The Role of Nuclear Power in Illinois' Energy Landscape

Why Illinois is America's Nuclear Powerhouse: A Statistical Deep Dive

When it comes to nuclear energy, Illinois stands in a class by itself. The state's nuclear fleet has profoundly shaped its energy economy, environmental profile, and electricity market in ways that affect every ratepayer.

Illinois Nuclear Generation by the Numbers

The statistics underscore Illinois' nuclear dominance:

• National rank: #1 in nuclear electricity generation among all U.S. states
• Operating reactors: 11 nuclear reactors at 6 power stations
• Total capacity: Approximately 11,500 megawatts (MW)
• Share of state generation: Nuclear produces roughly 50% of all electricity generated in Illinois
• Share of national nuclear output: Illinois generates about 12% of all U.S. nuclear electricity
• Carbon-free output: Over 90 million megawatt-hours of carbon-free electricity annually

Illinois' Nuclear Fleet

Illinois' nuclear plants are operated by Constellation Energy (formerly Exelon Generation):

These plants have been operating since the 1970s and 1980s, with operating licenses extended to continue generation through the 2040s.

Nuclear's Unique Generation Characteristics

Nuclear power differs fundamentally from other electricity sources in ways that affect the grid and markets:

Baseload operation: Nuclear plants run at full capacity nearly continuously, providing steady, predictable output. They typically achieve 90%+ capacity factors—far higher than any other generation source.

No fuel price volatility: While natural gas prices can swing dramatically (affecting electricity prices), nuclear fuel costs are minimal and stable. Uranium represents only about 5% of nuclear generation costs.

Zero carbon emissions: Nuclear generation produces no direct carbon dioxide, sulfur dioxide, nitrogen oxides, or particulates. This makes it essential for Illinois' clean energy goals.

Grid reliability: Nuclear plants provide inertia and voltage support that help stabilize the grid—services increasingly valuable as variable renewables grow.

Historical Context: How Illinois Became Nuclear-Dominant

Illinois' nuclear development resulted from decisions made decades ago:

1960s-1970s: Commonwealth Edison (now ComEd) invested heavily in nuclear as a response to the 1970s oil crises and concerns about coal's environmental impacts.

1980s-1990s: Illinois' nuclear fleet was completed and operated as regulated utility assets with costs passed to ratepayers.

1997-2007: Electric restructuring in Illinois created competitive wholesale markets. Nuclear plants transitioned from regulated assets to competitive generators.

2010s: Low natural gas prices and subsidized renewables squeezed nuclear economics. Byron and Dresden faced potential closure.

2016-2021: The Future Energy Jobs Act (2016) and CEJA (2021) established support programs to keep nuclear plants operating.

Comparing Illinois to Other States

Illinois' nuclear profile differs markedly from neighboring states:

• Indiana: No nuclear plants; heavily dependent on coal and natural gas
• Wisconsin: One nuclear plant (Point Beach) provides ~15% of generation
• Iowa: One nuclear plant (Duane Arnold, closed 2020); now mainly wind
• Missouri: One nuclear plant (Callaway) provides ~10% of generation

This comparison highlights how Illinois' nuclear concentration is unique in the region, affecting both electricity prices and carbon intensity.

Nuclear's Bottom Line: How Illinois' Plants Directly Impact Your Commercial Energy Costs

For businesses operating in Illinois, nuclear power's dominance has tangible effects on electricity costs, price stability, and long-term energy planning.

Nuclear's Effect on Wholesale Electricity Prices

Nuclear power influences wholesale electricity markets in several ways:

Merit order effect: In competitive electricity markets, generators are dispatched in order of their marginal costs (the "merit order"). Nuclear plants have very low marginal costs (mostly fuel and operations), so they typically run whenever they're available, providing cheap baseload power.

Price suppression: When nuclear plants generate, they reduce the need for higher-cost natural gas generation, tending to lower wholesale prices during times of moderate demand.

Price stability: Because nuclear output is steady and not dependent on fuel prices, it provides a stable foundation that moderates price swings. When natural gas prices spike, having 50% of generation from nuclear limits the price impact.

The Cost of Nuclear Support Programs

Keeping nuclear plants operating requires ratepayer support through several mechanisms:

Zero Emission Credits (ZECs): Established by the Future Energy Jobs Act (2016), ZECs compensate nuclear plants for their carbon-free generation. The cost appears as a line item on customer bills—typically $0.001-0.002 per kWh.

Carbon Mitigation Credits (CMCs): CEJA expanded support through CMCs, providing additional compensation tied to the social cost of carbon. These costs also flow through to ratepayers.

Total impact: For a typical commercial customer, nuclear support charges might add $50-200 monthly to bills, depending on consumption. While not insignificant, this is generally less than the alternative—replacing nuclear with higher-cost resources.

What Would Happen Without Nuclear?

