ELK POINT, S.D. -- Methane emissions from the Hyperion Energy Center would be nearly twice as great as a previous estimate, developers of the proposed oil refinery and power plant in rural Union County have told state regulators.
Hyperion Refining now projects the energy center to annually emit 979 tons of methane, a greenhouse gas, up from 498 tons the company projected in an October filing with the South Dakota Department of Environment and Natural Resources.
The revision came after the Texas-based company adding data from the refinery's coking units, which would turn a refinery byproduct into hydrogen, steam and electricity to power the refinery.
In its 54-page filing with the DENR in October, the company "inadvertently omitted the coke drum steam vents," which are a potential source of methane emissions, Hyperion project manager Colin Campbell said in a letter posted on the DENR website this week.
Methane, an odorless gas, is considered a more potent greenhouse gas, trapping heat in the atmosphere at a rate 20 times greater than CO2 over a 100-year period, according to the U.S. Environmental Protection Agency.
The greenhouse gas analysis was conducted for Hyperion by RTP Environmental Associates, a Raleigh, N.C.-based environmental consulting firm.
Hyperion spokesman Eric Williams noted Thursday the latest revisions only marginally increases the energy center's projected carbon dioxide equivalent emissions, from 16.93 million tons to 16.94 million tons annually.
"I calculate that on a CO2e basis, the increase is 0.06 percent, and if calculated on a mass basis (not as C02e), the increase is 0.003 percent," Williams said in an email.
Kirk Rombough, an air quality engineer for the DENR, said Hyperion brought the omission of the coke drum steam vents to the agency's attention.
The most recent filing is the latest chapter in Hyperion's bid to obtain a state air quality permit required to construct its $10 billion refinery just north of Elk Point.
The state Board of Minerals and Environment approved the permit on Aug. 20, 2009, but the Sierra Club and two local groups, Save Union County and Citizens Opposed to Oil Pollution, quickly filed a lawsuit seeking to overturn the decision on the grounds that it violates the federal Clean Air Act and other environmental rules. Hyperion also filed its own, more limited, appeal, asking that the board's decision on a carbon monoxide limit be overturned.
In June, a 6th Circuit Court judge put the appeal on hold and granted Hyperion's request to reopen the permitting in order to delay the required start of construction by 18 months, from February to August 2012. During the delay, the company amended its design and application to reflect various EPA rules adopted after the air permit was approved.
Most notably, the EPA adopted new regulations under the Clean Air Act that require refineries, power plants and factories that emit at least 100,000 tons of greenhouse gases annually to use best available technology to control the emissions.
Hyperion had argued it would not be subject to the "tailoring rules,'' which are scheduled to take effect Jan. 2, because the state board had earlier approved its air permit.
South Dakota is among the states challenging the EPA's greenhouse gas rules. Rombough referred addition questions about the legal challenge to the state's attorney genearl's office.
Rombough said DENR staff is still reviewing Hyperion's amended application for its air permit. The agency will be required to take additional public comments. It's uncertain how soon the Board of Minerals and Environment will take up the issue again, he said.
The air permit is among a number of permits and approvals Hyperion needs to start construction on the refinery, which would turn 400,000 barrels of Canadian tar sands per day into low-sulfur gasoline, diesel fuel and jet fuel.
Despite the regulatory delays, Hyperion has insisted it will maintain its current construction timeline for the energy center, which would be built on a 3,292-acre site just north of Elk Point in Union County.
The largest project in Siouxland history would create an average of 4,500 construction jobs over four years, and around 1,800 permanent jobs.