In the central United States, coal continues to demonstrate its economic viability for power generation, particularly within the Midcontinent Independent System Operator (MISO) region. Data analyzed by the U.S. Energy Information Administration (EIA), drawing from S&P Global Market Intelligence, indicates that the economics favoring coal generation have persisted into the early months of 2026. This competitiveness is largely measured by comparing the profitability of coal-fired plants against those powered by natural gas, using metrics known as the dark spread and spark spread, respectively.
The dark spread, representing the revenue from wholesale electricity sales minus the cost of coal, has consistently shown favorable conditions for coal generation in MISO since late 2024. This trend accelerated in 2025, with the dark spread experiencing a significant 111% increase compared to the previous year. This surge was driven by electricity prices climbing at a faster rate than the costs associated with generating power from coal. Over the same period, coal prices saw a modest increase of only 3%, causing the dark spread to widen from an average of $11 per megawatthour (MWh) in 2024 to $23/MWh in 2025.
In contrast, the spark spread, which measures the profitability of natural gas-fired generation, saw a more moderate increase of 18% from 2024 to 2025. The rising costs of natural gas generation acted as a counterbalance to the increasing electricity prices, limiting the spark spread's growth. Natural gas prices escalated by 63% between 2024 and 2025, significantly impacting the spark spread. Consequently, the spark spread's increase was constrained to just $2/MWh, moving from $12/MWh in 2024 to $14/MWh in 2025. This disparity highlights the differing cost dynamics between coal and natural gas power generation.
Winter Storm Fern, which occurred in January, starkly illustrated the divergence between coal and natural gas economics. During this period, daily average power prices in MISO reached extreme highs, exceeding $260/MWh for six consecutive days, even as electricity demand was lower than typical for the same weekdays. These elevated prices were primarily a result of sharp increases in natural gas prices, driven by heating demand. Natural gas prices surged from $25/MWh on January 20 to $549/MWh by January 27. The EIA notes that coal prices, however, are far less susceptible to such rapid demand fluctuations. This is due to the logistical differences in fuel procurement: natural gas can be delivered almost immediately to power plants connected to pipeline infrastructure, whereas coal requires a lead time of about a month for transportation, keeping its prices relatively stable during the storm.
The impact of Winter Storm Fern on the spreads was substantial. For six consecutive days, there were significant differences between the dark and spark spreads. The EIA's analysis for the first four months of 2026 shows that the average dark spread in MISO was $28/MWh, representing a 39% increase compared to the same period in 2025. The average spark spread for the same period in 2026 was $9/MWh, a 15% year-over-year increase. These figures further underscore the sustained economic advantage of coal generation in the region, even after accounting for extreme weather events.
The methodology used for calculating these spreads involves specific heat rates: 10,579 British thermal units per kilowatthour (Btu/kWh) for coal (dark spread) and 8,365 Btu/kWh for natural gas (spark spread). These figures, along with adjustments to heat contents, were detailed in a 2017 EIA article. The observed trends in MISO differ somewhat from analyses conducted for other regions, such as the PJM market, suggesting unique regional market dynamics at play.
Overall, the data from the first four months of 2026 indicates that the combination of electricity prices and fuel costs continues to favor coal-fired power generation in the MISO region. While natural gas prices experienced significant volatility during Winter Storm Fern, coal prices remained more stable, reinforcing coal's competitive position. This sustained economic advantage is a key factor in the ongoing energy mix decisions within the central United States.
