Alexandra Moreno
The coal to gas transition in US power generation comes down to simple economics: gas plants convert fuel to electricity more efficiently, cost less to ship, and avoid the toxic ash disposal that burdens aging coal fleets, making gas the obvious replacement for retiring coal units.
At a Glance
- Gas boilers need about 7,500 BTUs per kilowatt hour versus roughly 10,000 for coal, a heat rate gap that is hard to overcome
- No new coal fired power plants are under construction in the US, while about 116,000 megawatts of gas capacity are either being built or in planning
- Coal plant retirements slowed sharply, from over 12 gigawatts announced in 2022 to just 2.6 gigawatts last year
- Levelized cost of energy data puts onshore wind at $29.58 per megawatt hour, well below gas at $64.55 and coal at $73
- Battery storage is already undercutting gas peaking plants in markets like California by roughly 10 percent on cost
Why Utilities Keep Choosing Gas Over Coal
Electricity behaves like any other commodity: buyers gravitate toward whoever produces it cheapest, and scarcity rarely changes that math. Utility executives have spent the last two decades applying that logic to their fuel choices, and gas has consistently come out ahead of coal on four fronts.
The heat rate advantage is the biggest factor. A coal boiler burns through about 10,000 BTUs of fuel to generate one kilowatt hour of electricity, while a combined cycle gas plant needs only around 7,500 BTUs for the same output. That efficiency gap alone is tough for coal to close.
Transportation costs pile on more disadvantage for coal. Gas moves through pipelines cheaply, while coal typically travels by rail, and in some cases rail freight accounts for half the total delivered cost of a ton of coal. Add in the long term expense of treating and storing toxic coal ash, a cost gas plants simply do not carry, and coal falls further behind. Aging coal units also require more frequent shutdowns for maintenance than their gas counterparts, adding yet another line item to the cost comparison.
The Numbers Behind the Coal Retirement Slowdown
None of this is theoretical. The US Energy Information Administration puts the average age of a coal plant in the country at about 45 years, against an expected useful life of roughly 50. Yet even with plants approaching retirement age, the pace of shutdowns has slowed dramatically as electricity demand has surged. In 2022, utilities announced more than 12 gigawatts of coal plant retirements. Last year that figure dropped to just 2.6 gigawatts, and some owners have pushed back previously announced retirement dates, choosing to keep aging units running longer than planned.
What is not happening is any new coal construction. Nobody in the United States has announced plans to build a new coal fired power plant. Gas, meanwhile, is in an active build cycle, with about 18,000 megawatts under construction and another 98,000 megawatts in site selection or planning, for a combined total near 116,000 megawatts.
Quick Facts
- Coal LCOE: $73 per megawatt hour (Lazard figure)
- Combined cycle gas LCOE: $64.55 per megawatt hour
- Solar photovoltaic plus battery storage: $53.44 per megawatt hour
- Onshore wind: $29.58 per megawatt hour, the cheapest option in the comparison
- Offshore wind: $88.16 per megawatt hour, close to new gigawatt scale nuclear costs
Where Renewables Fit Into the Coal to Gas Transition
Wind, solar and batteries are now doing to gas what gas did to coal: undercutting it on price while delivering the same product. The EIA's levelized cost of energy data, drawn from its Annual Outlook 2025 published in April 2025, makes the comparison explicit. Coal comes in most expensive at $73 per megawatt hour. Combined cycle gas follows at $64.55. Solar paired with batteries lands at $53.44, and onshore wind undercuts everything at $29.58. Offshore wind is the outlier among renewables, priced at $88.16, putting it roughly in line with new large scale nuclear.
The economic logic is straightforward. Coal and gas plants carry substantial lifetime fuel costs. Wind, solar and battery projects have none, since there is no fuel to buy once the equipment is installed. In a business where the cheapest producer eventually wins, that difference matters more with each passing year.
Why Gas Plants Could Become Stranded Assets
This creates an awkward tension. The industry is in the middle of a massive gas construction boom even as renewable costs continue to undercut gas on a levelized basis. That raises a real possibility that some of these new gas plants could become stranded assets before the end of their expected operating lives, especially if renewable and storage costs keep falling relative to gas.
California already offers a preview. Battery systems that discharge during peak demand periods are increasingly replacing gas fired peaking units in the state, largely because batteries now beat gas peakers on cost by about 10 percent according to LCOE figures. That is a narrow margin today, but it is the kind of gap that tends to widen as battery manufacturing scales up and prices keep falling.
How Long the Fossil Fuel to Renewable Shift Might Take
New nuclear and small modular reactors look particularly exposed in this cost hierarchy, given that no LCOE data was even included for SMRs in the EIA's analysis and offshore wind already sits near nuclear's price range.
None of this means coal or gas disappears overnight. Older, less efficient plants often keep running alongside newer, cheaper technology for years or even decades before the economics finally force a shutdown, which is part of what makes energy transitions so hard to time from an investment standpoint. The direction of travel, though, looks increasingly set: as battery costs keep falling and wind and solar keep widening their price advantage, the pressure on higher cost generators, coal first, then potentially gas, will only build.
