Coal, a fossil fuel, originates from plant remains that date back millions of years. Over these vast periods, layers of plant debris were subjected to intense heat and pressure, triggering a transformation process. This process involved the consolidation and compression of plant matter between other rock layers, known as strata.

These conditions, over time, metamorphosed the plant matter into a dense, carbon-rich substance we now identify as coal. The creation of coal seams, essentially layers or bands of coal embedded within other rock strata, is a result of this prolonged geological process. This process is referred to as ‘coalification’, and the rank and quality of coal are determined based on the degree of metamorphosis it undergoes.

The energy we extract from coal today is stored solar energy from millions of years ago. During their lifespan, plants absorb sunlight through photosynthesis, converting it into chemical energy. This energy was then stored in the plant matter, eventually transforming into coal. Hence, when we burn coal, we harness and utilise this ancient solar energy.

Coal is classified into four main types: lignite, sub-bituminous, bituminous, and anthracite.

Bituminous and anthracite coals are commonly called hard coals, while lignite can be known as ‘brown’ coal. Subbituminous coal is a rank between hard and brown coal, sharing some characteristics of both.

Confusion can lie within the hard coals, as this category includes both thermal (or steam) and metallurgical types of coal, each with distinct properties that make them suitable for different uses but cannot replace each other easily.

The term “Coalification” refers to the maturation process that coal undergoes, transitioning from peat (a precursor of coal) to anthracite (the highest rank of coal). This transformation process significantly impacts coal’s physical and chemical properties and is often referred to as its ‘rank’. The rank of coal is determined by the degree of transformation the original plant material has undergone into carbon. The more extensive the transformation, the higher the rank of the coal. The quality of each coal deposit is determined by:

• Types of vegetation from which the coal originated.
• Depths of burial.
• Temperatures and pressures at those depths.
• Length of time the coal has been forming in the deposit.
• In addition to carbon, coal contains hydrogen, oxygen, nitrogen, and varying amounts of sulphur.
• The highest-rank coals can be high in carbon and heat value but low in hydrogen and oxygen, making them slow-burning and less suited for typical power boilers.
• The lowest-rank coals can be low in carbon but high in hydrogen and oxygen content, sometimes in the form of inherent moisture, giving them a low heating value and requiring specialist boiler designs. The apparent low quality of low-rank coals does not preclude them from being used in modern applications. Some of the world’s most efficient power plants use such coals.

Power plants located near coal mines, often called mine-mouth coal plants, typically procure their coal from local sources. These plants are specifically engineered to operate on these local coals, and substituting them with coals from different locations isn’t always straightforward, although a certain degree of blending with foreign coals may be achievable. The coal value chain for these plants is logistically so simple the cost of generating heat and power from minemouth plants can be extremely low.

Power plants situated further away from coal mines have specific performance standards based on the parameters of internationally traded coals. These plants require a certain quality of coal, often achieved by blending different types from different countries. This process ensures that the coal not only meets the performance standards of the plant but also adheres to the specified quality requirements.

Coal is vital in global electricity generation, providing 36% of the world’s electricity. It is projected to maintain its significance, with predictions suggesting it could still account for 22% of global electricity by 2040, reinforcing its position as the leading single power source worldwide.

Steam coal, or thermal coal, is utilised in power stations for electricity generation. The coal is initially ground into fine powdery dust in rolling mills, which increases the surface area and promotes fast controlled combustion.

In pulverised coal combustion (PCC) systems, commonly known as a pulverised fuel (PF) system, the powdered coal is blown with hot air (340oC or 650 oF) into the combustion chamber of a boiler where it is ignited and burns at high temperature (1030-1330 oC). The hot gases and heat energy produced converts water – in tubes lining the boiler – into super-heated steam (540-670 oC).

This high-pressure steam is then passed into a turbine containing thousands of propeller-like blades. The steam propels these blades, causing the turbine shaft to rotate at high speed (1800-3600 revolutions per minute, RPM).

A generator consisting of carefully wound wire coils is attached at one end of the turbine shaft. Electricity is produced when these coils are rapidly spun within a strong magnetic field.

Once the steam has passed through the turbine, it is condensed and returned to the boiler for reheating. In more sophisticated plants, the steam can be quickly recirculated to the turbine for a first or even a second reheat before the condensing stage.

The electricity generated is transformed into higher voltages – up to 400,000 volts – used for economical, efficient transmission via power line grids.

When it nears the point of consumption, such as our homes, the electricity is transformed to the safer 100-250 voltage systems used in the domestic market.

The existing coal abatement technologies are a range of efficient technologies that support power and heat utilities, while end-of-pipe or in-boiler emission control systems can capture up to 99% of emissions. These include high-efficiency and low emissions (HELE) plants such as Ultra-supercritical (USC), Combined Heat and Power (CHP), electricity production from coal gasification (Integrated Gasification in Combined Cycle (IGCC)), and co-firing coal with biomass. To achieve these high rates of emission control, sulphur dioxides (SOx), nitrogen oxides (NOx), and particulate matter (PM) can all be captured, and the waste by-products reused in industry and construction. Even other emissions, such as heavy metals, can be captured.

