Whether you run a power plant, refinery, industrial site, mining site or medical center, you’re mindful of the amount of fuel your temporary power generators use and the emissions they produce. One way to lower both is by renting generators with load demand built into the controller.

“We set up probably 30 to 40 percent of paralleling applications to load demand,” said Wayne Davis, senior engineer, specialized, with the United Rentals Power & HVAC group.

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Load demand works by automatically turning paralleled generators on or off as the power demand varies. Say you have two 2,000-KW generators, or 4,000 KW of potential power, and the power need drops in the evening from 3500 KW to 1600 KW. One of the generators will automatically shut down. In morning, when the load starts coming back up, the second generator will automatically come on when the first generator is operating at a certain percent of capacity, usually 80 percent.

Check out these advantages to generators with load demand.

Lower emissions

Generators generate more than power —they create emissions, too. Some states follow strict emissions standards for generators. In these states in particular, generators with load demand are especially useful for customers.

“Our customers want the capacity there but they don’t want to use it unless they absolutely need it,” said Davis.

Less fuel

Of course, running only one generator instead of two when the power demand decreases saves fuel. But load demand can save fuel in another way, as Eric Bateman, regional product development manager with the United Rentals Power & HVAC group, explained.

“If a customer needs 450 kW of continuous load but the start load is 650 kW, most suppliers would bring out a 1-MW generator and just turn it on, consuming nearly 100 gallons of fuel per hour. United Rentals would bring out two smaller generators and put them in parallel. Both would run when the 650 kW load started, and then just one generator would take over, saving kW output, NOx and particulate matter.”

Power redundancy

Rental generators with load demand can also help prevent loss of power. With load demand, “If one unit fails, the unit that’s sitting in reserve will automatically start in less than 10 seconds,” said Davis.

When the power absolutely can’t go out even for 10 seconds — let’s say a generator at a power plant or refinery is powering a large motor, which can take 20 or 30 seconds to stop and start again — United Rentals might recommend having two paralleled generators in reserve instead of one so that power is never lost.

A matter of convenience

Generators that turn on and off by themselves can save man hours and therefore money.

When a water treatment plant that relies solely on generators for power needed to do work on its owned generators, United Rentals supplied five 2-MW generators with load demand. All five units run during summer, but in the winter, only two or three units are needed. Shutting down the ones that aren’t needed without the benefit of load demand would require manually monitoring the load and manually taking units offline and back online. With load demand, however, no human is necessary.

“It’s all done automatically — you don’t have to monitor the load manually or even think about it,” said Davis.

Whether you’re looking to limit fuel costs or emissions, boost the reliability of your power supply or reduce the man hours required by manual load monitoring, paralleled generators with load demand may be a smart solution.

Contact the United Rentals Power & HVAC group to learn more.

Marianne Wait is an editor and writer who creates content for Fortune 500 brands.