Showing papers by "Cranfield University published in 2021"

Global terrestrial water storage and drought severity under climate change

Abstract: Terrestrial water storage (TWS) modulates the hydrological cycle and is a key determinant of water availability and an indicator of drought. While historical TWS variations have been increasingly studied, future changes in TWS and the linkages to droughts remain unexamined. Here, using ensemble hydrological simulations, we show that climate change could reduce TWS in many regions, especially those in the Southern Hemisphere. Strong inter-ensemble agreement indicates high confidence in the projected changes that are driven primarily by climate forcing rather than land and water management activities. Declines in TWS translate to increases in future droughts. By the late twenty-first century, the global land area and population in extreme-to-exceptional TWS drought could more than double, each increasing from 3% during 1976–2005 to 7% and 8%, respectively. Our findings highlight the importance of climate change mitigation to avoid adverse TWS impacts and increased droughts, and the need for improved water resource management and adaptation.

Piezoelectric Materials for Energy Harvesting and Sensing Applications: Roadmap for Future Smart Materials

Abstract: Piezoelectric materials are widely referred to as "smart" materials because they can transduce mechanical pressure acting on them to electrical signals and vice versa. They are extensively utilized in harvesting mechanical energy from vibrations, human motion, mechanical loads, etc., and converting them into electrical energy for low power devices. Piezoelectric transduction offers high scalability, simple device designs, and high-power densities compared to electro-magnetic/static and triboelectric transducers. This review aims to give a holistic overview of recent developments in piezoelectric nanostructured materials, polymers, polymer nanocomposites, and piezoelectric films for implementation in energy harvesting. The progress in fabrication techniques, morphology, piezoelectric properties, energy harvesting performance, and underpinning fundamental mechanisms for each class of materials, including polymer nanocomposites using conducting, non-conducting, and hybrid fillers are discussed. The emergent application horizon of piezoelectric energy harvesters particularly for wireless devices and self-powered sensors is highlighted, and the current challenges and future prospects are critically discussed.

Globally observed trends in mean and extreme river flow attributed to climate change

Abstract: Anthropogenic climate change is expected to affect global river flow Here, we analyze time series of low, mean, and high river flows from 7250 observatories around the world covering the years 1971 to 2010 We identify spatially complex trend patterns, where some regions are drying and others are wetting consistently across low, mean, and high flows Trends computed from state-of-the-art model simulations are consistent with the observations only if radiative forcing that accounts for anthropogenic climate change is considered Simulated effects of water and land management do not suffice to reproduce the observed trend pattern Thus, the analysis provides clear evidence for the role of externally forced climate change as a causal driver of recent trends in mean and extreme river flow at the global scale

Expert assessment of future vulnerability of the global peatland carbon sink

Abstract: The carbon balance of peatlands is predicted to shift from a sink to a source this century. However, peatland ecosystems are still omitted from the main Earth system models that are used for future climate change projections, and they are not considered in integrated assessment models that are used in impact and mitigation studies. By using evidence synthesized from the literature and an expert elicitation, we define and quantify the leading drivers of change that have impacted peatland carbon stocks during the Holocene and predict their effect during this century and in the far future. We also identify uncertainties and knowledge gaps in the scientific community and provide insight towards better integration of peatlands into modelling frameworks. Given the importance of the contribution by peatlands to the global carbon cycle, this study shows that peatland science is a critical research area and that we still have a long way to go to fully understand the peatland–carbon–climate nexus. Peatlands are impacted by climate and land-use changes, with feedback to warming by acting as either sources or sinks of carbon. Expert elicitation combined with literature review reveals key drivers of change that alter peatland carbon dynamics, with implications for improving models.

