Clean coal is another avenue for improving fuel conversion efficiency. Investigations are underway into super-clean coal (35 percent ash) and ultraclean coal (less than 1 percent ash). Super-clean coal has the potential to enhance the combustion efficiency of conventional pulverized fuel power plants. Ultraclean coal will enable coal to be used in advanced power systems such as coal-fired gas turbines which, when operated in a combined cycle, have the potential to achieve much greater efficiencies.
Compared with ordinary coal, new, ‘clean’ coals may generate power:
Result:
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Option 2: "More cleanly and more efficiently."
Explanation: The text discusses how clean coal technologies, such as super-clean and ultraclean coal, improve combustion efficiency and reduce CO2 emissions. This aligns with the idea that new clean coals generate power more cleanly and efficiently, as they enhance fuel conversion efficiency and are suitable for advanced power systems.
Option 1: "More cleanly but at a higher cost."
Explanation: The text does not mention anything about the cost of new clean coals compared to ordinary coal. Therefore, this option introduces information that is not present in the text, making it incorrect.
Option 3: "More cleanly but much more slowly."
Explanation: The text does not indicate that clean coals generate power more slowly. In fact, it suggests that clean coals improve efficiency, which contradicts the idea of slower power generation.
Option 4: "More cleanly but less efficiently."
Explanation: This option contradicts the information in the text, which states that clean coal technologies enhance combustion efficiency. Therefore, it cannot be correct to say that they generate power less efficiently.
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