Predator-prey: interactions between the spiny waterflea (Bythotrephes longimanus) and pumpkinseed sunfish (Lepomis gibbosus)

Small pumpkinseed sunfish ( Lepomis gibbosus), were found to be capable of removing the spine of Bythotrephes longimanus, an invasive cladoceran. Because fish consumption may be important in the dispersal or control of Bythotrephes, aquarium feeding experiments were conducted to 1) establish if the spine removal behavior of the pumpkinseeds was locally unique; 2) quantify how frequently pumpkinseeds exhibit the behavior; 3) determine if pumpkinseed handle Bythotrephes more quickly than other species of fish; and 4) verify if Bythotrephes\u27 resting eggs pass through the digestive systems of pumpkinseeds in viable condition. The experiments revealed that pumpkinseeds (45-70 mm TL) from two geographic regions were more successful (100%) at removing Bythotrephes\u27 spine, and handled Bythotrephes more quickly than yellow perch (Perca flavescens) (49-57 mm TL) and smallmouth bass (Micropterus dolomieu) (50-57mm TL) used in the study. Of 244 live Bythotrephes\u27 resting eggs fed to the pumpkinseeds, 104 (42.6%) passed through their digestive systems. From those eggs, only 10 successfully hatched. Preliminary enclosure experiments were carried out and indicated that pumpkinseeds will consume Bythotrephes in natural settings. These findings provide new evidence that certain fish, with specialized morphology for prey manipulation, have the ability to influence the distribution and establishment of Bythotrephes

Renewable Energy Production from Municipal Solid Waste to Mitigate Climate Change: A Spatially Explicit Assessment for Malaysia

The utilization of municipal solid waste (MSW) as a renewable resource could overcome waste disposal issues, generate power for fossil fuel displacement, and mitigate CO2 emissions from landfill. However, the availability of waste feedstock varies with the effectiveness of waste management while the profitability and the environmental impact are mostly dependent on the conversion technology, plant location, and plant capacity. This study aims to evaluate the complexity of waste-to-energy (WTE) supply chain networks for energy production and the CO2 mitigation potential through a spatially explicit approach. The Malaysian peninsular is selected as a case study area. This study adapted the IIASA techno-economic engineering model for optimizing renewable energy systems (BeWhere) and developed a WTE optimization component. The model minimizes the full supply chain cost of WTE, optimizes the capacity and location of WTE production plants, and assesses the energy and by-product potentials. Several scenarios were designed to analyze the impact of energy and carbon mitigation potential of WTE with varying the fossil fuel prices or carbon tax in the supply chain. The results show that incineration and hydrothermal for power production are the preferred options, primarily because of the low economic investment and the high energy conversion efficiency. Apart from the power as the main product, the system produces biofuel as by-product. It is found that most of the plants are installed in more highly populated cities with large potential for waste biomass, hence reducing logistical costs and emissions from transportation. The preliminary results show that WTE could be substituted for about 9% of the Malaysian power production following a business-as-usual scenario. The study proved that BeWhere for MSW provides a robust spatial explicit solution for WTE with assessment of the energy production and CO2 mitigation potential

Low Noise 1 THz–1.4 THz Mixers Using Nb/Al-AlN/NbTiN SIS Junctions

We present the development of a low noise 1.2 THz and 1.4 THz SIS mixers for heterodyne spectrometry on the Stratospheric Observatory For Infrared Astronomy (SOFIA) and Herschel Space Observatory. This frequency range is above the limit for the commonly used Nb quasi particle SIS junctions, and a special type of hybrid Nb/AlN/NbTiN junctions has been developed for this project.We are using a quasi-optical mixer design with two Nb/AlN/NbTiN junctions with an area of 0.25 µm^2. The SIS junction tuning circuit is made of Nb and gold wire layers. At 1.13 THz the minimum SIS receiver uncorrected noise temperature is 450 K. The SIS receiver noise corrected for the loss in the LO coupler and in the cryostat optics is 350–450 K across 1.1–1.25 THz band. The receiver has a uniform sensitivity in a full 4–8 GHz IF band. The 1.4 THz SIS receiver test at 1.33–1.35 THz gives promising results, although limited by the level of available LO power. Extrapolation of the data obtained with low LO power level shows a possibility to reach 500 K DSB receiver noise using already existing SIS mixer

Penning collisions of laser-cooled metastable helium atoms

We present experimental results on the two-body loss rates in a magneto-optical trap of metastable helium atoms. Absolute rates are measured in a systematic way for several laser detunings ranging from -5 to -30 MHz and at different intensities, by monitoring the decay of the trap fluorescence. The dependence of the two-body loss rate coefficient $\beta$ on the excited state ($2^3P_2$) and metastable state ($2^3S_1$) populations is also investigated. From these results we infer a rather uniform rate constant $K_{sp}=(1{\pm}0.4)\times10^{-7}$ cm$^3$/s.Comment: 8 pages, 9 figures, Revte

