Sequential Oxygen Reduction and Adsorption for Carbon Dioxide Purification for Flue Gas Applications
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Energy & Fuels↗
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Transcriptome and metabolome integration in sugarcane through culm development
Abstract Sugarcane (Saccharum sp.) is a tropical and subtropical C4 plant with a high photosynthetic and carbon assimilation efficiency that stores sucrose. Culm biomass is also composed of bagasse fibre, a by‐product of the sugarcane industry. This high‐yielding grass, high in sucrose and lignocellulosic biomass, is considered an optimal feedstock as an alternative to fossil fuels and to produce a broad range of high‐value biomaterials. The ideal sugarcane production system would optimise the relative production of sugar and these new products. Multi‐omics correlation analysis was used to generate a global view of the essential metabolic pathways identifying critical genes involved in carbon partitioning during different stages of development. This research employed an unprecedented metabolic and transcriptomic dataset of 360 samples from a selection of 1440 culms of 24 genotypes at five different development stages. Chemical composition and metabolome analysis showed an increase through the culm development of lignin, sucrose, carbon, and amino acids such as aspartic acid, serine, alanine, methionine, threonine 3‐cyano‐L‐alanine, and citric acid. Transcriptome analysis revealed functionalities such as transcription, nucleotide transport and metabolism, and the biosynthesis of amino acids that are highly activated during the immature stage and highly down‐regulated during the most mature age.
Perlo, Virginie↗
How the low price of oil can spur CCS research innovation
The global consumption of oil grew in 2015 as prices fell due to oversupply. Low oil prices are problematic for greenhouse gas (GHG) reduction efforts because they tend to discourage use of energy-efficient vehicles and encourage driving and related CO 2 emissions. From this perspective, low oil prices would seem to be entirely detrimental to lowering GHG emissions. When you factor in the fact that low oil prices have reduced oil-company-sponsored funding for carbon capture and storage (CCS) research efforts which aim to develop safe and feasible ways to reduce GHG emissions from the use of fossil fuels, the picture for lowering GHG emissions seems even gloomier. But there is at least one potential silver lining in low oil prices for CCS research and development, and this involves utilization, and in particular, geologic interim storage of CO 2 .
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Bringing research findings to the real world is an essential and rewarding experience
The pending changes in the U.S. presidential administration and Congress threaten the ongoing progress being made in lowering U.S. greenhouse gas (GHG) emissions. Yet the need for reducing emissions and directly addressing the energy-climate crisis has never been greater. The energy-climate crisis is defined as the situation created by reliance on fossil fuels for 80% of global energy supply, the combustion of which releases CO 2 , the main greenhouse gas causing global warming. Instead of allowing the U.S. national political situation to be a distraction, scientists, engineers, and policy experts need to push even harder to turn research findings into practical applications so those findings can contribute to actually reducing emissions. In addition, scientists and engineers need to communicate research results to lawmakers and the public to reinforce the urgency of directly addressing the energy-climate crisis. Without giving away still-developing conclusions of the ongoing project, this paper describes that facilitating practical application of research results can be a very rewarding and satisfying experience.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Carbon capture, utilization, and storage hub development on the Gulf Coast
Abstract The Gulf Coast of the United States hosts diverse power generation, refining, and petrochemical processing facilities, resulting in the nation's largest volumetric concentration of industrial CO 2 emissions, rivaled only by the Ohio River Valley. These emissions sources are concentrated in specific industrial clusters that allow combining emissions streams to achieve economies of scale. The region is currently undergoing globally significant industrial expansion and investment as a result of abundant and inexpensive regional unconventional natural gas availability, and is a growing exporter of liquefied natural gas (LNG). Opportunities to integrate CO 2 emission management within the diverse energy chains in the region are volumetrically significant and include both concentrated and dilute sources. Significant examples of capture, transport, and storage exist. Offshore storage is particularly attractive, as it provides simplified land leasing models (single governmental land owner), proven reservoir quality, and presents fewer risks to both protected groundwater and populated areas. Projects can now take advantage of recently expanded opportunities under section 45Q of the Internal Revenue Service tax code. The region continues to evolve as an active carbon‐handling hub, and is uniquely suited to justify additional investment in carbon capture, utilization, and storage (CCUS) technologies via a large‐scale integrated project development. Continued development of integrated projects will allow the region to continue to grow economically within its strong fossil‐fuel handling competence focus while advancing low‐carbon energy technologies that maintain globally competitiveness. © 2021 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.
