What’s good for this school turns out to be good for the environment, too.

By Amy Kurland

Once the Cape Cod Regional Technical High School jumped on the energy savings wagon, it really got rolling. Over the past four to five years, the school had become more energy conscious, actively looking for ways to save costs and support the environment. Now, in 2007, it’s just installed a trigen to sharply lessen its dependency on the local grid. What makes this tech school’s trigen particularly unique is not its structural makeup, but rather the fact that it’s the first prepackaged, factory-tested trigen to be installed in the United States.

Since 2003, when energy and oil costs started to skyrocket, the tech school began making a lot of energy-efficiency changes to the campus. “The rising prices really made us look hard at what we had been doing and what we could be doing differently,” says Bob Sanborn, business administrator at the Cape Cod Regional Technical High School.

“Over the past few years we had been doing a lot of things around the building to become more energy efficient,” he continues. “We didn’t have to pay anything for the initial upgrades, due to the Cape Light Compact, which paid for them all. They revamped our whole building with very efficient lighting and put an energy-management system in our computer to regulate our HVAC system. We also have a very small-scale onsite wind turbine, a solar awning over one of our science rooms, and a solar array outside our building, as well.” The school also has a biodiesel machine to make diesel fuel out of cooking oil.

After these upgrades, the tech school started thinking bigger: It was time to address the way it had been generating its power. Originally the school received 100% of its power from NStar, the local power company. It was the traditional setup: a chiller system powered by electricity and dual-capacity boilers running on oil.

The school put out a couple of Chapter 25A energy management bids to get proposals from companies that could advise on energy alternatives. It received a proposal from one company but didn’t like it. However, this proposal did open the business department’s eyes to two things that would ultimately lead it to the school’s current trigen contractor and manufacturer: 1) an energy performance savings contract and 2) the use of a cogen system.

Around this time the school was also contemplating whether to replace a campus cooling tower and decided to do so. As it investigated cogen systems and how they might work for the school, it was able to narrow down the scope of what was needed. So the school put out a second, more streamlined request for proposal (RFP), which included replacing the cooling tower and getting a trigen system installed. This RFP led to Preferred Mechanical, the installing contractor, which partnered with Aircogen CHP Solutions Inc., the trigen designer/manufacturer.

The Structural Lowdown
For the school, Aircogen selected its Nimbus 250L, a prepackaged trigen system. Although the cooling tower was not an energy-efficiency measure, the school ended up folding that piece of equipment, installed in April, into its contract with Preferred Mechanical.

The school’s trigen runs on natural gas, comparable in price to oil but capable of using the energy more efficiently. It’s also much better for the environment. Besides efficiently and cost-effectively addressing the school’s energy needs, the trigen is especially beneficial at the school because the campus is the hurricane shelter for Cape Cod. “If the electricity goes out, as it does often on the cape, the system will then give the school 250 kilowatts of electricity, which can sustain most of its load during normal operation,” explains Steve Zilonis, director of business development at Aircogen. Because the system is independent of the grid, this estimate includes cooling for the summer months. It’s also 250 kW of energy that the grid won’t have to generate, which means the grid is that much less likely to become maxed out.

“Our system is really an addendum to the school’s existing systems,” Zilonis says of the trigen. “If it comes offline, they still have all their existing HVAC equipment. We do nothing to the existing system; we simply add another level of security. They still have the electric utility, but the trigen is designed to reduce their reliance on the grid as much as possible.”

“Pre” to the Max
“Prepackaged, designed, factory-tested systems are the rave around the world, but in the United States we’re just catching on,” says Zilonis. “Most of the time when combined heat and power systems are installed here, all the various parts of the system are brought in individually and retrofitted into the existing facility. The installers have to break into or replace the existing systems, and 15 or so vendors come in with their various products and try to make everything communicate as one, once installed.” And surprise, surprise—oftentimes when they start to run the system, it doesn’t work very well. The whole process is difficult to organize and, therefore, often not very efficient or effective.

However, with a prepackaged system, the system is first engineered on paper. A certain amount of analysis is done to determine the lowest common denominator of electric and thermal use. “You always size a cogen to follow the thermal requirements of the site, not the power,” says Zilonis. “This way you always use all the heat instead of wasting it like a power plant does. The school’s trigen is sized to provide about 25% to 50% of the school’s total daily energy usage, but it does so utilizing close to 100% of its total energy output as far as possible, which is dramatically more efficient than traditional methods.”

