Life cycle inventories of electricity generation and power supply in version 3 of the ecoinvent database—part II: electricity markets

Purpose

Representative, consistent and up-to-date life cycle inventories (LCI) of electricity supply are key elements of ecoinvent as an LCI background database since these are often among the determining factors with regard to life cycle assessment (LCA) results. ecoinvent version 3 (ev3) offers new LCI data of power supply (electricity markets) in 71 geographies. This article gives an overview of these electricity markets and discusses new ecoinvent features in the context of power supply.

Methods

The annual geography- and technology-specific electricity production for the year 2008 specifies the technology shares on the high-, medium- and low-voltage level electricity markets. Data are based on IEA statistics. Different voltage levels are linked by transformation activities. Region-specific electricity losses due to power transmission and voltage transformation are considered in the market and transformation activities. The majority of the 71 power markets are defined by national boundaries. The attributional ecoinvent system model in ev3 with linking to average current suppliers results in electricity markets supplied by all geography-specific power generation technologies and electricity imports, while the consequential system model generates markets only linked to unconstrained suppliers.

Results and discussion

The availability of LCI data for 71 electricity markets in ev3 covering 50 countries reduces the “Rest-of-the-World” electricity supply not covered by country- or region-specific inventories to 17 % for the year 2008. Specific power supply activities for all countries contributing more than 1 % to global electricity production are available. The electricity markets show large variations concerning contributions from specific technologies and energy carriers. Imports can substantially change the national/regional power mix, especially in small markets. Large differences can also be observed between the electricity markets in the attributional and the consequential database calculation. Region-specific total power losses between production on the high voltage level and consumer on the low voltage level are on the order of 2.5–23 %.

Conclusions

Electricity supply mixes (electricity markets) in the ecoinvent database have been updated and substantially extended for v3. Inventories for electricity supply in all globally important economies are available with geography-specific technology and market datasets which will contribute to increasing quality and reducing uncertainties in LCA studies worldwide and to allow more accurate estimation of environmental burdens from global production chains. Future work should focus on improving the details of country-specific data, implementation of more countries into the database, splitting of large countries into smaller regions and on developing a more sophisticated approach specifying country-specific electricity mixes in consequential system models.

     

Resource depletion assessment of renewable electricity generation technologies—comparison of life cycle impact assessment methods with focus on mineral resources

Purpose

Renewable energies are promoted in order to reduce greenhouse gas emissions and the depletion of fossil fuels. However, plants for renewable electricity production incorporate specifically higher amounts of materials being rated as potentially scarce. Therefore, it is in question which (mineral) resources contribute to the overall resource consumption and which of the manifold impact assessment methods can be recommended to cover an accurate and complete investigation of resource use for renewable energy technologies.

Methods

Life cycle assessment is conducted for different renewable electricity production technologies (wind, photovoltaics, and biomass) under German conditions and compared to fossil electricity generation from a coal-fired power plant. Focus is given on mineral resource depletion for these technologies. As no consensus has been reached so far as to which impact assessment method is recommended, different established as well as recently developed impact assessment methods (CML, ReCiPe, Swiss Ecoscarcity, and economic scarcity potential (ESP)) are compared. The contribution of mineral resources to the overall resource depletion as well as potential scarcity are identified.

Results and discussion

Overall resource depletion of electricity generation technologies tends to be dominated by fossil fuel depletion; therefore, most renewable technologies reduce the overall resource depletion compared to a coal-fired power plant. But, in comparison to fossil electricity generation from coal, mineral resource depletion is increased by wind and solar power. The investigated methods rate different materials as major contributors to mineral resource depletion, such as gallium used in photovoltaic plants (Swiss Ecoscarcity), gold and copper incorporated in electrical circuits and in cables (CML and ReCiPe), and nickel (Swiss Ecoscarcity and ReCiPe) and chromium (ESP) for stainless steel production. However, some methods lack characterization factors for potentially important materials.

Conclusions

If mineral resource use is investigated for technologies using a wider spectrum of potentially scarce minerals, practitioners need to choose the impact assessment method carefully according to their scope and check if all important materials are covered. Further research is needed for an overall assessment of different resource compartments.

