Power-to-Gas Concept for Integration of Increased Photovoltaic Generation into the Distribution

AbstractAccording to the Energy Strategy 2050 set forth by the Swiss federal government, Photovoltaic (PV) energy shall make up one fifth of the nation's total energy production in 2050. Such a drastic expansion rate of PV and the resulting excess energy thereof can lead to so-called reverse power flow in the low voltage (LV) grid as demonstrated in previous studies. Power-to-Gas (PtG) represents a suitable storage solution to resolve the situation by absorbing the excess PV energy. This paper presents a qualitative and quantitative feasibility analysis of the PtG technology in the future Swiss LV grid. For this purpose, PtG is integrated in simulation into the grid for absorbing the excess PV energy while producing hydrogen. This hydrogen is assumed to be sold in the mobility sector. Three different operational scenarios are established with respect to the input energy source to the PtG plant, including the excess PV energy, curtailed PV excess energy and PV excess energy plus the energy from the grid. Summing up the results, it can be concluded that the PtG plant is still far from economically viable even though significant improvement can be accomplished to the hydrogen production costs by adopting the active PV curtailment and by purchasing additional energy from the grid. The future study to be undertaken by the authors, with respect to economical viability of the PtG, will include other sources of value, including production of methane as main product, production of oxygen and heat as by-products, and provision of services such as biogas upgrading, frequency regulation and voltage

Visual ecology of aphids – a critical review on the role of colours in host finding

We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

Evaluation der Ökomassnahmen: Bereich Biodiversität

1993 führte der Bund ökologische Direktzahlungen ein; seit 1999 ist die Erbringung des ökologischen Leistungsnachweises (ÖLN) durch die Landwirtschaftsbetriebe die Voraussetzung zum Bezug von Direktzahlungen. Heute werden 97 % der landwirtschaftlichen Nutzfläche nach den Regeln des ÖLN bewirtschaftet. Die wichtigste Massnahme des ÖLN, welche einen Einfluss auf die Biodiversität hat, ist, dass die Betriebe 7 % ihrer landwirtschaftlichen Nutzfläche (LN) als ökologische Ausgleichsflächen (öAF) auszuweisen haben (bei Spezialkulturen 3,5 %). Weitere Anforderungen des ÖLN (ausgeglichene Nährstoffbilanz, geregelte Fruchtfolge, Bodenschutz, gezielter Einsatz von Pflanzenschutzmitteln, tiergerechte Haltung der Nutztiere) können ebenfalls einen Einfluss haben, stehen jedoch weniger im Vordergrund

Contribution of brain or biological reserve and cognitive or neural reserve to outcome after TBI: a meta-analysis (prior to 2015)

Brain/biological (BR) and cognitive/neural reserve (CR) have increasingly been used to explain some of the variability that occurs as a consequence of normal ageing and neurological injuries or disease. However, research evaluating the impact of reserve on outcomes after adult traumatic brain injury (TBI) has yet to be quantitatively reviewed. This meta-analysis consolidated data from 90 studies (published prior to 2015) that either examined the relationship between measures of BR (genetics, age, sex) or CR (education, premorbid IQ) and outcomes after TBI or compared the outcomes of groups with high and low reserve. The evidence for genetic sources of reserve was limited and often contrary to prediction. APOE ∈4 status has been studied most, but did not have a consistent or sizeable impact on outcomes. The majority of studies found that younger age was associated with better outcomes, however most failed to adjust for normal age-related changes in cognitive performance that are independent of a TBI. This finding was reversed (older adults had better outcomes) in the small number of studies that provided age-adjusted scores; although it remains unclear whether differences in the cause and severity of injuries that are sustained by younger and older adults contributed to this finding. Despite being more likely to sustain a TBI, males have comparable outcomes to females. Overall, as is the case in the general population, higher levels of education and pre-morbid IQ are both associated with better outcomes.Jane L. Mathias, Patricia Wheato

The utility of power-to-gas concept for integration of increased photovoltaic generation into the distribution grid

