Westar Energy Inc. is about to spend up to $380 million at its power plant at the northern edge of Lawrence, and the bulk of the investment will go for an industrialized version of a relatively common household appliance.

A vacuum cleaner.

The specialized equipment — collectively known as a pulse jet fabric filtration system — will be installed by the end of 2012, in time to meet federal air-quality standards that require such upgrades by 2014.

The project will be expected to begin early next year, with as many as 350 people to be working on the job as it moves along, said Greg Greenwood, Westar’s vice president for generation construction.

“The hotels will be busier,” he said. “The restaurants and grocery stores will be busier.”

And, he said, once the work is complete the air in and around Lawrence will be cleaner.

New filtration systems to be installed on two of the Lawrence Energy Center’s generation units will be designed to clear the air. With the new systems in place, more than 99 percent of the ash will be removed from flue gas leaving the center, said Dave Holt, project manager for Black & Veatch, the company hired by Westar to design and oversee the project.

Instead of shooting into the air, the fine particulates of ash — a dusty byproduct of burning coal — will gather on the outsides of more than 13,000 filter bags, each 33 feet long and 6 inches in diameter.

“The only way it has to get out to the chimney is through the filter bags,” Holt said, of the filters made from fiberglass, Teflon and other heavy-duty polymers. “It’s a bit like a vacuum-cleaner bag, if you will.”

Cleaning the filter bags will take some work. Once enough ash has accumulated, a massive compressor will generate pulses of air to compress each filter — “to wrinkle the bag, somewhat violently,” Holt said — so that ash can drop into a hopper for proper removal.

Greenwood said that the filters would be expected to last for three years before needing replacement, a life span that compares favorably to the disposable versions in normal household vacuums.

After all, he said, “we’ll be vacuuming every day.”

The filter project is only part of the work planned for the Lawrence Energy Center, which generates 19 percent of all power consumed by Westar’s 684,000 customers. Westar also plans upgrades to address emissions of nitrous oxide, another project intended to meet federal air-quality standards by 2014.