     

Second generation ethanol in Brazil: can it compete with electricity production?

Much of the controversy surrounding second generation ethanol production arises from the assumed competition with first generation ethanol production; however, in Brazil, where bioethanol is produced from sugarcane, sugarcane bagasse and trash will be used as feedstock for second generation ethanol production. Thus, second generation ethanol production may be primarily in competition with electricity production from the lignocellulosic fraction of sugarcane. A preliminary technical and economic analysis of the integrated production of first and second generation ethanol from sugarcane in Brazil is presented and different technological scenarios are evaluated. The analysis showed the importance of the integrated use of sugarcane including the biomass represented by surplus bagasse and trash that can be taken from the field. Second generation ethanol may favorably compete with bioelectricity production when sugarcane trash is used and when low cost enzyme and improved technologies become commercially available.     

Integrated mechanism for the generation of the 5′ junctions of LINE inserts

To elucidate the molecular mechanism of the integration of long interspersed elements (LINEs), we characterized the 5′ ends of more than 200 LINE de novo retrotransposition events into chicken DT40 or human HeLa cells. Human L1 inserts produced 15-bp target-site duplications (TSDs) and zebrafish ZfL2-1 inserts produced 5-bp TSDs in DT40 cells, suggesting that TSD length depends on the LINE species. Further analysis of 5′ junctions revealed that the 5′-end-joining pathways of LINEs can be divided into two fundamental types—annealing or direct. We also found that the generation of 5′ inversions depends on host and LINE species. These results led us to propose a new model for 5′-end joining, the type of which is determined by the extent of exposure of 3′ overhangs generated after the second-strand cleavage and by the involvement of host factors.     

Immunoglobulin A: A next generation of therapeutic antibodies?

Although immunoglobulin (Ig) A is commonly recognized as the most prevalent antibody subclass at mucosal sites with an important role in mucosal defense, its potential as a therapeutic monoclonal antibody is less well known. However, IgA has multifaceted anti-, non- and pro-inflammatory functions that can be exploited for different immunotherapeutical strategies, which will be the focus of this review.Key words: IgA, SIgA, dIgA, CD89, FcαRI, therapy, pro-inflammatory, mucosal defence, tumor, ITAM     

Alterations in phosphatidylethanolamine levels affect the generation of Aβ

Several studies suggest that the generation of Aβ is highly dependent on the levels of cholesterol within membranes' detergent-resistant microdomains (DRM). Indeed, the β-amyloid precursor protein (APP) cleaving machinery, namely β- and γ-secretases, has been shown to be present in DRM and its activity depends on membrane cholesterol levels. Counterintuitive to the localization of the cleavage machinery, the substrate, APP, localizes to membranes' detergent-soluble microdomains enriched in phospholipids (PL), indicating that Aβ generation is highly dependent on the capacity of enzyme and substrate to diffuse along the lateral plane of the membrane and therefore on the internal equilibrium of the different lipids of DRM and non-DRM domains. Here, we studied to which extent changes in the content of a main non-DRM lipid might affect the proteolytic processing of APP. As phosphatidylethanolamine (PE) accounts for the majority of PL, we focused on its impact on the regulation of APP proteolysis. In mammalian cells, siRNA-mediated knock-down of PE synthesis resulted in decreased Aβ owing to a dual effect: promoted α-secretase cleavage and decreased γ-secretase processing of APP. In vivo, in Drosophila melanogaster, genetic reduction in PL synthesis results in decreased γ-secretase-dependent cleavage of APP. These results suggest that modulation of the membrane-soluble domains could be a valuable alternative to reduce excessive Aβ generation.     

Recombinant antibodies: towards a new generation of antivenoms?

Poisoning by scorpion venoms is a major health hazard in tropical and subtropical regions and serum therapy, which was discovered in 1894, remains the only specific treatment. No real progress has been made since this time and the therapeutic use of antivenoms which still consists in polyclonal antibody fragments from the sera of immunized animals may be associated with major drawbacks. Protein engineering now allows to design novel recombinant antibody fragments which are superior to polyclonal antivenoms in homogeneity, specific activity and possibly safety. Several single-chain antibody fragments (scFvs) which neutralize scorpion toxins have been produced and characterized over the last few years. These scFvs can also be used as building blocks to engineer more complex structures including multivalent monospecific antibody fragments (diabodies, triabodies) and bispecific molecules (tandem-scFv). Some of these molecules neutralize scorpion neurotoxins and protect mice from experimental envenoming. Thus, research projects currently underway suggest that new strategies might soon be available to treat poisonings in the absence of socio-economic considerations.     

