Coal fueled the rise of the Industrial Revolution and the proliferation of everything from personal cars to iron ore smelting. The advent of new technology that harnessed coal’s massive energy density led to massive spikes in the quality of life for many industrialized countries. However, while coal became an industrial energy source mainstay, innovations in other areas exposed coal’s downsides.

Advancements in science and medicine helped us understand more about the world, including the impacts that our activities were having. Particulate matter from the combustion process became linked to cancer, lung disease, and premature deaths. In cities where coal was widely utilized, toxic smog continued to shorten lives and reduce visibility. But as time passed, innovation only accelerated ways to reduce and eliminate many of coal’s harmful side-effects.

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“Clean Coal” technologies address a variety of coal’s inherent weaknesses. More intensive physical as well as chemical coal washing techniques have allowed many toxins like sulfur and excess ash to be removed before combustion. During the combustion process, machines called electrostatic precipitators work to remove fly ash from coal plants exhaust gas. These machines are in widespread use due to their efficiency in removing upwards of 99 percent of ash from exhaust. Exhaust gas desulfurization technology also removes upwards of 97 percent of the sulfur dioxide produced by the combustion process by injecting lime into exhaust gas to scrub away sulfur dioxide into a solid form that then can be collected. 

Simply treating the exhaust from coal plants helps reduce harmful particulates, but increasing the efficiency of the plant’s combustion process translates to greater energy generation and less waste leftover. The Integrated Gasification Combined Cycle (IGCC) allows for most coal to be converted into a pressurized synthetic gas. This allows for more efficient and in-depth carbon capture and a higher thermal efficiency, thereby reducing waste even further. Ultra clean coal (UCC) has been developed by scientists to remove many of the 15 percent mineral matter and other pollutants that are found within coal. By utilizing UCC and other technologies that increase power plant’s efficiency, less CO2 will be emitted per kilowatt hour (kwh) during the combustion process. 

During the actual combustion process, several more innovative technologies have reduced or eliminated the creation of gaseous toxins. Nitrogen Oxide (NO) is naturally produced during the combustion process by oxygen reacting with the heated coal. Low NO burners were developed to restrict the flow of oxygen in the combustion chamber to negate the formation of nitrogen oxide. This technology is now employed at 75 percent of existing coal power plants. To furthermore counteract NO generation, Selective Catalytic Reduction (SCR) systems treat exhaust gas with NO by running in through a machine where it reacts with ammonia and a catalyst. This chemical reaction produces nitrogen and water, which can be easily and cleanly disposed of.   

Finally, carbon capture storage (CCS) technology has allowed coal plants and other fossil fuels to directly capture much of their own CO2 emissions for storage underground. Existing CCS technology can capture up to 90 percent of carbon dioxide emissions from power plants. CCS can be outfitted to collect emissions from the smokestacks of power plants, where the CO2  is then compressed into a liquid form and pumped at least one kilometer underground. The CO2 must be dispersed under an impermeable rock to mitigate leaking and can be held in place underground in a plethora of different geologic formations. CCS allows for the capture and containment of the emissions that cannot be eliminated with other forms of technology.  

From basic scrubbers and filters capturing particulate matter to refinements in the combustion process, technology has made it possible to use coal for power generation without threatening the health of surrounding populations. Coal itself has a dirty footprint, but the electricity generation processes capture and prevent the worst side effects from ever materializing – truly a feat of engineering and innovation.

All of these innovative technologies combined mean that current coal-burning power plants emit far less than they previously have. In the U.S., coal leads to less than a tenth of the deaths that the global average experiences from coal, and nearly a twentieth of the coal deaths from China due to deployment of these technologies. Several of these technologies are currently being implemented on a wider scale in the U.S., while others have continued to push for greater utilization in existing coal plants. Both in terms of its environmental and health impacts, coal technology has allowed it to remain a viable source of energy in the U.S. While coal’s share of the U.S. energy mix continues to shrink, these innovations in utilizing coal as an energy source showcase how continuous innovation makes coal cleaner today than it was even 10 years ago.  


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Written by Roy Mathews, Public Policy Associate


The Alliance for Innovation and Infrastructure (Aii) is an independent, national research and educational organization. An innovative think tank, Aii explores the intersection of economics, law, and public policy in the areas of climate, damage prevention, energy, infrastructure, innovation, technology, and transportation.