The thermal performance of the existing coal fleet can be improved by applying proven and reasonable cost mechanical tuning solutions. Coal power generation has many advantages when done with excellence in operations and maintenance. This article is based on my presentation to the EPRI Heat-Rate Conference last week and it is written for experienced electric power generation professionals, thus this is somewhat technical. The purpose is to show both the importance of coal power and to highlight some of the opportunities to improve coal plant thermal performance.

First, Apply the Fundamentals!

Our approach to coal plant performance improvement has always been: First apply the fundamentals which we refer to as the 13 Essentials for Optimum Combustion and the 22 Boiler Controllable Heat-Rate Variables. More on these later. After these have been applied, then consider modifications and upgrades of bottlenecking components.

The charts of coal use in the world below highlight the absolute importance of coal power as a major source of primary energy. Paraphrasing Mark Twain’s comment on seeing his Obituary, and applying it to coal: “The reporting of the demise of coal has been greatly exaggerated”...

Coal Remains Vital as a Source of American Primary Energy

Some of us nuts and bolts practical engineers knew the importance for coal fuel to meet the demand of last week’s winter storm. The U.S. Grid Dashboard helped document that need. However, this seems new to many academics and government policy makers.

In fact, here is the U.S. electricity generation by fuel for January 30^th. Note that coal is shown generating 128,526 MW. This is about 22% of the total generation. During this cold period, this is a very important 22% of Dispatchable and affordable generation.

Coal powered well over 60% of the low country of South Carolina last week. To be fair, SCPSA owns about 322 MW of Summer nuclear plant and that power is not shown on the display below. Like many areas of the U.S. coal, nuclear and gas provided over 80% of the total electricity generation.

The chart below is a screenshot of MISOENERGY. For this region, coal was over 39% during winter storm Fern.

Coal literally saved the Grid during winter storm Fern. And, nearly all of the expert forecasts of electricity Demand show about 100,000 MW of new generation needed by 2030. So, my question is, why aren’t new base load coal plants under construction right now?

The charts above show the importance of coal as recent as last week. However, the Deep State Bureaucrats, NGOs. state Legislatures and much of the public still resist facing the energy reality that coal offers many advantages for at least the next two decades. Well, let’s move on to getting the best performance from the existing coal fleet by first, applying the fundamentals!

Getting the Inputs Right

Achieving excellence in operating a coal plant takes hard work and vigilance of paying attention to the details. Rankine plants are tough, resilient and forgiving but when attention is paid to the details it can make a huge difference in heat rate. Here is a typical spread of plant efficiencies as performed by an NETL study. 

This is old timey data but, in my experience, it represents the spread between the Best Run and those that are run with Mediocrity. The chart below is from Electric Light and Power, Nov./Dec. 2014. This shows the top 20 Rankine Cycle coal plans for the year 2013. Net Heat-Rate for that year. Excellence in O&M as well as design. Notice, Turk Plant at the top of the list. More on Turk later.

I  coauthored an article in POWER Magazine with Dr. Robert Peltier entitled, “How Stealth Losses in Combustion Can Lower Efficiency”. This article was based on experiences and proven results. It has been shown that by excellence in O&M, Heat-Rates can be influenced by as much as 1,200 BTU/kWh. Later a couple examples will be shown where the magnitude of 500 BTUs/kWh in Heat-Rate improvements were achieved by applying the 13 Essentials and the 22 Boiler Controllable Variables. This was accomplished by testing to identify the opportunities and then correcting them. Most of the improvements have been through optimizing primary airflow, improving coal fineness, correcting air in-leakage and reducing upper furnace exit gas temperatures (FEGT). The reduced FEGT then improves thermal performance by reducing S.H. and R.H. de-superheating spray water flow and reducing cycle losses from soot blowing.

Getting the Inputs Right!

The first step to optimizing combustion and heat rate, is to apply the 13 Essentials. All 13 are important, but nine of the 13 are pulverizer, fuel and fuel line related.  This list of 13 essentials is the best and most important single document for optimizing combustion on a large PC Fired Utility Boiler. I am dead serious. These are NOT optional for a pulverized coal fueled boiler.

Some of the most common opportunities for improvement that we have found and then corrected for mechanical tuning with great results are:

• Pulverized coal fineness
• High Primary Airflow
• High FEGT due to secondary combustion
• Air In-Leakage
• Air Heater Leakage
• Fuel line imbalance
• Secondary air imbalance
• Burner tuning optimization

I know that there are other combustion tuning and controls manufacturers believe that airflow management to different zones of the furnace is not important, However, it is our experience that airflow management is in fact, crucial. We know from experience that these do work very well and where we have implemented the 13 Essentials they have always created a positive result for improved efficiency, reduced slagging, less tube metal overheating, best NOx performance, improved ESP (Electrostatic Precipitator) performance and more.

