Over the next 10 years, Illinois is pushing ahead with $57 billion in data centre investment, raising expectations of an employment effect of more than 120,000 jobs. But after facilities are completed, the number of direct permanent jobs left behind is expected to be about 2,800.

TechRadar reported on Oct. 6 that the Illinois Economic Policy Institute (ILEPI) and the University of Illinois' Project for Middle Class Renewal analysed the planned data centre investment through 2035 as generating about 121,000 direct and indirect jobs. Many would be temporary or spillover jobs from construction, supply chains and increased worker spending.

The report estimated about 39,000 skilled jobs would be created during the construction phase, with another 41,751 spillover jobs added in areas such as restaurants and manufacturing from increased consumer spending. By contrast, permanent employment directly sustained after data centres begin operating, including IT and engineering jobs, was estimated at about 2,800. A simple division of the $57 billion investment implies about $20.2 million, or 2.71 billion won, spent per permanent job.

Property tax was cited as an economic benefit. Once all data centres are operating, they could pay about $300 million, or 402.5 billion won, in property tax a year. An analysis said that without tax breaks, property-tax burdens for residents in an average-sized county could fall 3 to 10 percent. As tax benefits provided to developers increase, the gains for local communities also shrink.

Power costs sit on the other side. Researchers estimated that in a mid-range scenario in which data centres add 6.5 gigawatts of electricity demand by 2035, household power bills could rise by about $12, or 16,100 won, a month and $150, or 201,230 won, a year. Total costs across the power system could also rise about 10 percent. Separately, U.S. regional grid operator PJM Interconnection suggested data centre demand in northern Illinois' ComEd area could rise by 10.7 gigawatts by 2035.

The analysis said the economics of expanding data centres should be weighed not only against a construction boom and higher tax revenue, but also long-term employment, tax benefits and grid investment costs.