Since the school had been previously getting 100% of its electricity and heat from the grid and oil-fired boilers, the school’s trigen needed to dramatically reduce the operational hours of these boilers. “This meant making sure that the school got enough hot water from the trigen so that the boilers didn’t turn on or at least didn’t turn on as often,” explains Zilonis. “We wanted to meet their heating demand as much as possible in the winter seasons, and in the summer meet all their cooling demand by offsetting the electric chillers with the absorption chiller, utilizing waste heat from the trigen unit. What we discovered was that after looking at all the heating bills and how many British thermal units they used per hour, this was approximately 1.3 million British thermal units of hot water for heating, which equates to a 250-kilowatt generator. We then had to profile and confirm that the school’s baseload for electricity was approximately 250 kilowatts, which it was.”

With traditional power generation, only one-third of the energy going into the power generating station is used. “The other two-thirds is being wasted as heat,” he says. “These cogen units are still only approximately 30% electrically efficient, but about 85% of the total energy they produce is used, including the waste heat for the heating and the absorption chiller.”

One of the problems with cogen systems, notes Zilonis, is that they’re often oversized by the engineer or end user. There’s no savings when this happens, because when a cogen produces too much energy, it needs to be shut off. “When this happens, cogens can become a stranded asset,” he says. “They only save money when they run fully utilized, so you want to run them as much as you can to utilize all the energy as much as possible. At the tech school, as soon as the school is hot enough or cool enough, the machine is designed to switch over to a load-tracking mode to follow the thermal demand. At this point, if the thermal was met and it started to dump heat, it would fall down to 30% efficiency instead of 85%. However, although we have designed a dump mode, we don’t expect to ever use it, as the machine is designed for the school to utilize 100% of the energy output as far as possible.”

Before the Big Test
After analyzing usage and sizing the system, the next step was ordering certain pieces for the trigen so that it can function as a single plant. Of these pieces, the most integral are the engine and the cooling/chiller system. The results of the school’s electricity and thermal usage analysis determined which manufacturers Aircogen would order these components from for the best heat balance.

For 250 kW of power, Aircogen decided that a Man engine would be best in this case. It chose Man due to that company’s familiarity with Aircogen designs and that fact that Man engines have been running internationally in the Aircogen fleet for about 15 years. In fact, there are 28 similar Man engines already running in trigen and cogen systems in the Boston area.

For the school’s cooling system, Aircogen went with absorption chiller technology, choosing a Broad absorption chiller because of its robust and advanced qualities. “They’re the largest absorption chiller manufacturer in China,” adds Zilonis. “That’s all they make, and they stay ahead with the technology.”

Once the engine and the cooler were selected, the remaining components were ordered independently from various US manufacturers. “Then we take all the components of the trigen and bring them into our Barnesville, Georgia, factory to build them into one package,” he says. The lead time for ordering most trigen and cogen equipment around the world is anywhere from 40 to 50 weeks, depending on the prime mover’s lead times. Man was pretty quick, however, delivering the engine to Aircogen within about 20 weeks. It would typically take Aircogen 12–18 weeks to build the system once it has the parts, but what usually ends up taking so long is lead time from the principal component manufacturers.

Once all the components were installed in the trigen, the system was ready for factory testing. When the tests were passed at the Aircogen facility, the trigen was transferred to the school. “It was just plug and play from there,” adds Zilonis.

The trigen unit is delivered in an all-weather enclosure with a pitched roof.

Ready, Set…
Before the installation could begin, there was, of course, governmental red tape to deal with. When bidding, the tech school had to conform to a law in Massachusetts called CH 25A: Section 11C, which lays out the requirements for bidding on energy management services in Massachusetts. “It’s a pretty lengthy document, and it went out to all the contractors,” explains Sanborn. “In some ways it streamlined the bidding process for us. When you’re undertaking an energy-related project to save money, the rules of this law make it a little easier for you.”

Preferred Mechanical, which is certified by the Division of Capital Asset Management, did all the prep work for the installation. Aircogen supervised the actual installation. “We give the contractor the package and blueprints, and then they plug it in,” says Zilonis. “If the client prefers, we’ll offer a guaranteed turnkey installation that’s approximately 15% more than the total package equipment cost on average.”

Because the system was already tested by the time it arrived at the school in August, the installation was very simple. It required piping tie-ins into the cold and hot water loops and utilizing a breaker on the school’s electric panel. “We prepared for a tie-in right there,” says Zilonis. “There were four pipes and a breaker that we had to plug into when we arrived. It was a very easy job.”

