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Optically controlled millimetre-wave switch with stepped-impedance lines
摘要： Nitrogen (N) placement can impact nitrogen use efficiency, but its effect on greenhouse gas (GHG) emissions remain unclear. The objective of this study is to compare the effects of four different N horizontal placement methods (i.e., annular canal (An), radial canal (Ra), band (Ba), and nest fertilization (Ne)) with urea broadcast (Br) on nitrous oxide (N2O), methane (CH4), and soil heterotrophic respiration carbon dioxide (CO2) emissions from an apple orchard to assess the seasonal and spatial variations in these gas emissions. The total cumulative GHG emissions are determined through spots that are differentiated as fertilized or unfertilized. A field simulation study is conducted in an apple orchard, and all N sources have an application rate of 300 kg N ha?1. from the Br treatment are significantly lower than those of other treatments, and the emissions from the Ne treatment are 1.7-fold higher than those of the Br treatment. Surprisingly, the cumulative N2O emissions from the Br treatment are significantly higher than those of the other four treatments. N horizontal placement does not significantly influence the soil CH4 sink. The CO2 emissions in the Br treatment are higher than in other treatments. High N2O emissions in the Br treatment result in a significantly higher GHG exchange than in other treatments, while the Ne treatment significantly reduces the GHG exchange throughout the measurement period. Therefore, optimizing N placement may serve as an effective way to reduce GHG emissions from arable soils.
关键词： nitrogen placement,nitrous oxide,nest fertilization,greenhouse gas emissions,nitrogen use efficiency
更新于2025-09-23 15:19:57
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Performance analysis of photovoltaic-thermal air collectors combined with a water to air heat exchanger for renewed air conditioning in building
摘要： In this work, a new solar system that includes photovoltaic-thermal (PVT) air collectors coupled to a water-to-air heat exchanger is investigated. The considered system generates sufficient energy for cooling and heating of the ambient air injected in a 300 m2 tertiary building and saves its total energy consumption. Therefore, it allows the minimization of greenhouse gas emissions of the building. A numerical model is developed to ensure comfortable temperatures during summer and winter, including days with the highest energy needs. The results show that the proposed system can generate the required heating and cooling needs using an airflow rate equal to 0.25 kg/s and a PVT area of 17 m2. It was found that the coupling of the PVT air collectors with a water to air heat exchanger minimizes the total required area for heating by ~ 33%. Moreover, the PV module’s efficiency was enhanced by 2.0% in winter and 5.1% in summer. The thermal energy saved for heating, thermal energy saved for cooling and the electrical energy saved are, respectively, equal to 15.30 kWh/day, 24.79 kWh/day, and 3.14 kWh/day. This represents an average emission reduction of 11.4 kg CO2 per day.
关键词： Water to air heat exchanger,Energy saving,Thermal comfort in buildings,Photovoltaic air collectors,Renewable energies,Greenhouse gas emissions
更新于2025-09-23 15:19:57
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Regional economic and environmental impacts of renewable energy developments: Solar PV in the Aachen Region
摘要： The energy transition is a challenge that affects regions on various scales. This paper presents the economic chances of deploying the renewable energy technology solar photovoltaic in a German region. Total regional economic effects of 280 PV plants, installed in 2014 with a cumulative capacity of 3.7 MW, lead to a regional value added of approximately €3.8 million (€1019/kW installed, €57/MWh electricity generated) and employment effects of 42 full-time person years (11 person years/MW installed), occurring from 2014 to 2034. The avoided greenhouse gas emissions of these plants are 2365 tons CO2 equivalents per year (0.7 kgCO2-eq/kWh generated) and the avoided air pollution is 0.97 tSO2 per year, 1.48 tNOx per year, and 0.07 t NMVOCs per year in 2014. The total economic effects of regional value added, avoided CO2 emissions, and avoided air pollution per year in 2014 range from €0.8 million - €1 million or (€208–€277 per kW installed, €231–€307 per MWh electricity generated).
关键词： Economic impact assessment,Regional economic impact assessment,Greenhouse gas emissions,Renewable energies,Solar PV,Air pollutants
更新于2025-09-10 09:29:36
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Managing Global Warming || Solar energy
摘要： I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.
关键词： photovoltaic,solar thermal energy,greenhouse gas emissions,renewable energy,solar energy
更新于2025-09-10 09:29:36
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Calibration and instrumental line shape characterization of a set of portable FTIR spectrometers for detecting greenhouse gas emissions
摘要： A comprehensive calibration procedure for mobile, low-resolution, solar-absorption FTIR spectrometers, used for greenhouse gases observations, is developed. These instruments commend themselves for campaign use and deployment at remote sites. The instrumental line shape (ILS) of each spectrometer has been thoroughly characterized by analyzing the shape of H2O signatures in open path spectra. A setup for the external source is suggested and the invariance of derived ILS parameters with regard to chosen path length is demonstrated. The instrumental line shape characteristics of all spectrometers were found to be close to nominal. Side-by-side solar observations before and after a campaign, which involved shipping of all spectrometers to a selected target site and back, are applied for verifying the temporal invariability of instrumental characteristics and for deriving intercalibration factors for XCO2 and XCH4, which take into account residual differences of instrumental characteristics. An excellent level of agreement and stability was found between the different spectrometers: the uncorrected biases in XCO2 and XCH4 are smaller than 0.01 and 0.15 %, respectively, and the drifts are smaller than 0.005 and 0.035 %. As an additional sensitive demonstration of the instrumental performance we show the excellent agreement of ground pressure values obtained from the total column measurements of O2 and barometric records. We find a calibration factor of 0.9700 for the spectroscopic measurements in comparison to the barometric records and a very small scatter between the individual spectrometers (0.02 %). As a final calibration step, using a co-located TCCON (Total Carbon Column Observation Network) spectrometer as a reference, a common scaling factor has been derived for the XCO2 and XCH4 products, which ensures that the records are traceable to the WMO in situ scale.
关键词： calibration,XCO2,XCH4,FTIR spectrometers,instrumental line shape,greenhouse gas emissions
更新于2025-09-04 15:30:14