Potential workaround

Refiners will use carbon-dioxide — in place of the ubiquitous crude oil — in the future as a raw material for making fuels, chemicals. A liability now will be an asset tomorrow! The concentration of carbon-dioxide (CO2) in the atmosphere has increased from 280 ppm before the industrial revolution to 419.8 ppm presently. The supply chain from fossil feedstock cannot sustain forever as all these energy sources will diminish within three centuries. From the economic point of view, importing fossil fuels from foreign countries is a waste of foreign exchange. Further, the Russia-Ukraine war has given a severe jolt to all oil-dependent economies. Government of India (GoI) wants to reduce import of oil by developing new technologies including renewable resources. India accounts for more than a quarter of net global primary energy demand growth between 2017-2040, according to BP Energy; 42% of this new energy demand is met through coal. In order to achieve the Paris Climate goal, a 20/20/20 strategy was adopted — meaning 20% decrease in CO2 emissions, rise in renewable energy market share by 20% and 20% increase in efficiency of current technology. For meeting a target of 400 GW solar power, an investment of USD 500 billion is needed.

Reducing CO2 concentration in the atmosphere while meeting the energy demands of an increasing population requires long-term planning and implementation. Shifting from fossil to renewable fuels, CO2 capture and storage (CCS), and CO2 capture and utilisation (CCU) are the possible areas for systematic control and reduction of atmospheric CO2. Carbon Capture and Utilisation and Storage (CCUS) is one of the key areas that can achieve CO2 emission targets while simultaneously contributing to the production of energy, fuels, and chemicals. In CCU, carbon dioxide is captured and separated from emission gases and then converted into valuable products. Thus, CO2 may become the future of oil through the development of synthetic fuels starting from the mixtures of carbon dioxide and hydrogen with specific catalytic chemical reactors. But, in every case, new catalytic processes and chemical plants are needed to develop this future industry. Flue gases from fossil fuel-based electricity-generating units are the major concentrated CO2 sources in India. If CO2 is to be separated, as much as 100 MW of a typical 500-MW coal-fired power plant would be necessary for today's CO2 capture processes based on the alkanolamines absorption technologies. Therefore, it would be highly desirable if the flue gas mixtures are used for carbon dioxide conversion but without its pre-separation.

As an economical, safe, and renewable carbon source, CO2 turns out to be an attractive C1 chemical building block for making organic chemicals, materials, and carbohydrates (e.g., foods). The utilisation of CO2 as a feedstock for producing chemicals not only contributes to alleviating global climate change, but also provides a grand challenge in exploring new concepts and opportunities for catalytic and industrial development. CO2 can be catalytically converted to methane, methanol, dimethyl ether, liquid hydrocarbons, formic acid, gaseous hydrocarbons, urea, organic carbonates, etc. Methanol can be produced from methane either through steam reforming (SR) or direct partial oxidation (DPOM) or dry reforming (DR) with carbon dioxide. This author is working in collaboration with the ONGC Energy Centre on green hydrogen production and CO2 conversion technologies — having obtained several patents. And SR and DPOM are comparably economical. Methanol can be converted into a host of valuable chemicals including olefins in promotion of the so-called methanol economy, a concept advocated by the NITI Aayog. Dimethyl ether (DME) has many fascinating attributes as a fuel which can be produced from carbon dioxide using innovative catalysts, reactors, and separators. DME is the cleanest high-efficiency compression ignition fuel as a substitute for diesel. DME's auto-ignition property and high-octane number (55 to 60) allow it to be used as a propane and butane substitute in LPG as a cooking fuel. The CO2 conversion into gaseous or liquid hydrocarbon requires high temperature (250-450 °C) and pressure (20-40 bar), but the conversion is low due to difficulty in the activation of CO2. Various catalysts need to be actively investigated to enhance CO2 conversion and to control selectivity toward specific target products. In fact, hydrogen will play an important role in all these chemicals. Hydrogen is regarded as an energy carrier, and it can only be produced by using energy from other sources. The ICT, in collaboration with OEC, has developed a novel Cu-Cl cycle for thermochemical hydrogen production. This closed loop Cu-Cl cycle is a green and zero discharge process capable of producing hydrogen on a large scale.

Steelmaking releases more than 3 billion metric tons of CO2 each year, having the biggest climate impact. To help limit global warming, the steel industry will need to shrink its carbon footprint significantly. Thus, hydrogen can substitute fossil fuels in some carbon intensive industrial processes, such as steel, chemical and allied industries. It can present solutions for difficult to abate parts of the transport system, in addition to what can be accomplished through electrification and other renewable and low-carbon fuels.

Biogas, typically containing 50-75% methane and 25-50% carbon dioxide, is produced by anaerobic fermentation from almost all types of biomasses. Another incentive for using gaseous biofuels for transport applications is the prospect to diversify feedstock sources. Biomethane, also called renewable natural gas (RNG), or sustainable natural gas (SNG), which is separated from biogas, is the most efficient and clean burning biofuel available today. Biomethane is upgraded to a quality fossil natural gas, having a methane concentration of 90% or greater, by which it becomes possible to distribute the gas to customers via the existing gas grid within existing appliances. In addition to syngas, gaseous hydrocarbons (C2 to C4), liquid hydrocarbons (C5 to C11+) and oxygenates can be produced in methane conversion with the co-feed of carbon dioxide.

Plastic refining is greenhouse-gas intensive. Carbon dioxide emissions from ethylene production are projected to expand by 34% between 2015 and 2030. Worldwide, about 40% of plastics are used as packaging. Typically, packaging is meant for single use, so there is a fast turnaround disposal. Packaging can be handled in three different ways: landfill, incineration, or recycling. Waste incineration has the biggest climate impact of the three options. The World Energy Council predicts that if plastics production and incineration increase as anticipated, GHG will increase to 49 million metric tons by 2030 and 91 million metric tons by 2050. Landfilling has a much lower climate impact than incineration. But the location of landfills can be associated with similar environmental injustices. Recycling is a different ball game with an entirely different set of problems. Compared to the low costs of virgin materials, recycled plastics are high cost with low commercial value. This makes recycling profitable only rarely, so it requires considerable government subsidies. Eventually, cutting emissions associated with plastics may require an all-of-the-above strategy. If government-established recycling targets are to be attained, the relationships between consumers, municipalities, and petrochemical production must be enhanced.

So, to sum it up: carbon-dioxide refineries are not far away to be seen and to be believed. Net zero should happen much before 2050 during the lifetime of many readers.

The writer is an engineering-scientist and Padmashri awardee (2016) and was recently elected to the US National Academy of Engineering and selected as National Science Chair by DST. Views expressed are personal