Dive Brief:

• A report funded by the Advanced Energy Economy Institute and the American Wind Energy Association concluded the United States' power mix is changing, largely due to cheaper natural gas, flat demand and more efficient generation.
• And while the shift has forced a significant amount of coal-fired generation offline, the Analysis Group's research concludes the transition to a cleaner mix of fuels is not harming the reliability of the power grid.
• The new analysis comes ahead of a similar study the U.S. Department of Energy is expected to release this month, addressing whether clean energy policies are forcing coal and nuclear plants offline and threatening power reliability.

Dive Insight: 

There's been some concern that DOE's study of the power grid may be weighted towards fossil fuels, given President Trump's many statements about bringing back the coal industry. So it's fair to point out the results of the AWEA and AEE-funded study are not particularly surprising.

Fundamentally, the report concludes the addition of highly efficient new gas-fired resources, low natural gas prices, and flat demand for electricity "are primarily responsible for altering the profitability of many older merchant generating assets in the parts of the country with wholesale competitive markets administered by Regional Transmission Organizations."

The end result has been retirement of some plants — many coal-fired facilities, but also some gas and nuclear generators.

The report identifies an array of other factors: newer energy technologies with falling costs, while state policies and consumer preference "also contribute to reducing the profitability of less economic assets."

In the last two decades, utilities have announced more than 100 GW of coal generation retirements, and they now make up the bulk of plants being pulled offline. In 2015, coal accounted for 80% of the nearly 14 GW taken offline, but nuclear plants and even some gas generators have felt the pressure.

But Analysis Group concluded power systems are becoming more fuel-diverse thanks to the addition of newer gas and renewable technologies and an array of advanced energy technologies, including frequency and voltage management, ramping and load following capabilities, and others.

"Increasing quantities of natural gas and renewable generation are increasing the diversity of the power system and supporting continued reliable operations," the report concludes.

The report's results mirror the conclusions of a number of independent studies performed by national laboratories and regional grid operators. 

"Coal is now largely irrelevant in New England," ISO-NE CEO Gordon van Welie, recently told E&E News. "How do we maintain resilience in New England if we don't have coal and everyone else says we need coal to maintain resilience? That just doesn't compute for me."