January 10, 2017 at 3:00 PM
This story has been updated.
The first large scale U.S. "clean coal" facility was declared operational Tuesday — by the large energy firm NRG Energy and JX Nippon Oil & Gas Exploration Corp.
Their Petra Nova project, not far outside of Houston, captured carbon dioxide from the process of coal combustion for the first time in September, and has now piped 100,000 tons of it from the plant to the West Ranch oil field 80 miles away, where the carbon dioxide is used to force additional oil from the ground. The companies say that the plant can capture over 90 percent of the carbon dioxide released from the equivalent of a 240 megawatt, or million watt, coal unit, which translates into 5,000 tons of carbon dioxide per day or over 1 million tons per year. They're calling it "the world's largest post-combustion carbon capture system."
"There are not many coal plants that are being built these days," said Mauricio Gutierrez, the president and CEO of NRG. "We think that actually having an experience in installing a [carbon capture and storage] technology in existing coal plants will have a pretty significant application in the current plants that exist throughout the country, and for that matter, throughout the world."
But there is another coal plant near completion in the United States that will also capture carbon dioxide — but using a very different approach. It's the Kemper Plant, being operated by Mississippi Power, a subsidiary of Southern Co., and expected to be operational Jan. 31. This plant has been designed to turn lignite, a type of coal, into a gas called syngas, stripping out some carbon dioxide in the process. The syngas is burned for electricity and the CO2 is then again shipped to an oil field to aid in additional oil recovery.
Thus, at Petra Nova the capturing of carbon occurs after the coal has been burned — or "post-combustion" — whereas at Kemper, it happens beforehand.
The arrival of Petra Nova and Kemper comes as the incoming Trump administration will have to try to deliver on sweeping promises made to the struggling coal industry. It remains unclear if that will involve any type of support for carbon capture technology or for the industry, but Trump did allude to "clean coal" while campaigning.
The two very different plants together mark the arrival of a technology, often called "CCS" for short, that has been heralded as essential to the future of coal burning in particular (though it has many other applications), but has struggled despite considerable subsidies from the U.S. Department of Energy. Several projects have seen their Energy Department funding withdrawn, but these two now stand at or near the finish line.
According to the Global CCS Institute, which tracks this fledgling industry, there are 21 carbon capture projects worldwide on a large scale that are either operating or have been built, but relatively few of these are in the power generation sector — making Petra Nova and Kemper quite novel in context of the United States. In Canada, the Boundary Dam Carbon Capture and Storage Project, also a "post-combustion" capture plant using coal, has been operational since 2014.
The Energy Department provided grants totaling $ 190 million to the Petra Nova facility, which cost $1 billion overall. Kemper is a considerably more expensive project, representing a $6.91 billion expenditure for a massive plant with a capacity of 582 megawatts. That includes $270 million in support from the Energy Department, also as part of its Clean Coal Power Initiative.
The Department hailed the news Tuesday. "As the world's largest post-combustion carbon capture system, the Petra Nova project confirms that carbon capture and storage technologies can play a critical role in ensuring the nation's energy security and providing good jobs for American workers, all while helping us reduce carbon emissions from coal-fired power plants," said Christopher Smith, Assistant Secretary for Fossil Energy, in a statement.
For Petra Nova, a key part of the operation of the plant involves its pairing of power generation with oil recovery. Carbon dioxide injected into the oil field will increase its production, and with oil prices at $50 a barrel or higher, the plant is economical, according to NRG spokesman David Knox. Some of the carbon dioxide then remains sequestered in the oil field after the enhanced oil recovery process.
The plant's completion is a milestone, says Gutierrez, and a doorway into a wider world of using carbon capture and storage. "I think in the future, this is a technology that is going to be necessary for gas units, as natural gas becomes this bridge fuel," he said.
Furthermore, Gutierrez said, while the Petra Nova plant is paired with an oil field to help make it economical, that may not always be so with future projects. "We really chose the enhanced oil recovery to improve the economics of the plant to the extent that there is not a price on carbon," he said. "Potentially that is not necessary to make the economics work."
The company does not have any immediate plans to adapt a second coal plant with carbon capture technology, but Gutierrez said that if it wanted to do so, the know-how gained at Petra Nova would make the second plant cheaper.
The International Energy Agency and the United Nations Intergovernmental Panel on Climate Change have both said that carbon capture and storage will be a necessary technology to curb humanity's greenhouse gas emissions.
"Any country that is in need to increase their power generation, and that is happening through fossil fuels, they will be looking at this technology as a way to mitigate the impact of carbon," said Gutierrez.
Read more at Energy & Environment: