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What is the plan?

U.S. EPA's Clean Power Plan was expected to reduce carbon dioxide emissions from power plants 32 percent below 2005 levels by 2030.

For each state, the rule established a target emissions rate, or the amount of carbon dioxide that could be emitted per megawatt-hour of power produced.

The emissions rate reductions required of states ranged from 7 percent in Connecticut to 47 percent in Montana. (Alaska, Hawaii, Guam and Puerto Rico were excluded from the rule because they are noncontiguous. Vermont and Washington, D.C., were excluded because they don't have power plants that would be considered under EPA's framework.) The percentages represented how much states would have to reduce their power fleet emissions rates below 2012 levels.

States originally were expected to submit final carbon-cutting plans or initial plans with two-year extension requests by Sept. 6, 2016.

They were expected to start working toward interim emissions goals beginning in 2022 and meet final goals in 2030 and beyond.

How did EPA set state goals?

EPA looked at three "building blocks," or carbon-cutting measures that states in three different regions could use. The agency used the building blocks as the "best system of emissions reduction" to determine what the power system could "reasonably" do to cut CO2.

The building blocks: operating coal plants more efficiently and burning less coal, running existing gas plants more often in place of coal, and ramping up renewable power. States aren't required to use the building blocks.

To set state goals, EPA looked at how much power states got from coal and natural gas. The agency applied the building blocks to the average emissions rates for those plants to determine what carbon cuts to request of generators.

What were the technical requirements of the rule?

States first would decide whether to pursue rate-based or mass-based plans.

A rate-based plan would require the power fleet to adhere to an average amount of carbon per unit of power produced. A mass-based plan would cap the total tons of carbon the state's power sector could emit each year.

Both types of plans could involve trading programs, in which generators could purchase credits from entities inside or outside their state to offset carbon emissions from coal plants.

States that refused to comply with the rule or submitted inadequate plans would be subject to a federal plan, which the Obama administration's EPA never finalized. That federal plan would likely assign goals to power generators and call on them to use carbon trading to comply.

Last updated on March 29, 2017 at 11:46 AM

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