Understanding the counterfactual helps contextualize nuclear's value:

If Illinois nuclear closed:

• Approximately 50% of state generation would need replacement
• Most likely replacement: natural gas plants (increasing fuel price exposure)
• Wholesale electricity prices would likely increase significantly
• Carbon emissions would surge (potentially 30-50 million tons annually)
• Grid reliability challenges would increase

Estimated cost impact: Various analyses suggest closing Illinois nuclear could increase wholesale electricity costs by 20-40%, more than offsetting the nuclear support charges customers currently pay.

Nuclear and Price Predictability

For businesses managing energy budgets, nuclear's stability is valuable:

Reduced volatility: States with high natural gas dependence (like Texas) experience dramatic price swings during extreme weather or supply disruptions. Illinois' nuclear base provides insulation from these events.

Forward price stability: When businesses lock in electricity contracts, nuclear's presence helps keep forward prices more stable and predictable than in markets dominated by gas or renewables.

Long-term planning: Nuclear plants operate for decades with known cost structures. This longevity provides more certainty for long-term business planning than resources with shorter or less predictable lifespans.

Nuclear in Your Supply Mix

When you purchase electricity in Illinois' deregulated market, your supply includes nuclear whether you choose it or not:

Default utility supply: ComEd and Ameren procure supply through competitive auctions. The generation mix serving default customers includes nuclear, renewables, and natural gas based on market conditions.

ARES supply: Alternative retail suppliers source power from the wholesale market, which includes nuclear generation. Some may offer explicit "nuclear-free" products using renewable energy credits, but the physical electrons are still a market mix.

Green energy products: If you want to support specific generation types, products backed by renewable energy credits (RECs) let you claim 100% renewable sourcing. However, nuclear remains part of the overall grid mix that maintains reliability.

The CEJA Effect: Is Nuclear Power the Cornerstone of Illinois' Clean Energy Goals?

The Climate and Equitable Jobs Act (CEJA) of 2021 established Illinois' path to 100% carbon-free electricity by 2045. Nuclear power is essential to achieving this goal—though it occupies a unique position in the policy framework.

Nuclear's Role in CEJA's Clean Energy Vision

CEJA targets 100% "carbon-free" rather than 100% "renewable" electricity by 2045. This distinction is crucial:

Renewable vs. carbon-free: Renewables (solar, wind) count toward both renewable portfolio standard requirements and carbon-free goals. Nuclear doesn't count as "renewable" but is recognized as carbon-free.

The math works like this:

• Current nuclear: ~50% of Illinois generation (carbon-free)
• Target renewable by 2050: ~50% of generation
• Nuclear + renewables = 100% carbon-free goal achieved

Why this matters: Without nuclear, Illinois would need to nearly double its renewable energy buildout to achieve the same carbon-free target—a dramatically more expensive and challenging proposition.

CEJA's Nuclear Support Mechanisms

CEJA established and expanded programs to keep nuclear plants operating:

Carbon Mitigation Credits (CMCs):

• Provide compensation to nuclear plants based on the avoided carbon emissions
• Calculated using the social cost of carbon
• Ensures nuclear remains economically viable against subsidized renewables and cheap natural gas
• Subject to adjustment based on market conditions and plant economics

Contract structure:

• Five-year terms with Illinois Power Agency
• Indexed to market prices (support decreases if market prices rise)
• Financial transparency requirements for plant owners
• Ratepayer cost caps to limit bill impacts

Nuclear and Illinois' Carbon Trajectory

Nuclear power's continued operation is essential for Illinois' emissions profile:

Current emissions: Illinois' power sector emissions are relatively low (compared to coal-heavy states) specifically because of nuclear's carbon-free generation.

Without nuclear: If nuclear plants closed and were replaced by natural gas:

• Annual CO2 emissions would increase by approximately 30-50 million tons
• Illinois would become one of the higher-emitting power sectors in the Midwest
• CEJA's 2045 carbon-free target would become essentially unachievable

With nuclear: The existing fleet provides half of the carbon-free generation needed, making the renewable buildout required to reach 100% carbon-free manageable.

The Fossil Fuel Phase-Out Timeline

CEJA mandates closure of fossil fuel plants on a defined schedule:

• 2030: All privately-owned coal plants close
• 2035: Municipal coal plants begin closing
• 2045: All fossil fuel plants must close or convert to carbon-free fuels

Nuclear plants are explicitly exempted from these closure requirements, recognizing their carbon-free status and importance to grid reliability.

Nuclear's Long-Term Outlook Under CEJA

Looking ahead to 2045 and beyond:

License extensions: Most Illinois nuclear plants have licenses extending into the 2040s. Further extensions to 60-80 years of operation may be possible if plants remain economically viable and technically sound.

Economic viability: As carbon pricing becomes more prevalent and fossil fuel plants close, nuclear economics may improve, potentially reducing or eliminating need for ratepayer support.

Advanced nuclear: CEJA doesn't specifically address new nuclear development, but doesn't preclude it. Advanced reactor designs (small modular reactors, etc.) could potentially complement existing plants in the future.