Coal continues to play a crucial role in the energy supply of over 80 countries, not only in terms of electricity but also heat production. It is projected to remain the world’s largest single source of electricity by 2040, according to the International Energy Agency (IEA). In many countries, coal is used for residential heating during colder months from district heating systems supplied by coal power and heat plants. Therefore, while the focus is often on electricity generation, it’s important to remember that coal’s contribution to global heat supply is also significant.

According to the International Energy Agency’s (IEA) Coal Market Update, 10,440 terawatt hours (TWh) of electricity was generated from coal in 2022. This figure represented 36% of the world’s total electricity generation. The report further projects that by 2040, coal will continue to be the single largest source of electricity worldwide.

It’s important to note that these figures reflect coal’s significant role in the global energy landscape. Despite the growing emphasis on renewable energy sources, coal remains a key player due to its abundance, cost-effectiveness, and established infrastructure in many countries.

However, this also underscores the importance of developing and implementing cleaner and more efficient coal technologies to mitigate environmental impacts. Source: https: //www.cnbc.com/2023/07/27/coal-consumption-hit-an-all-time-high-in-2022-iea-says.html

Hydrogen is poised to play a pivotal role in aiding countries’ transition towards cleaner energy sources and ensuring a sustainable future for coal. It is projected that by 2050, hydrogen will account for 14% of the world’s anticipated energy demand.

The cost of producing hydrogen from coal with CCUS three times less expensive than producing low-carbon hydrogen through water electrolysis, the latter which costs 3.0-7.5 US$/kg H2. According to the International Energy Agency (IEA), the average cost of producing hydrogen from coal with CCUS is 1.4-3.1 US$/kg H2. Another source suggests that coal gasification with CCUS typically costs 1.9−2.4 US$/kg H2, with costs as low as 1.6 US$/kg H2 in China.

The conversion of coal to hydrogen represents an innovative application of coal abatement technologies. It simultaneously assists coal-dependent nations in achieving their development goals and decarbonisation ambitions.

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Coal supports agriculture in two significant ways:

• Coal can be used to produce ammonia through gasification. Ammonia serves as a nitrogen source for plant growth. Over the last 50 years, ammonia fertiliser production has surged to 176 million tonnes.
• Coal, derived from plants, can be used as a source of humates. These can be extracted and used to supplement soils. This practice is gaining acceptance, especially in Asia, where the demand for humic products is increasing by 10% annually. It also offers an alternative use for immature coal.

These practices are aiding in mitigating food scarcity by reducing the reliance on nitrogen fertilisers, cutting costs, minimises waste and pollution, as well as providing crucial support to food production.

Coal and coal waste are rich sources of critical heavy metals that are indispensable in modern life.

These metals can be found directly in coal or in the surrounding rock layers and play a pivotal role in numerous applications.

When coal is burned, it produces valuable coal ash that reduces the climate impact of cement production.

Additionally, coal ash and coal sludge contain thousands of tonnes of essential heavy metals, including aluminium, cobalt, copper, iron, lead, silver, nickel, and zinc.

Coal plays a crucial role in modernisation efforts across various industries. It is a key component in the manufacturing of steel, which is used in everything from buildings and bridges to cars and appliances.

In the production of cement, coal serves as a heat source, facilitating the high-temperature processing of a blend of raw materials. Additionally, waste products such as ash from coal power plants and slag from steel manufacturing can substitute these raw materials, thereby decreasing the consumption of fuel and its related emissions.

Aluminium production also relies on coal. Extracting aluminium from its ore requires significant amounts of electricity. To this affordably, it is often generated from coal-fired power plants notably in India and China. In 2019, two-thirds of the power needed globally for electrolysis in the sector came from coal.

Moreover, coal contributes to the infrastructure of renewable energy sources. For instance, the steel used in wind turbines is made from coking coal. Similarly, the production of solar panels involves high-temperature processes that are often powered by coal. Even battery storage technologies, essential for managing the intermittent nature of wind and solar power, involve materials that require high-temperature processing, often powered by coal.

In essence, while renewable energy technologies are part of the solution to our environmental challenges, their production and operation still involve conventional energy sources like coal. This underlines the importance of continuing to improve the efficiency and environmental performance of our coal usage.

Coal provides a process material or energy fuel for:

• 70% of the world’s steel
• 90% of the world’s cement
• 61% of energy used to make aluminium

TCoal plays a vital role in manufacturing wind turbines, particularly as China, a prominent coal leader globally, leads the way in manufacturing wind turbines. Each turbine requires 260 tonnes of steel made from 170 tonnes of coking coal and 300 tonnes of iron ore.

World Trade Coal has enrolled a responsible and innovative membership of global coal participants across the whole coal value chain, all committed to ensuring responsible investment in coal and coal abatement technologies to support coal-dependent nations in their transition to clean energy and contribution to the country’s economy through beyond combustion opportunities.

Coal requires policy settings where all energy sources and all clean technologies are considered equally, consistent with the caveats of the Paris Agreement (Article 10.2). Paris therefore requires the world to take action using all means necessary.