The correction of these individual items then complement each other to provide synergy which compounds the improvements. Such as: Reducing high primary airflows will usually result in better fineness, lower flyash carbon in ash losses, reduced upper furnace gas temperatures (FEGT), reduced sootblowing, less de-superheating spray water flows and reduced dry gas losses as a result of lowered tempering air flows. When all 13 Essentials have been earnestly applied and the O&M Team bought in on constantly maintaining them with vigilance, good RESULTS have been achieved. I will provide a couple examples later in this discussion.

The potential improvements and the synergism between them is shown on the chart below to show how about 600 BTUs/kWh in Heat-Rate can be achieved by focusing on boiler and combustion optimization. The data and examples shown have been proven in full size coal power plants and in at least one complete Utility that adopted the approach over a several year period.

Here is a figure which shows several of the most important “Essentials” of optimum combustion. Key to best coal fineness, best airheater “X” Ratio, fuel balance and good reliability is, a repeatable and optimized Primary air curve. An example of a preferred primary airflow ramp is shown below.

Pulverizer performance is important and it has been our experience, that unless pulverizers are undersized, the fineness and fuel distribution can be corrected to within the parameters of 75% passing 200 mesh and 1.8 #air/#fuel and +/- 10% Fuel line balance. Truly, the pulverizers are the heart of a PC fired boiler.

One of the simplest tests to ascertain whether high carbon in ash is due to combustion issues or pulverizer performance is to run a three-part flyash carbon in ash test. First, obtain a representative ash sample and pass a measured quantity through a 200 mesh sieve. Then measure the LOI (Loss on Ignition) of the coarse and fine particles. If most of the carbon loss is in the coarse particles, then the high loss due to carbon in ash is pulverizer performance related. If high LOI in the fine particles, then fuel balancing, air balancing or high post combustion air in-leakage is the problem. I am not one to promote shortcuts, but this is an easy test to conduct and it is very informative with regard to combustion performance and pulverizer performance. However, the flyash sample MUST be Representative!

Stealth Heat-Rate Losses

Stealth heat rate losses are those losses in Rankine Cycle efficiency due to controllable losses, some are located at the Boiler Island. Here is a list of 22 Controllable Losses that are controllable by optimization of the steam generator and combustion system performance.

Application of these practical steps have been accomplished on numerous single units and on several total utility systems. All Utility boiler furnace exit gas temperatures should be in the range of 2,150 degrees F. to 2,,300 degrees F. Often, the first indication of a problem is in the use of an HVT probe with a 310 ss radiation shield and the metal and thermocouple literally melt. The melting temperature of 310 ss is about 2,600 degrees F.  The pre-requisite for achieving good furnace performance is to apply the 13 Essentials as covered above and when the are, lower FEGT’s are attainable. (FEGT=Furnace Exit Gas Temperature)

The stealth losses compound together because of poor furnace combustion, this leads to flame quenching, overheated S.H. and R.H. tube metals, high S.H. and R.H. spray water flows, higher exit gas loss, slagging and fouling, increased draft loss, increased sootblower operation and consequent cycle steam losses, increased fan horsepower and carbon in ash losses. These seemingly small, individual issues when corrected, compound to create significant heat rate improvements as will be shown later. Never underestimate the adverse impact of poor pulverizer performance on overall unit Heat-Rate!

High primary airflow contributes to poor coal fineness, higher FEGT, increased NOx, high metal temperatures in the S.H. and R.H., requires increased soot blower operation, fouls the convection pass, air heater and SCR and much more. High primary airflows are very commonly found by our test teams. One of the most frequent opportunities for improvement.

Non-optimized combustion then creates Rankine cycle Thermodynamic losses through increased de-superheating water spray flows. The R.H. sprays are particularly harmful to Heat-Rate.

Case Studies of Large Utility Steam Generator Successes

Here is an example of a 450 MW 2400 psi/1000/1000 unit which has a design best heat rate of about 9,200 Btus/kWh. In this case study the 13 essentials were applied but these alone did not correct the high FEGT. To correct secondary air imbalances windbox baffles and perforated plates were installed in the burner inlets. These secondary airflow system changes corrected secondary air maldistribution. The result was about a 300-500 Btu/kWh heat rate improvement. 