This paper presents a qualitative and quantitative feasibility analysis of the Power-to-Gas (PtG) technology in the future Swiss power grid which will be characterized by a significant share of intermittent renewable energy sources (RES), especially Photovoltaic (PV) energy.The Energy Strategy 2050 set forth by the Swiss federal government includes a plan of a strong expansion of renewable energy sources. PV, for example, shall make up one fifth of Switzerland’s total energy production in 2050. Such a drastic expansion rate of PV can lead to so-called reverse power flow in the low voltage (LV) grid, as indicated in a previous case study conducted in a Zürich area.This paper demonstrates the impact of the PtG technology through three different scenarios in the above-mentioned case. The scenarios are established with respect to the input energy source to the PtG plant. The PtG plant is integrated into the LV grid for absorbing the excess PV energy for producing hydrogen. For each scenario, the produced hydrogen is assumed to be sold in the mobility sector. The results of this simulation give the insights concerning the technical as well as economical feasibility of the integration of PtG into the existing LV grid

Growth rates and relative change in non-structural carbohydrates of dipterocarp seedlings in response to light acclimation

Background: Acclimation to light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their demographic rates and traits trade-off. Aims: We examined light niche divergence in six dipterocarp species and hypothesised that seedlings can be functionally grouped, and allocate resources to either growth or storage in response to light changes. Methods: A pot experiment was performed to measure size-specific growth rate, wood density and total non-structural carbohydrate (NSC) concentrations of dipterocarp seedlings exposed to a simulated gap opening. Results: Light-demanding species responded to a gap opening with increased growth and decreased wood density, whereas shade-tolerant species showed a greater relative increase in NSC concentration. Iditol – an alditol – was identified, and Dryobalanops lanceolata responded to a gap opening with a significantly smaller increase in alditol concentration compared to other species. Conclusions: We group light-demanding and shade-tolerant species based on their acclimation to light and show that a generalist species is unique based on its response of NSC concentration to a gap opening. Our findings emphasise that the ecology of these species needs to be further studied in the context of their physiology to support their effective use in large-scale forest restoration efforts

Feasibility study of power-to-gas technology as a solution to facilitate the integration of solar energy on the Swiss distribution grid

According to the Energy Strategy 2050 set forth by the Swiss federal government, Photovoltaic (PV) energy shall make up one fifth of the nation’s total energy production in 2050. Such a drastic expansion rate of PV and the resulting excess energy thereof can lead to so-called reverse power flow in the low voltage (LV) grid as demonstrated in previous studies. Power-to-Gas (PtG) represents a suitable storage solution to resolve the situation by absorbing the excess PV energy. This report presents qualitative and quantitative feasibility analysis of the Power-to-Gas (PtG) technology in the future Swiss low voltage (LV) grid, which will be characterized by a significant share of intermittent renewable energy sources (RES). For this purpose, a model of producing hydrogen or methane with Photovoltaics (PV) excess energy and additional energy from the grid is established. Data and results from a load flow analysis of a previous study serves as the basis for the analysis. Impact of the PtG technology is demonstrated through nine different operating scenarios established. The input energy source to the PtG plant comprises the excess PV energy and the energy from the grid. Economic values, such as levelized cost of energy (LCOE) and levelized value of electricity (LVOE), are calculated to assess the economic feasibility. Moreover, sensitivity analysis is conducted to identify the parameters having the strongest impact on the electricity cost

Case-specific monitoring of adult butterflies to determine potential effects of transgenic Bt-maize in Switzerland

