What Technology Can Make Coal a Cleaner Fuel?

Photograph

The Kemper County power plant in Mississippi. Credit Josh Haner/The New York Times

Engineering holds the promise of enabling coal power plants, which produce much of the world's electricity, to run more cleanly, emitting far less of the pollution that causes climate change. But these projects have been difficult to brand a reality because they are complicated and expensive. Here is a quick primer.

1. ​What is "make clean coal"?

   The term "clean coal" has been popularized by the coal industry, electric utilities and policy makers. It refers to the hopeful notion that technology volition enable power plants to burn coal only release far less pollution. C.C.South., which stands for carbon capture and storage, or carbon capture and sequestration, is a type of make clean coal engineering that would forestall carbon dioxide (CO _two ) exhaust from entering the atmosphere from power plants that burn coal, natural gas and biomass, or other sources of carbon emissions like atomic number 26 or steel factories and oil refineries. Since the early on 2000s, there has been a wave of optimism that this engineering science could play a vital part in slowing climate alter by cleaning up some of the biggest emitters of carbon pollution. Now in that location is significant skepticism that the technology can be scaled up affordably, reliably and soon plenty to make a difference.
   

2. ​Is C.C.S. necessary?

   Most energy experts, including officials at the International Energy Agency, say that the technology is needed to slow climatic change because it tin can significantly reduce carbon emissions from fossil fuels, which they predict will remain a large portion of the global energy mix through 2050. Many environmentalists, on the other paw, say that C.C.S. is a costly half-measure that delays the transition to renewable energy sources like wind and solar.
   

3. ​How is the CO_ii captured?

   A power found can trap carbon dioxide in one of 3 ways. After combustion, the carbon dioxide is captured from the frazzle of a power constitute by absorbing it in a liquid, which is afterwards heated to release the gas for storage. CO ₂ can too be captured before combustion. In this instance, a controlled amount of oxygen is used to turn coal or natural gas into "syngas," a mixture of carbon monoxide and hydrogen. Before it is burned to generate power, the syngas is treated with steam, producing carbon dioxide. A tertiary method involves burning fossil fuels in oxygen. That results in an exhaust stream of water vapor and CO ₂ , which are then separated past cooling and compressing the gas stream.
   

4. ​What happens to the CO₂ later information technology is captured?

   The carbon dioxide is usually compressed and transported through a network of pipes for reuse or storage. It can then be stored by beingness injected directly into hole-and-corner geological formations such as oil fields, gas fields, saline formations, coal seams that cannot be mined, and saline-filled basalt formations. It tin can likewise be compressed and shipped through a pipeline to an oil field, where it can be pumped cloak-and-dagger in a process known equally enhanced oil recovery, to help push button up oil in a management where it tin be reached.
   

6. Will the Obama assistants'due south new limits on power plant emissions help promote C.C.S.?

   Non likely. The Ecology Protection Agency has proposed a rule that in issue requires new coal-fired power plants to employ carbon capture engineering science. Opponents of the dominion maintain, however, that because C.C.S. is still so expensive, utilities will choose to provide energy from a different source similar natural gas rather than invest in enquiry and development of C.C.S. for coal-powered plants. They say that instead of advancing the technology, the rule will steer interest abroad from coal altogether, because it will get too plush to build coal plants. And with the current low toll of natural gas, no one is building them anyhow.

7. What steps has the administration taken to regulate power constitute emissions?

   As part of President Obama's attempt to tackle climate change, the E.P.A. is reining in carbon emissions from ability plants, including all time to come coal and natural gas plants built in the United States. The agency has finalized two rules for ability plants: one for new or modified power plants and another, the Clean Power Plan, for existing power plants. Though some states are moving forwards with strategies to comply with the Make clean Power Plan, it has been stalled past the Supreme Court awaiting the resolution of legal challenges.
   

8. ​Will coal plants be able to satisfy the Obama regulations?

   Information technology won't exist like shooting fish in a barrel. The limits on coal plants are stringent enough that utilities will probably exist able to build new coal facilities only if the plants can capture nearly forty percent of the carbon they produce.
   

10. ​What is the biggest obstacle to C.C.S.?

    Cost. The technology works. The economics don't. Ability plants with C.C.South. cost nigh 75 percentage more than regular coal plants, and the infrastructure required to send and store CO ₂ is enormous. It'southward besides essentially still free for plants to emit carbon dioxide into the air. Until there is a existent cost to companies for emitting carbon unchecked, the financial case for C.C.South. will come up up short.
    

11. ​Why are C.C.S. plants so expensive?

    Coal plants that capture carbon are expensive partly considering they are so complex. As the New York Times reporter Henry Fountain explained, "removing carbon dioxide from the swirl of gases unleashed at a power institute is challenging, akin to plucking but a few colored Ping-Pong assurance out of the air from a swarm of mostly white ones." That toll rises farther because capturing and compressing the carbon requires so much energy, sometimes sapping more than than 20 per centum of the electricity that the found is supposed to produce for consumers.
    

