Grid-Connected Energy Storage Systems: State-of-the-Art and Emerging Technologies

High penetration of renewable energy resources in the power system results in various new challenges for power system operators. One of the promising solutions to sustain the quality and reliability of the power system is the integration of energy storage systems (ESSs). This article investigates the current and emerging trends and technologies for grid-connected ESSs. Different technologies of ESSs categorized as mechanical, electrical, electrochemical, chemical, and thermal are briefly explained. Especially, a detailed review of battery ESSs (BESSs) is provided as they are attracting much attention owing, in part, to the ongoing electrification of transportation. Then, the services that grid-connected ESSs provide to the grid are discussed. Grid connection of the BESSs requires power electronic converters. Therefore, a survey of popular power converter topologies, including transformer-based, transformerless with distributed or common dc-link, and hybrid systems, along with some discussions for implementing advanced grid support functionalities in the BESS control, is presented. Furthermore, the requirements of new standards and grid codes for grid-connected BESSs are reviewed for several countries around the globe. Finally, emerging technologies, including flexible power control of photovoltaic systems, hydrogen, and second-life batteries from electric vehicles, are discussed in this article.This work was supported in part by the Office of Naval Research Global under Grant N62909-19-1-2081, in part by the National Research Foundation of Singapore Investigatorship under Award NRFI2017-08, and in part by the I2001E0069 Industrial Alignment Funding. (Corresponding author: Josep Pou.

BHPR research: qualitative1. Complex reasoning determines patients' perception of outcome following foot surgery in rheumatoid arhtritis

Background: Foot surgery is common in patients with RA but research into surgical outcomes is limited and conceptually flawed as current outcome measures lack face validity: to date no one has asked patients what is important to them. This study aimed to determine which factors are important to patients when evaluating the success of foot surgery in RA Methods: Semi structured interviews of RA patients who had undergone foot surgery were conducted and transcribed verbatim. Thematic analysis of interviews was conducted to explore issues that were important to patients. Results: 11 RA patients (9 ♂, mean age 59, dis dur = 22yrs, mean of 3 yrs post op) with mixed experiences of foot surgery were interviewed. Patients interpreted outcome in respect to a multitude of factors, frequently positive change in one aspect contrasted with negative opinions about another. Overall, four major themes emerged. Function: Functional ability & participation in valued activities were very important to patients. Walking ability was a key concern but patients interpreted levels of activity in light of other aspects of their disease, reflecting on change in functional ability more than overall level. Positive feelings of improved mobility were often moderated by negative self perception ("I mean, I still walk like a waddling duck”). Appearance: Appearance was important to almost all patients but perhaps the most complex theme of all. Physical appearance, foot shape, and footwear were closely interlinked, yet patients saw these as distinct separate concepts. Patients need to legitimize these feelings was clear and they frequently entered into a defensive repertoire ("it's not cosmetic surgery; it's something that's more important than that, you know?”). Clinician opinion: Surgeons' post operative evaluation of the procedure was very influential. The impact of this appraisal continued to affect patients' lasting impression irrespective of how the outcome compared to their initial goals ("when he'd done it ... he said that hasn't worked as good as he'd wanted to ... but the pain has gone”). Pain: Whilst pain was important to almost all patients, it appeared to be less important than the other themes. Pain was predominately raised when it influenced other themes, such as function; many still felt the need to legitimize their foot pain in order for health professionals to take it seriously ("in the end I went to my GP because it had happened a few times and I went to an orthopaedic surgeon who was quite dismissive of it, it was like what are you complaining about”). Conclusions: Patients interpret the outcome of foot surgery using a multitude of interrelated factors, particularly functional ability, appearance and surgeons' appraisal of the procedure. While pain was often noted, this appeared less important than other factors in the overall outcome of the surgery. Future research into foot surgery should incorporate the complexity of how patients determine their outcome Disclosure statement: All authors have declared no conflicts of interes

Basic science232. Certolizumab pegol prevents pro-inflammatory alterations in endothelial cell function