For cogen or trigen installations of this sort, Aircogen sends out three men, and it typically takes an average of two days to do the hookups. Since the equipment has already been running in the factory, there’s no mystery as to what it will do once it’s installed. Still, to play it safe, about a half dozen engineers were at the school for at least a week to commission the equipment. “When that’s all fine, they sign off,” adds Zilonis. “And within two days of the hookup the equipment is usually up and running.”

The trigen is delivered in an all-weather enclosure with a pitched roof. The trigen, which is built and stored in this box, is located just outside the school. It’s right by the school’s oil tanks, outside the on-campus plumbing shop and the campus boiler room. It’s connected to the school’s chiller and current boilers, and it supplies hot water to those areas first, before the school needs to use any electricity and oil.

Before such a trigen goes live, Aircogen needs about one day to control the client’s power system. For instance, the main breaker or the boilers may need to be shut off for a short period of time for testing and commissioning. “So for this job we grabbed hours when the school was not occupied,” says Zilonis.

The Cost of Power
The school went with an energy performance contract, a very low-risk type of financing plan that incrementally pays off the new equipment with the money that equipment saves each month. “I’m going to continue to budget during these five years as if I didn’t have this equipment,” says Sanborn. “For instance, we’ll budget for oil, but most of the money that remains will go to pay off the lease on that equipment. The money will go to the lease company and to Aircogen instead of the electric or oil company. And when it’s over, in five years, we will hopefully be seeing a lot of savings.”

The school had set up a third-party leasing agreement with a bank. It also got some financial help from Keyspan (the cape’s local natural-gas utility), which gave the tech school $145,000 in rebates. “This money will go directly to the people doing the work,” Sanborn says. “So we borrowed that much less money for our lease on the equipment.” The total cost was about $845,000, which includes the new cooling tower.

A Teaching Tool?
As far as maintenance is concerned, the school doesn’t have to lift a finger on the trigen system. “This is a hands-free maintenance agreement throughout the term of the lease,” says Sanborn. “At the end of the lease, Aircogen and ourselves will have to renegotiate the maintenance agreement. But we [the school] will never have to worry about doing any of it ourselves.”

“The user never has to touch the system,” elaborates Zilonis. “And we have a very sophisticated remote monitoring system. Sensors are on virtually every piece of the machine—there’s approximately 100 points of monitoring.” The monitoring is done through the Internet, with screens that are watched around the clock in England, Georgia, and Massachusetts. “There’s always one set of eyes watching. When there’s an issue, an alarm goes off on the computer screen. Then we can control the machine remotely to fix the problem. We can intersect and correct 95% of the events this way.” For the remaining 5%, when the machine might actually go down or when Aircogen decides to fix an issue offline, a service company in Massachusetts will drive out to the site.

And because it’s at a tech school, the school will be incorporating the trigen into its lessons. Although the specifics of exactly how this will happen have not yet been finalized, the general idea is that there will be some kind of real-time monitoring of the equipment that can be watched in the classrooms. “We have an HVAC department, a science department, and a plumbing department,” begins Sanborn. “There will be a kiosk on campus to show how the trigen works and where tours will be run. There will also be visuals, to be seen on computer screens, with real-time viewings. And there’s also the possibly of having students go on maintenance calls with the technicians.”

Spreading the Word
Every cogen that’s installed has a positive environmental impact by greatly reducing the amount of greenhouse gas emissions. “By putting the trigen in at the school, it’s the environmental equivalent of planting hundreds of acres of forest a year to sequester the carbon dioxide or greenhouse gases that would’ve been created had it not been used,” says Zilonis.

Why, then, is the United States so slow to catch on? Political oil issues aside, part of the reason is a basic lack of awareness. Many people are simply unfamiliar with the technology. The tech school, however, is doing its part in promoting awareness of its recent installation. “We’ll be doing PR on this. Even with all the energy management and energy conservation activities we’ve been doing already, it’s an ongoing push to make the effort to tell people that we’re taking big steps to drive down the cost of utilities.” But it’s well worth the effort, since promoting the installation will inevitably inform people about the very viable option of using cogen.

At the end of the five-year lease, the school is aiming to break even but hoping to see some savings. “Our long-term goal and hope is that the trigen will free up money that we could then spend on different priorities for the school,” says Sanborn. In this case, what’s good for the environment is also good for the school.

Journalist Amy Kurland specializes in marketing communications.

DE - September/October 2007