National growth dynamics of wind and solar power compared to the growth required for global climate targets

Abstract: Climate mitigation scenarios envision considerable growth of wind and solar power, but scholars disagree on how this growth compares with historical trends. Here we fit growth models to wind and solar trajectories to identify countries in which growth has already stabilized after the initial acceleration. National growth has followed S-curves to reach maximum annual rates of 0.8% (interquartile range of 0.6–1.1%) of the total electricity supply for onshore wind and 0.6% (0.4–0.9%) for solar. In comparison, one-half of 1.5 °C-compatible scenarios envision global growth of wind power above 1.3% and of solar power above 1.4%, while one-quarter of these scenarios envision global growth of solar above 3.3% per year. Replicating or exceeding the fastest national growth globally may be challenging because, so far, countries that introduced wind and solar power later have not achieved higher maximum growth rates, despite their generally speedier progression through the technology adoption cycle. Growth of wind and solar energy share demonstrates different dynamics between the initial phases of adoption as compared with the advanced stages. Cherp et al. study the growth dynamics of renewable energy and show that laggards may continue to struggle to achieve high growth rates despite learning from early adopters’ experience.

Hydrogen Production, Distribution, Storage and Power Conversion in a Hydrogen Economy - A Technology Review

Abstract: To meet ambitious targets for greenhouse gas emissions reduction in the 2035-2050 timeframe, hydrogen has been identified as a clean “green” fuel of interest. In comparison to fossil fuel use the burning of hydrogen results in zero CO2 emissions and it can be obtained from renewable energy sources. In addition to zero CO2 emissions, hydrogen has several other attractive properties such as higher gravimetric energy content and wider flammability limits than most fossil fuels. However, there are practical limitations to its widespread use at present which include low volumetric energy density in the gaseous state and high well-to-wheel costs when compared to fossil fuel production and distribution. In this paper a review is undertaken to identify the current state of development of key areas of the hydrogen network such as production, distribution, storage and power conversion technology. At present high technology costs still are a barrier to widespread hydrogen adoption but it is envisioned that as scale of production increases, then costs are likely to fall. Technical barriers to a hydrogen economy adoption are not as significant as one might think as key technologies in the hydrogen network are already mature with working prototypes already developed for technologies such as liquid hydrogen composite cryotanks and proton exchange membrane fuel cells. It is envisioned that with continuous investment to achieve requisite scale that a hydrogen economy could be realised sooner rather than later with novel concepts such as turboelectric distributed propulsion enabled by a shift to hydrogen-powered network.

Agriculture's Contribution to Climate Change and Role in Mitigation Is Distinct From Predominantly Fossil CO2-Emitting Sectors.

Abstract: Agriculture is a significant contributor to anthropogenic global warming, and reducing agricultural emissions – largely methane and nitrous oxide – could play a significant role in climate change mitigation. However, there are important differences between carbon dioxide (CO2) which is a stock pollutant, and methane (CH4) which is predominantly a flow pollutant. These dynamics mean that conventional reporting of aggregated CO2-equivalent emission rates is highly ambiguous, and does not straightforwardly reflect historical or anticipated contributions to global temperature change. As a result, the roles and responsibilities of different sectors emitting different gases are similarly obscured by the common means of communicating emission reduction scenarios using CO2-equivalence. We argue for a shift in how we report agricultural greenhouse gas emissions and think about their mitigation to better reflect the distinct roles of different greenhouse gases. Policy-makers, stakeholders and society at large should also be reminded that the role of agriculture in climate mitigation is a much broader topic than climate science alone can inform, including considerations of economic and technical feasibility, preferences for food supply and land-use, and notions of fairness and justice. A more nuanced perspective on the impacts of different emissions could aid these conversations.

QoE-Aware Efficient Content Distribution Scheme for Satellite-Terrestrial Networks

Abstract: The satellite-terrestrial networks (STN) utilize the spacious coverage and low transmission latency of Low Earth Orbit (LEO) constellation to distribute requested content for ground subscribers. With the development of storage and computing capacity of satellite onboard equipment, it is considered promising to leverage in-network caching technology on STN to improve content distribution efficiency. However, traditional ground network caching schemes are not suitable in STN, considering dynamic satellite propagation and time-varying topology. More specifically, the unevenness of user distribution results in difficulties for assurance of quality of experience. To address these problems, we firstly propose a density-based block division algorithm to divide the content subscribers into a series of blocks with different sizes according to user density. The LEO satellite orbit and time-varying network model is established to describe STN topology. Next, we propose an approximate minimum coverage vertex set algorithm and a novel cache node selection algorithm for optimal user blocks matching. The simulation results prove that the proposed density-based content distribution method can obviously reduce the average transmission delay of content distribution under different network conditions and has better stability and self-adaptability under continuous time variation.

