Why gas turbines remain vital to US power generation

Since being patented in 1791, gas turbines have become a cornerstone of energy and power generation. That they have remained highly relevant for more than 200 years is thanks to their ability to adapt to evolving technology and energy demands throughout their history. Today, they provide a technological link between power generation’s fossil-fueled past and its net zero future.

Nowhere is this more apparent than in a country as vast and heterogeneous as the United States.

Enabling the transition away from coal

Up until the middle of the last century, coal was the standard fuel for power generation. However, burning coal only has a thermal efficiency of around 35% and generates substantial greenhouse gas emissions, such as CO₂ and noxious particulates.

The growing availability of natural gas in the latter half of the 20th century gave the world a much more effective and environmentally-friendly way of generating electricity. This is because burning natural gas emits significantly less CO₂ than coal.

What is more, gas turbines are more efficient than coal plants, and efficiencies have improved continuously since those early days, lowering fuel consumption. Modern gas turbine combined cycle (GTCC) technology can achieve more than 60% efficiency.

Taken together, these advantages can translate into emission reductions of 65% compared to traditional coal power plants.

Thanks to these CO₂ savings, natural gas has helped the US power sector cut its emissions by nearly half (47%) since 2005, according to the Carnegie Mellon Power Sector Carbon Index.

Gearing up for the end of coal power generation

As coal’s share in the energy mix declines further, around 54 GW of coal-powered plants are due to retire by 2030, the Financial Times reports. The challenge the US faces now is replacing this capacity, explains Mark Bissonnette, Executive Vice President and Chief Operating Officer of Power Generation at Mitsubishi Power Americas.

Though their availability and accessibility vary across the country, renewable energy sources are growing substantially where they are. They now make up 21.4% of electricity generated in the US, with clean energy investments continuing to expand. From $200 billion in 2022, they reached $280 billion in 2023, overtaking US investments in fossil fuels.

However, sources like wind and solar don’t provide continuous power. When there is not enough sunshine or wind, another energy source is needed. Natural gas is the obvious choice for the US, says Bissonnette, pointing to yet another transformation of the role gas turbines play in the US energy mix.

When renewables cannot keep up with demand, a type of gas-powered energy generation called a "peaker plant" can step in – and be taken offline again quickly when demand drops or renewable generation picks up.

Gas turbines to support America’s growing power needs

That said, gas turbines won’t just pick up the slack left by phasing out coal plants and intermittent renewable power generation. They will also reinvent themselves yet again to meet the United States’ growing energy needs; analysts estimate demand will increase 4.7% over the next five years, according to the Financial Times.

Two trends are driving this rise. One is the growth in industrial activity and onshoring of manufacturing, with a surge in new factories being built, particularly in the southern US.

The other is the exponential growth of artificial intelligence (AI) driving demand for more data center capacity. Goldman Sachs forecasts that data center power demands will increase by a compound annual growth rate of 15% between 2023 and 2030 – 60% of this will be met by natural gas and 40% by renewables.

“Data centers have such a large need for power generation. Their operators are continuing to ramp up renewables, but they're using gas turbines to balance those,” says Donald Daniels, Chief Strategy Officer (CSO) at Mitsubishi Power Americas.

“Yet, their interest in gas turbines is not just driven by reliability. We see data center operators combining renewables, battery energy storage and gas turbines simply to achieve the high volumes of electricity they need.”

Gas turbines’ evolution in a renewables-led energy mix

Of course, despite the continued relevance of gas turbines and their substantial emission improvements over coal, it is important to acknowledge that natural gas is still a fossil fuel.

To address this, companies like MHI are readying their turbines for co-firing natural gas and hydrogen, which emits no CO₂ during combustion. In 2023, the company validated a large gas turbine using a fuel mixture of 30% hydrogen and natural gas at its T-Point 2 facility in Japan. The goal is to move all turbines to 100% hydrogen in 2030 or thereafter . A similar roadmap is in place for ammonia, another zero-carbon fuel, again underlining the immense adaptability of gas turbines.

Alongside, there is renewed interest in carbon capture, utilization and storage (CCUS), especially for decarbonizing industry and other historically hard-to-abate sectors. The US leads the world in CCUS, and capacity is set to increase sevenfold by 2035, supported by the current government’s incentives. One recent CCUS project is a food processing plant in Decatur, Illinois. Here, a gas turbine provides power and steam for the plant while capturing CO₂ emissions and sequestering them permanently in underground storage wells.

Since US power needs and resources are heterogeneous, and renewable energy still has a long way to go, Daniels emphasizes the stability and reassurance gas turbines offer:

“The great thing about the gas turbine is that we have alternatives. We don't have to pick a winner today.” 

Instead, power users can create their own energy mix and adapt it to their needs over time, smoothing their energy transition path – and gas turbines are ready to evolve with them.