Seashells for Cleaner Power

Coal powered the industrial revolution; however, the use of coal and other fossil fuels has had immense environmental consequences, including greenhouse gas (GHG) emissions as well as sulphur dioxide emissions leading to acid rain. Surprisingly, seashells may offer an affordable means to reduce the global impact of burning coal for power.

Coal: Energy versus the Environment

Many countries are seeking to end the use of coal for power generation, but coal reserves still exceed that of oil and gas, and according to the World Coal Association coal remains the largest single source of electricity and is expected and will still contribute 22% in 2040 . Despite many countries seeking to phase out the use of coal for energy generation, coal use is growing elsewhere due to its affordability and rising demand for energy which is expected to increase by 50% to 2030, and also oil and gas are considered the principal feedstock of about 90% of chemicals produced worldwide.

Burning coal releases pollutants such as carbon dioxide (CO2), sulphur oxides, nitrogen oxides, hydrogen sulphide (H2S), and fly ash into the environment. Exposure of these gases to the atmosphere is driving climate change and directly affects human health by causing lung and heart diseases. Therefore, it is crucial to develop efficient technologies to produce clean energy from coal.

The Potential for Clean Coal

The term “clean coal” has been applied to many technologies, ranging from wet scrubbers, which remove sulphur dioxide from coal-generated gas to coal washing. Hypothetically, the term could be applied to anything that makes coal plants more efficient. However, CCS (Carbon Capture and Storage) plants are expensive to build and maintain. Retrofitting the technology onto older plants will be expensive. There are only 51 CCS plants across the globe (with only 19 currently operating). It is estimated that could cost $100 billion annually to develop CCS and that the technology represents “a classic catch-22 scenario”. The only way costs can decrease is by installing many more CCS projects worldwide. India the World’s third-biggest emitter of greenhouse gases expects to invest $54.5 billion in clean coal projects over the next decade as it seeks to increase its energy security .

How can seashells help to clean our air?

Reducing Carbon Emissions

It has been found that limestone can also be used to remove carbon dioxide from flue gases. Calcium oxide (CaO) sorbent material from eggshells or seashells has proven a good candidate for carbon dioxide capture from the flue gas stream of power plants. The process is based on the reaction of carbon dioxide with calcium carbonate and water to form calcium hydrogen carbonate, potentially seashells may be substituted for mined limestone to provide a more natural and sustainable source of calcium carbonate for the process.
Unlike the adsorption process for CO2 capture using activated carbon or zeolite adsorbent materials, eggshells and seashells biomaterials are low-cost and offer exclusive environmental and economic benefits.

Combatting Acid Rain

Sulphur emissions from power plants can cause localised air pollution problems such as acid rain. However, limestone and shell-based adsorbents can also be used to remove sulphur from power station flue gas . This is often done using commercially mined limestone-based calcium oxide. Wet scrubbers are used in utilities, paper mills, and chemical plants to remove sulphur dioxide (SO2) and other pollutants from gas streams. Undesirable pollutants are removed by contacting the gases with an aqueous solution or slurry containing a sorbent. The most common sorbents are lime (Ca[OH]2) and limestone (CaCO3). Oyster shells with a higher % of calcium carbonate can also react with sulphur dioxide and turn it into sulphates, which become part of the ash.

• “Seashells are useful biomaterials rich in calcium carbonate, and subsequently, a large source of calcium oxide and offer a sustainable and natural alternative and are a good absorbent for removing acidic gases.”

Work in Korea has confirmed that waste seashells can be a viable alternative to mined limestone. The Korea Western Power (Kowepo) is already using recycled oyster shells to create a material that can transform sulphur dioxide emitted from fossil fuel plants into ashes . The company is currently assessing the commercial viability of the operation, if it is deemed feasible, the company will roll out the technology to all its power plants.

Conclusion

Seashells as well as oyster shells provide a natural solution to the environmental problems created by coal-burning power plants. Morgan Agro provides the highest quality seashells from the Caspian Sea, and our products are great for use in a range of applications. If you need shell-based absorbents or you are interested in developing clean coal or other environmental technologies then contact us to find out more about how our shells can help.

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