The possible end of Southern Co.’s flagship "clean coal" project in Mississippi isn’t the death knell for carbon capture and sequestration technology, industry analysts say.
Instead, the problems at the Kemper County Energy Facility — which state regulators want to turn into a natural gas plant after years of delays and cost overruns — resulted from a unique series of events and a coal gasification system that was scaled up too fast.
The plant’s equipment to capture and store carbon dioxide didn’t cause its current challenges and is still an option for coal and other fossil fuels, said Erin Burns, a policy adviser in the clean energy program at Third Way, a centrist Democratic think tank.
"This is absolutely not the death of CCS," she said.
A string of CCS successes this year, including the launch of the world’s largest retrofit of a coal plant with carbon capture technology, make it clear the technology works, she said. Other large projects have opened in the Middle East and Illinois this year to trap CO2 from steel and ethanol manufacturing.
Still, both critics and boosters of making coal cleaner in a world worried about climate change have been looking to Kemper as a model for future development. For many, Kemper was at least part of the future of coal.
That’s why so many observers were shocked when on Wednesday the Mississippi Public Service Commission asked Southern Co. subsidiary Mississippi Power to find a settlement within 45 days that would abandon the Kemper plant’s coal and CCS operations (Energywire, June 22).
The PSC said it was seeking a solution that would "eliminate ratepayer risk for unproven technology." Under the framework, Kemper would operate solely on natural gas, a fuel that has already been running the plant for years.
In a statement, Mississippi Power emphasized that no final decisions have been made, and that discussions with the PSC are ongoing.
"The PSC provided several guidelines to consider for the negotiations, including the possibility of the project only operating as a natural gas-fueled combined cycle plant. We look forward to reviewing the order," the company said.
Kemper, with a price tag now around $7.5 billion, has been under construction since 2010. Developers envision gasifying lignite coal into synthetic gas and capturing 65 percent of the resulting CO2 emissions.
If fully operational, it would be the second U.S. coal plant to capture the majority of its carbon emissions, after NRG Energy Inc.’s Petra Nova project in Texas, which launched this year.
Most of the recent setbacks for Kemper centered around its two gasifiers, which turn lignite coal from a mine near the plant into synthetic gas.
In January 2016, for instance, Mississippi Power said one of the gasifiers got hotter than anticipated during testing, causing cracks in the lining. The plant has operated approximately 200 days on lignite, said the company.
What’s significant is that the gasifiers are separate from the carbon capture or "clean coal" portion of the plant, said John Thompson, director of the fossil transition project at the Clean Air Task Force.
The capture unit involves an antifreeze-like solvent called Selexol to strip CO2 that has been in use in other facilities since the 1960s.
"The capture equipment was actually the most mature part of this plant," Thompson said.
The same cost overruns and delays would have occurred even if Kemper had never tried to use CCS, he said, noting that coal gasification in general has been done successfully elsewhere with different technology.
In Mississippi, Southern was trying out its new transport integrated gasification (TRIG) technology, designed to be a model for gasifying "low-rank" lignite coals, which are common in countries like India.
Southern’s experience differed from others in the sense TRIG was not tested extensively at commercial scale before being tried at a power plant. The gasifier was used at a testing center, but at a size about one-hundredth that of Kemper.
"They went from the pilot plant level to, like, 600 megawatts. People at the time thought they were way too ambitious. And it’s been proven out," said Massachusetts Institute of Technology carbon capture expert Howard Herzog.
Kemper also ran into other issues not related to CCS, such as labor challenges and expiring Department of Energy grants. It didn’t help that a consistent drop in natural gas prices after the plant’s groundbreaking seven years ago made the idea of turning coal into gas less of a viable concept.
Kemper’s fate also may have been sealed before it ever broke ground. In an interview last year, Southern CEO Tom Fanning said the one thing he would change about the project was committing to a fixed price for customers with only 10 percent of the plant’s engineering work completed.
"If we had taken more time to do more engineering … we would have circumvented a lot of the problems that we incurred," Fanning said.
Critics of CCS have long said that Kemper was a huge waste of funds that could have been directed to other clean-energy solutions.
In a report last year, Friends of the Earth and Taxpayers for Common Sense said Kemper is "a stark reminder of why carbon capture and sequestration is a waste of our tax dollars and a false solution to the climate crisis."
Whether the plant’s woes will hurt support for CCS policy is an open question. Thompson and other CCS supporters say advancing carbon capture and putting new incentives in place for it is critical for climate change because of the world’s ongoing reliance on coal.
Supporters on Capitol Hill are pushing for an expansion of existing tax credits to provide more certainty to developers, among other incentives (E&E Daily, Dec. 6, 2016).
Problems for Southern
Kemper was a potential model in places like China, which has a lot of facilities that are gasifying coal to make chemicals and venting the CO2 into air, said Thompson.
But Petra Nova, which began operations on budget and on time, is perhaps the more relevant model for CCS because of its status as a retrofit, according to many analysts. That is especially relevant in the U.S., which is not building new coal plants, much less coal gasification plants.
While gasification has worked elsewhere, it has "totally soured" as a concept for the power sector, according to Herzog. You don’t need to gasify to do CCS, he said.
"Look at Petra Nova," he said. In addition to not gasifying coal, Petra Nova completed 90 percent of its conceptual design before it began construction.
Regardless of what Kemper may mean for CCS in general, it does mean a lot for Southern, which could be left with a CO2 pipeline, coal mine and gasifier system to nowhere in a natural-gas-only scenario.
Issues that have to be addressed include an existing contract with Denbury Resources Inc. to use Kemper’s CO2 in enhanced oil recovery.
The utility signed several memorandums of understanding in recent years to explore the use of its TRIG technology at overseas projects. In December 2015, for instance, Southern penned a letter of intent with a South Korean company to evaluate the deployment of TRIG at a new 1,000-MW power plant.
One thing that might not be an option if the plant becomes gas-only is use of the existing carbon capture infrastructure. Selexol typically is used when the CO2 concentration in flue gas is high, which is much more suited to coal than natural gas, according to Thompson.
He called for an investigation into all the factors that led to this point. "There really needs to be an analysis of what went wrong," Thompson said.