The deep freeze that tested the nation's electric grid this month will take center stage in the Senate this week as the energy committee probes how the grid performed during single-digit temperatures.

The Senate Energy and Natural Resources Committee's Tuesday hearing will feature Kevin McIntyre, the Republican head of the Federal Energy Regulatory Commission, testifying for the first time since taking the commission's helm in December.

It is also the first time McIntyre will be testifying before the Senate since he and his fellow four commissioners voted unanimously to reject Energy Secretary Rick Perry's plan to provide incentives for coal and nuclear power plants.

Perry wanted the commission to approve new regulations directing regional grid operators to give coal and nuclear power plants market-based subsidies. The incentives would reward the power plants for being able to maintain an adequate supply of fuel when the grid is stressed by extreme weather events such as the bomb cyclone.

Perry and his deputies, rather than express disappointment with FERC, have said they are encouraged that the commission, while rejecting the grid plan, has initiated a review of grid resilience.

The Energy Department has said the need to address grid reliability and resilience was punctuated by the two-week cold snap, which ended with the "bomb cyclone" snowstorm in the Northeast.

No Energy Department officials will testify at the hearing. Even though President Trump appointed McIntyre as FERC chairman, the commission is an independent agency and regulator. It is technically part of the Energy Department, but does not have to follow the directives of the administration.

Instead, McIntyre will be joined by the grid operators that his agency oversees and regulates, PJM Interconnection and the Midcontinent Independent System Operator.

Both grid operators reported that coal use soared during the cold snap in the Midwest and East Coast. Coal and nuclear were the top power sources during the freeze, while natural gas, the usual frontrunner, was third.

Coal provided about 40 percent of the electricity during the chill.

Senators also will hear from FERC's reliability watchdog, the North American Electric Reliability Corporation, which is in charge of monitoring grid reliability and enforcing standards to ensure against blackouts.

The committee also will get the environmentalist perspective at the hearing. Alison Clements, the head of the consulting firm Goodgrid, will be testifying.

Clements had been one of environmental groups' top FERC experts when she worked at the Natural Resources Defense Council and its offshoot, the Sustainable FERC Project. She focuses on how to advance clean energy through grid policy.

Clements told the Washington Examiner she wants to address what is causing the Energy Department and FERC to focus on grid resilience, which she said is climate change and the threat of a cyber or physical attack on the power system.

"I’m planning to talk about the importance of the issues causing the current focus on resilience – i.e., climate change and the threat of attack," Clements said in an email.

She also wants to make sure everyone is on the same page for the definition of resilience.

"I’m planning to make sure we are clear on the definition of resilience, which is the ability of the transmission and distribution systems to plan for, manage and mitigate, and recover from extreme disruptions," Clements said. "It is not a concept related to specific power technologies or fuel sources."

She says she does not believe that there needs to be federal standards, or "metrics," to ensure the grid is resilient. But she does think Congress should "support local and state resilience and emergency preparedness planning" while making sure FERC's policies remain "technology neutral."

McIntyre and his complement of four commissioners vowed to keep the nation's grid policy technology neutral on Thursday at their first public hearing since the rejection of the Perry grid plan.