12. ​Does fracking play a role in the economics of C.C.S.?

    Yes. Fracking, a method of increasing product from drilled wells, has unlocked huge reserves of natural gas, which has driven downwards the cost of natural gas to below $ii per unit of measurement. Generally speaking, natural gas prices need to be college than $seven per unit for new coal plants to be competitive. This is a major reason no new coal plants are likely to be built in the U.s. anytime before long.
    

14. ​Are in that location other costs to C.C.S.?

    The technology generally eliminates only carbon pollution and does not remove other air toxins that cause asthma, lung disease, and heart attacks. It also does not reduce the environmental toll of mining methods like "mountaintop removal." And if the captured carbon is used to foster more oil employ, there are ecology costs to called-for additional fossil fuels.
    

15. ​Can the CO₂ leak after it is stored underground?

    Carbon dioxide injected hush-hush could possibly escape, defeating the entire purpose of the carbon capture system. Merely the chances of that happening are extremely low, according to energy experts. The International Energy Agency says that depleted oil and gas fields are the well-nigh probable candidates for CO _ii storage. These sites frequently contain multiple holes and wells built on these fields that create pathways for carbon dioxide to escape. The CO _ii could taint drinking h2o or eventually rise to the surface and bubble into the atmosphere. In Cameroon, a volcanic lake suddenly released a cloud of naturally forming carbon dioxide in 1986, suffocating 1,700 people to death. If carbon dioxide is liquefied, injecting it deep underground tin nowadays problems, also. Pumping wastewater from oil and gas production into the ground has been linked to a serial of small earthquakes in Arkansas, Ohio, Oklahoma and other states. Because of all this, long-term monitoring of storage sites volition exist required.
    

16. ​The technology is proven, right?

    Carbon capture and storage has been shown to piece of work in many pilot projects, which mostly do not operate at the scale envisioned by proponents equally a solution to climate change. And then the claiming is scaling it up to larger-chapters power plants. While there are some projects being designed or under structure, at to the lowest degree ii power plants currently capture and stores carbon on a commercial scale. One is the SaskPower's Boundary Dam three in Saskatchewan. The other is the Weyburn project, which gets its CO ₂ from a coal gasification institute in N Dakota and and then sends it through a pipeline to the Weyburn oil fields in Saskatchewan for injection. Simply as The Times's Ian Austen explained in March, Purlieus Dam iii has meet some problems. Subsequently initially maxim that the projection was working as intended, capturing ninety pct of the plant's carbon, Cathy Sproule, a member of Saskatchewan'south Legislative Assembly, unveiled confidential documents in November 2022 indicating that the plant was working at only 45 percent of capacity. According to the Times article: "One memo, written a month after the government publicly boasted about the project, cited eight major problem areas. Fixing them, it said, could take a year and a one-half, and the memo warned that it was not immediately apparent how to resolve some bug."
    

18. ​How many C.C.S. projects are there?

    There are 22 big-scale C.C.S. projects globally. Sixteen are operating. Four others, including the Kemper coal establish in Mississippi, are under construction; one is consummate only awaiting a concluding let; and i has been closed. Of all those projects, merely four are coal plants. The residue are refineries, or natural gas, fertilizer, ethanol or steel plants. Only ii of the four coal-based C.C.S. projects are operational: Boundary Dam three and Weyburn.
    

19. ​If we surrender on C.C.S., is slowing climatic change withal feasible?

    Slowing climate change is possible without carbon capture and storage. Proponents, nevertheless, see it equally vital to achieving carbon dioxide emissions reductions because countries will continue to rely upon fossil fuels like coal and oil every bit they take steps to boring climatic change. In arguing that C.C.Due south. is the best solution, advocates point to forecasts showing that an energy scenario without information technology would brand combating climatic change much more expensive than with C.C.Southward. At the same time, C.C.S. has been slow to deploy, and many believe that even if the technology is scalable, information technology would come too late to reduce carbon emissions in a meaningful way compared with investments in renewables. Those who oppose C.C.Due south. insist that cost estimates for carrying it out are highly speculative.
    

20. ​What would it look like for governments to commit fully to C.C.S.?

    The chief executive of the Global CCS Institute, Brad Folio, has said that to meet the target of keeping global temperature increases under 2 degrees Celsius, 130 full-scale carbon capture and storage projects will need to be operational past 2020. For C.C.S. to work on a national scale, the plants would besides crave a network of pipelines to transfer carbon. That network would have to be congenital in the next 30 to xl years and be about 100 times the size of the current network, and be similar in size to what exists now for oil and natural gas. Deploying C.C.S. technology at this scale would require extensive and rapid government and individual support.
    

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Source: https://www.nytimes.com/interactive/2016/07/01/science/what-is-clean-coal.html