Background: Cardiovascular disease is a major comorbidity of rheumatoid arthritis (RA) and a leading cause of death. Chronic systemic inflammation involving tumour necrosis factor alpha (TNF) could contribute to endothelial activation and atherogenesis. A number of anti-TNF therapies are in current use for the treatment of RA, including certolizumab pegol (CZP), (Cimzia ®; UCB, Belgium). Anti-TNF therapy has been associated with reduced clinical cardiovascular disease risk and ameliorated vascular function in RA patients. However, the specific effects of TNF inhibitors on endothelial cell function are largely unknown. Our aim was to investigate the mechanisms underpinning CZP effects on TNF-activated human endothelial cells. Methods: Human aortic endothelial cells (HAoECs) were cultured in vitro and exposed to a) TNF alone, b) TNF plus CZP, or c) neither agent. Microarray analysis was used to examine the transcriptional profile of cells treated for 6 hrs and quantitative polymerase chain reaction (qPCR) analysed gene expression at 1, 3, 6 and 24 hrs. NF-κB localization and IκB degradation were investigated using immunocytochemistry, high content analysis and western blotting. Flow cytometry was conducted to detect microparticle release from HAoECs. Results: Transcriptional profiling revealed that while TNF alone had strong effects on endothelial gene expression, TNF and CZP in combination produced a global gene expression pattern similar to untreated control. The two most highly up-regulated genes in response to TNF treatment were adhesion molecules E-selectin and VCAM-1 (q 0.2 compared to control; p > 0.05 compared to TNF alone). The NF-κB pathway was confirmed as a downstream target of TNF-induced HAoEC activation, via nuclear translocation of NF-κB and degradation of IκB, effects which were abolished by treatment with CZP. In addition, flow cytometry detected an increased production of endothelial microparticles in TNF-activated HAoECs, which was prevented by treatment with CZP. Conclusions: We have found at a cellular level that a clinically available TNF inhibitor, CZP reduces the expression of adhesion molecule expression, and prevents TNF-induced activation of the NF-κB pathway. Furthermore, CZP prevents the production of microparticles by activated endothelial cells. This could be central to the prevention of inflammatory environments underlying these conditions and measurement of microparticles has potential as a novel prognostic marker for future cardiovascular events in this patient group. Disclosure statement: Y.A. received a research grant from UCB. I.B. received a research grant from UCB. S.H. received a research grant from UCB. All other authors have declared no conflicts of interes

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Ni-SiO2 Catalysts for the Carbon Dioxide Reforming of Methane: Varying Support Properties by Flame Spray Pyrolysis

Silica particles were prepared by flame spray pyrolysis (FSP) as a support for nickel catalysts. The impact of precursor feed rate (3, 5 and 7 mL/min) during FSP on the silica characteristics and the ensuing effect on catalytic performance for the carbon dioxide, or dry, reforming of methane (DRM) was probed. Increasing the precursor feed rate: (i) progressively lowered the silica surface area from ≈340 m2/g to ≈240 m2/g; (ii) altered the silanol groups on the silica surface; and (iii) introduced residual carbon-based surface species to the sample at the highest feed rate. The variations in silica properties altered the (5 wt %) nickel deposit characteristics which in turn impacted on the DRM reaction. As the silica surface area increased, the nickel dispersion increased which improved catalyst performance. The residual carbon-based species also appeared to improve nickel dispersion, and in turn catalyst activity, although not to the same extent as the change in silica surface area. The findings illustrate both the importance of silica support characteristics on the catalytic performance of nickel for the DRM reaction and the capacity for using FSP to control these characteristics

Light‐Enhanced Conversion of CO2 to Light Olefins: Basis in Thermal Catalysis, Current Progress, and Future Prospects

Carbon dioxide (CO2) valorization to light olefins via sustainable energy input poses great industrial significance for the synthesis of key chemical feedstocks and reduces emission of this potent greenhouse gas. Solar energy, harnessed using light‐capturing catalytic materials, can negate external heat requirements for the energy‐intensive reaction. Presently, photothermal CO2‐Fischer–Tropsch synthesis (FTS)‐dedicated studies remain limited and are focused on the nonselective synthesis of C2+ hydrocarbons. A possible extension in catalyst design may be leveraged upon re‐examination of the better‐established thermal CO2‐FTS in conjunction with studies on photothermal FTS. To this end, herein, a narrative on the prominent chemical mechanisms and existing strategies for Fe‐based catalyst design within thermal CO2‐FTS as a foundation is established. Then, with the intent of regulating product selectivity, a gap in the adaptation of encapsulated structures involving zeolitic frameworks for CO2‐FTS is discussed. Next, current photothermal studies on C2+ hydrocarbon synthesis via FTS, CO2‐FTS, and relevant thermal‐assisted photocatalytic systems involving CO2 conversion are examined. Finally, the possible applications of structures encapsulated by porous media for boosting light utilization for photothermal CO2‐FTS are considered. Overall, the potential for the uptake of strategies aimed at producing multifunctional, light‐responsive future catalysts suitable for CO2‐FTS is explored

