CHICAGO (WLS) — The I-Team reported in February that there were 164 operating data centers in Illinois, with dozens more in the works.

The city of Joliet recently voted to approve plans for a large data center.

That vote came after hours of public meetings, packed with people eager to weigh in. Joliet city leaders said it would bring tax revenue and financial benefits for the community.

Some residents expressed concerns about the potential environmental impacts.

But, what exactly is a data centers and why are some communities eager to attract them?; Why are so many people opposed to them?

“A data center is going to be a building that provides the space, the power and the infrastructure for everything that we do online today,” said Brad Tietz, the director of state policy for the Data Center Coalition. “So, when you look at where demand is going, for data, so everything we’re doing on the internet, the average household has 21 connected devices to it. We’re going to use twice the amount of data in the next five years than we’ve used in the last ten years.”

When it comes to the types of jobs created by data centers, he says it depends on the size of the facility.

“There’s going to be technicians, service engineers, etcetera. The real value, especially for Illinois residents, is going to be on the construction side,” Tietz said.

In some communities considering data centers, residents are concerned about their water usage.

“The data center industry has been a large water user, historically, but by no means the largest compared to other industries. And if you look at how efficient the industry is getting, and I’ll remind you too, not every data center uses water. Some are actually using, especially in a colder climate like Illinois, the outdoor air temperature to help cool their facilities,” Tietz said.

Jen Walling is the Chief Executive Officer of the Illinois Environmental Council.

She wrote in Crain’s that “Big Tech” is coming to Illinois and that the state isn’t ready.

“We don’t have the guardrails in place that are going to be necessary to protect our environment, to keep our rates low, to protect our communities and most importantly, protect our water,” Walling said.

She says the Alliance for the Great Lakes has put out a report where they’ve looked at water usage, and some data centers aren’t using much water.

“Some data centers are using up to five million gallons of water a day. These are huge water users, and they can be taking from different sources including Lake Michigan,” she explained.

“We’re also very concerned about air pollution and the energy usage, these are huge energy users,” Walling said.

She also explained the concerns for people living nearby.

“They need to be on with energy all the time. So, all of these facilities have backup diesel generators. And the residents in the [Aurora] community said that they could smell the methane gas that was being burned, the diesel gas that was being burned. And that’s particulate matter, it’s odor, so these communities face real consequences when something happens,” she said.