The present study investigated whether case-specific monitoring (CSM) would be an appropriate optionto detect possible effects on butterflies during commercial cultivation of Bt-maize (Cry1Ab). The analysisof an existing dataset on butterfly communities in Switzerland allowed quantifying the variability inspecies richness and abundance of nine ecological groups of butterflies resulting from habitat features,agricultural field management, landscape features, regional farming characteristics, spatial variabilityand temporal fluctuations. The data set also enabled to estimate the sample size needed to detectpotential effects of Bt-maize in a CSM programme within the determined variability. Fifteen of the 24tested descriptors of environmental and farming context induced significant variability in butterflyspecies richness and abundance of generalist butterflies. In case regulatory authorities would request aCSM, a stratified sampling design considering habitat, landscape, and regional farming types would beessential to account for existing sources of variability. However, recording only the presence andabundance of butterfly species will not be sufficient to explain occurring changes and sampling ofadditional explaining variables is crucial. The analysis showed that CSM will at best detect large effectson ubiquitous butterflies, whilst the detection of small effects would need a considerable samplingeffort. A sampling effort of 100 pairs of fields or field margins will only allow detecting changesexceeding 30% in species richness or abundance of the most abundant species. Rare butterfly species canhardly be monitored in CSM and causalities between changes in butterfly communities and thecultivation of Bt-maize will be difficult to determine due to the high variability of communities and themultitude of influencing environmental factors. CSM is thus unlikely to reduce remaining uncertaintieson potential effects on butterflies during commercial cultivation of Bt-maize. Ultimately, potentialeffects might be evaluated more rigorously in pre-market risk assessment by studying hazard andexposure of sensitive butterfly stages to Bt-maize through experimental toxicity studies in the laboratoryor in the greenhouse

Chemical profiles accross the last glacial termination: First results from the EPICA-DML ice core

The European Project of Ice Coring in Antarctica (EPICA) aims at reconstructing past climate andenvironmental conditions from two deep ice cores in Antarctica. The two cores are drilled in theDome C area (at 75°06' S, 123° 21'E, 3233m a.s.l.) and in Droning Maud Land (DML, at 75°00'S;00°04'E, 2892 m.a.s.l). Here we will present chemical data from the first approx. 1550 m of theDML core.Continuous ice core melting was employed for sample preparation and decontamination.Continuous profiles were measured on-line for Na, Ca and NH4 soluble ion concentrations bycontinuous flow analysis (CFA) methods as well as for insoluble microparticle concentrationstarting at 113m depth. These profiles will be presented at low resolution (1.0 m) together withsections of high resolution data exemplary for mid-Holocene, Preboreal and the last Glacialperiods.From the high resolution data the annual layer thickness will be derived and the possibilities ofcounting annual layers will be explored during the different periods mentioned. If possible, also theseasonal phasing and shifts thereof will be investigated for the measured species. The lowresolution data will provide an overview of the last glacial termination. The measured componentswill be discussed in terms of degree of relative change and of timing differences. Furthermore, thecontributions of the two main sources for Ca (crustal matter and sea salt aerosol) will be discussed.Presenting Author:Dr. Urs Ruth / Alfre-Wegener-Institute / 27568 Bremerhaven / Columbusstraße / Germany /+4947148311173 / [email protected] Reference No.: ABS-4150-0009

Chronology for the EDML ice core from Dronning Maud Land, Antarctica, over the last 150 000 years

A chronology called EDML1 has been developed for the EPICA ice core from Dronning Maud Land (EDML). EDML1 is closely interlinked with EDC3, the new chronology for the EPICA ice core from Dome-C (EDC) through a stratigraphic match between EDML and EDC that consists of 322 volcanic match points over the last 128 ka. The EDC3 chronology comprises a glaciological model at EDC, which is constrained and later selectively tuned using primary dating information from EDC as well as from EDML, the latter being transferred using the tight stratigraphic link between the two cores. Finally, EDML1 was built by exporting EDC3 to EDML. For ages younger than 41 ka BP the new synchronized time scale EDML1/EDC3 is based on dated volcanic events and on a match to the Greenlandic ice core chronology GICC05 via 10Be and methane. The internal consistency between EDML1 and EDC3 is estimated to be typically ~6 years and always less than 450 years over the last 128 ka (always less than 130 years over the last 60 ka), which reflects an unprecedented synchrony of time scales. EDML1 ends at 150 ka BP (2417 m depth) because the match between EDML and EDC becomes ambiguous further down. This hints at a complex ice flow history for the deepest 350 m of the EDML ice core