45Q↗
Quantifying adherence of oxide scales on steels exposed to high temperature and pressure steam
Oxide scale exfoliation is a major concern in fossil fuel power generation because it can cause tube blockages and erode valves and steam turbine components downstream. There is still considerable scientific and commercial interest to improve the mechanistic understanding of oxide failures by developing models to predict exfoliation and the extent of tube blockage as a function of operating conditions and component geometries. Tensile testing inside a scanning electron microscope was conducted on ferritic–martensitic and austenitic steel specimens with the steam side (Fe,Cr)-rich oxides grown after exposures for up to 1000 h in steam with ~100 ppb O 2 at 276 bar and 550°C. Multiple oxide layer cracks and delamination events were observed and analyzed in detail during the tests. Results from the testing agreed well with earlier observations that had identified the failure location at the outer–inner oxide layer for all tested materials. Calculated adhesion energies identified the outer–inner oxide interface of alloy 347HFG as the weakest interface.
36 MATERIALS SCIENCE↗
Polyolefin Innovations Toward Circularity and Sustainable Alternatives
The unprecedented growth and socioeconomic impacts of polyolefins clearly outline a major success story in the world of polymer science. Polyolefins revolutionizes industries such as health care, construction, and food packaging. Despite the benefits of polyolefins, there is a rising concern for the environment due to high production volume (i.e., fossil fuel consumption), often short usage time, and problems related to waste management and accumulation in the natural environment. Creating a circular economy for polyolefins through effective recycling technologies has the potential to decrease the environmental impact of these materials. This perspective discusses polyolefins and their impact, existing and emerging recycling/upcycling solutions, and recycle-by-design alternatives that are challenging the status quo.
circular economy↗
Updated sustainability status of cadmium telluride thin‐film photovoltaic systems and projections
This paper provides a comprehensive assessment of the up-to-date life-cycle sustainability status of cadmium-telluride based photovoltaic (PV) systems. Current production modules (Series 6 and Series 7) are analyzed in terms of their energy performance and environmental footprint and compared with the older series 4 module production and current single-crystalline Silicon (sc-Si) module production. For fixed-tilt systems with Series 6 modules operating under average US irradiation of 1800 kWh/m 2 /year, the global warming potential (GWP) is reduced from 16 g CO 2eq /kWh in Series 4 systems to 10 CO 2 eq /kWh in Series 6 systems. For operation in US-SW irradiation of 2300 kWh/m 2 /year, the GWP is reduced from 11 to 8 CO 2eq /kWh and for 1-axis tracking systems operating in Phoenix, Arizona, with point-of array irradiation of 3051 kWh/m 2 /year the GWP is reduced to 6.5 CO 2eq /kWh. Similar reductions have happened in all environmental indicators. Energy payback times (EPBT) of currently installed systems range from 0.6 years for fixed–tilt ground–mounted installations at average US irradiation at latitude tilt installations to 0.3 years for one-axis trackers at high US-SW irradiation, considering average fossil-fuel dominated electricity grids with fuel to electricity conversion efficiency of 0.3. The resulting energy return on energy investment (EROI) also depends on the conversion efficiency of the electricity grid and on the operation life expectance. For a 30-year operational life and grid conversion efficiency of 0.3, EROI ranges from 50 (at US average irradiation) to 70 for US-SW irradiation. The EROI declines with increased grid conversion efficiency; for CdTe PV operating in south California with grid conversion efficiency of 49%, the EROI is about 50 and is projected to fall to 30 when the state's 2030 target of 80% renewable energy penetration materializes. Material alternatives that show a potential of further reductions in degradation rates and materials for enhanced encapsulation that would enable longer operation lives have also been investigated. A degradation rate of 0.3%/year, which has been verified by accelerated testing, is assumed in 30-year scenarios; this is projected to be reduced to 0.2%/year in the near-term and potentially to 0.1%/year in the longer term. With such low degradation rates and enhanced edge-sealing, modules can last 40- to 50-years. Consequently, all impact indicators will be proportionally reduced while EROI will increase. This detailed LCA was conducted according to ISO standards and IEA PVPS Task 12 guidelines. Furthermore, the study revealed that the choices of system models, methods and temporal system boundaries can significantly impact the results and points out to the need to include assumptions regarding these choices in the “transparency in reporting” requirements listed in the IEA PVPS Task 12 Guidelines.
