The Most Efficient Thermal Power Generation Plants in America

This is the seventh in the series of newsletters on energy and electric power production from thermal power plants. Previous newsletters have focused on coal, natural gas, and oil fueled energy systems exploring the operations of large coal plants, Gas Turbine Combined Cycle plants, reciprocating engines, and Combined Heat and Power (CHP) facilities. The purpose of this month’s letter is to preview several major electric utility plants in America that have demonstrated the highest level of efficiency in power production as a precursor to the “Introduction to Thermal Power Plants” course being offered this summer at Williamson College of the Trades. During this three-day course, participants will receive in-depth presentations spanning the energy production field in addition to touring five operating power plants. The basic theme of this extensive course is electric power generation from Thermal Power Generation. Another term to describe thermal power generation is, power generation from “Heat Engines”. Over 80% of America’s electric power generation is from “Heat Engines”. As a reminder, nuclear power generation plants are “Heat Engines” and also utilize the Rankine steam cycle.

I’d like more information about Williamson’s 2018 Introduction to Thermal Power Plants course!

The most efficient coal plant in recent history has been the Longview Plant in West Virginia. This plant, pictured above, recently received top honors in being rated the best Heat-Rate plant of 2016

Figure 1. (above) Longview Plant in West Virginia

The description of the Longview Power plant below is from POWER Magazine.

The 2.1 Billion dollar, 700-MW coal-fired station located in Maidsville, West Virginia had a number of problems following its construction and commissioning in December 2011. Persistence and diligence pays and as a result of a lot of good engineering and hard work, the Longview plant reached the pinnacle of top efficiencies in the U.S., achieving a Heat-Rate of 8,999 Btu’s per kWh. This is an overall thermal efficiency of 38%. This includes low loads, high loads and plant startups. In other words, actual operation. Actual operating efficiencies are always slightly lower than design efficiencies because a power plant rarely operates at the most efficient load point.

If we take a walk down memory lane, a local plant once very important for PECO/Exelon, is the Eddystone station. This plant is one of those to be toured. Now the historic Edddysone #1 has been decommissioned, but Eddystone #1 was once the most efficient design for coal power generation.

In 1960 Exelon’s Eddystone Station Unit #1 was the world’s most efficient Ultra-Supercritical Power Plant (2). It was coal fueled and designed for a thermal efficiency of 41%. This plant was a pace setting facility. Low cost power production made possible by its high efficiency and low fuel cost. Now decommissioned, the plant remained in operation for over fifty years. Given its importance to the industry, the Eddystone facility is now an American Society of Mechanical Engineers (ASME) historical landmark. (2)

The newest coal fueled Ultra-Supercritical Power Plant is the John Turk Plant owned by American Electric Power near Fulton, Arkansas. This plant was commissioned in 2012 and was featured in POWER Magazine’s, August 2013 issue.(3) The Turk Plant uses coal fuel and is designed for an operating efficiency of 40%.


Figure 2. John Turk Plant near Fulton, Arkansas

Another relatively new coal plant is the KCP&L Iatan #2 facility. Also successful and operating at an overall efficiency of about 38%. Links to read more on these plants are provided in the references.


Figure 3. KCP&L Iatan #2 Facility


Figure 4. Duke Energy commissioned the Ultra-Supercritical Cliffside #6 Unit in 2013. It is also featured in POWER Magazine as a Top Plant of 2013.

Longview, Turk, Cliffside and Iatan are amongst the cleanest coal plants in the world with Flue Gas Desulfurization, minimal NOx and particulate emissions. The visible plumes from clean coal plants is water vapor from the Flue Gas Desulfurization (FGD) system, not pollution. Additional information on these highly efficient facilities is available in the references.

Fuel diversity is important. Planning for reliable power generation during extreme weather is one reason for a diverse fuel portfolio. The infographic below (Figure 5), prepared by the National Energy Technology Laboratories (NETL), highlights the importance of large coal and nuclear plants during the extremely cold weather of January 2018.


Figure 5: Electric power generation from nuclear power plants utilize steam turbines for prime movers and therefore are also considered heat engines. As shown on the NETL figure above, Thermal Power Plants provided 82% of the power generation during the deep freeze.


Efficiency is important for two main reasons; 1) For economic power generation, and 2) To reduce the environmental impact. Regarding economic power generation, the fuel cost is the primary driver to produce the lowest cost power. Typical current fuel costs are listed below in dollars per million Btu’s.

  • Coal about $2.50 per million Btu’s
  • Natural Gas about $3.00 per million Btu’s
  • Diesel Fuel about $17.00 per million Btu’s

As the fuel costs illustrate, running a Diesel power plant that is extremely efficient (up to 48%) but utilizes the most expensive fuel is not solely competitive. For cost-effective electricity production it takes both a reasonably cheap and abundant fuel, as well as a high efficiency. Fuel cost comprises approximately 75-80% of the production cost of electricity for coal plants. The cost of fuel in a Gas plant consumes roughly 90% of the production cost of electricity. From this the importance of high efficiency and reasonable fuel costs can be seen. Both high efficiency and low fuel cost are important to produce electricity at reasonable cost.

