John Kemp, Reuters

For political reasons, the Trump administration has become obsessed by saving old and inefficient coal-fired power plants rather than preparing the electricity industry to face the challenges of the future.

Senior officials appear to have an almost romantic attachment to the hard physical labor of the coal mines and saving existing coal-fired power plants, most of which are now more than 40 years old and wearing out.

At the Department of Energy, Secretary Rick Perry has proposed a grid resiliency rule which would increase payments to coal-fired power producers that can promise secure on-site fuel supplies.

And Environmental Protection Administration chief Scott Pruitt has announced his intention to repeal the Obama administration’s Clean Power Plan to try to keep coal-fired power plants running longer.

The Trump administration blames its predecessor for waging a war on coal and pushing hundreds of coal-fired power plants into premature retirement.

Trump officials have pledged to reverse the anti-coal drive, drawing predictable outrage from Democrats, climate campaigners and renewables advocates as well as allies of convenience in the natural gas and power industries.

But protecting the coal industry has assumed enormous symbolism out of all proportion to its economic importance.

Fewer than 100,000 people are now employed in coal mining, down from 250,000 in 1979 and about 1 million in 1920.

Coal miners make up less than 0.04% of non-farm employees in the U.S. And coal mining accounted for less than 0.3% of value added and domestic production in 2016, down from 0.7% in 1979 and 1.3% in 1949.

Coal accounted for 30 to 35% of U.S. electricity generation in 2015-2016 down from a peak of 57% in 1988.

Coal Closures

Trump administration officials complain the war on coal has forced early closure of hundreds of coal-fired power plants and jeopardized the future of many more, but nearly all of these plants would have closed anyway.

Between 2000 and 2016, more than 500 coal-fired power generating units were closed, according to an analysis of data from the U.S. Energy Information Administration. But most of these plants were very old and very small.

The average coal-fired generating unit that closed between 2000 and 2016 first began generating in the mid-1950s and was producing less than 100 megawatts (MW).

By contrast, the average coal-fired unit that has remained in service started generating in the mid-1970s and has an output of 200 to 250 MW. The average gas-fired combined-cycle plant already in service has an output of almost 150 MW and entered service as recently as 2002. And even more combined-cycle plants are under construction or planned for the next few years with a typical capacity of 250 MW.

Moreover, many of the coal-fired power plants which have retired were very inefficient.

The best coal-fired power plants had a thermal efficiency of about 38% but the worst were less than 28% efficient, according to a 2008 survey by the U.S. National Energy Technology Laboratory (NETL).

In other words, the worst-performing coal plants were turning just 28% of the energy actually contained in the fuel into electricity.

In 2015, even after many of the least-efficient units had retired, the average coal unit still achieved a thermal efficiency of just 34 percent compared with almost 45% for the average combined-cycle unit.

Even at the top end, the most modern ultra-supercritical coal-fired power plants can achieve efficiencies of 40 to 45%, but still trail below the most modern combined-cycle units which now get more than 60%.

Flexible Gas

As well as being more efficient, combined cycle plants are also more flexible and able to produce power at short notice and in varying amounts in response to changing demands on the electricity grid.

Gas-fired combined-cycle power plants can achieve synchronization and start feeding power into the grid within two to five minutes of receiving an instruction from grid controllers, even from a cold start.

By contrast, coal units need an hour and a half to achieve synchronization from a hot start and up to seven from a cold start.

After initial synchronization, combined-cycle units can reach full power output within 15 to 30 minutes, while coal units need 1 to 4 hours to reach full load.

Gas-fired combined-cycle units are better adapted to running as both baseload and two-shifting (operating only to meet the morning and evening peaks in electricity demand).

Combined-cycle units can provide all the ancillary services needed by the grid—including frequency regulation, voltage control, reactive power, stand-by reserves and black start—more flexibly than coal.

Design Life

The typical power plant is designed to operate for a minimum of 25 years without major modifications, though many operate for 40 years or more.

But the efficiency of coal-fired units, never very high to start with in the case of older plants, degrades over time.

Replacing old and worn out coal units with entirely new ultra-supercritical coal plants has proved uneconomic in almost all cases—gas plants are simply cheaper to build and run, and offer more flexibility.

The alternative is to extend the life of existing coal plants by replacing worn out components and upgrading them with new equipment to improve thermal efficiency.

There are well established technologies which can be retrofitted to existing coal plants to boost their thermal efficiency.

Installing coal pulverizers and new turbine blades, or upgrading the steam condenser, can all yield efficiency improvements ranging from a few tenths to about 2% each. But even after multiple, expensive, upgrades and retrofits, coal-fired power plants remain less efficient and less flexible than combined-cycle units.

Power Planning

The Trump administration and its supporters in the coal industry hope the grid resiliency rule and end of the Clean Power Plan will help support the remaining coal units. Even if no new coal-fired power plants are built, they hope regulatory changes will extend the life of those that are left.

But the average coal unit is now more than 40 years old and the cost of maintenance and upgrades will continue rising.

In most cases, power generators will likely continue closing coal units in favor of newer, cheaper, more efficient and more flexible combined-cycle gas. The reasons for the closures are primarily economic and have nothing to do with politics or views on climate change.

The Trump administration wants to put a thumb on the scale to save the coal plants, countering the thumb on the scale that the Obama administration used for renewables.

Support for the coal industry is an important way for the Trump administration to show it is keeping faith with its voters and delivering on promises made during the 2016 election campaign.

But in striving to keep the existing coal units in service, the Trump administration is trying to buck market forces and sustain an increasingly outdated technology.

The administration may be able to achieve a few small symbolic victories, but the history of energy shows market forces and technological change always win in the end.