14 SOLAR ENERGY↗
Recent advances in polymeric facilitated transport membranes for carbon dioxide separation and hydrogen purification
Membrane and membrane process have been widely considered as one of the best candidates for mitigating CO 2 emissions from the combustion or utilization of fossil fuels. Various amine-containing polymers constitute an important class of membranes, where the highly selective CO 2 transport is achieved by the facilitated transport mechanism. In this review, the amine–CO 2 chemistry is discussed in conjunction with the mechanism of the reaction-mediated CO 2 transport. A wide variety of amine-containing polymers are discussed based on two synthesis motifs: (a) polyamines with amino groups covalently bound to the polymer backbone and (b) small molecule amines embedded in a polymer matrix. This review concludes with the remarks on the facilitated transport membranes for post-combustion carbon capture (CO 2 /N 2 ) and hydrogen purification (CO 2 /H 2 ).
42 ENGINEERING↗
ToF-SIMS Analysis of Chemical Composition of Atmospheric Aerosols in Beijing
Atmospheric aerosols collected from each season in urban Beijing have been studied using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The chemical composition of atmospheric aerosol particles during various atmospheric pollution levels were analyzed and distinguished by principal component analysis (PCA). The differences and sources of the components of the aerosol particles were explored. The results showed that the fine particulate matter from heavily polluted days mainly consists of inorganic salts and organic compounds, such as hydrocarbons, nitrogen- or sulfur-containing hydrocarbons, and their oxides. Samples collected from clean days in the four seasons were also analyzed. Only the samples collected in spring showed a significant difference from the other three seasons. We concluded that the main source of pollution in the Beijing urban area was fossil fuel combustion from motor vehicles.
ToF-SIMS, principal component analysis↗
Cu Based Dilute Alloys for Tuning the C 2+ Selectivity of Electrochemical CO 2 Reduction
Electrochemical CO 2 reduction is a promising technology for replacing fossil fuel feedstocks in the chemical industry but further improvements in catalyst selectivity need to be made. So far, only copper-based catalysts have shown efficient conversion of CO 2 into the desired multi-carbon (C 2+ ) products. This work explores Cu-based dilute alloys to systematically tune the energy landscape of CO 2 electrolysis toward C 2+ products. Selection of the dilute alloy components is guided by grand canonical density functional theory simulations using the calculated binding energies of the reaction intermediates CO*, CHO*, and OCCO* dimer as descriptors for the selectivity toward C 2+ products. Here, a physical vapor deposition catalyst testing platform is employed to isolate the effect of alloy composition on the C 2+ /C 1 product branching ratio without interference from catalyst morphology or catalyst integration. Six dilute alloy catalysts are prepared and tested with respect to their C 2+ /C 1 product ratio using different electrolyzer environments including selected tests in a 100-cm 2 electrolyzer. Consistent with theory, CuAl, CuB, CuGa and especially CuSc show increased selectivity toward C 2+ products by making CO dimerization energetically more favorable on the dominant Cu facets, demonstrating the power of using the dilute alloy approach to tune the selectivity of CO 2 electrolysis.
