There’s a good chance you heard that the EPA changed their coal power plant environmental regulations this week. Here’s a quick summary of what those changes are.

The story starts in 2013 when the EPA (under the Obama Administration) issued regulations that applied to new coal fired electricity generation plants.  The rules were called “New Source Performance Standard” or “NSPS.”

The NSPS required that any new generation units fueled by natural gas meet a limit of 1,000 pounds of CO2 per megawatt-hour and allowing new coal plants to emit 1,100 pounds of CO2 emissions per megawatt-hour of electricity generated.  The coal industry didn’t like the rule because the most advanced coal-fired power plants emit 1,700 pounds per megawatt-hour.
The EPA then issued a 2nd rulemaking in 2015 with the “Existing Source Performance Standard” or “ESPS” Rules.  The ESPS rule aimed to reduce overall emissions of CO2 from the nation’s power sector by 32% from 2012 to 2030. Under the 2015 rules, existing coal plants would have had to comply with a 1,300 pounds of carbon per megawatt hour standard (this irritated the industry because the best plants can only achieve 1,700 lbs per megawatt hour).

The U.S. Chamber Litigation Center filed a lawsuit challenging the EPA’s 2015 rules and the US Supreme Court issued a stay on the rules which halted implementation of those 2015 ESPS rules. 

This week the EPA repealed and replaced the ESPS rules (for existing plants) with what they call the Affordable Clean Energy (ACE) rule- which essentially gives states three years to create their own plans to cut emissions at existing plants mainly by encouraging coal-fired power plants to improve their efficiency. The old carbon standards were eliminated. 

The new rules set some guidelines for states to develop performance standards for power plants that boost the amount of power produced per ton of carbon. The original draft proposal would have allowed new coal plants to skip the federal permitting process and use the new “ACE” process, but that was dropped from the final ACE rule.

Arizona has 5 coal burning plants: the Apache Generating Station (Cochise County), the Cholla Power Plant (Navajo County), the Coronado Generating Station (Apache County), the Navajo Generating Station (Apache County & closing later this year), and the Springerville Generating Station in Apache County.  Under the new rules issued this week, these facilities will now be subject to state regulation via the new ACE standards- presumably by ADEQ.

Over the long run, the percentage of energy generation that comes from coal in the US will continue to decline because coal power generation  is simply more expensive than natural gas and solar and wind sources.

To look at the cost of generation for the various approaches you can visit this US Energy Information Administration Document which compares the capital, operational and transmission costs for various forms of energy generation-  and you’ll see that coal is way more expensive than natural gas, wind, and solar technologies.