Assessing the environmental impacts of using demineralized coal for electricity generation

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    The energy sector is the source of two-thirds of global greenhouse-gas emissions, and is the main target ofclimate policies among authorities and governments. The share of fossil coals (hard coal and lignite) in world total net electricity generation is 40% in 2010. Demineralization or ash removal of the coal is thought to be beneficial for reducing ash-related problems, such as slagging and fouling in the combustion chamber,increasing the heating value, increasing thermal efficiency and reducing airborne emissions. A novel method for removing ash is alkali-acid leaching where the coal is washed in alkaline and acidic solution to dissolve and remove the ash. This process is well-studied on lab scale but has only to a small extent been tried on a full scale. This assessment is conducted as an aid for further developing thetechnology, allowing for early identification of environmental impacts and possible improvements. Experimental studies conducted so far have shown better performance of demineralized coal than its original raw coal during combustion, gasification, and coke making process. However a thorough analysis ofthe impacts from demineralization has not yet been conducted. We take a life cycle perspective, to assessthe environmental impacts from removing ash in coal, and assess how this affects the combustion in terms of higher thermal efficiency. We assess 260 different data points applying alkali-acid leaching or acidleaching and assess how the treatment and subsequent energy generation will affect the environment.The results showed that demineralization in some cases were beneficial for regional impacts such asparticulate matter formation because emission of particles and SO2 were reduce. In the contrary globalimpacts such as climate change did not benefit from demineralization because of the large energy use forrunning the demineralization process. Local and regional environmental impacts were shown to improve from demineralization for low ranking coals or lignite where the ash content is above ≈25 % and the carboncontent is less than ≈50 %. Overall, it can be concluded that demineralization of coal is not advised for high quality coals as the additional energy required for removing the ash outweighs the benefits from the increase thermal efficiency.
    Original languageEnglish
    Title of host publicationAbstract Book - DTU Sustain Conference 2014
    Number of pages1
    Place of PublicationKgs. Lyngby
    PublisherTechnical University of Denmark
    Publication date2014
    Publication statusPublished - 2014
    EventDTU Sustain Conference 2014 - Technical University of Denmark, Lyngby, Denmark
    Duration: 17 Dec 201417 Dec 2014


    ConferenceDTU Sustain Conference 2014
    LocationTechnical University of Denmark
    Internet address

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