Environmental sustainability of cellulose-supported solid ionic liquids for CO2 capture

Solid ionic liquids (SoILs) with cellulose as a support have been demonstrated recently to be effective and low-cost sorbents for CO2 capture. However, at present it is not clear whether they remove more CO2 than is released in the rest of the life cycle, including their manufacture, regeneration and disposal. It is also unknown what other impacts they may have over the whole life cycle while attempting to mitigate climate change. Therefore, this study evaluates for the first time the life cycle environmental sustainability of cellulose-supported SoILs in comparison with unsupported SoILs and some other sorbents. Four SoILs are assessed for 11 life cycle impacts, including global warming potential (GWP), with and without the cellulose support: methyltrioctyl ammonium acetate ([N1888][Ac]), tetraethyl ammonium acetate ([N4444][Ac]), tetra-octylammonium bromide ([N8888]Br) and 1-butyl-4-methylimidazolium bromide ([Bmim]Br). They are compared with one of the ILs in the liquid state (trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][124Triz])) and with three conventional sorbents: monoethanolamine (MEA), zeolite powder and activated carbon. The results show that SoILs with cellulose loading in the range of 70%–80 wt% have better environmental performance per unit mass of CO2 captured than the unsupported SoILs. The net removal of CO2 eq. over the life cycle ranges from 20% for pure [Bmim]Br to 83% for [N1888][Ac] with 75% cellulose and for [N4444][Ac] with both 75% and 80% loadings. However, pure [N8888]Br generates three times more CO2 eq. over the life cycle than it removes. Among the SoILs, [N4444][Ac] with 80% cellulose has the lowest life cycle impacts for eight out of 11 categories. When compared to the conventional sorbents, it has significantly higher impacts, including GWP. However, it is more sustainable than [P66614][124Triz]. The results of this study can be used to target the hotspots and improve the environmental performance of cellulose-supported SoILs through sustainable design

Kinetic and economic analysis of reactive capture of dilute carbon dioxide with Grignard reagents

Carbon Dioxide Utilisation (CDU) processes face significant challenges, especially in the energetic cost of carbon capture from flue gas and the uphill energy gradient for CO2 reduction. Both of these stumbling blocks can be addressed by using alkaline earth metal compounds, such as Grignard reagents, as sacrificial capture agents. We have investigated the performance of these reagents in their ability to both capture and activate CO2 directly from dried flue gas (essentially avoiding the costly capture process entirely) at room temperature and ambient pressures with high yield and selectivity. Naturally, to make the process sustainable, these reagents must then be recycled and regenerated. This would potentially be carried out using existing industrial processes and renewable electricity. This offers the possibility of creating a closed loop system whereby alcohols and certain hydrocarbons may be carboxylated with CO2 and renewable electricity to create higher-value products containing captured carbon. A preliminary Techno-Economic Analysis (TEA) of an example looped process has been carried out to identify the electrical and raw material supply demands and hence determine production costs. These have compared broadly favourably with existing market values

A novel approach to ammonia synthesis from hydrogen sulfide

There are a number of shortcomings for currently-available technologies for ammonia production, such as carbon dioxide emissions and water consumption. We simulate a novel model for ammonia production from hydrogen sulfide through membrane technologies. The proposed production process decreases the need for external water and reduces the physical footprint of the plant. The required hydrogen comes from the separation of hydrogen sulfide by electrochemical membrane separation, while the required nitrogen is obtained from separating oxygen from air through an ion transport membrane. 10% of the hydrogen from the electrochemical membrane separation along with the separated oxygen from the ion transport membrane is sent to the solid oxide fuel cell for heat and power generation. This production process operates with a minimal number of processing units and in physical, kinetic, and thermal conditions in which a separation factor of ~99.99% can be attained

Plasma-based CO2 conversion

The conversion of CO2 to chemicals and consumables is a pioneering approach to utilize undesired CO2 emissions and simultaneously create new products out of sustainable feedstock. Volume 1 gives an introduction to CO2 chemistry, utilisation and sustainability and further discusses its capture and separation. Volume 2 describes several routes to transform CO2 into various compounds by catalytic and electrochemical as well as photo- and plasma induced reactions. The set combines fundamentals of CO2 chemistry, its capture and separation as well transformative reactions. Both volumes are available individually: Vol1: ISBN 978-3-11-056309-2 and Vol2: 978-3-11-066503-1. Both volumes are also included in a set ISBN 978-3-11-066549-9. Vol2, Part VI: Photo- and plasma induced reactions of CO, Chapter 28.</p

Electron Transfer from Cyt b559 and Tyrosine-D to the S2 and S3 states of the water oxidizing complex in Photosystem II at Cryogenic Temperatures