36 MATERIALS SCIENCE↗
Sustainable Production of Biomass‐Derived Graphite and Graphene Conductive Inks from Biochar
Abstract Graphite is a commonly used raw material across many industries and the demand for high‐quality graphite has been increasing in recent years, especially as a primary component for lithium‐ion batteries. However, graphite production is currently limited by production shortages, uneven geographical distribution, and significant environmental impacts incurred from conventional processing. Here, an efficient method of synthesizing biomass‐derived graphite from biochar is presented as a sustainable alternative to natural and synthetic graphite. The resulting bio‐graphite equals or exceeds quantitative quality metrics of spheroidized natural graphite, achieving a RamanI D /I G ratio of 0.051 and crystallite size parallel to the graphene layers (L a ) of 2.08 µm. This bio‐graphite is directly applied as a raw input to liquid‐phase exfoliation of graphene for the scalable production of conductive inks. The spin‐coated films from the bio‐graphene ink exhibit the highest conductivity among all biomass‐derived graphene or carbon materials, reaching 3.58 ± 0.16 × 10 4 S m −1 . Life cycle assessment demonstrates that this bio‐graphite requires less fossil fuel and produces reduced greenhouse gas emissions compared to incumbent methods for natural, synthesized, and other bio‐derived graphitic materials. This work thus offers a sustainable, locally adaptable solution for producing state‐of‐the‐art graphite that is suitable for bio‐graphene and other high‐value products.
Chemistry↗
Codesigning Alloy Compositions of CdSe y Te 1− y Absorbers and Mg x Zn 1− x O Contacts to Increase Solar Cell Efficiency
Thin‐film solar cells such as CdTe are a major commercial photovoltaic technology, with more than 25 GW installed worldwide and levelized costs of electricity competitive with fossil fuels. Further progress may result from integrating CdSe y Te 1− y absorbers with Mg x Zn 1− x O contacts, but the device efficiency is difficult to maximize due to coupled dependence on chemical composition of both alloys. Herein, a high‐throughput approach is demonstrated to codesign chemical compositions in alloyed Mg x Zn 1− x O/CdSe y Te 1− y thin‐film solar cells, using combinatorial libraries of PV devices with orthogonal composition gradients in CdSe y Te 1− y absorbers and Mg x Zn 1− x O contacts. It is found that the solar cell performance is a strong and coupled function of both elemental compositions, with efficiency up to 17.7% ( V OC = 836 mV, fill factor = 69%, J SC = 30.6 mA cm −2 ) at atomic compositions of Mg/(Mg + Zn) ≈18% and average Se/(Se + Te) ≈4%. These performance trends among >100 devices are explained by >100 ns lifetime of photoexcited charge carriers at the Mg x Zn 1− x O/CdSe y Te 1− y interface where strong Se accumulation is also observed. This study reports the optimal compositions of the commercially relevant Mg x Zn 1− x O/CdSe y Te 1− y solar cells and demonstrates a general approach to codesigning performance of alloyed thin‐film solar cells and other optoelectronic devices.
14 SOLAR ENERGY↗
What can molecular simulation do for global warming?
Carbon capture is necessary to reduce CO 2 emissions from burning fossil fuels, which has led to global warming. Molecular simulations offer chemical insights and design principles for new separation media and for understanding the separation process. In this review, we summarize recent applications of simulation methods from ab initio and density functional theory to classical molecular dynamics and Grand canonical Monte Carlo in understanding ionic liquids and porous carbonaceous materials for CO 2 separation, especially the postcombustion CO 2 / N 2 separation. We highlight design and simulation of the porous two‐dimensional ( 2D ) materials as the highly selective membranes for CO 2 separation. Simulated structure–property relationships for the materials are discussed in connection to the corresponding chemisorption, physisorption, or membrane process. In chemisorption, the focus is on reducing the heat of reaction with CO 2 ; in physisorption, the key is to increase the binding strength via CO 2 ‐philic groups; in membrane process, the key is to increase solubility for ionic‐liquid membranes and to control pore size for 2D materials. Challenges and opportunities for simulating emerging materials are also discussed. WIREs Comput Mol Sci 2016, 6:173–197. doi: 10.1002/wcms.1241 This article is categorized under: Structure and Mechanism > Computational Materials Science Electronic Structure Theory > Density Functional Theory Molecular and Statistical Mechanics > Molecular Interactions
Tian, Ziqi↗
Interdisciplinary research in climate and energy sciences
