I received a response from the author of the paper, Chi-Jen Yang:
I looked up the Dakota Gasification Company’s website. According to the website:
. Dakota Gas captures about 3 million tons of CO2 per year.
. As of Dec. 31, 2012, Dakota Gas has captured more than 24.5 million metric tons of CO2.
The Synfuels Plant captures more carbon dioxide (CO2) from coal conversion than any facility in the world, and is a participant in the world’s largest carbon sequestration project. Dakota Gas sends carbon dioxide through a 205-mile pipeline to Saskatchewan, Canada, where oil companies use it for enhanced oil recovery (EOR) operations that result in permanent CO2 geologic sequestration.
The language is a little bit ambiguous here. You must know that, not all EOR operations result in permanent CO2 geologic sequestration. In fact, it is cheaper for EOR operators to release the wasted CO2 into the air than sequestrate it underground. We know that Dakota Gas sell its CO2 for EOR, and at least some of them are sequestrated, but how much is unclear.
At 1.5 billion cubic meter annual capacity, assuming 90% utilization of capacity, Dakota Gas should produce roughly 1.35 billion cubic of methane per year. In SNG production, each cubic meter of SNG would emit roughly 16 kg of CO2. So Dakota Gas should produce roughly 21.6 million tons of CO2 per year. Roughly 3 million tons is captured, with unknown percentage sequestered underground. Let’s make it simple by assuming the unknown percentage is 100%. Then Dakota Gas would be sequestering about 14% of its annual CO2 emissions. Chinese SNG plant without carbon capture emits 7X CO2 as regular natural gas, which is a nightmare. Dakota’s SNG emits 6X CO2 as regular natural gas, making it a blessing? Really?
Let’s also look at it from a lifecycle perspective. The Dakota SNG plant has been operating for about 30 years. During the 30 years, it emitted roughly 648 million tons of CO2, among which 24.5 million tons were captured (sequestered?). In other word, roughly 3.8% of CO2 in the SNG plant’s first 30 years of life was captured. Chinese SNG plant emitting 100% of its CO2 is a climate disaster. Dakota’s SNG that has emitted 96% of its CO2, is the greatest CO2 story ever told. Really?
Actually, I do agree that Dakota Gas is probably the most successful pioneer in Carbon Capture and Storage (CCS). They are indeed doing much better than most of CCS projects I know.
I mean no disrespect to the operators and engineers at Dakota Gas. They are doing a terrific job in demonstrating CCS technology. The nature of SNG is simply very carbon-intensive. Capturing some of the CO2 is never going to make it climate-friendly. If the Great Plains Synfuels were never built, we would have avoided half a billion tons CO2 emissions, and the lack of SNG would not have caused any shortage of natural gas. Was it wrong to build the SNG plant in the 1980s? Of courses it was. But I would not assign the blame to those remarkable operators and engineers at Dakota Gas today. It was not their fault that investors made a mistake 30 years ago.
To assert that CCS will make SNG environmental friendly is like saying bypass surgery will make heart attack desirable. Of course we must keep developing the technology. But no matter how well the technology develops, we must never encourage people to have more heart attacks, or to build more SNG plants.
I want to say again that I hold the highest respect to the operators and engineers at Dakota Gas. I only hope the Chinese SNG plants would someday become as good as the Dakota plant. The most significant CCS project in China’s coal conversion sector, from what I know, is the Shenhua Ordos coal-to-liquid plant. This CCS facility is now capturing roughly 1% of CO2 emissions from the plant. Shenhua calls this coal-to-liquids plant a demonstration of clean coal technology. Greenpeace has recently released a report on how the local villagers’ lives have changed since the plant’s operation. It is a very interesting report:
I would expect most China’s SNG plants to have environmental performance more similar to Shenhua than to Dakota Gas. I really wish there will not be more of them.
Center on Global Change
This is a thoughtful response, though I am not clear on where the numbers you use to calculate how much CO2 results from each cubic meter of SNG. According to Dakota Gas they capture nearly 50% of their CO2 production every year. Granted, just because they capture the gas and move it up to Canada it does not mean it all ends up sequestered. One would have to investigate the work in the oil fields to find out how much of the gas is successfully sequestered. For all we know the oil company may only use half of the gas they purchase and dump the rest, but that is just speculation.
Carbon Capture and Sequestration is a notoriously difficult problem and oil field EOR is hardly a universal solution even if it is the best option demonstrated so far. Lots of people are working on new solutions to utilize CO2 for useful purposes, but not much of anything has been commercialized so far. Hopefully someone will crack the code.
I agree with Chi-Jen that relative to conventional natural gas, coal based SNG is totally inferior. Chi-Jen has made the argument that there is a lot of conventional natural gas available and coal SNG is simply unnecessary, and perhaps he is correct.
Lets not throw the baby out with the bath water though. Gasification technologies enable the conversion of a wide variety of dirty resources into high quality fuels and chemicals and help transform the criteria pollutants: sulfur, nitrogen, lead, mercury, particulates, etc. into commodity products rather than allowing them to foul the air. I think this is a huge benefit and the cities in China and everywhere else can certainly benefit from not burning coal directly. The World Health Organization just announced a new study attributing lung cancer to air pollution, which should not really be a surprise to anyone.
To the extent we can leave filthy coal and petroleum in the ground we should. To the extent that society needs these resources lets clean them up and make the best of them. There is no perfect zero impact solution to be had. If we can eliminate cancer today in a trade for global warming tomorrow, I would support eliminating cancer today.