Backup power is critical for almost all, if not all, facilities. Design of a backup generator system and its capacity depends on the purpose of a business or facility. Hospitals need a complete backup in the event of a power outage; the lives of patients can depend on it. Some businesses, such as data centers, require reliable backup generator systems to run their entire facility and protect data in the event of a power outage, or the operators may lose business. When faced with an emergency or power loss, residential complexes often need backup generator systems that keep their critical systems going.
“In the event of an emergency in the building, the operation of the life safety systems becomes paramount in terms of the ability to successfully evacuate the building occupants because it’s a matter of keeping people safe, protecting them in the event of an emergency situation,” said Frank Kelly, project manager, J.M. Electrical Co. Inc., Lynnfield, Mass. “The emergency power is used to ensure the operation of systems, such as fire alarm detection and warning systems, including voice evacuation as well as stair pressurization and emergency lighting.”
J.M. Electrical recently completed a project of that type in a 29-story residential building in Boston that involved the low-voltage interlock and control wiring between the roof-mounted generator and the main fuel oil tank and pumping station located in the building basement. In addition, the project included the installation of a leak-monitoring system to check and alarm for leaks associated with the containment piping carrying the fuel oil throughout the building.
J.M. Electrical worked with a typical emergency power system design; the generator was on an upper floor or the roof, and, according to code, the fuel oil tanks and pumps were in the basement.
What’s typical, though, prompted real problems when Hurricane Sandy hit New York City in late October 2012. Millions of gallons of water spilled into the basements of many of the city’s buildings, disabling the fuel oil tanks and pumps that were needed to power the generators. Fuel-pump failure and problems with the tanks were the culprits.
Yet, while the power went out in many buildings, the power stayed on at Bellevue Hospital Center. Why? Bellevue employees and the U.S. National Guard hauled fuel up the stairs to operate the generators. It was probably not the backup- generator plan envisioned by the engineers who designed the generator system or the facility.
“In many cases in New York City, the generators were up on the roofs,” said Michael Mayfield, vice president of Mission Critical and Design Build Projects, E.J. Electric Installation Co., Long Island City, N.Y. “The biggest problem we saw as a result of the hurricane is that the fuel systems became compromised because the fuel tanks and pumps were on the street level. Fuel-oil pumps and controls were under water and became incapable of pumping the fuel out of the tanks.”
Mayfield has overseen 71 repair projects of backup generator systems that lost power in New York City, including three hospitals, 45 housing properties that were 18 stories or higher, and 23 commercial buildings.
“We found that the tanks themselves were fairly solid, but they were not anchored properly,” he said. “When water flooded the basements, some of the tanks floated up and away, and, in pulling away, the fuel lines were broken. Another problem was that water entered into the fuel oil tanks and contaminated the fuel.”
As part of the repair efforts in New York City, various solutions have been implemented in different properties, including floodgates and waterproofed rooms with submarine-style doors to protect mechanical and electrical systems. One issue still remains: fuel-pump placement.
“In New York City, we didn’t have a choice,” Mayfield said. “We couldn’t lift fuel tanks to put them in the building. We’ve now put them outside and braced and bracketed them to a concrete wall or steel bracing in such a way that they won’t shift or float away. And the fuel tanks themselves are now waterproofed.
“In some areas, we built concrete walls on grade that would bring the wall above what the city has designated as the 100-year flood plain. That wall was also waterproofed and behind it is space for conduit runs and mounted at the top of the wall is the equipment.”
But is that enough protection?
“What everyone is forgetting in floodproofing everything is that most fuel tanks have maybe a 24-hour run time,” Mayfield said. “If trucks can’t get in to replenish the fuel, you’ve spent a lot of money for nothing. Now we’re looking at generators that are fueled by natural gas and fuel oil. As long as natural gas is available, a generator would run. We’re also looking at a combination of natural gas and diesel.”
A requirement passed by New York’s City Council in November 2013 makes it easier to install backup generators and generators that run on natural gas.
One building owner in New York City has since taken that option by installing two natural-gas-powered generators on the roof of the building to run the fire-alarm system, the emergency egress lighting, the elevators, and the electrical and mechanical support equipment.
Not all the power outages were due to fuel-tank problems. In some cases, the generators themselves were swamped with water and disabled. Moving them to an upper floor might seem like a solution, yet that has its own set of restrictions.
“If you move a generator to an upper level, a building owner loses rental space, which changes the value of the building,” Mayfield said. “In some cases, we could put the generator on the roof, but that can also be complicated. In one building in a landmark area, we found a space on the roof where we could relocate the generator, but the landmarks commission had to decide if it meets the criteria of the surrounding area. In that sort of area, every detail is specific.”
As part of the safety aspect of E.J. Electric’s work, the company was also tasked with carrying out floodwater cleanup procedures that affect the quality of the indoor environment. The job entailed disposing affected wallboard and insulation, cleaning surfaces among other tasks and, afterward, moisture management and microbial sampling of suspect surfaces.
Another issue that E.J. Electric faced was repair of storm-damaged equipment. In many cases, manufacturers of damaged equipment were out of business. E.J. Electric had interface components custom-fabricated. A decision was also made to avoid trade stacking.
“In those areas, electrical conduits were placed on the floor and covered with lightweight concrete while mechanical piping was ceiling-hung,” Mayfield said.
On the opposite coast, the lessons of hurricanes Sandy and Katrina were not lost on engineers and architects in California. However, it is not the water but the land itself that is prompting changes in California’s generator design. As the Jerry Lee Lewis song goes, there is “a whole lot of shakin’ goin’ on” in earthquake country.
“In older hospitals, generators are usually installed in the basement, and all the paralleling gear is in the same room, but, since Sandy and Katrina, our designs have changed,” said Duc P. Bui, president, DPB Engineers, Tustin, Calif. “Now we don’t put generators in the basement or even in the building. We install them as a self-contained unit on the ground level along with the paralleling gear.”
For example, in designing the system for two Southern California hospitals, DPB Engineers’ plan called for the generator installation outside on the ground floor with the fuel supply underground to limit potential damage to exposed fuel lines.
“In California, we are dealing with earthquakes and, the higher above ground the generator is, the longer the fuel line is exposed and thus potential for damage is increased,” Bui said.
Then one must consider the fuel pumps. Bui no longer designs a generator system of a single motor pump; he instead designs a duplex system with dual power feeds. If one pump fails, the other pump will take over.
Another earthquake-related problem concerns day tanks, which are usually placed next to a hospital generator.
“We discovered that, during earthquakes, the day tank can move and the fuel lines snap off,” Bui said. “Now when we upgrade generator systems, we put the day tank right under the generator. The generator sits on the tank, and the two are integrated together and structurally anchored to resist high seismic forces. During a quake, the two move together. The result is that there’s no exposed fuel line to the outside and no chance for the generator to move one way and the tank to move the other way. Now, it’s integrated into one system. This system is designed to satisfy the seismic requirements for California.”
Backup generator systems are designed to provide backup power during a power outage. In most situations, they function as designed. In some situations, Mother Nature gets the better of them. Creating a foolproof design for emergency generator power systems is an evolving process.