However, the largest economic gain came from improved fuel flexibility where lower cost coal with a lower fusion temperature could be burned and this provided better generation economics and increased load factor operation, which also helped to achieve a better heat rate from the increased operational hours at higher loads.

The next case study is a 600 MW class 2400/1000/1000 unit in northern Kentucky. The heat rate was about 1,000 Btu above achievable. Again, first step was the application of the 13 essentials for combustion optimization. But also, a very effective team effort was organized by the plant manager to place priority on all of the heat rate factors on the steam generator and all of the balance of plant. Including the condenser cleaning and cooling tower fill corrections.

The results of the coordinated efforts of the operations and maintenance team plus the heat-rate engineer and Storm Technologies testing, resulted in a step change in heat rate improvement of about 800 Btus/kWh. The primary pre-requisite for this success was TEAMWORK! All of the O&M Team bought in on the approach and the end result was extremely gratifying to all.

The main factors in this unit’s success were: Pulverizer optimization, fuel balancing, optimized primary airflow program (reduced PA flows), secondary air balancing, correcting air in leakage, correction of cooling tower fill problems, reducing secondary combustion, reduced high spray flows, reduced soot blower operation, reduced air preheater leakage and reduced system losses. 

The typical opportunities that are found are worth about 600 Btus/kWh in heat rate improvement. Here is a breakdown of where these opportunities are typically found:

A frequently found opportunity is air in-leakage. Especially on older boilers.  Any air that enters the boiler setting without passing through the air preheater, constitutes a Dry Gas Loss. Also, if it is large enough, can contribute to secondary combustion due to low furnace oxygen content, upper furnace secondary combustion and high FEGT’s. 

The air preheater is the last heat trap on 99% of all the coal plants we have worked. Improving the performance or ultimately replacing the air preheaters with newer, reduced leakage and higher efficiency preheaters can drastically improve overall unit performance.

For older plants and especially those that have poor performing air preheaters such as the Rothemuhle type, then installing an upgraded new air preheater can provide a step change in improved performance. 
It is my hope that New Source Review and any other restrictive Regulations against modifications to improve performance are gone forever. 

Another upgrade option is to change the superheater and/or Reheater surface areas for optimum steam temperatures and overall performance. Also, possible changes in tube lane spacing, sootblower lane erosion protection and upgraded higher alloy tubing.

America’s last new coal plants went into service over a dozen years ago. Three of the newest and highest efficiency units are Duke’s Cliffside, AEP’s Turk and Kansas City Gas and Electric’sIatan. All of these are supercritical and capable of heat rates of about 8,300-9,000 Btus/kWh. About 38-41% thermal efficiency. https://www.powermag.com/plant-of-the-yearkcpls-iatan-2-earns-powers-highest-honor/
The Europeans, Japanese and Americans advanced the state of the art for Rankine cycle plants to approach 42% thermal efficiency. These improvements were in steam turbines, steam generator design and metallurgy. Then, we stopped building coal plants. The Chinese, on the other hand, had the advantage of applying all of the improvements that the west had achieved and then they kept on working to advance the state of the art even further. Indeed they have approached 50% thermal efficiency with their coal plant designs.  However, the Chinese plant Heat-Rates are reported on a fuel LHV basis. To be a fair comparison to the Best units in America, such as Turk or Cliffside the efficiencies should be based on the fuel HHV. These Chinese units (and Turk and Cliffside)  have been featured in Power Magazine.

The American advancement of coal plant design in the modern age, for the best thermal efficiency possible, began with the Eddystone Unit # 1 designed in the 1950’s.

Quest for Improved Thermal Efficiency

In my personal experiences, I began my career in the power industry in 1962. This is when Philadelphia Electric’s Eddystone Station was new. Eddystone started up in 1960. At that time, this was the most efficient power plant in the world. Steam conditions were at throttle pres. 5,000 psi 1,250 degree Superheat and two stages of Reheating at 1,050 degrees F. The design Heat-Rate from 1950’s technology was 8230 Btu/kWh or 41% thermal efficiency.  Since that time, America’s coal fleet has held pretty steady for the “Best” coal plants. Eddystone was the “Best” in 1960 at 41% Thermal efficiency. The most recent U.S. Ultra-supercritical plants, Turk, Cliffside and Iatan are capable of about the same efficiency as Eddystone was. However, I should mention that today’s clean coal plants use much more auxiliary power to drive the Flue Gas Cleanup equipment. FGD, SCR, ESP’s, Baghouses etc. These were not yet invented when Eddystone started up and therefore were not installed at Eddystone. For new plants such as Turk to achieve similar thermal performance with the backend environmental cleanup gear represents a true advancement in the state of the art.

