The U.S. Environmental Protection Agency has approved revisions to an Arkansas regional haze plan that aligns with a pending court settlement over the fate of two Entergy Arkansas LLC coal plants headed for retirement.
The approved revisions, announced by the EPA on Sept. 10, exempt the Entergy Corp. subsidiary's 1,639-MW White Bluff and 1,657-MW Independence plants from installing additional pollution control equipment required by an Obama-era federal implementation plan, or FIP.
Under the Clean Air Act's regional haze program, which is designed to improve visibility in 156 national parks and wilderness areas, states were first required to submit compliance plans in 2007. Comprehensive periodic revisions to those initial plans are due in 2021, 2028 and every 10 years thereafter.
In determining what is known as the "best available retrofit technology" to control haze-forming emissions, the Clean Air Act allows states to consider five factors when developing SIPs: compliance costs, energy and non-air quality environmental impacts, existing pollution controls at a source, a facility's remaining useful life, and potential visibility gains.
In 2012, the Obama administration disapproved parts of a SIP submitted by the Arkansas Department of Environmental Quality covering the regional haze program's first compliance period. Arkansas' plan must include measures to improve four wilderness areas: the Upper Buffalo River and Caney Creek, which are both in that state, and the Hercules Glades and Mingo National Wildlife Refuge in Missouri.
The Obama EPA subsequently issued a FIP in September 2016 addressing the disapproved portions of the state plan. Over Entergy Arkansas' objections, the federal plan required sulfur dioxide, or SO2, and nitrogen dioxide, or NOx, controls at Independence Units 1 and 2. The federal plan also set emissions limits that effectively required SO2 controls at White Bluff Units 1 and 2.
At the time, the EPA estimated that its FIP would achieve annual SO2 emissions reductions of approximately 21,000 tons per year more than Entergy Arkansas' alternative proposal of burning low-sulfur coal at those four units.
Entergy Arkansas petitioned the EPA to reconsider the FIP after it was finalized, asserting that the plan would impose $2 billion in compliance costs in exchange for minimal visibility benefits.
After considering the company's request, the Trump administration in April 2017 stayed the emission control requirements established in the Obama-era FIP. In January 2018, the Trump EPA approved an initial round of SIP revisions submitted by the Arkansas Department of Environmental Quality primarily dealing with how the state planned to control NOx emissions to reduce regional haze.
Meanwhile, following extensive negotiations, Entergy Arkansas in November 2018 reached a settlement with the Sierra Club and the National Parks Conservation Association pursuant to which the advocacy groups agreed to drop a long-running Clean Air Act lawsuit against the utility. As part of the agreement, Entergy agreed to stop using coal entirely at White Bluff by the end of 2028 and at Independence by the end of 2030.
That agreement is still pending before an Arkansas federal judge. But the state's Republican attorney general, Leslie Rutledge, moved to intervene in the case and asked for a court order directing the Arkansas Public Service Commission to investigate the deal.
An Entergy spokeswoman said Sept. 11 that the EPA's latest round of SIP approvals for the state lines up with the provisions of the pending consent agreement, which also would not require the White Bluff or Independence plants to install additional controls in exchange for further clean energy investments.
"The plan is consistent with Entergy Arkansas' ongoing strategy to transform the company's generation portfolio to better meet customers' needs today and in the future with cleaner, highly efficient resources of electricity," spokeswoman Kerri Case said in an email.
The consent agreement calls for the utility, starting no later than the end of June 2021, to use only low-sulfur coal at the White Bluff and Independence plants. Its provisions also call for retiring the 528-MW Lake Catherine gas plant by the end of 2027 along with developing 800 MW of renewable energy projects. At least half of that renewable capacity must come online by the end of 2022 and the remainder by the end of 2027.