Implication of the β2-microglobulin gene in the generation of tumor escape phenotypes

Classical MHC molecules present processed peptides from endogenous protein antigens on the cell surface, which allows CD8(+) cytotoxic T lymphocytes (CTLs) to recognize and respond to the abnormal antigen repertoire of hazardous cells, including tumor cells. The light chain, β2-microglobulin (β2m), is an essential constant component of all trimeric MHC class I molecules. There is convincing evidence that β2m deficiency generates immune escape phenotypes in different tumor entities, with an exceptionally high frequency in colorectal carcinoma (CRC) and melanoma. Damage of a single β2m gene by LOH on chromosome 15 may be sufficient to generate a tumor cell precommitted to escape. In addition, this genetic lesion is followed in some tumors by a mutation of the second gene (point mutation or insertion/deletion), which produces a tumor cell unable to express any HLA class I molecule. The pattern of mutations found in microsatellite unstable colorectal carcinoma (MSI-H CRC) and melanoma showed a striking similarity, namely the predominance of frameshift mutations in repetitive CT elements. This review emphasizes common but also distinct molecular mechanisms of β2m loss in both tumor types. It also summarizes recent studies that point to an acquired β2m deficiency in response to cancer immunotherapy, a barrier to successful vaccination or adoptive cellular therapy.     

The inhibitory effect of human interferon α on the generation of lymphokine-activated killer activity

Summary The generation of lymphokine-activated killer (LAK) activity and the proliferative response to human recombinant interleukin-2 (IL-2) were significantly reduced by the presence of human recombinant leukocyte interferon (IFN) in cultures of human peripheral blood mononuclear cells (PBMC). Mature natural killer (NK) cells can be depleted from PBMC with the toxic lysosomotropic agentl-leucine methyl ester. The generation of cytotoxic cells from lymphocytes depleted in leucine methyl ester was also inhibited by indicating that the IFN- effect is not limited to mature cytotoxic NK cells. Depletion of adherent cells from PBMC did not affect the suppression of LAK induction by IFN-. Surface marker analyses of Tac antigen and transferrin receptor (TfR) showed that the presence of IFN throughout the culture period significantly suppressed the typical increase in IL-2-induced Tac- and TfR-positive cells. In contrast, IFN treatment before and after IL-2 culture enhanced LAK cytotoxic activity. Therefore, combinations of these biological response modifiers for clinical use should take into account the dual effect of IFN on key features of the IL-2 response.This work was supported in part by USPHS grant CA34442. Y. T. is a UCLA visiting scientist from the Department of Surgery, School of Medicine, Tokai University, Kanagawa, Japan and recipient of a fellowship from the University of California Cancer Research Coordinating Committee. N. E. is a UCLA visiting scientist from the Department of Surgery, School of Medicine, Tohoku University, Sendai, Japan     

Structural genomics of human proteins – target selection and generation of a public catalogue of expression clones

Background  

The availability of suitable recombinant protein is still a major bottleneck in protein structure analysis. The Protein Structure Factory, part of the international structural genomics initiative, targets human proteins for structure determination. It has implemented high throughput procedures for all steps from cloning to structure calculation. This article describes the selection of human target proteins for structure analysis, our high throughput cloning strategy, and the expression of human proteins in Escherichia colihost cells.     