The Mn4CaO5 cluster of photosystem II (PSII) catalyzes the oxidation of water to molecular oxygen through the light-driven redox S-cycle. The water oxidizing complex (WOC) forms a triad with Tyrosine(Z) and P-680, which mediates electrons from water towards the acceptor side of PSII. Under certain conditions two other redox-active components, Tyrosine(D) (Y-D) and Cytochrome b (559) (Cyt b (559)) can also interact with the S-states. In the present work we investigate the electron transfer from Cyt b (559) and Y-D to the S-2 and S-3 states at 195 K. First, Y-D (aEuro cent) and Cyt b (559) were chemically reduced. The S-2 and S-3 states were then achieved by application of one or two laser flashes, respectively, on samples stabilized in the S-1 state. EPR signals of the WOC (the S-2-state multiline signal, ML-S-2), Y-D (aEuro cent) and oxidized Cyt b (559) were simultaneously detected during a prolonged dark incubation at 195 K. During 163 days of incubation a large fraction of the S-2 population decayed to S-1 in the S-2 samples by following a single exponential decay. Differently, S-3 samples showed an initial increase in the ML-S-2 intensity (due to S-3 to S-2 conversion) and a subsequent slow decay due to S-2 to S-1 conversion. In both cases, only a minor oxidation of Y-D was observed. In contrast, the signal intensity of the oxidized Cyt b (559) showed a two-fold increase in both the S-2 and S-3 samples. The electron donation from Cyt b (559) was much more efficient to the S-2 state than to the S-3 state

From Traditional Farming in Morocco to Early Urban Agroecology in Northern Mesopotamia: Combining Present-day Arable Weed Surveys and Crop Isotope Analysis to Reconstruct Past Agrosystems in (Semi-)arid Regions

Published by Informa UK Limited, trading as Taylor & Francis GroupWe integrate functional weed ecology with crop stable carbon and nitrogen isotope analysis to assess their combined potential for inferring arable land management practices in (semi-)arid regions from archaeobotanical assemblages. Weed and GIS survey of 60 cereal and pulse fields in Morocco are combined with crop sampling for stable isotope analysis to frame assessment of agricultural labour intensity in terms of manuring, irrigation, tillage and hand-weeding. Under low management intensity weed variation primarily reflects geographical differences, whereas under high management intensity fields in disparate regions have similar weed flora. Manured and irrigated oasis barley fields are clearly discriminated from less intensively manured rain-fed barley terraces in southern Morocco; when fields in northern and southern Morocco are considered together, climatic differences are superimposed on the agronomic intensity gradient. Barley δ13C and δ15N values clearly distinguish among the Moroccan regimes. An integrated approach combines crop isotope values with weed ecological discrimination of low- and high-intensity regimes across multiple studies (in southern Morocco and southern Europe). Analysis of archaeobotanical samples from EBA Tell Brak, Syria suggests that this early city was sustained through extensive (low-intensity, large-scale) cereal farming

Carbon footprint of Power-to-X derived dimethyl ether using the sorption enhanced DME synthesis process

Dimethyl ether (DME) could have a promising future as a sustainable diesel fuel replacement as it requires only relatively minor engine modifications. It can be produced from renewable H2 and captured CO2 using Power-to-X technologies. To gain support through the EU Renewable Energy Directive, the production and use of CO2-derived DME as a fuel needs to produce emission savings of at least 70% over the petrodiesel alternative. This study assesses the carbon footprint of producing DME via the sorption-enhanced DME synthesis (SEDMES) process and using it as a transport fuel, compared to producing and using fossil-based petrodiesel. The cradle-to-grave (well-to-wheel) carbon footprint of using DME as a transport fuel is found to be 77% lower than for petrodiesel, if offshore wind power is used for H2 synthesis and DME production. If renewable energy is also used for CO2 capture and waste heat is used for the DME production and purification steps, the DME carbon footprint has the potential to be over 90% lower than that of the fossil-fuel comparator

Manuring and stable nitrogen isotope ratios in cereals and pulses: towards a new archaeobotanical approach to the inference of land use and dietary practices

This paper explores the impact of animal manure application on the δ15N values of a broad range of crops (cereals and pulses), under a range of manuring levels/regimes and at a series of locations extending from northwest Europe to the eastern Mediterranean. We included both agricultural field experiments and areas where ‘traditional’ farming is practised. Our aim is to ground-truth interpretation of δ15N values in archaeobotanical crop remains as evidence of past growing conditions and husbandry practices. The results confirm the potentially radical impact of manuring on δ15N values in cereals, depending on manuring level, but indicate only a slight effect on pulses, which can fix atmospheric nitrogen. The expected geographical trend towards greater δ15N with increasing climatic aridity is not apparent, probably because the growing conditions for crops are ‘buffered’ through crop management. Each of these observations has fundamental implications for archaeobotanical interpretation of δ15N values as evidence of land use practices and (together with analysis of bone collagen/tooth enamel in potential consumers) palaeodiet