Thermodynamic assessment of CO2 to carbon nanofiber transformation for carbon sequestration in a combined cycle gas or a coal power plant

Abstract

a b s t r a c tMolten carbonate electrolyzers offer a pathway to capture emitted CO 2 from the flue gas of the power plants and transform this greenhouse gas emission at low energy and high yield instead into a specific, value added, hollow carbon nanofiber product, carbon nanotubes. The present day value of the carbon nanotubes product is $10,000 that of proposed, or in place, current carbon tax costs of $30 per ton, strongly incentivizing carbon dioxide removal. The recent progress in high-temperature molten carbonate electrolysis systems for carbon dioxide utilization and the impact these advances have on developing a CO 2 -free fossil fuel power plant for electricity generation is presented. A thermodynamic model analysis is presented for a molten Li 2 CO 3 electrolysis system incorporated within a combined cycle (CC) natural gas power plant to produce carbon nanofibers (CNF) and oxygen. Such a CC CNF plant system is shown to require 219 kJ to convert one mole of CO 2 to carbon, and generates electricity at higher efficiency due to pure oxygen looped back to the gas turbine input from the CO 2 splitting, with the added advantages that (i) the CC CNF plant emits no CO 2 and (ii) all CO 2 is converted to value added carbon nanotubes useful for strong, lightweight construction, batteries and nanoelectronics. Converting to power and ton units, per metric ton of methane fuel consumed the CC CNF plant is thermodynamically assessed to produce 8350 kW h of electricity and 0.75 ton of CNT and emits no CO 2 , while the CC plant produces 9090 kW h of electricity and emits 2.74 ton CO 2 . The required energy balance for a carbon nanotube production from an analogous coal power plant consumes a larger fraction of the coal energy, and encourages co-generation with renewable electric energy.

Carbon Nano‐Onions Made Directly from CO2 by Molten Electrolysis for Greenhouse Gas Mitigation

“…[23] Carbon nano-onions can also be synthesized using arc discharge, laser ablation and plasma processes, shock compression techniques, autoclave processes (catalytic and noncatalytic), and by carbonization routes, [24] thermal pyrolysis of alcohol at high 2700 K, [25] and high fluence 120 keV implantation of carbon ions into copper and silver. In 2015 we introduced a chemistry to synthesize CNTs at high yield by electrolysis of CO 2 , [1,[29][30][31][32][33][35][36][37][38][39] rather than their conventional CVD synthesis from organometallics. [6] Challenges to the bulk production of bulk carbon nano-onions has limited their commercial availability.…”

“…[35,36] High yield, low electrolysis voltage, and high uniformity CNTs were demonstrated to be produced from dissolved CO 2 in a variety of alkali and alkali-earth carbonate electrolytes, [32,33] and straight (low defect) or tangled (high defect) were controlled through the addition or exclusion of oxide added to the molten carbonate electrolyte. [35,36] High yield, low electrolysis voltage, and high uniformity CNTs were demonstrated to be produced from dissolved CO 2 in a variety of alkali and alkali-earth carbonate electrolytes, [32,33] and straight (low defect) or tangled (high defect) were controlled through the addition or exclusion of oxide added to the molten carbonate electrolyte.…”

SO2 removal characteristics using waste CaO from calcium looping CO2 capture process

“…[6][7][8][9] Several corresponding demonstration projects have been built in Germany, Spain, Canada, and other places, and good CO 2 capture efficiency has been demonstrated. As one of the most significant GHGs, CO 2 is the key to alleviating global warming.…”

“…Therefore, CaL is considered to be one of the most promising CO 2 capture technologies and has been drawing increasing attention in the last decade. [6][7][8][9] Several corresponding demonstration projects have been built in Germany, Spain, Canada, and other places, and good CO 2 capture efficiency has been demonstrated. [10][11][12][13] Although remarkable progress has been made in calcium looping, CO 2 capture capacity of CaO-based sorbents usually decreases significantly with the increase of cycle number.…”

Effect of molten carbonate composition on the generation of carbon material

“…These ndings based on experiments strongly demonstrate the fact that ambient CO 2 could act as raw feedstock in industrial production, and this transformation provides a path to eliminate carbon dioxide emissions from power or cement plants. 39,42,43 XRD characterization (Fig. 5) was performed to reveal the crystal characteristics of the carbon product prepared at different molten salts composition, wherein no obvious sharp diffraction peak of carbon appears, signifying that the obtained carbon product in this work is mostly amorphous.…”