Will we ever be able to get all of our energy from renewable sources? There is certainly enough supply available. Enough sunlight hits the Earth every hour to power the entire human world for a year. But right now, it would take a 310,000-square-mile solar farm (about twice the size of Oregon), or 6 million wind turbines to capture enough sunshine or wind to provide all of the world’s electrical power.
If that sounds like a lot, it is-- which is why we will continue to use a mix of sources including natural gas and coal to meet our electrical demand for some time to come. The renewable numbers will continue to shrink as long as the technology and our efficiency improves faster than the population grows. In the mean time, coal, despite being the dirtiest fuel available, is still abundant and still produces 30 percent of the world’s energy. In 2012, the U.S. used coal to produce 43 percent of our electricity, while in China coal produced 81 percent. In other places, like South Africa, it contributed over 90 percent.
While there are a number of problems associated with burning coal, the biggest is the amount of carbon dioxide it produces: Coal combustion generates anywhere between 200 and 230 pounds of CO2 for every million BTUs of heat produced. That is roughly twice the amount emitted by natural gas.
The new EPA Clean Power Plant rule will put pressure on utilities to either clean up their coal plants or switch to a cleaner fuel. Many are already switching to natural gas, but another approach that has been talked about for a long time, carbon sequestration, is finally getting a chance to demonstrate its capabilities in a full-scale commercial operation.
Just this week, NRG announced the Petra Nova Carbon Capture Project, the world’s largest post-combustion carbon capture power generation plant. The project will be a joint venture between NRG’s wholly-owned subsidiary Petra Nova Holdings, and JX Nippon Oil & Gas Exploration Corp.
According to the press release, this commercial-scale carbon capture and storage (CCS) system will utilize existing technology to capture 90 percent of the carbon dioxide (CO2) in the processed flue gas from an existing coal plant in Fort Bend County, southwest of Houston. Construction on the project has already begun.
One reason that this technology has been slow to catch on is that CO2 capture represents a substantial cost and energy burden to the operator. If this could be offset by finding a productive use for the CO2, that would make the economics more attractive.
That’s exactly what NRG will be doing here. The company will pump the CO2 into the ground to pressurize an otherwise depleted oilfield to improve its yield in a process called enhanced oil recovery (EOR). EOR has been around since 1972, utilizing various injection fluids including steam, water, natural gas and CO2. To date, most of the CO2 that’s been used has come from naturally-occurring reservoirs. Demonstrations of this combined approach already exist in Salah in Algeria, Sleipner in the North Sea, and Weyburn in Saskatchewan. The Weyburn operator, which gets its CO2 from the Dakota Gasification plant 200 miles to the south, estimates that EOR could add an additional 25 years to the oil field’s life, yielding an additional 130 million barrels.
The NRG Petra Nova project is expected to boost production at the nearby West Ranch oilfield from 500 to 15,000 barrels per day.
“Our objective is simple: We want to continue to provide safe, affordable and reliable power to our customers, but without risking the health of the planet as a result of our activities,” David Crane, president and CEO of NRG Energy, said in a press release. “This project is an enormous step in that direction, plus it continues the trend of enhancing domestic oil production; thus further reducing our national dependence on foreign sources of oil.”
The project will receive a grant of up to $167 million from the DOE as part of the Clean Coal Power Initiative Program (CCPI), a cost-shared collaboration between the federal government and private industry, as part of President Barack Obama’s all-of-the above energy policy.
Environmentalists have opposed CCS technology in the past -- claiming that it is expensive, unproven and that it perpetuates the mining, transportation and combustion of coal, all of which are fraught with environmental impacts. They say the money would be better invested in inherently cleaner technologies.
The point is well-taken, though it looks past the fact that coal is still very much with us -- especially in places like China, where the use of this technology could certainly make a difference. In the meantime, natural gas has taken the spotlight, due to the vast amounts of natural gas now being produced here in the U.S. Ideally we will begin to see carbon-capture and storage technology applied to natural gas plants, which will improve their carbon footprint from simply being “cleaner than coal,” to actually being clean.
Image credit: NRG
RP Siegel, PE, is an author, inventor and consultant. He has written for numerous publications ranging from Huffington Post to Mechanical Engineering. He and Roger Saillant co-wrote the eco-thriller Vapor Trails. RP sees it as his mission to help articulate and clarify the problems and challenges confronting our planet at this time, as well as the steadily emerging list of proposed solutions. His uniquely combined engineering and humanities background help to bring both global perspective and analytical detail to bear on the questions at hand.
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