Workforce transition: CEJA includes provisions for workers in closing fossil fuel plants. Nuclear plants continue providing high-quality employment for thousands of Illinoisans.

Strategic Energy Procurement: Navigating Illinois' Nuclear-Dominant Future

For businesses making energy decisions in Illinois, understanding nuclear's role helps inform procurement strategy, sustainability planning, and risk management.

Nuclear and Electricity Procurement

When contracting for electricity, consider nuclear's implications:

Price stability: Illinois wholesale prices tend to be less volatile than gas-dependent markets. This affects both spot market exposure and forward contract pricing.

Off-peak prices: Nuclear's always-on generation tends to keep overnight and weekend prices relatively low (when demand is lower and nuclear represents a larger share of generation).

On-peak prices: During peak demand periods, natural gas plants typically set marginal prices, so nuclear's dampening effect is less pronounced.

Procurement implications:

• Fixed-rate contracts in Illinois may be competitively priced due to nuclear's stable baseload
• Time-of-use strategies can leverage low off-peak prices influenced by nuclear
• Long-term contracts may offer stability reflecting nuclear's predictable cost structure

Nuclear in Sustainability Reporting

Nuclear power creates interesting considerations for corporate sustainability:

Emissions accounting: Electricity from the Illinois grid has a relatively low carbon intensity (compared to regional peers) specifically because of nuclear. Companies using Illinois grid power can accurately report lower Scope 2 emissions.

Renewable vs. carbon-free goals: Some corporate sustainability commitments specify "renewable" energy, which excludes nuclear. Others target "carbon-free" or "clean" energy, which can include nuclear. Understand your commitments' definitions.

RECs and nuclear: Nuclear doesn't generate Renewable Energy Credits (RECs), so claiming "100% renewable" requires purchasing RECs from actual renewable sources. However, if your goal is simply carbon-free operations, Illinois grid power is already approximately 50% carbon-free from nuclear alone.

Risk Management Considerations

Nuclear's presence affects several risk factors:

Plant closure risk: While CEJA provides support, individual plants could still close if economics deteriorate significantly. Closure of a major plant would likely increase wholesale prices and reduce carbon-free generation.

Regulatory risk: Future changes to nuclear support programs could affect costs. CEJA includes cost caps, but policy can always change.

Extended outage risk: When nuclear plants undergo refueling or unexpected outages, wholesale prices typically increase. Multiple simultaneous outages (rare but possible) could significantly impact market prices.

Mitigating risks:

• Diversify energy procurement across fixed and market-based products
• Consider on-site generation (solar, backup) to reduce grid dependence
• Monitor nuclear plant operating status and market conditions
• Stay informed about policy developments affecting nuclear support

Planning for Illinois' Clean Energy Future

As Illinois progresses toward 100% carbon-free electricity:

Short-term (2025-2030):

• Nuclear continues providing ~50% of generation
• Renewable capacity grows significantly
• Coal plants begin closing per CEJA timeline
• Electricity rates may face moderate upward pressure from grid investments

Medium-term (2030-2040):

• Nuclear maintains baseload role as renewables scale
• Energy storage becomes increasingly important for grid balancing
• Carbon-free electricity percentage rises toward 75-90%
• Business opportunities in flexibility and storage emerge

Long-term (2040-2045):

• Final push to 100% carbon-free generation
• Nuclear plants reaching end of extended licenses may face decisions on further extensions or retirement
• Grid design increasingly optimized for renewable + nuclear + storage
• Businesses operating in a nearly carbon-free electricity environment

For current electricity options and rate comparisons, explore our Illinois electricity marketplace or review our analysis of CEJA's effects on rates.

Frequently Asked Questions

Conclusion: Nuclear Power as Illinois' Clean Energy Foundation

Nuclear power isn't just a component of Illinois' electricity system—it's the foundation that makes the state's ambitious clean energy goals achievable. By providing half of the state's electricity from carbon-free sources, nuclear plants give Illinois a head start that most states lack.

For businesses and residents, nuclear's presence has practical implications: relatively stable electricity prices, reduced exposure to natural gas price volatility, and electricity that's already approximately 50% carbon-free before any renewable purchases or efficiency investments.

The path forward under CEJA preserves this foundation while building on it with renewable energy. Nuclear provides the stable baseload that complements variable wind and solar generation. Together, they create a reliable, carbon-free electricity system that will serve Illinois through 2045 and beyond.

Understanding nuclear's role helps inform energy decisions at every level. Whether you're evaluating electricity supply contracts, setting corporate sustainability targets, or simply trying to understand your electricity bill, nuclear power is part of the picture. Illinois' unique position as America's nuclear leader shapes opportunities and challenges that affect every energy consumer in the state.

As the clean energy transition accelerates, nuclear will remain central to Illinois' energy story—a bridge to a renewable future and a cornerstone of grid reliability in a changing climate.