An example of a large electric utility that has a diverse fuel supply, is Duke Energy.

To illustrate, let’s take Duke Energy as an example. For the year 2017 fuel diversity for Duke Energy, a 49,500 MW Utility, is captured in Figure 6 below (source: To produce competitive low-cost power, it is important for all utilities to maintain a diverse fuel portfolio. Duke Energy’s fuel portfolio is a fine example of fuel diversity.


Figure 6: Duke Energy Fuel Diversity (2017)

As can be seen from figure 6, over the course of a year, the fuels used for power generation at Duke Energy provided 95% Thermal Power Generation. The Duke Sustainability Report, included as a reference, also illustrates past and future projections of fuel diversity (6). All fuels are important and coal, as seen in Figure 5, coal can be extremely important for Base Load and during extreme weather.

Currently Most Popular and Most Efficient Thermal Generation is by Natural Gas Combined Cycle Plants


Thanks to President Eisenhower and Admiral Rickover, the “Atoms for Peace” program of the 1950’s shared America’s (actually the brainchild of Hyman G. Rickover) invention of nuclear power generation with the Free World. Today, France relies heavily on nuclear power, from the basic design of Admiral Rickover. In fact, since the late 1980s, uranium atoms have been used to generate more than 75% of France’s electricity—the highest nuclear power percentage of any country in the world. France’s nuclear power infrastructure relied heavily on the design of the U.S. Navy’s Rickover/Westinghouse pressurized nuclear steam system, first perfected on the USS Nautilus in the 1950’s and commercialized at the Shippingport, PA power plant of Duquesne Light Company. (29)

But times may be changing.

Since EDF and GE installed the first commercial 9HA gas turbine in the Bouchain plant, the outcome was great: A world record for combined cycle efficiency—62.22%. See POWER Magazine reference article. (8)

The Bouchain plant is similar to two of the plants that we will tour during Williamson’s summer course, Liberty and Marcus Hook Energy Center.

When gas prices are low and the supply abundant, as they have been for several years, the production cost of high efficiency facilities combined with low fuel cost make Gas Turbine, Combined Cycle the power generation plant of choice.

This summer’s course at Williamson College will provide presentations on common fossil fueled plants including coal, oil and natural gas. The Rankine and Brayton cycles will also be described. By the way, the nuclear plants that provide 75% of France’s power and about 20% of America’s also use the Rankine Cycle. Heat Engines are marvels at the heart of the prosperity of the modern developed world. Come to our course and you will learn many details of most forms of Thermal Power Generation, including the most efficient technique of all, CHP (Combined Heat and Power) as we use on the Williamson Campus.
Hope you can make it to our summer course, there are still a few seats left!

Richard F. (Dick) Storm, PE, CEM
Williamson class of 6W2

Registration is now open for Williamson’s 2018 Introduction to Thermal Power Plants course!


  2. ASME Eddystone Station Landmark Plant
  3. AEP/SWEPCO John Turk Plant. POWER Magazine
  4. SWEPCO web site for John Turk Power Plant
  5. POWER Magazine article on KCP&L Iatan #2, 2011
  6. Duke Energy Sustainability Report, 2017
  7. Longview Power, POWER Magazine Plant of the Year, 2016
  8. G-E Bouchain GTCC Power Plant, EDF, France
  9. Toshiba Energy Systems
  10. G-E Gas Turbine, Combined Cycle Plant designed for up to 64% Thermal Efficiency
  11. POWER Magazine, April 2017 World’s Most Efficient Coal Plants
  12. Duke Cliffside Unit #6 POWER Magazine, 2013
  13. Wartsila 46DF Marine Engine
  14. Toyota Gasoline Engine reaches 38% Thermal Efficiency
  15. Caterpillar Natural Gas Engine G3412C Gas Engine Technical Data
  16. EIA (Energy Information Agency) Electricity Cost of Production Chart
  17. U.S. Chamber of Commerce Publication, “Here is Where Your State stacks up in Electricity Prices”
  18. U.S. Department of Energy Combined Heat and Power “Better Buildings” Web-Site
  19. Engineering Toolbox for Fuel Heating Values and analyses
  20. The Importance of Power Generation by Coal and Nuclear Plants during January 2018, by NETL/DOE.
  21. National Mining Association cost of electricity by each state and the percentage of coal generation in each state
  22. Combined Heat and Power article, Power Engineering:
  23. “The Rickover Effect, How One Man Made a Difference” by Theordore Rockwell, Naval Institute Press and iUniverse, 1992
2018-05-10T12:20:33-04:00 May 10th, 2018|