Gas Turbines Have Become by Far the Best Choice for Add-on Generating Power

They offer instant-on power that's compact, mobile, quiet, economical, durable, and matchlessly efficient

2 min read
Illustration: Stuart Bradford
Illustration: Stuart Bradford

Eighty years ago, the world’s first industrial gas turbine began to generate electricity in a municipal power station in Neuchâtel, Switzerland. The machine, installed by Brown Boveri, vented the exhaust without making use of its heat, and the turbine’s compressor consumed nearly three-quarters of the generated power. That resulted in an efficiency of just 17 percent, or about 4 MW.

The disruption of World War II and the economic difficulties that followed made the Neuchâtel turbine a pioneering exception until 1949, when Westinghouse and General Electric introduced their first low-capacity designs. There was no rush to install them, as the generation market was dominated by large coal-fired plants. By 1960 the most powerful gas turbine reached 20 MW, still an order of magnitude smaller than the output of most steam turbo generators.

In November 1965, the great power blackout in the U.S. Northeast changed many minds: Gas turbines could operate at full load within minutes. But rising oil and gas prices and a slowing demand for electricity prevented any rapid expansion of the new technology.

The shift came only during the late 1980s. By 1990 almost half of all new installed U.S. capacity was in gas turbines of increasing power, reliability, and efficiency. But even efficiencies in excess of 40 percent—matching today’s best steam turbo generators—produce exhaust gases of about 600 °C, hot enough to generate steam in an attached steam turbine. These combined-cycle gas turbines (CCGTs) arrived during the late 1960s, and their best efficiencies now top 60 percent. No other prime mover is less wasteful.

Gas turbines are now much more powerful. Siemens now offers a CCGT for utility generation rated at 593 MW, nearly 40 times as powerful as the Neuchâtel machine and operating at 63 percent efficiency. GE’s 9HA delivers 571 MW in simple-cycle generation and 661 MW (63.5 percent efficiency) by CCGT.

Their near-instant availability makes gas turbines the ideal suppliers of peak power and the best backups for new intermittent wind and solar generation. In the United States they are now by far the most affordable choice for new generating capacities. The levelized capital cost of electricity—a measure of the lifetime cost of an energy project—for new generation entering service in 2023 is forecast to be about US $60 per megawatt-hour for coal-fired steam turbo generators with partial carbon capture, $48/MWh for solar photovoltaics, and $40/MWh for onshore wind—but less than $30/MWh for conventional gas turbines and less than $10/MWh for CCGTs.

Gas turbines are also used for the combined production of electricity and heat, which is required in many industries and is used to energize central heating systems in many large European cities. These turbines have even been used to heat and light extensive Dutch greenhouses, which additionally benefit from their use of the generated carbon dioxide to speed up the growth of vegetables. Gas turbines also run compressors in many industrial enterprises and in the pumping stations of long-distance pipelines. The verdict is clear: No other combustion machines combine so many advantages as do modern gas turbines. They’re compact, easy to transport and install, relatively silent, affordable, and efficient, offering nearly instant-on power and able to operate without water cooling. All this makes them the unrivaled stationary prime mover.

And their longevity? The Neuchâtel turbine was decommissioned in 2002, after 63 years of operation—not due to any failure in the machine but because of a damaged generator.

This article appears in the December 2019 print issue as “Superefficient Gas Turbines.”

This article was corrected on 25 November 2019 to specify that the matter being measured is the levelized capital cost of electricity.

The Conversation (0)

Smokey the AI

Smart image analysis algorithms, fed by cameras carried by drones and ground vehicles, can help power companies prevent forest fires

7 min read
Smokey the AI

The 2021 Dixie Fire in northern California is suspected of being caused by Pacific Gas & Electric's equipment. The fire is the second-largest in California history.

Robyn Beck/AFP/Getty Images

The 2020 fire season in the United States was the worst in at least 70 years, with some 4 million hectares burned on the west coast alone. These West Coast fires killed at least 37 people, destroyed hundreds of structures, caused nearly US $20 billion in damage, and filled the air with smoke that threatened the health of millions of people. And this was on top of a 2018 fire season that burned more than 700,000 hectares of land in California, and a 2019-to-2020 wildfire season in Australia that torched nearly 18 million hectares.

While some of these fires started from human carelessness—or arson—far too many were sparked and spread by the electrical power infrastructure and power lines. The California Department of Forestry and Fire Protection (Cal Fire) calculates that nearly 100,000 burned hectares of those 2018 California fires were the fault of the electric power infrastructure, including the devastating Camp Fire, which wiped out most of the town of Paradise. And in July of this year, Pacific Gas & Electric indicated that blown fuses on one of its utility poles may have sparked the Dixie Fire, which burned nearly 400,000 hectares.

Until these recent disasters, most people, even those living in vulnerable areas, didn't give much thought to the fire risk from the electrical infrastructure. Power companies trim trees and inspect lines on a regular—if not particularly frequent—basis.

However, the frequency of these inspections has changed little over the years, even though climate change is causing drier and hotter weather conditions that lead up to more intense wildfires. In addition, many key electrical components are beyond their shelf lives, including insulators, transformers, arrestors, and splices that are more than 40 years old. Many transmission towers, most built for a 40-year lifespan, are entering their final decade.

Keep Reading ↓ Show less