Due to the complex nature of climate change, interdisciplinary research approaches involving knowledge and skills from a broad range of disciplines have been adopted for studying changes in the climate system as well as strategies for mitigating climate change (i.e., greenhouse gas emissions reductions) and adapting to its impacts on society and natural systems. Harnessing of renewable energy sources to replace fossil fuels is widely regarded as a long-term mitigation strategy that requires the synthesis of knowledge from engineering, technology, and natural and social sciences. In this study, we examine how the adoption of interdisciplinary approaches has evolved over time and in different geographic regions. We conducted a comprehensive literature survey using an evaluation matrix of keywords, in combination with a word cloud analysis, to evaluate the spatiotemporal dynamics of scholarly discourse about interdisciplinary approaches to climate change and renewable energy research and development (R&D). Publications that discuss interdisciplinary approaches to climate change and renewable energy have substantially increased over the last 60 years; it appears, however, that the nature, timing, and focus of these publications vary across countries and through time. Over the most recent three decades, the country-level contribution to interdisciplinary research for climate change has become more evenly distributed, but this was not true for renewable energy research, which remained dominated by the United Sates and a few other major economies. The research topics have also evolved: Water resource management was emphasized from 1990s to 2000s, policy and adaptation were emphasized from the 2000s to 2010 – 2013, while vulnerability became prominent during the most recent years (2010 – 2013). Lastly, our analysis indicates that the rate of growth of interdisciplinary research for renewable energy lags behind that for climate change, possibly because knowledge emanating from climate change science has motivated the subsequent upswing in renewable energy R&D.
54 ENVIRONMENTAL SCIENCES↗
Estimating the impacts of natural gas power generation growth on solar electricity development: PJM's evolving resource mix and ramping capability
Abstract Expansion of distributed solar photovoltaic (PV) and natural gas‐fired generation capacity in the United States has put a renewed spotlight on methods and tools for power system planning and grid modernization. This article investigates the impact of increasing natural gas‐fired electricity generation assets on installed distributed solar PV systems in the Pennsylvania–New Jersey–Maryland (PJM) Interconnection in the United States over the period 2008–2018. We developed an empirical dynamic panel data model using the system‐generalized method of moments (system‐GMM) estimation approach. The model accounts for the impact of past and current technical, market and policy changes over time, forecasting errors, and business cycles by controlling for PJM jurisdictions‐level effects and year fixed effects. Using an instrumental variable to control for endogeneity, we concluded that natural gas does not crowd out renewables like solar PV in the PJM capacity market; however, we also found considerable heterogeneity. Such heterogeneity was displayed in the relationship between solar PV systems and electricity prices. More interestingly, we found no evidence suggesting any relationship between distributed solar PV development and nuclear, coal, hydro, or electricity consumption. In addition, considering policy effects of state renewable portfolio standards, net energy metering, differences in the PJM market structure, and other demand and cost‐related factors proved important in assessing their impacts on solar PV generation capacity, including energy storage as a non‐wire alternative policy technique. This article is categorized under: Photovoltaics > Economics and Policy Fossil Fuels > Climate and Environment Energy Systems Economics > Economics and Policy
29 ENERGY PLANNING, POLICY, AND ECONOMY↗
Recent In Situ/Operando Characterization of Lithium-Sulfur Batteries
To address the ever-increasing energy demand due to the increase in the population and at the same time depleting fossil fuel reserves, new energy storage systems, such as batteries, are being developed. Among various battery systems, Li-S batteries have comparatively high theoretical energy density and lower cost, making Li-S batteries very promising for next-generation secondary batteries. However, the current energy density and capacity decay with cycling of Li-S batteries do not fulfill the industrialization needs. To overcome the drawbacks of Li-S batteries and improve its performance, better mechanism understanding is necessary. A great deal of ex situ characterization research has been conducted making a lot of progress in the understanding of the working mechanism. Considering the complexity of the intermediate lithium polysulfides and the inherent multi-electron reaction pathways, advanced in situ/operando techniques are highly required. In this chapter, recent progress of a few typical in situ/operando characterization techniques used in Li-S battery studies is reviewed. These techniques provide more in-depth understanding of Li-S batteries in different aspects and could be enlightening for other energy storage systems too.
Yang, Yan↗