Blockchain adoption in food supply chains: a review and implementation framework

Abstract: Blockchain technology has received significant attention from the food industry; however, due to the scarcity of successful Blockchain projects and sector-specific studies, a step-by-step approach ...

Does green public procurement encourage firm's environmental certification practice? The mediation role of top management support

Abstract: The environmental certification acts as a sustainable practice for firms to improve their competitive advantage and its motivation has been widely discussed. However, existing researches ignore the important market driving force of green public procurement (GPP) as a policy tool. To fill this gap, this study, focusing on manufacturing firms in China and three typical environmental certifications, explores the relationship between GPP market pressure and firm's environmental certification practice based on institutional theory. Additionally, from a strategic perspective of green human resource management, this study unveils the influence mechanism of top management support in this relationship by using upper echelons theory. According to the empirical results, we find that GPP market pressure is positively associated with environmental certification practice, and top management support partially mediates this relationship. This study provides new insights into the explanation of firm's environmental certification practice, and provides practical implications for firm managers and government administrator.

Sorption-enhanced Steam Methane Reforming for Combined CO2 Capture and Hydrogen Production: A State-of-the-Art Review

Abstract: The European Commission have just stated that hydrogen would play a major role in the economic recovery of post-COVID-19 EU countries. Hydrogen is recognised as one of the key players in a fossil fuel-free world in decades to come. However, commercially practiced pathways to hydrogen production todays, are associated with a considerable amount of carbon emissions. The Paris Climate Change Agreement has set out plans for an international commitment to reduce carbon emissions within the forthcoming decades. A sustainable hydrogen future would only be achievable if hydrogen production is “designed” to capture such emissions. Today, nearly 98% of global hydrogen production relies on the utilisation of fossil fuels. Among these, steam methane reforming (SMR) boasts the biggest share of nearly 50% of the global generation. SMR processes correspond to a significant amount of carbon emissions at various points throughout the process. Despite the dark side of the SMR processes, they are projected to play a major role in hydrogen production by the first half of this century. This that a sustainable, yet clean short/medium-term hydrogen production is only possible by devising a plan to efficiently capture this co-produced carbon as stated in the latest International Energy Agency (IEA) reports. Here, we have carried out an in-depth technical review of the processes employed in sorption-enhanced steam methane reforming (SE-SMR), an emerging technology in low-carbon SMR, for combined carbon capture and hydrogen production. This paper aims to provide an in-depth review on two key challenging elements of SE-SMR i.e. the advancements in catalysts/adsorbents preparation, and current approaches in process synthesis and optimisation including the employment of artificial intelligence in SE-SMR processes. To the best of the authors’ knowledge, there is a clear gap in the literature where the above areas have been scrutinised in a systematic and coherent fashion. The gap is even more pronounced in the application of AI in SE-SMR technologies. As a result, this work aims to fill this gap within the scientific literature.

Blockchain technology’s impact on supply chain integration and sustainable supply chain performance: Evidence from the automotive industry

Abstract: The study investigates the relationship between the information and communication-enabled supply chain integration (SCI) and sustainable supply chain performance (SSCP). Moreover, to the best of our knowledge, there is no empirical evidence on the impact of blockchain technologies (BT) on the SSCP. Therefore, the primary aim of this study is to assess the relationship between BT and SSCP. More specifically, the study was conducted to examine the direct influence of BT on SCI and SSCP and the interactive effect of BT and SCI on SSCP. Based on the dynamic capability theoretical lens, the present study conceptualizes the use of BT as a specific IT resource to collaborate and reconfigure the ties with the upstream and downstream supply chain members to achieve SSCP. The results of the study support the hypothesis stating that BT positively influences the SSCP. The results recognize the role of SCI as a significant mediating variable between the BT and SSCP. The result indicates the strong influence of SCI with full mediation effect on the relationship between the BT and SSCP.