Overproduction of fungal ribotoxin α-sarcin in Escherichia coli: generation of an active immunotoxin

α-Sarcin is a ribonucleolytic protein secreted by the mold Aspergillus giganteus. DNA encoding α-sarcin was isolated from the host and cloned into T7 promoter based E. coli expression vectors. Using bacterial outer membrane protein A (OmpA) signal sequence, properly processed recombinant (re-) protein was secreted into the culture medium while in the absence of a signal sequence protein remained insoluble in the bacterial inclusion bodies. The re-α-sarcin was purified to homogeneity by simple chromatographic techniques both from the insoluble and soluble sources with respective yields of 40–50 μg/ml and 2–3 μg/ml. The re-ribotoxin was functionally as active as the native toxin and preserved its specificity. The re-α-sarcin was used in the construction of an active immunotoxin targeted at the human cancer cells overexpressing transferrin receptor (TFR).     

Removal of H₂O₂ and generation of superoxide radical: role of cytochrome c and NADH

In cells, mitochondria, endoplasmic reticulum, and peroxisomes are the major sources of reactive oxygen species (ROS) under physiological and pathophysiological conditions. Cytochrome c (cyt c) is known to participate in mitochondrial electron transport and has antioxidant and peroxidase activities. Under oxidative or nitrative stress, the peroxidase activity of Fe³⁺cyt c is increased. The level of NADH is also increased under pathophysiological conditions such as ischemia and diabetes and a concurrent increase in hydrogen peroxide (H₂O₂) production occurs. Studies were performed to understand the related mechanisms of radical generation and NADH oxidation by Fe³⁺cyt c in the presence of H₂O₂. Electron paramagnetic resonance (EPR) spin trapping studies using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) were performed with NADH, Fe³⁺cyt c, and H₂O₂ in the presence of methyl-β-cyclodextrin. An EPR spectrum corresponding to the superoxide radical adduct of DMPO encapsulated in methyl-β-cyclodextrin was obtained. This EPR signal was quenched by the addition of the superoxide scavenging enzyme Cu,Zn-superoxide dismutase (SOD1). The amount of superoxide radical adduct formed from the oxidation of NADH by the peroxidase activity of Fe³⁺cyt c increased with NADH and H₂O₂ concentration. From these results, we propose a mechanism in which the peroxidase activity of Fe³⁺cyt c oxidizes NADH to NAD^•, which in turn donates an electron to O₂, resulting in superoxide radical formation. A UV-visible spectroscopic study shows that Fe³⁺cyt c is reduced in the presence of both NADH and H₂O₂. Our results suggest that Fe³⁺cyt c could have a novel role in the deleterious effects of ischemia/reperfusion and diabetes due to increased production of superoxide radical. In addition, Fe³⁺cyt c may play a key role in the mitochondrial “ROS-induced ROS-release” signaling and in mitochondrial and cellular injury/death. The increased oxidation of NADH and generation of superoxide radical by this mechanism may have implications for the regulation of apoptotic cell death, endothelial dysfunction, and neurological diseases. We also propose an alternative electron transfer pathway, which may protect mitochondria and mitochondrial proteins from oxidative damage.     

Is mitochondrial generation of reactive oxygen species a trigger for autophagy?

Autophagy is a conserved lysosomal degradation pathway that has been extensively studied in recent years. However, the mechanism of autophagy induction is still not clear. Mitochondria are important regulators of both apoptosis and autophagy. One of the triggers for mitochondrial mediated apoptosis is the production of reactive oxygen species (ROS). Recently, several studies have indicated that ROS may be also involved in induction of autophagy. ROS are molecules or ions that are formed by the incomplete one-electron reduction of oxygen, including superoxide (O2 (*-)), hydrogen peroxide (H2O2), hydroxyl radical ((*)OH), nitric oxide (NO), and peroxynitrite (ONOO-). Our recent studies provide strong evidences for the involvement of mitochondrially-generated ROS production in the induction of autophagy as determined by the formation of autophagosomes and autolysosomes. This was accomplished through treatment with mitochondrial toxins that inhibit the electron transport chain in transformed and cancer cells. In addition, we have determined that H2O2 and 2-methoxyestradiol (inhibitor of superoxide dismutases and electron transport chain) induce autophagy leading to cell death. In contrast, normal astrocytes fail to induce autophagy following treatment with mitochondrial toxins. Herein, we discuss several important points of our studies and provide a model for mitochondrially-induced autophagic cell death mediated by ROS.     

Reactivity of carbon nanotubes: Free radical generation or scavenging activity?

