ROCK SPRINGS -- PacifiCorp’s Jim Bridger coal-fired power plant is Wyoming’s largest source of carbon dioxide emissions, generating about 18 million tons of the greenhouse gas per year.
The pulverized coal-fired power plant happens to be located above geologic formations that scientists believe could provide one of the best CO2 storage sites in the nation.
The Rock Springs Uplift contains two highly permeable saline formations capped by tight Cretaceous shales some 5,000 feet thick, providing a massive geologic seal, according to the Wyoming State Geological Survey.
“There’s more than enough capacity to handle all the CO2 emissions Wyoming is going to generate for almost the next 100 years,” said State Geologist Ron Surdam.
The potential CO2 storage capacity of the Rock Springs Uplift often has been described in terms of Jim Bridger’s CO2 output. For example, there’s enough storage capacity to accept the CO2 output of two Jim Bridgers for more than 50 years, according to a February press release by the Wyoming State Geological Survey.
But despite their shared geographic location, the Jim Bridger power plant and the Rock Springs Uplift have almost nothing to do with each other.
Carbon capture challenge
Even if CO2 injections began today, state leaders believe it would do little to preserve Wyoming’s existing coal-fired power generation and coal-export industry. The latter accounts for about one-third of state revenue.
That’s because the CO2 would not come from Jim Bridger or any other existing coal-fired power plant in the 37 states that burn Wyoming coal.
The technology to capture CO2 from existing coal-fired power plants remains technically and economically elusive, according to both those who support and those who oppose coal. Most agree that today’s carbon capture technology would create a parasitic load, gobbling up about 20 percent of the electrical generation output on a coal-fired unit.
“There is not yet a commercially viable technology to capture CO2. You can’t walk into a store and say, ‘I want to buy your carbon capture technology and plug it into my plant,’” said Daryl Hill, spokesman for Basin Electric Power Cooperative.
Paul Fahlsing is engineering and environmental manager at PacifiCorp’s Jim Bridger power plant. During a recent tour, Fahlsing described several upgrades being made to one of the four generation units at the plant, including several aimed at further reducing emissions of sulfur dioxides and nitrogen oxides.
In the actual scrubbers, the flue gas bubbles through perforated trays loaded with a sodium-based reagent which triggers a chemical reaction that removes sulfur dioxides from the flue gas. The process generates a large amount of material waste even though the constituents make up a very small portion of the coal burned. At Jim Bridger, the coal is only about .5 percent sulfur by weight, according to Fahlsing.
The same type of process to remove CO2 would multiply the volume of sorbent many times over, and would have to divert a huge volume of CO2 gas.
“When it comes to removing CO2, you’re talking about a volume 100 times more,” Fahlsing said.
Hill said even if some type of sorbent is developed to efficiently separate CO2 from the flue stream, the equipment required to do so would be extremely difficult to “shoehorn” onto existing power plants. Yet figuring out carbon capture is so vital to maintaining the current fleet of coal-fired power plants, most utilities are actively pursuing a variety of efforts.
Basin Electric Power Cooperative, for example, is partnered with Doosan Babcock and HTC Purenergy. The partnership will attempt to capture CO2 through about 25 percent of the slipstream of a 450-megawatt coal-fired power plant in North Dakota.
And just this month, the “Carbon Dioxide Capture Technology Act” was advanced by the U.S. Senate, offering monetary awards for research teams to find a quantum leap forward in the technology.
Experts say that while it remains a question whether carbon capture will work for the existing fleet of coal-fired power plants, the ability to capture carbon from coal gasification is a certainty. That’s why state leaders feel comfortable with forging ahead on carbon sequestration.
While the state and University of Wyoming continue to work with industry and the U.S. Department of Energy on carbon capture, Gov. Dave Freudenthal said he views carbon sequestration as the vital foundation to the future coal market.
"It may turn out that we figure out how to capture a lot more CO2 out of the existing flue gas streams. I don’t want to say it won’t happen, but that seems to be the least promising, and it also appears to be really expensive,” Freudenthal said.
And if carbon capture does prove to be viable one day, it won’t do any good if there’s not a place to put the CO2.
Instead of diverting Jim Bridger’s CO2 emissions from the smokestack down to the Weber sandstone and Madison limestone formations below, the Rock Springs Uplift is more likely to serve as a hub for coal-gasification facilities.
“What we’re really doing is getting ready for the next generation of coal power plants,” said Surdam, who will soon leave his post as state geologist to head UW’s new Carbon Management Group. “If we’re going to burn coal in the next generation of plants, we’re going to have to use sequestration."