Role of support in photothermal carbon dioxide hydrogenation catalysed by Ni/CexTiyO2

Nickel was supported on varied ratios of ceria-titania mixed oxides (Ni/CexTiyO2) to evaluate the role the support plays in photothermal carbon dioxide hydrogenation to produce methane. In a batch photothermal reactor system, Ni/CeO2 achieved the highest conversion rate, reaching a conversion of 93% in approximately 60–90 min. To decouple the influence of light and heat, the CO2 hydrogenation was examined in an in-house designed photothermal reactor, whereby heat can be applied externally. Decoupling experiments revealed that heat from the thermalisation by light was the main driving force for the reaction. In addition, the conversion and temperature profile of the different catalysts revealed that the catalyst performance was governed by catalyst reducibility. H2-TPR analyses showed that the Ni became more readily reducible with increasing CeO2 content, suggesting that the oxide plays a role in activating the Ni. The reduction temperature of the nickel catalyst (following a reduction and passivation process) was below 200 °C, which meant that the inherent heating temperature of the photothermal reactor was sufficient to initiate Ni/CexTiyO2 catalyst activity. The exothermic methanation reaction was then able to heat the system further, ultimately reaching a temperature of 285 °C. The ancillary rise in temperature promotes further nickel reduction and methane formation, leading to a “snow-ball” effect. The findings demonstrate that, to achieve a “snow-ball” effect in a photothermal system, designing a catalyst which is easy to reduce, active for CO2 hydrogenation, and capable of converting light to heat for its initial activation is critical. Keywords: Photothermal, CO2 Methanation, Ceria, Titania, Nickel, Reducibilit

Low-Temperature CO2 Methanation: Synergistic Effects in Plasma-Ni Hybrid Catalytic System

Thermodynamic and kinetic limitations can restrict the feasibility and scalability of conventional catalytic processes for CO2 methanation at the industrial level. Due to its nonequilibrium nature, nonthermal plasma (NTP) promises to reduce reaction barriers and make this gas conversion approach viable even at low temperatures. However, the current understanding of the fundamental chemical and physical behaviors in the hybrid plasma catalytic interactions is insufficient. This study demonstrates plasma-driven CO2 conversions approaching the reaction equilibrium with high methane yields even at low temperature (150 °C). It was observed that the addition of plasma to the catalytic bed enhanced the CO2 conversion around 20 times relative to thermal activity, whereas the CH4 selectivity increased around 5 times by introducing the nickel catalyst into plasma discharge compared to plasma only (at 150 °C). Moreover, the findings provide new insights into the gas phase activation of reactants (CO2 and H2) and the reaction over Ni0 to decouple the plasma and catalyst synergy. The catalyst did not undergo significant structural changes under plasma discharge, apart from a slight decrease in Ni crystallite size, while an enhanced metal dispersion was evident (24% to 42%, from CO pulse chemisorption). The optimized system achieved a CO2 conversion of 60% with a CH4 selectivity of over 97% at 150 °C, which required much higher temperatures (320-330 °C) to achieve equivalent conversion in thermal catalysis. This study is a step toward an understanding and effective control of the plasma enhanced catalytic CO2 transformation via low energy reaction pathways that utilize the NTP for low-temperature CO2 methanation with high conversion, selectivity, stability, and controllability.</p

Two Steps Back, One Leap Forward : Synergistic Energy Conversion in Plasmonic and Plasma Catalysis

Hybrid catalytic systems are poised to maximize the efficiency of energy conversion. When coupling heat with visible light or plasma sources, known thermally active catalysts are commonly used. The question becomes whether adapting thermally activated catalysts to hybrid energy systems is the ideal strategy. Differences in reaction pathways, including how the energy is exchanged within hybrid systems, mean new catalyst design approaches are needed. To enable a leap forward in designing hybrid systems and accelerate effective plasma/light catalyst development, there is a need to take two steps back to (i) revise the current strategies used to design appropriate catalysts and (ii) identify the criteria critical to regulating system behavior. Spotlighting carbon dioxide valorization, current routes to catalyst design for hybrid systems are evaluated. As these systems are playing an ever-increasing role in a clean energy future, catalyst design strategies involving ongoing retrospection and realignment toward prevailing energy coupling/conversion mechanisms are discussed to facilitate the leap forward.</p