Design/Build Excellence in the Mountains

The fuel produced by biomass is burned in a special combustion unit attached to the new boiler system, along with a new hot water distribution loop.

The ribbon-cutting for the biomass plant took place in March 2005, and was attended by Senator Jeff Bingaman and Congressman Tom Udall, both of New Mexico.

ECI tied the plant and the seven existing propane boilers into the hot water distribution loop.

Located in Gallina, NM, 90 miles northwest of Sante Fe, NM, Jemez Mountain Schools (JMS) faces relatively long, harsh winters, with equally harsh heating bills.

So when school officials were looking for an environmentally friendly, energy-efficient solution for the heating retrofit of its mechanical system, they saw a unique opportunity to heat its campus with wood waste from small diameter trees and wood waster from the surrounding Rocky Mountain Forest.

To manage forest areas and reduce the risk of forest fires, the United States Forest Service has implemented a strategy to turn wood chips obtained from forest thinning projects into a fuel source called biomass.

Although biomass systems are increasingly being used in regions such as the Northeast, the Jemez Mountain School Biomass Project is the first of its kind in the Southwest. The fuel produced by biomass is burned in a special combustion unit attached to a new boiler system installed at the school, along with a new hot water distribution loop.

While the concept for this project was great in theory, finding enough funding to get it off the ground initially proved to be difficult.

The school district was slated to receive a $400,000 grant from the New Mexico Energy, Minerals, Natural Resources Department, which the U.S. Forest Service had agreed to match.

The school contracted with an architect and engineer to design the system, and during the course of three years, JMS was presented with several design options. However, they were all beyond the $800,000 funding available for the heating plant. In fact, the last quote exceeded $2 million.

Just when JMS was about to abandon the project, Energy Control Inc. (ECI) Rio Rancho, NM came to the rescue.

ECI has a reputation as a topnotch Design/Build firm, and is well-know for its ability to bring third-party financing to projects.

Jack McGowan, CEM, ECI's president, relates, "We received a call from the New Mexico Department of Energy, stating that this job required a Design/Build contractor that could find ways to value engineer the project and make it more affordable."

To tackle this project, ECI teamed up with with CME Inc. (as the engineer of record) and with ASA Architects.

After performing an energy analysis, the team identified numerous measures to save money, such as a lighting retrofit and automated controls. "We were able to create a $600,000 guaranteed savings contract to supplement the existing funding and to obtain another $200,000 in grants and district funding," McGowan says. "As a result, we had $1.6 million, which was enough to complete the project."

Creative Solutions
During the design of JMS' heating plant, ECI looked at every possible way to factor in cost savings. For example, the original design featured a new building to house the boiler plant.

Instead, ECI opted to renovate an existing 4,000 sq.ft. building to accommodate the plant. The team also created an addition to make room for a fuel storage facility, a school bus maintenance area, and storage shed.

"We started with a decentralized boiler system, with each boiler serving a different part of the building," McGowan explains. "While the biomass plant needed to be separate from the school, we still needed to tie the plant and the seven existing propane boilers into the hot water distribution loop."

To bring everything together, the initial CME design involved a heating loop requiring a halfmile trench across the campus. Together, ECI and CME found a faster, less expensive solution.

"Instead of digging for a half-mile, we were able to trench across the parking lot about 30 ft., and take the piping up the side of the building and into the plenum above the ceiling," says McGowan.

ECI also left the propane boilers in place as a back-up heat for the biomass unit during the peak heating season. "They can also be used during late fall and early spring when you only need some heat in the morning," McGowan adds.

How It Works
According to Pat Gibson, ECI's vice president of operations, the school location factored into the system's design.

"Since the school is located at more than 7,000 ft. above sea level, it was necessary to derate the equipment," he says.

The 5 million Btuh, 180-hp unit is a " completely automatic true combustion system with a big induction fan that brings in the gases. Hot air goes through the boiler to the 120 tubes inside the unit where water flows and heat exchange occurs," Gibson adds.

The system's combustion unit burns at 1800F, with air supplied at different stages. There's also an extended zone that allows complete combustion of all carbon from the fuel.

The system can use up to 1,400 lbs. of biomass fuel per hour during peak operating months such as December and January. It also has an automatic fuel feed based on temperature demands controlled at various facility locations and an automatic de-ash feature.

"The system injects air at different levels to complete the combustion cycle. It burns clean, so you don't see smoke coming out of system," says Gibson. "As the fuel goes through the boiler, there's a cyclone that takes care of any remaining fine particulate before it can leave the building."

Gibson adds, "Working with a solid fuel can be tricky, because its consistency and moisture content can vary. The system senses these variances, and induces more or less oxygen, depending on the type of material we're burning. To help control these variables in system performance, all of the fans are outfitted with variable frequency drives."

During the course of a year, the system generates less that six tons of ash from the 400 tons of fuel. Depending on the heat output for the school, the combustion process should generate less than a 55 gal. drum of ash per month. "The ash makes an excellent fertilizer. In fact, people have been fighting over it to use in their gardens," Gibson says.

Comfort & Control
While energy efficiency was a driving factor in ECI's design, the team also took the students' and teachers' comfort into account.

"The biomass unit could have worked flawlessly, but if the classrooms weren't comfortable, everyone would have said that the project was a failure," says McGowan.

Therefore, the ECI team used direct digital controls for the biomass unit and for the classrooms. They also rehabbed some of the zone level heating and ventilating units.

For further control, there are VFDs on the heating loop pumps and system fans, which help reap savings by reducing speed and electrical consumption.

ECI also monitors JMS' system performance and energy usage by Internet, and is under a 10-year contract to measure energy savings.

"We have real-time access to the system so we can troubleshoot, diagnose, and analyze any problems, which is important since our office is 180 miles from the school," says Mc-Gowan.

Lessons Learned
While the ECI team learned a great deal about using a new fuel source during the installation of JMS' biomass system, one of the more interesting lessons learned wasn't even HVAC-related.

The original plans included the construction of a fuel storage bunker for the biomass system, featuring 4 ft.-deep concrete foundation walls. The bunker's design also included an elaborate system that would allow a semi-truck to dump fuel into the bunker, using a "walking floor" — a process that moves the fuel via a conveyer system into the boiler.

"Because the cost for this bunker was going to be very high, we came up with an alternative plan to use semi-trailers as the storage facility," says Mc-Gowan.

The team searched for semi-trailers they could outfit-with a fuel delivery system capable of moving the contents out of the trailers and into the boiler.

"We finally found a trailer with a walking floor option. Nevertheless, we then had to figure out how to get it to work once the trailer was no longer connected to the truck," he adds.

As a solution, ECI developed an automated hydraulic pump package that mimics the truck's power take-off.

"We learned how a willingness to be creative from both a mechanical and technological point of view can go far in solving problems," says Wayne Yevoli, principal, CME Inc.

A Happy Ending
Since the biomass system's installation, JMS students and teachers alike have been happy with how comfortable they are in their classrooms. School officials are equally happy with the energy savings.

ECI also helped the school district apply for a Collaborative Forest Restoration grant, which they were awarded in July 2005. The three-year grant provides JMS $120,000 per year to pay for fuel, and to develop educational programs to teach children and adults how biomass technology benefits the environment.

McGowan adds, "If this project had been anything but Design/Build, our hands would have been tied to specs of the project. However, because we were able to complete it in Design/Build fashion, we were able to partner with the school district, analyze their needs, and ensure the project's success."