Carbon nanotubes (CNTs) currently attract intense research efforts because of their unique properties which make them suitable for many industrial applications. When inhaled, CNTs constitute a possible hazard to human health. Several studies have shown that when instilled in the lung of experimental animals, CNTs induced an inflammatory and fibrotic response similar to that caused by other toxic particles which might be the result of oxidative stress caused by particle- and/or cell-derived free radicals. There is, however, no direct experimental evidence of a capacity of carbon nanotubes to generate directly free radicals. Here we report that multiwall carbon nanotubes (MWCNT) in aqueous suspension do not generate oxygen or carbon-centered free radicals in the presence of H2O2 or formate, respectively, as detected with the spin-trapping technique. Conversely, we observed that, when in contact with an external source of hydroxyl or superoxide radicals, MWCNT exhibit a remarkable radical scavenging capacity. It is therefore possible that the inflammatory reaction reported in vivo must be ascribed to MWCNT features other than particle-derived free radical generation.     

Tuning the HNN experiment: generation of serine–threonine check points

We describe here the tunability of the HNN experiment to obtain certain residue specific peak patterns in the spectra of (¹⁵N, ¹³C) labeled proteins. This is achieved by tuning a band-selective 180° pulse on the carbon channel in the pulse sequence, whereby one can tamper with the C^α–C^β coupling evolutions for the different residues. Specifically, we generate distinctive peak patterns for serine and threonine and their neighbors in the different planes of the three dimensional spectrum. These provide useful anchor points during sequential assignment of backbone resonances. The performance of this experiment, referred to as HNN-ST here, is demonstrated using two proteins, one properly folded and the other completely denatured. With the availability of high field spectrometers, techniques such as TROSY, and ever increasing sensitivities in the probes, this experiment with its large number of check points has a great potential for rapid and unambiguous backbone resonance assignment in large proteins.     

Spontaneous and induced generation of optical activity in racemic 1,1′-Binaphthyl

Summary A racemic mixture of the molecularly dissymmetric compound 1,1-binaphthyl will spontaneously develop optical activity when melted, cooled, and allowed to crystallize. The distribution of optical rotations in individual samples shows that the resolutions occur in a truly spontaneous manner (i.e., without the influence of any external chiral agent). However, addition of small amounts of certain chiral compounds promotes the generation of one enantiomeric form of binaphthyl. The results are often not completely consistent and this suggests that the nucleation of binaphthyl is sensitive to very low concentrations of unknown chiral agents.Presented at the International Symposium on Generation and Amplification of Asymmetry in Chemical Systems, Jülich, September 24–26, 1973.     

Inhibition of dynamin-dependent endocytosis increases shedding of the amyloid precursor protein ectodomain and reduces generation of amyloid β protein

Background  

The amyloid precursor protein (APP) is transported via the secretory pathway to the cell surface, where it may be cleaved within its ectodomain by α-secretase, or internalized within clathrin-coated vesicles. An alternative proteolytic pathway occurs within the endocytic compartment, where the sequential action of β- and γ-secretases generates the amyloid β protein (Aβ). In this study, we investigated the effects of modulators of endocytosis on APP processing.     

Bioelectrochemical analysis of a hyperthermophilic microbial fuel cell generating electricity at temperatures above 80 °C

We examined whether a hyperthermophilic microbial fuel cell (MFC) would be technically feasible. Two-chamber MFC reactors were inoculated with subsurface microorganisms indigenous to formation water from a petroleum reservoir and were started up at operating temperature 80 °C. The MFC generated a maximum current of 1.3 mA 45 h after the inoculation. Performance of the MFC improved with an increase in the operating temperature; the best performance was achieved at 95 °C with the maximum power density of 165 mWm^?2, which was approximately fourfold higher than that at 75 °C. Thus, to our knowledge, our study is the first to demonstrate generation of electricity in a hyperthermophilic MFC (operating temperature as high as 95 °C). Scanning electron microscopy showed that filamentous microbial cells were attached on the anode surface. The anodic microbial consortium showed limited phylogenetic diversity and primarily consisted of hyperthermophilic bacteria closely related to Caldanaerobacter subterraneus and Thermodesulfobacterium commune.