Electrocatalytic Reactor – A carbon capture solution producing value-added products from waste

Dr S. Harinipriya, Chief Scientist and Technology Officer of Ramcharan Company (P) Ltd, has a doctorate in chemistry from IIT Madras with 20 years of R&D experience in academia and industries of repute. In this article, she discusses Electrocatalytic Reactor – A carbon capture solution capable of generating value-added products from waste.

Flue gas (a mixture of combustion products) from stationary sources is found to be a major contributing factor to the accumulation of carbon dioxide in the atmosphere. The major contribution to the GHG emissions in India comes from the Flue gas and CO₂ emissions of various industries.

• Steel Production
• Distilleries
• Oil & Gas, Coal/Lignite and thermal power plants
• Automobile sector

India is the second largest producer of steel globally. The utilisation of steel is bound to increase multi-fold globally by 2050 to cater to the national and international demand and supply. In 2017, the National Steel Policy of India set an ambitious goal of increasing production to treble capacity by 2030. Approximately 7% of the GHG emissions come from the steel production industry in India. In addition, India has set an aspiring goal of achieving net zero carbon by 2070. Due to stringent GHG emission reduction goals, currently, steel industries in India adopt carbon capture by blast furnaces, utilisation of syngas as alternate fuel and green hydrogen as fuel in steel production, use of renewables like solar, wind and hydro, recycling of steel scrap, etc.

Analogously, 2.4kg of CO2 is emitted per litre production of alcohol by distilleries. To reduce the carbon footprint, most distilleries use 50% of their energy consumption by renewables or Refuse Derived Fuels (RDF).

It is reported that 68.47% of the GHG emissions in India come from energy industries (Fig 1).

The automobile industry contributes to approximately 16% of GHG emissions in India, leading to around 3 billion metric tons of CO₂ in 2020.

(Source – https://timesofindia.indiatimes.com/blogs/voices/green-road-ahead-for-the-automotive-sector/).

Fig 1: GHG emissions in India sector-wise in the year 2014 (Source: WRI CAIT 4.0, 2017, FAOSTAT, 2018)

To achieve net zero emissions by 2070, the approaches adopted by the industries mentioned above are a step in the right direction, as they result in lesser emissions but do not eliminate them. Thus, to expedite and achieve net zero GHG emissions, the emissions need to be converted into valuable products such as alternate fuels and energy carriers. This would eradicate the carbon footprint from the industry and the atmosphere.

Electrocatalysis-based reactors – working on the principle of asymmetric C-C coupling, can capture the GHG emissions at the source and convert them into alcohols such as methanol, ethanol, propanol, butanol and isoamyl alcohols, acetates like ethyl acetate and metal acetates as value-added products that can assist in circular economy and supply chain sustenance.

The alcohols generated from CO₂ can be blended with fossil fuels and used as alternate hybrid fuel in automobiles. Other value-added products, including ethyl acetates and metal acetates, are important in the food and medical industries.

The flue gas emitted by Steel, Oil & gas, Coal and Lignite industries, and thermal power plants can be fed into an electrocatalytic reactor to produce energy carriers such as ammonia.

Ethanol produced is a vital fuel for the automobile industries and an essential precursor to the medicine and food industries. Ammonia is an important energy carrier and is in high demand in the mobility, energy, food and medicine industries. Produced ammonia can be stored as ammonium hydroxide, avoiding investment and safety issues associated with handling and storage.

The innovation lies in the ability of the reactor and the electrocatalyst to handle the flue gas or any GHG emissions without purification and convert them into useful products with zero carbon footprint. The innovative technology can handle CO2-rich emissions and N2-rich emissions separately or together to achieve the desired products.

CO₂ or CO-rich flue gas

Although different organic molecules may be obtained from electrochemical CO₂ reduction, such as formic acid, hydrocarbons (methane, ethane), and alcohols (methanol, ethanol, propanol, butanol and isoamyl alcohol), the production of ethanol specifically becomes important due to the utility of ethanol as an alternate fuel and as an important organic commodity chemical. Ethanol possesses high energy density and compatibility with present-day IC engines and thus can be blended with fossil fuel and used as automotive fuel. Ethanol is also a key precursor in the synthesis of various chemical compounds that cater to the medical and food industries. The extensively followed procedure for the production of ethanol worldwide is via fermentation of starch-rich biomass such as sugarcane, corn, paddy, etc.

N2-rich flue gas

Electrochemical N₂ reduction leads to the formation of cost-effective energy carrier ammonia and becomes an important and inevitable process due to the utility of ammonia as a storage medium for the green fuel Hydrogen, an alternate and clean fuel. Ammonia is also a stable chemical and can be stored in gaseous and liquid forms (as ammonium hydroxide) and is a key precursor in the synthesis of various chemical compounds that cater to the energy, medical and food industries. The extensively energy-intensive procedure for producing ammonia worldwide is the Haber-Bosch process and requires high purity, temperature and pressure of the N₂ and H₂ gases. In addition, handling gaseous H₂ at high temperatures and pressure also involves costs associated with safety measures and equipment, adding to the CAPEX of the process. Alternatively, electrochemical reduction of N₂ to ammonia is a potentially more effective and sustainable technology where the conversion efficiency is almost 100% and Faradaic efficiency is > 90%. The economic feasibility of electrochemical reduction of N2 on the scaling up of the process and/or technology for mass production of ammonia is very high as the process does not handle gaseous H2; instead, it generates H₂ in-house and utilizes the same for electroreduction of N₂. This approach reduces the CAPEX involved in H₂ pipelines and safety equipment associated with handling and storing H₂ gas.

Unique Selling Propositions (USPs) of the project/process/product

Chennai-based Ramcharan Company Private Limited is actively involved in discussions with major automobile sectors, Oil & gas companies, and Thermal and Coal power plants in India and abroad to employ its Electrocatalytic reactor.

Also Read: Understanding Hydrogen: Alternative fuel of future