After decades of relatively stable energy demand, forecasted load growth—driven primarily by data center development—is at its highest level in the past two decades. Across the United States, soaring demand is straining available capacity and inflating prices. Simultaneously, grid operators face a growing gap between their system’s installed nameplate capacity and the accredited capacity resources can deliver during the highest-risk hours. 

Rapid demand growth is colliding with the retirement of dispatchable resources and their replacement by predominantly intermittent renewables. A Goldman Sachs report infers that AI-driven growth could require another 47 gigawatts (GW) of power by 2031, the equivalent of California’s 2024 peak load. Meanwhile, NERC reports that 115 GW—comprised mostly of large, dispatchable resources—will retire by 2034, and 85 percent of the replacement megawatts will come from weather dependent resources.

In systems nationwide, the expanding gap between installed and accredited capacity highlights the need for resources like reciprocating internal combustion engines (RICE) to deliver dependable, dispatchable capacity. This widening resource adequacy delta is not solely attributed to weather-dependent resources. In the Midcontinental Independent System Operator's (MISO's) latest Planning Resource Auction, poor availability of older coal and natural gas generation reduced system-wide accredited capacity by nearly 5 GW. Moreover, as high-demand events during the shoulder months become more common, planned maintenance removes critical thermal generation during the spring and fall.

As resource adequacy rules evolve to emphasize reliability, flexibly dispatchable resources like RICE are positioned to outperform turbine technologies. For example, Energy Information Administration data shows that across PJM, MISO, and the Southwest Power Pool, engine power plants consistently demonstrate strong rated capacity performance–averaging 12.5 percent better in summer and 2.75 percent better in winter than turbines.

RICE’s competitive edge is ascribed to its resilient technological attributes. When turbine output derates as ambient temperature rises, RICE’s output remains stable as temperatures climb above 100°F. Conversely, when cold temperatures strain natural gas availability, engines maintain reliability at 80 percent lower gas pressure than aeroderivative turbines. Additionally, when planned maintenance removes turbine plants from service, modular engine systems enable maintenance to be performed in rotation while continuing to supply megawatts to the grid. During unplanned outages, RICE’s modularity provides redundancy that reduces the likelihood of catastrophic, whole-plant outages.

Amid unprecedented load growth and rising costs, grid operators nationwide are implementing market reforms that incentivize resources with higher accreditation values. With resiliency-minded attributes and unmatched flexibility, Wärtsilä’s RICE systems should be a contender for any load-serving entity committed to reliability and long-term value.

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Flexibility refers to a generator's ability to respond to rapid changes in electricity supply or demand. With resource attributes designed for flexibility and fast response, Wärtsilä's reciprocating internal combustion engines (RICE) are the superior choice to maintain reliability and affordability.

Mileage Separates Flexible Technologies From Traditional Dispatchable Generation

Flexible generation, like RICE, can quickly ramp to the exact output needed and quickly turn off when not needed. Inflexible generation—like coal, natural gas boilers, and combined cycles—are limited by slower startups, longer runtimes and downtimes, and higher minimum operating levels. Although these technologies are dispatchable because their output is controllable, they are not flexible enough to respond to minute-by-minute grid intermittency. Just like an odometer measures a car’s movement, a generator's mileage quantifies its total movement over an operating period. When net demand spikes, flexible RICE generation can start up in five minutes, quickly ramp to the exact output needed, and then turn off almost instantly when load is served. When net demand climbs again, Wärtsilä engines can turn back on without any minimum downtime. Since inflexible generators cannot ramp up or down as frequently as flexible generators, they do not provide as much mileage as flexible dispatchable generation.

Flexible Generation Captures Sub-Hourly Value

In this example, net load at an Energy Reliability Council of Texas (ERCOT) node rises by 600 megawatts (MW) between Point A and Point C in two hours. During that same period, intrahour variability exceeds 3,500 MW. Both inflexible and flexible generation resources can satisfy the hourly net load at Point A, Point B and Point C, but only flexible RICE generation can track sub-hourly fluctuation and capture untapped value.

