More Power to You

Nov. 16, 2001
Reclaiming the economic potential of on-site emergency and standby generators

By Bhavesh S. Patel

When on-site power units - emergency and standby generators - sit unused, except during power outages and periodic testing, it's like throwing away potential. Using them to generate power during normal operation can reduce a building's energy expense. Such practices accrue directly to the bottom line.

There's never been a better time to take advantage of these assets. Energy shortages are spreading across the country. Electricity costs continue moving upward, sometimes at alarming rates. Moreover, there's increasing demand for more reliable power.

The opportunities hang like ripe fruit on a low branch waiting to be picked. Rather than cherries and apples, though, they're called peak shaving, curtailment, aggregation, etc. Selecting which to pick is just a matter of deciding what meshes better with your building's energy requirements.

Peak shaving, for example, reduces the amount of utility-provided electricity that your building uses during times of greatest demand for electricity, usually from 12:00 p.m. to 5:00 p.m. on hot summer afternoons. These peak periods total about 200 kilowatt-hours per year and are generally the most expensive electricity you can buy. In fact, many utilities pay commercial customers to cut their demand in this way. Talk about a "no-brainer" way to cut costs.

Curtailment is the other side of the peak shaving coin. Curtailment can be voluntary or mandatory. Another name for mandatory curtailment is rolling blackout. In either case, you have no choice: When the utility needs to reduce its total electrical load, your building is elected. Operations stop. Work stands still. People sit around. How much does that cost you, or your tenants? They won't be happy campers.

Solve the problem by using your on-site power units. They can help make up the difference in power, depending on their generation capacity. Building operations keep humming. People keep working.

Aggregation pools the generation capacity of your on-site units with others. You and other facilities professionals agree to start your units when power is required and it collectively reduces demand - as if the energy flowed out across the utility distribution system to where it's needed. Unlike peak shaving and curtailment, your units are generating power to get better pricing for a larger volume of electricity.

Using on-site power units for these purposes, however, can be a difficult decision for building owners and facilities managers. Does the electrical code allow it? What happens if a power outage occurs while the units are satisfying other power needs?

It's okay, according to the National Electric Code, to use emergency gen-sets this way. Specifically, NFPA 70, Art. 700, 701, and 702 - which addresses installation and operation of emergency, legally required, and optional standby power systems - allows the use of these systems for peak shaving.

In addition, if an unexpected power outage occurs while the on-site units are operating, power from the units is immediately transferred to the intended emergency or standby load.

With today's pressure to optimize return on investment in a building, "waking up" on-site power units can provide an unexpected - and welcome - economic benefit.

Bhavesh S. Patel is manager of Strategic Business Development at ASCO Power Technologies (, Florham Park, NJ. ASCO is a world leader and pioneering innovator in transfer switch technology for on-site power units and other applications.

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