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By Thomas A. Westerkamp
Power & Communication Article Use Policy
The emergence of onsite power technology as an alternative to the traditional power grid offers institutional and commercial facilities the potential of tapping into a more reliable flow of electricity. At the same time, however, the technology is creating tough challenges — and some opportunities — for maintenance and engineering managers seeking to maintain these systems using in-house personnel.
By assessing these management considerations and looking ahead at possible advances in onsite power technology — primarily microturbines, fuel cells and photovoltaic systems — managers can develop more comprehensive strategies for operating and maintaining these systems efficiently and cost-effectively.
Currently, the most popular onsite power-generation equipment includes diesel- and natural-gas-powered reciprocating and turbine generator sets, with transfer switches ranging from 30-3,000 amps, sound-attenuated, along with weather- and impact-resistant enclosures.
Other key components of these generator sets are digital controls and electronic logs that provide fully automatic operation around the clock. On a smaller scale for more limited applications are: microturbines; several fuel-cell technologies, including solid oxide; and solar, or photovoltaic and other solar-reflector technologies.
Microturbines operate at eight times the rpm of turbine gensets — around 100,000 rpm. Maintenance technicians must understand and perform precision balancing and leveling equipment, as well as proper gas-bearing seal and compressed-air system maintenance to ensure long, uninterrupted service life. Also, they must understand electricity and thermodynamics as they apply to these systems.
Hybrid microturbine/solid-oxide fuel-cell technology also offers the promise of an efficient onsite power system up to 400 kilowatts (kW) range. The development of the two technologies is not at the same level. Microturbines are in the early mass-production stage, while fuel cells not quite as advanced.
Fuel cells produce energy by oxidizing natural gas, LP gas, gasoline or diesel fuel within a ceramic substrate to produce DC power, which is converted to AC. The only emissions are water vapor and carbon dioxide, and the systems produce little noise. It is believed that, with natural gas fuel and heat recovery, a combined microturbine/ solid-oxide fuel-cell system could have an energy efficiency of about 80 percent. The fuel-cell development goal is to get costs to approximate those of natural gas, LP gas, and diesel gensets.
One photovoltaic development project of note in use today educates students on operating a building first with natural systems — such as daylight and natural draft — then using only mechanical systems when natural systems aren’t enough. The photovoltaic array adds 1,700 watts, providing 300-350 kilowatt hours (kWh) per month to the total load of about 2,000 kWh needed.
Finally, key combined heat and power onsite power systems, while still in their early stages of development, are becoming more popular. The main players in this area are microturbines, photovoltaic cells, fuel cells, passive solar and wind energy.
All of these emerging technologies will require further reliance on maintenance technicians‚ understanding of digital controls, integrated information technology networks, computerized equipment diagnostics and, equipment history databases in order to optimize decisions on preventive maintenance and repair methods and frequencies.
“Out of sight, out of mind” is one of the challenges that managers face daily, and onsite power systems are no exceptions. Generators sit quietly for long periods and do not seem to demand any attention until an emergency happens. If technicians do not cycle an onsite power system weekly and inspect it periodically as a part of an annual preventive maintenance program, trouble is certain to lurk for facilities that rely on them.
Consider this example: A backup diesel generator at a hospital outside New Orleans failed to start during hurricane Katrina. The culprit? Diesel fuel that had deteriorated over time undetected, leaving sections of the facility without power when high winds knocked out the hospital’s primary electric service.
The lesson learned in this case is that even in a facility that is properly equipped with auxiliary power equipment, the presence of other vital components — training in maintenance methods, annual preventive maintenance schedules, logs to assure management that systems are cycling properly, and adequate staffing to perform the maintenance on time — are essential. Otherwise, the facility remains vulnerable to such power interruptions, which can be very dangerous to safety and health and cause very costly interruptions in any type of facility.
Another challenge is customizing an onsite power system to minimize the risk, so the system is more likely to operate in a range of emergencies, from a minor interruption to a major hurricane or other severe disruption.
Consider the example of an organization located near New Orleans that provides business office services for the healthcare industry. The facility is located just west of Katrina’s landfall and east of hurricane Rita’s path. Though above the tidal surge, the business nevertheless was in an area in which more than 100 utility poles had to be replaced after Rita. The organization has 3,600 square feet of office space with 50 workstations for employees on two shifts.
The company relied for power on it 45 kW, natural-gas-fueled onsite generator installation. Installing the system required permits, an underground gas line from the street, and a meter to the genset. It is installed outside in a weatherproof, impact-resistant, low-noise enclosure.
Fully automatic operations tailored to the organization’s needs include power transfer after 25 seconds interruption or brownout; power control; transfer to primary power when it is restored; weekly cycling; and onboard events log. No fuel storage is required.
The system’s installer performs several preventive maintenance physical inspections each year under a service contract, giving the organization and its clients greater peace of mind in an emergency.
The enactment of the Energy Policy Act of 2005 (EPAct) creates a number of incentives for managers and organizations considering capital improvements to their facilities, including those related to onsite power. Among the relevant highlights:
It is clear that many benefits await managers who keep onsite power systems up to date. These benefits include reduced losses through greater business continuity, more predictable energy costs, greater fuel efficiency, enhanced power quality, and greater power reliability. Also, consider this: Energy experts suggest that a doubling of onsite and combined heat and power generation systems could produce 46 gigawatts of new, clean electric capacity.