Spatial Harmonizing of Protected Areas and Renewable Energy Production

Climate change mitigation requires transboundary strategies for the expansion of renewable energies (RE) that are compatible with conservation objectives. The diversity of protected areas (PAs) gives room for integration of a sustainable RE development with nature conservation, but the lack of consistency between PAs designations remains a challenge for transboundary planning. We propose a methodology to harmonize compatibility assumptions between PA and RE potential production. The methodology is based on the International Union for Conservation of Nature’s (IUCN) System of Protected Areas in order to be independent from national and regional PA designations. Our approach is based on protection scenarios in order to address the multiple uncertainties regarding compatibility assumptions. Three scenarios were defined as: reduced, medium, and increased protection levels. The three scenarios assigned different compatibility levels for RE potentials to the different PA classes, varying from no restrictions for RE to total incompatibility. The methodology was tested in the Alpine region for four different RE technologies: bioenergy, wind power, solar PV plants, and hydropower. A spatial analysis was carried out using GIS and the sustainable as well as the economic potential for each RE technology were determined using a techno-economic engineering model for RE systems (BeWhere) developed at IIASA. The results showed considerable trade-offs between nature protection and the potential for RE production, with significant differences depending on the scenario assumptions. Available area and potential for RE production was notably reduced when higher restrictions were assumed (lower compatibility levels, additional buffer with restrictions to protect the strictest PAs, and exclusion of Natura 2000 sites). This study evidences the importance of clear definition of PA management objectives for strategic planning of sustainable RE expansion

Noise Properties of Superconducting Coplanar Waveguide Microwave Resonators

We have measured noise in thin-film superconducting coplanar waveguide resonators. This noise appears entirely as phase noise, equivalent to a jitter of the resonance frequency. In contrast, amplitude fluctuations are not observed at the sensitivity of our measurement. The ratio between the noise power in the phase and amplitude directions is large, in excess of 30 dB. These results have important implications for resonant readouts of various devices such as detectors, amplifiers, and qubits. We suggest that the phase noise is due to two-level systems in dielectric materials.Comment: 4 pages, 3 figures, accepted for publication in Applied Physics Letter

Carbon-negative emissions: Systemic impacts of biomass conversion: A case study on CO2 capture and storage options

This paper is a contribution to the ongoing debate on carbon-negative energy solutions. It deals with biomass conversion in dedicated biopower plants equipped with CCS (BECCS), or co-fired plants retrofitted with CCS in order to generate negative CO2-emissions. In this context, bioenergy refers to the use of biomass to generate electricity (i.e. biopower) in compliance with the needs of nations and regions without seasonal space heating demand. In this paper, direct-fired and co-fired systems will be addressed, combined mainly with post-combustion flue gas cleaning. The question is which CCS alternative should be preferred in order to obtain negative emissions: either building multiple smaller biopower units, or employing co-firing of biomass and coal in existing large coal power plants. Based on efficacy and the potential for mitigating greenhouse gas emissions as key indicators, some major differences between the alternatives are shown. In the event that a coal power plant equipped with CCS is readily available, more net electric energy (in MWh) can be provided from the feedstock of biomass than would be obtainable from an independent BECCS plant, although the amount of CO2 captured and stored from the biomass (per tonne) will be essentially the same. Further case-specific cost-benefit analyses will be required to determine the feasibility of carbon-negative energy solutions. Although the study is carried out from the perspective of actual biomass sources as regards biomass composition and available technology (i.e. expected efficiency levels) using Indonesian agricultural residues, its main conclusion is fairly general

Power-to-gas and Power-to-liquids for Managing Renewable Electricity Intermittency in the Alpine Region

Large-scale deployment of renewable energy sources (RES) can play a central role in reducing CO2 emissions from energy supply systems, but intermittency from solar and wind technologies present grid integration challenges. High temperature co-electrolysis of steam and CO2, in the so-called power-to-gas (PtG) and power-to-liquid (PtL) configuration, could provide a path for utilizing the excess intermittent electricity from a power system by converting it into chemical fuels that can be directly utilized in other sectors, such as transportation and heating. The chemical fuels could also be used in the power sector during periods of deficit in supply. Here, we study the economic and engineering potential of PtG/PtL systems deployment as storage for intermittent renewable electricity and as a source of low-carbon heating and transportation energy among the different energy sectors in the Alpine region, using the BeWhere model, a geographic explicit cost minimization model. Preliminary results indicate large-scale deployment of the PtG/PtL technologies for producing chemical fuels from excess intermittent electricity is feasible, particularly when incentivized by carbon prices. In addition, large volumes of captured CO2, as much as 30 Mt CO2 /year are utilized in the synthesis of the chemical fuels, providing as much as 23% of liquid transportation fuels. In this context, it can be concluded that PtG/PtL technologies can enable greater integration of RES into the energy supply chain, with application worldwide

Internalizing the external costs of biogas supply chains in the Italian energy sector

In Italy biogas support schemes are being revised to include subsidies for the production of biomethane. Energy policies should foster environmentally optimal solutions, especially because social acceptance issues often arise in the case of biogas. In this paper we use the external cost methodology to quantify the environmental impact of airborne emissions associated with biogas-based energy vectors and their corresponding fossil substitutes These are evaluated at supply chain level and incorporated in a spatially explicit optimization model. The method is applied to northern Italy to compare the potential impact of alternative policy options. It is found that, while the external costs of biogas-based pathways are always lower than corresponding fossil fuel based pathways, the differences are generally so small that policies based on internalization of external costs alone would not lead to further development of biogas-based technologies. For all utilization pathways, consideration of local externalities leads to a less favourable evaluation of biogas-based technologies, which results in external costs even higher than the substituted fossil fuel if biogas is allocated to local heating