Select Fossil Fuels – A Closer Look (Part 4)
This week we look at the bottom most rankers from our list of select fossil fuels. In this part we will just briefly look into the
Earlier, we ranked some more popularly used fossil fuels in terms of:
1.????? Specific Energy (Energy per unit of Mass of Fuel – Terajouls per Gigagrams)
2.????? Emissions Intensity by Energy basis (Mass of CO2 emissions per unit of Energy – kg of CO2 per Terajoule)
3.????? Emissions Intensity by Mass basis (Mass of CO2 emissions per unit Mass of Fuel – kg of CO2 per Ton of Fuel)
Overall Ranking of fossil fuels:
We saw that:
We had ranked all these fuels based on the above. We scaled them and scored them across each parameter. Then we added the scores. Figure 1 below ranks the fuels from highest scores to lowest scores.
The “Least Preferred” fossil fuels:
We see from figure 1 the Coal dominates the lower ranking fossil fuels.
We will only look at the 2 most widely used fuels from this.
Figures 2 and 3 show the some of these coal-types:
Sub-Bituminous Coal:
Sub-bituminous coal is a type of coal that falls between lignite (the lowest rank) and bituminous coal (the second-highest rank) in terms of thermal maturity. It's a brownish-black, medium-hard coal containing 35-45% carbon and a high moisture content (15-30%). Its lower carbon content means it generates less energy per unit mass than bituminous coal but burns more readily.
Usage:
Sub-bituminous coal is primarily used for power generation. Its abundance and relatively low cost make it a popular choice for electricity production, especially in developing countries.
Industrial boilers: for generating steam in various industries like cement, paper, and chemicals.
Residential heating: particularly in regions with limited access to other fuels.
Gasification: converting coal into a synthetic gas for various applications.
Annual Production: Global production of sub-bituminous coal surpassed 3 billion tons in 2020, accounting for nearly 40% of total coal production. Major producing countries are China (leading producer), India, United States, Indonesia, Russia
Substitutes: Since it is largely used in power generation, it is can easily be replaced by the following:
Renewable energy sources: Wind, solar, hydro, and geothermal energy can replace coal for power generation, reducing greenhouse gas emissions.
Natural gas: Cleaner-burning than coal, natural gas can be used in power generation and industrial processes.
Biomass: Sustainable forms of biomass like wood pellets can be used for power generation and heating.
Nuclear power: Though controversial, nuclear power offers a low-carbon option for electricity generation.
Some widely used types of coal:
Lignite is a young, brownish-black, soft coal with relatively low carbon content (approximately 40-60%) and high moisture content (up to 50%). It represents the initial stage of coal formation from decaying organic matter. Its low energy density and high moisture render it less efficient than higher-rank coals.
Usage:
While less desirable than other coals, lignite still finds applications in certain contexts:
Power generation: Primarily in developing countries due to its abundance and affordability. However, its low efficiency and high emissions raise environmental concerns.
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Industrial boilers: For steam generation in various industries, typically where alternative fuels are scarce or expensive.
Residential heating: In regions with limited access to other heating options, although concerns about air pollution exist.
Gasification: Similar to other coals, it can be converted into a synthetic gas for diverse uses.
Anthracite is a shiny, hard, black coal with the highest carbon content (up to 95%) and lowest moisture content (less than 5%) among all coal types. This translates to high energy density and clean burning characteristics. It represents the final stage of coalification, resulting in a near-pure carbon form.
Usage:
Due to its superior properties, anthracite has specific applications:
Residential heating: Widely used in homes and small businesses for its clean burning and high heating value.
Metallurgical processes: Employed in some iron and steelmaking processes requiring intense heat and minimal impurities.
Industrial boilers: In specific situations where high-quality heat and minimal emissions are crucial.
Carbon filtration: Anthracite's porous structure makes it suitable for water and air filtration applications.
Coke Oven Coke – for Steel and Iron production
Coke oven coke (usually just called "coke") is a hard, porous, and high-carbon fuel produced by heating coal in coke ovens under high temperatures (about 1,000-1,100°C) in the absence of air. This process, called carbonization, drives off volatile impurities from the coal, leaving behind the concentrated carbon that forms coke.
Usage:
Coke plays a crucial role in one key industry: Iron and steelmaking. Coke serves as the primary fuel and carbon source in blast furnaces, where iron ore is reduced to molten iron for steel production. Its high carbon content and heat resistance are essential for this process.
Annual Production:
Global coke production exceeds 500 million tons annually, primarily concentrated in major steel-producing regions like: China (leading producer), India, Japan, United States, Germany.
Substitutes:
While coke's role in steelmaking is vital, the search for more sustainable alternatives is ongoing:
Blast furnace injection technologies: Injecting alternative fuels like natural gas or hydrogen into blast furnaces alongside coke can decrease its reliance and reduce emissions.
Scrap-based steelmaking: Electric arc furnaces can melt and refine scrap steel directly, reducing the need for blast furnaces and coke.
Bio-coke: Research is exploring the development of bio-coke from sustainably sourced biomass as a potential substitute for coke oven coke.
Next week, in the concluding part of this series we will categorise the fuels in some more insightful ways.
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