By gasifying coal, you can separate CO2 at the front end of the refining process and end up with carbon-based feedstocks that can be used for low-emissions power generation or a variety of industrial products such as gasoline. In China, coal gasification is a major driver behind the country’s garment industry.
Keith White is General Electric’s director of gasification products. He said unlike carbon capture or large-scale geologic carbon sequestration, coal gasification has been in practice for decades.
“We do this today already. It’s not new technology,” White said.
But the cost of building a new coal-gasification plant is more expensive than building a new pulverized coal-fired power plant. GE is among a growing number of companies eager for the United States to implement climate legislation that would give financial institutions and utilities clear signals to make the investment.
In absence of federal climate legislation, White said the economics for coal gasification in Wyoming become attractive with carbon sequestration. If the ongoing modeling of the Rock Springs Uplift continues to produce favorable results, it could be an ideal location for coal gasification.
“Those places that have communities engaged are going to attract a lot of economic growth for power generation,” White said.
GE already sees the value of gasifying Wyoming coal. The technology giant has partnered with UW to build the High Plains Gasification-Advanced Technology Center in Cheyenne. The research partnership aims to refine GE’s coal-gasification technology using Wyoming’s vast sub-bituminous coal resource in the Powder River Basin.
“There’s going to be a robust market for coal in the U.S.,” White said.
Freudenthal agrees that with a price on carbon, places like the Rock Springs Uplift indeed could become hubs for coal-gasification facilities. But he doubts that electrical generation will be the focus.
He said it might make more sense to convert Wyoming coal to syngas and liquid fuels at the Rock Springs Uplift – and other economically viable CO2 storage sites – and ship those materials via the existing pipeline network for consumption and electrical generation in the urban markets of the West.
“Right now there’s enough gas coming on (to fill pipelines),” Freudenthal said. “But in the future you can see an era in which coal would be converted to gas or liquids and be shoved in the same pipeline system for distribution. And that’s why this work to find places to store CO2 in Wyoming is really important.”
Shipping coal products via pipeline sidesteps a lot of difficult and costly challenges to building new interstate electrical transmission.
With or without sequestration
Pressure to address climate change has helped “unplug” plans for more than 100 coal-fired power plants in the U.S. in recent years, according to the Sierra Club.
In many ways, Wyoming has already felt the ramifications of a carbon-constrained world. The California Energy Commission in 2004 set a greenhouse gas emissions standard that only allows California utilities to use coal-based power if CO2 is captured in the process.
In fact, distaste for coal in California was the demise of the proposed Frontier transmission project – a 6,000-megawatt capacity power line tying Wyoming’s coal and wind resources to the California market. Ironically, current Wyoming-to-California transmission proposals based solely on wind power are being held up due to California’s preference to first utilize its own in-state renewable energy sources.
Nonetheless, Wyoming leaders are working today to secure energy markets for tomorrow.
“The general consensus is we will be living in a carbon-constrained world, so it’s best to prepare for it,” said Rob Hurless, Freudenthal's energy adviser. “If you want to provide power to the California market, there’s a clear standard there.”
Until there’s a quantum leap forward in carbon capture for pulverized coal-fired power plants, America’s existing fleet seems destined for a gradual retirement. Just how gradually the plants come off line will depend on how federal climate legislation is crafted.
It may also depend on how quickly government and industry researchers can bring down the costs of coal gasification and carbon sequestration.
“If it comes fairly quickly, you can see them being replaced. If it comes more slowly, you can see efforts to extend the life of the existing plants,” Freudenthal said.
Environmentalists, however, remain skeptical. Groups including the Sierra Club say the coal industry continually dangles carbon sequestration, carbon capture and coal gasification like a carrot on a stick that the horse can never reach.
“I think carbon capture and sequestration is a straw man,” said Steve Thomas, western regional director of the Sierra Club.
Thomas said the Sierra Club believes coal should stop being burned for energy, period. But, it does recognize there will be a transition period to cleaner forms of energy.
“There’s all sorts of other problems with coal. There’s mercury and the health impacts of mercury, damage to the landscape and a whole list of other things,” Thomas said. “It just seems there’s not a real energy plan going on in the state, and how we transition to a cleaner energy business.”
Energy reporter Dustin Bleizeffer can be reached at (307) 577-6069 or firstname.lastname@example.org. Go to http://tribtown.trib.com/DustinBleizeffer/blog to read Dustin’s energy blog.