Wärtsilä’s Reciprocating Engines Offer Superior Reliability and Value for Utilities

Wärtsilä’s flexible generation outperforms other dispatchable technologies in balancing grid variability. Case Study: Performance of RICE versus Aeroderivative Turbines in ERCOT, 2022:

• RICE plants recorded nearly three times as many starts as the turbine plants.
• RICE plants provided four times as much mileage as turbine plants.
• RICE had 60-percent higher real time market revenue potential than turbine plants.

When graded against other dispatchable technologies, Wärtsilä’s flexible generation outperforms.

• Wärtsilä’s RICE technology starts more often than a less flexible peaking technology like aeroderivative turbines.
• Compared to turbines, Wärtsilä engines provide more mileage to address variability.
• Wärtsilä engines offer greater revenue generation and savings opportunities than less flexible turbines.

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Electric companies are under increasing pressure to deliver clean, reliable, and affordable energy. Wärtsilä’s reciprocating internal combustion engine (RICE) technology offers a flexible, efficient solution to meet these demands—especially as companies integrate more renewable energy onto the grid.

Wärtsilä's RICE plants deliver several advantages: fast startup times, flexible operation across varying power levels, strong part-load efficiency, and grid stability. These features make RICE ideal for balancing intermittent renewables and ensuring power system reliability. Additionally, Wärtsilä’s engines are future-proof, capable of running on hydrogenblended fuels to support decarbonization goals.

Flexibility is key to Wärtsilä’s success. Some companies deploy RICE exclusively; others use it alongside gas turbines to balance renewables. The technology adapts to a wide range of energy profiles, helping companies deliver clean power while keeping costs low for customers.

One standout example is WEC Energy Group, which serves 4.7 million customers across Wisconsin, Illinois, Michigan, and Minnesota. Starting a decade ago, WEC Energy sought modular, quick-start gas plants to enhance their generation fleet. They chose Wärtsilä for its strong global track record, U.S. presence, and proven technology solutions. Today, WEC Energy has 17 Wärtsilä engines in operation, with more planned.

Wärtsilä engines also achieved a major milestone: a successful hydrogen fuel blend test in an existing engine. In collaboration with WEC Energy Group, EPRI, and Burns & McDonnell, Wärtsilä demonstrated that its engines could operate on a 25 volume-percent hydrogen blend without any mechanical modifications. Over three days of testing, the engines maintained high efficiency and reduced greenhouse gas emissions, reaching 95 percent engine load with a 25 volume-percent hydrogen blend and 100 percent load at 17 volume-percent.

“The pilot was a success,” said Dan Krueger, Executive Vice President at WEC Energy Group. “It showed us these engines can run on a 25 percent hydrogen blend without significant efficiency impacts, while also reducing emissions.”

This project marks the first time a commercially operated balancing engine of this size has run on a hydrogen fuel blend and reinforces Wärtsilä’s leadership in hydrogen-ready technology. The company continues research and development efforts toward launching a 100-percent hydrogen-capable engine by 2026.

For WEC Energy Group, Wärtsilä’s flexible, modular, quick-ramping engines are crucial to the company’s energy transformation focused on reliability, affordability, and economic growth. They provide the adaptability needed to navigate rising electricity demand, new environmental regulations, and greater renewable energy integration.

The expansion of energy-intensive industries is one reason why companies are facing demands to add new, cleaner generation capacity quickly. Wärtsilä’s reciprocating engine technology helps address this challenge with relatively fast delivery timelines compared to timelines from gas-turbine manufacturers. These shorter lead times allow companies to bring flexible, reliable generation online faster than traditional large-scale infrastructure projects, helping them respond to demand growth without long delays.

With companies seeking scalable, future-ready solutions, Wärtsilä’s RICE technology stands out as a powerful tool for clean, affordable, and reliable energy.

Watch our video at wartsila.com/hydrogenblend.