The above chart shows the Thermal Efficiency progress of heat engines, since the days of Edison, Tesla and Westinghouse. As can be seen on the chart, the U.S. gas turbine fleet has progressed amazingly well and has reached design capabilities of over 60% thermal efficiency.

At the end of my EPRI presentation I showed the POWER Magazine information on the Chinese Pingsham, Phase ll coal plant that is advertised as being nearly 50% efficient. This is based on steam conditions of 4500 psi 1100 degrees F. steam temperatures with two stages of Reheat at 1100 degrees F. (close to Eddystone #1)
The EPRI Heat-Rate Conference is a technical meeting and the people in attendance are very sharp. It was quickly pointed out that the efficiency attributed to Pingsham ll of 49+% is based on fuel LHV and not HHV. Thus, the performance of Pingsham is just a couple points above the AEP Turk Plant in Arkansas. The John Turk Ultra-Supercritical coal plant went into operation in 2012 and is about 39% efficient. The steam conditions at Turk are: 3500psi throttle, 1100 degree S.H. and 1100 degree Reheat. Design Heat-Rate of Turk is 8730 Btus/kWh (39% Thermal efficiency)

My point is, the Chinese have taken advantage of all of the engineering and operational experiences gained in the U.S. and built on U.S. experience and knowledge to provide further advancements. Even though modest, the newest Chinese coal plants are more efficient than the U.S. newest coal plants. The Turk coal plant was started up in 2012 and only one other since then.  Duke Cliffside #6, 2013, which is similar overall efficiency as Turk. Another outstanding coal plant of high efficiency, built around the same time is the Prairie States Plant in Illinois.
Another point is the fact that the EPA restricted efficiency improvements for about 30 years. That is, if a U.S. coal plant implemented improvements to increase efficiency, they would be severely penalized. Now, with an energy friendly administration, the EPA “New Source Review” Rule, should not be a deterrent to implementing performance and even capacity improvements. In my view, the existing U.S. coal fleet should be capable of being upgraded in capacity, reliability, fuel flexibility and efficiency. In my Power Magazine article published in 2010, I showed several examples of plants that could be improved with new S.H. surfaces, larger fans, upgraded pulverizers and modifications such as these.

The Demise of Coal Has Been Drastically Exaggerated

Borrowing Mark Twain’s quote on the premature posting of his obituary, coal is needed, it is being widely utilized and it will not be easily replaced as a form of primary energy. Here below is a chart of electricity generation 2000-2023 from the G-20 nations presented by EPRI. Electricity generation from all fuels has steadily increased and will accelerate the electricity growth during the next 20 years.

As mentioned above, the U.S. worked hard at advancing thermal power generation efficiency. Gas turbines and combined cycle plants have made great progress. However, the war on coal stopped American progress for improving coal plant efficiency which effectively stopped in 2012. On the other hand, China continued to improve coal plant efficiency. Here below is one example of applied excellence in obtaining coal plant efficiency. I should point out that the 49+% Thermal Efficiency is based on the fuel LHV. Still, a commendable effort and results to achieve overall thermal performance in the high 40’s% is the Best I am aware of.

Coal: America’s Treasure of Primary Energy, Why Not Use it?

Coal power has at least a dozen solid advantages for electricity generation. Winter Storm Fern during the week of January 30, 2026 proved the importance and resiliency of coal plants. Even older plants that have not had the optimal maintenance once practiced. For reference, here is my list of the top dozen reasons that coal power is important.

Another important reason for new coal plants is that to provide the future demand in electricity growth, it is the most viable sources of primary energy to be utilized. I wrote on this before here and here. The electricity growth forecasts all show increases of about 100 GW needed by 2030 and about 800 GW by 2050. This is a lot of power and not easily built in 25 years. For example, the Roxboro coal generating station is four units and is capable of about 2400 MW when it is in top condition. Here is a photo of Roxboro Generating Plant. The first unit started up in 1966 and the newest one about 14 years later. Over 16 years of duration from the first contract signing till the 4th and last unit became commercial. Picture building 40 plants like this in four years to achieve the needed 100 GW of new Dispatchable generation by 2030. We can hope and wish. Sadly, the limitations of the Supply-Chain of manufactured components and craftspersons make this an impossible task today.

