As Illinois rewires its power system for the decade ahead, the stakes are tangible in Barrington—where stable electric service underpins everything from morning trains to small-shop point-of-sale systems. The state has ample capacity today, but new planning mandates and a debate over how to keep supply ahead of demand will influence what households and businesses here pay, and how reliably the lights stay on.

What the numbers show

Illinois enters 2026 with one of the nation’s deeper benches of power plants. The state’s net summer capacity was about 46,279 megawatts in 2024, and those resources produced roughly 185 million megawatt-hours last year, with nuclear power as the leading source, according to the U.S. Energy Information Administration.

That nuclear backbone defines the state’s mix. In 2024, generation was about 53.62% nuclear, 31.10% fossil fuels, and 15.28% renewables, data from the Illinois Clean Energy Dashboard shows. Wind and solar are growing fast—by the first quarter of 2025, wind capacity exceeded 10,326 megawatts and solar reached roughly 6,187 megawatts—yet they still trail nuclear by share of production, the Illinois Clean Energy Dashboard reports. Importantly for ratepayers and reliability, Illinois also generates more power than it consumes and is a net exporter, according to the Illinois Clean Energy Dashboard.

For Barrington, those figures mean the state’s overall balance is favorable. But adequacy is shaped by regional markets and transmission, and planners warn that a comfortable statewide ledger today does not guarantee smooth sailing through the end of the decade.

The adequacy question

Illinois regulators and energy agencies have sharpened their focus on the five- and ten-year outlooks. A new 2025 Resource Adequacy Study from state agencies points to potential capacity shortfalls in the PJM and MISO regions that serve Illinois, a risk that could affect businesses and consumers if not addressed, according to the Illinois Power Agency. In response, lawmakers required the Illinois Commerce Commission to lead an Integrated Resource Planning process that must secure adequacy for the five years immediately after approval and consider the subsequent ten-year horizon, the Illinois Power Agency notes.

Industry voices are also flagging timing risks. The Clean Energy Choice Coalition warned that rising demand—including growth from energy-intensive data centers—combined with ongoing generation retirements and delays in bringing replacement resources online, could contribute to capacity shortfalls beginning in 2029 unless mitigated, according to PR Newswire.

For Barrington, that outlook is not an alarm bell so much as a planning challenge: keep the power supply cushion ahead of demand growth so that peak summer afternoons and deep-winter mornings remain uneventful for homes, schools, and shops.

Local stakes

The question most residents ask first is cost. Investments to maintain reliability—new storage systems, additional transmission, or extended operation of aging plants—ultimately filter into rates if regulators allow them. The Illinois Manufacturers’ Association has warned that passing through the costs of large-scale storage and transmission could drive significant increases for industrial users, and it cites one analysis estimating that small food processors could see roughly $1,400 more on monthly electric bills in the first year, with larger annual impacts over time, according to the Illinois Manufacturers’ Association. For Barrington’s small manufacturers and distribution facilities, those kinds of swings can weigh on expansion plans and payrolls.

Even so, reliability carries its own price. Unplanned outages or regional capacity crunches can force utilities to buy power at a premium, costs that can also reach end users. The adequacy study’s warning about regional shortfalls underscores why northern Illinois communities benefit when capacity additions keep pace with demand, the Illinois Power Agency reports.

Barrington residents may notice the energy transition in practical ways over the next few years:

  • Targeted incentives and programs that aim to reduce peak demand through efficiency, as utilities expand offerings under new state law, according to WGLT.
  • More proposals for battery storage projects, which state policy now encourages alongside wind and solar, as reported by WGLT.
  • Periodic updates from state regulators as the Integrated Resource Plan takes shape on a five- and ten-year timeline, per the Illinois Power Agency.

Policy moves and options

Lawmakers moved aggressively last fall with the Clean and Reliable Grid Affordability Act, known as SB 25. The package creates new incentives for energy storage, expands utility energy-efficiency programs to trim peak demand, lifts a longstanding moratorium on large nuclear plants, and grants regulators new authority to craft and enforce integrated resource plans, according to reporting from WGLT.

Those policy levers speak to the emerging consensus: Illinois will likely need some combination of storage, efficiency, and dispatchable generation to bridge from today’s mix to a cleaner grid without compromising reliability. One analysis summarized by NRDC suggests that deploying about 3 gigawatts of four-hour battery storage, together with already planned new generation, could allow the state to retire fossil-fuel resources while maintaining reliability—and potentially avoid expensive transmission upgrades, according to NRDC. If pursued, that path could be particularly relevant in northern Illinois communities like Barrington, where storage projects sited near demand centers can help manage peak loads.

At the same time, the business community’s cost concerns are unlikely to subside. The Illinois Manufacturers’ Association argues that if large infrastructure expenses are rolled into rates, Illinois manufacturers will be placed at a competitive disadvantage. Policymakers will have to weigh those warnings against the costs that come with underinvestment in capacity.

What to watch

The data make clear that Illinois starts from a position of strength: a robust nuclear fleet, rising wind and solar capacity, and a status as a net exporter of electricity, per the U.S. Energy Information Administration and the Illinois Clean Energy Dashboard. The open question is how quickly the state can bring online the right mix of resources to meet growth in demand while keeping bills manageable.

For Barrington, the timeline is already set. The Integrated Resource Plan must address the first five years after approval and look out a decade, a process intended to keep supply ahead of need, according to the Illinois Power Agency. Advocates for clean energy point to storage as a way to retire fossil plants without sacrificing reliability, as NRDC reports; industry groups warn of rate pressures if large investments are passed through to customers, as the Illinois Manufacturers’ Association contends. Meanwhile, a coalition of energy interests urges vigilance as demand rises and older generators retire, flagging 2029 as a potential stress point without timely action, according to PR Newswire.

Between now and then, the most visible changes in Barrington may be incremental: more aggressive utility efficiency programs, proposals for storage projects, and a planning docket that spells out how new and existing resources will keep the grid stable. The state’s energy transition is not an abstraction; it will be measured in monthly bills, in how reliably businesses can operate, and in how well communities like Barrington navigate the next five to ten years of change.

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