Global changes in 20‐year, 50‐year, and 100‐year river floods

Abstract: Concepts like the 100-year flood event can be misleading if they are not updated to reflect significant changes over time. Here, we model observed annual maximum daily streamflow using a nonstationary approach to provide the first global picture of changes in: (a) the magnitudes of the 20-, 50-, and 100-year floods (i.e., flows of a given exceedance probability in each year); (b) the return periods of the 20-, 50-, and 100-year floods, as assessed in 1970 (i.e., flows of a fixed magnitude); and (c) corresponding flood probabilities. Empirically, we find the 20-/50-year floods have mostly increased in temperate climate zones, but decreased in arid, tropical, polar, and cold zones. In contrast, 100-year floods have mostly decreased in arid/temperate zones and exhibit mixed trends in cold zones, but results are influenced by the small number of stations with long records, and highlight the need for continued updating of hazard assessments.

Quantifying the impact of the COVID-19 lockdown on household water consumption patterns in England

Abstract: The COVID-19 lockdown has instigated significant changes in household behaviours across a variety of categories including water consumption, which in the south and east regions of England is at an all-time high. We analysed water consumption data from 11,528 households over 20 weeks from January 2020, revealing clusters of households with distinctive temporal patterns. We present a data-driven household water consumer segmentation characterising households’ unique consumption patterns and we demonstrate how the understanding of the impact of these patterns of behaviour on network demand during the COVID-19 pandemic lockdown can improve the accuracy of demand forecasting. Our results highlight those groupings with the highest and lowest impact on water demand across the network, revealing a significant quantifiable change in water consumption patterns during the COVID-19 lockdown period. The implications of the study to urban water demand forecasting strategies are discussed, along with proposed future research directions.

A review on the progress and challenges of binder jet 3D printing of sand moulds for advanced casting

Abstract: 3D sand mould printing using binder jet technology can enable many technical improvements in casting practice, including part consolidation, design of parts to optimise the consumption of materials and hazardous chemicals, and on-demand and flexible size part manufacturing near the customer. Incorporating artificial intelligence in optimising the design of moulds, printing process parameters, and solidification processes may help automate a production facility and reduce labour time. Elimination of hazardous chemicals from industrial use may be a challenge. Therefore, an alternative technology to fuse the sand particles during printing or an environmentally friendlier alternative option for the binders and other consumables should be utilised with the 3D sand printing process. Properties of parts produced using 3D printed sand moulds have the potential to be better than the properties of parts produced using traditional casting due to this technology's benefits. This technology is an enabling technology for traditional casting processes rather than a competing technology. It is causing a paradigm shift in casting design because of the mould geometries achievable by using additive manufacturing to produce the sand mould. This paper reviews the first twenty years of research and challenges in developing 3D sand printing processes as an innovation for sustainable manufacturing.

Soil spectroscopy with the use of chemometrics, machine learning and pre-processing techniques in soil diagnosis: Recent advances–A review

Abstract: Over the past two decades soil spectroscopy, particularly, in the infrared range, is becoming a powerful technique to simplify analysis relative to the traditional chemical methods. It is known as a rapid, cost-effective, quantitative and eco-friendly technique, which can provide hyperspectral data with narrow and numerous wavebands, both in the laboratory and in the field. In this context, the present article reviews the recent developments in mid and near infrared techniques coupled with chemometrics and machine learning tools in addition to the preprocessing transformations and variable selection strategies to diagnose soil physical and chemical properties. Both spectral techniques demonstrated a good ability to provide accurate predictions of specific properties. Moreover, the MIR spectroscopy outperformed NIR for the estimation of most indicators used for fertilizers recommendation. Herein, a detailed overview on the opportunities and challenges that soil spectroscopy offers as efficient diagnostic tool in soil science was provided.