So, what are the alternatives? Here is my view of what it will take. Nuclear is loved by everyone today. However, it took Southern Company about ten years to build Vogtle 3&4 which is about 2,200 MW of new Base Load capacity. This is a great plant, now the largest nuclear plant in the U.S., but building 14 of these each year just doesn’t seem plausible.

Conclusions

Thank you for reading this. There are numerous additional articles listed below in the references.

Yours very truly,

Dick Storm, Feb. 7, 2026

The words “Modifyand Upgrade” were dirty words with the EPA for about 30 years. Thanks to a misguided EPA the U.S. existing coal plants were forbidden to be upgraded in any way other than back end environmental emission equipment installation. Now, the EPA-NSR should no longer be a factor. References and for further reading:

1. POWER Magazine article on “Correcting Stealth Losses in Large Coal Power Stations”: https://www.powermag.com/how-stealth-combustion-losses-lower-plant-efficiency-part-1-the-problem/

2. Power Magazine, To Optimize Performance, Begin at the Pulverizers: https://www.powermag.com/to-optimize-performance-begin-at-the-pulverizers/

3. Power Magazine, Finessing Fuel Fineness: https://www.powermag.com/finessing-fuel-fineness/

4. Power Magazine, Managing Airflow to Optimize Performance:  https://www.powermag.com/managing-air-to-improve-combustion-efficiency/

5. Power Magazine, To Optimize Performance, Begin at the Pulverizers: https://www.powermag.com/to-optimize-performance-begin-at-the-pulverizers/

6. POWER Magazine, “What if New Source Review Was Repealed”: https://www.powermag.com/what-if-new-source-review-were-repealed/

7. Reasons Why New Coal Plants Should be Built in America: https://dickstormprobizblog.org/2026/01/28/one-hundred-twenty-quadrillion-btus-and-the-need-for-coal-to-provide-at-least-20-quads-of-americas-primary-energy-part-l/

8. Dick Storm blog on the advantages of Coal Power: https://powerfortheusa.com/2025/12/21/advantages-of-coal-fuel-for-electricity-generation/

9. Master Resource Blog: https://www.masterresource.org/heartland-institute/joe-bast-nyt-1999/

10. POWER Magazine article on Pingsham ll : https://www.powermag.com/chinas-pingshan-phase-ii-sets-new-bar-as-worlds-most-efficient-coal-power-plant/

11. ASME Engineering Milestone Historical review of Eddystone #1 325 MW Ultra-supercritical Power plant: https://www.asme.org/wwwasmeorg/media/resourcefiles/aboutasme/who%20we%20are/engineering%20history/landmarks/226-eddystone-station-unit.pdf

12. SWEPCO Fact Sheet on John Turk Plant: https://www.swepco.com/lib/docs/community/projects/TurkPowerPlantFactSheetrev3-21-13v3.pdf

13. POWER Magazine article on John Turk Coal Plant, 2013: https://www.powermag.com/aeps-john-w-turk-jr-power-plant-earns-powers-highest-honor/

14. POWER Magazine article on Iatan #2 Coal Plant, 2011: https://www.powermag.com/plant-of-the-yearkcpls-iatan-2-earns-powers-highest-honor/

15. POWER Magazine article on Duke Energy Cliffside Coal Plant:  https://www.powermag.com/cliffside-steam-station-unit-6-cliffside-north-carolina/

16. POWER Magazine, Top Plant, Prairie State Top Plant 2013: https://www.powermag.com/prairie-state-energy-campus-washington-county-illinois/

17 . Thomas J. Shepstone on Substack which Published article on the Enormity of 100 Quadrillion BTUs: https://open.substack.com/pub/energysecurityfreedom/p/the-enormity-of-100-quadrillion-btus?utm_campaign=post-expanded-share&utm_medium=web

18. Stu Turley, Energy News beat on Grid Risks, Feb. , 2026: https://theenergynewsbeat.substack.com/cp/186686693

19. EPA New Source Review settlements: https://www.gem.wiki/EPA_Coal_Plant_Settlements

20. EPA Settlements on NSR violations by WEPCO 2003: https://www.epa.gov/enforcement/wisconsin-electric-power-company-wepco-clean-air-act-civil-settlement 

21. Dissertation on the Sierra Club Success of Beyond Coal Campaign 2020: https://www.proquest.com/openview/b734be1b4fa402463fbb2ee03a7993e5/1?pq-origsite=gscholar&cbl=18750&diss=y

22. Inside the War on Coal Politico, The Agenda 2015: https://www.politico.com/agenda/story/2015/05/inside-war-on-coal-000002/