Clean Energy Engineering publications
Latest papers
Evaluating the climate impact of aviation emission scenarios towards the Paris Agreement including COVID-19 effects
Abstract
Aviation is an important contributor to the global economy, satisfying society’s mobility needs. It contributes to climate change through CO2 and non-CO2 effects, including contrail-cirrus and ozone formation. There is currently significant interest in policies, regulations and research aiming to reduce aviation’s climate impact. Here we model the effect of these measures on global warming and perform a bottom-up analysis of potential technical improvements, challenging the assumptions of the targets for the sector with a number of scenarios up to 2100. We show that although the emissions targets for aviation are in line with the overall goals of the Paris Agreement, there is a high likelihood that the climate impact of aviation will not meet these goals. Our assessment includes feasible technological advancements and the availability of sustainable aviation fuels. This conclusion is robust for several COVID-19 recovery scenarios, including changes in travel behaviour.
Experimental and quantum chemical investigation into the nature of jet fuel deposition on surfaces
Abstract
Chemical analysis of undissolved deposits formed on a simulated jet fuel burner feed arm suggest a higher concentration of oxidized polar fuel species at the wall-deposit interface. To investigate the nature of their adsorption, the adsorption energies of various jet fuel species classes were calculated using plane-wave DFT methods on two oxide surfaces FeO-(0001) and CrO-(0001), which were chosen to represent a stainless steel surface. A mixed termination approach was chosen to encapsulate the heterogeneous nature of stainless steel surfaces. On metal-terminated FeO and CrO surfaces, the order of the absolute adsorption energies was RSOH, RSOH, RCOOH, RSH, ROH, RCOH, RH. Dissociative chemisorption was observed for all the acid species, with sulfur acids having a higher absolute adsorption energy on CrO but carboxylic acids having a higher adsorption energy on FeO. On oxygen-terminated FeO, the order of the absolute adsorption energies was RSOH, RSR, RSOH, RSH, ROH, RCOH, RCOOH, RH. On the other hand, for oxygen-terminated CrO, the order of the absolute adsorption energies were RSOH, RSR, RSH, RSOH, RCOH, ROH, RCOOH, RH. In contrast to the metal terminated surface, acids do not chemisorb on the oxygen terminated surfaces. Instead, the sulfur acids are found to form surface hydroxyl species from the dissociation of the acidic -OH group. The reactivity of the surfaces followed the general pattern: metal terminated-FeO metal-terminated CrO, oxygen-terminated FeO CrO. Overall, a combination of experimental and quantum chemical techniques confirmed the theory that sulfur acids are the initial species to deposit on stainless steel.