhance
business and protect the environment.