Cross checking methodology using openwind for standard uncertainty in the long-term annual energy production estimate for P90, in an inner area of Bahia, Brazil

The projected increase in the world’s population requires an increase in the production of edible energy that would meet the associated increased demand for food. However, food production is strongly dependent on the use of energy, mainly from fossil fuels, the extraction of which requires increasing input due to the depletion of the most easily accessible deposits. According to numerous estimations, the world’s energy production will be dependent on fossil fuels at least to 2050. Therefore, it is vital to increase the energy efficiency of production, including food production. One method to measure energy efficiency is the energy return on investment (EROI), which is the ratio of the amount of energy produced to the amount of energy consumed in the production process. The literature lacks comparable EROI calculations concerning global food production and the existing studies only include crop production. The aim of this study was to calculate the EROI of edible crop and animal production in the long term worldwide and to indicate the relationships resulting from its changes. The research takes into account edible crop and animal production in agriculture and the direct consumption of fossil fuels and electricity. The analysis showed that although the most underdeveloped regions have the highest EROI, the production of edible energy there is usually insufficient to meet the food needs of the population. On the other hand, the lowest EROI was observed in highly developed regions, where production ensures food self-sufficiency. However, the changes that have taken place in Europe since the 1990s indicate an opportunity to simultaneously reduce the direct use of energy in agriculture and increase the production of edible energy, thus improving the EROI.

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Effects of Long-Term Flow Variation on Microhydropower Energy Production in Pressure Reducing Valves in Water Distribution Networks

Journal of Water Resources Planning and Management ◽

10.1061/(asce)wr.1943-5452.0000731 ◽

2017 ◽

Vol 143 (3) ◽

pp. 04016076 ◽

Cited By ~ 2

Author(s):

Jennifer Brady ◽

John Gallagher ◽

Lucy Corcoran ◽

Paul Coughlan ◽

Aonghus McNabola

Keyword(s):

Energy Production ◽

Water Distribution ◽

Distribution Networks ◽

Water Distribution Networks ◽

Flow Variation

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Damping Studies on PMLG-Based Wave Energy Converter under Oceanic Wave Climates

Energies ◽

10.3390/en14040920 ◽

2021 ◽

Vol 14 (4) ◽

pp. 920

Author(s):

Yue Hong ◽

Irina Temiz ◽

Jianfei Pan ◽

Mikael Eriksson ◽

Cecilia Boström

Keyword(s):

Wave Energy ◽

Energy Production ◽

Full Range ◽

Electrical Power ◽

Damping Coefficient ◽

Irregular Wave ◽

Ocean Wave Energy ◽

Optimal Damping ◽

The Impact

Wave energy converters (WECs), which are designed to harvest ocean wave energy, have recently been improved by the installation of numerous conversion mechanisms; however, it is still difficult to find an appropriate method that can compromise between strong environmental impact and robust performance by transforming irregular wave energy into stable electrical power. To solve this problem, an investigation into the impact of varied wave conditions on the dynamics of WECs and to determine an optimal factor for WECs to comply with long-term impacts was performed. In this work, we researched the performance of WECs influenced by wave climates. We used a permanent magnet linear generator (PMLG)-based WEC that was invented at Uppsala University. The damping effect was first studied with a PMLG-type WEC. Then, a group of sea states was selected to investigate their impact on the power production of the WEC. Two research sites were chosen to investigate the WEC’s annual energy production as well as a study on the optimal damping coefficient impact. In addition, we compared the WEC’s energy production between optimal damping and constant damping under a full range of sea states at both sites. Our results show that there is an optimal damping coefficient that can achieve the WEC’s maximum power output. For the chosen research sites, only a few optimal damping coefficients were able to contribute over 90% of the WEC’s annual energy production. In light of the comparison between optimal and constant damping, we conclude that, for specific regions, constant damping might be a better choice for WECs to optimize long-term energy production.

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Chlorine isotope composition in chlorofluorocarbons CFC-11, CFC-12 and CFC-113 in firn, stratospheric and tropospheric air

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-6867-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 6867-6877 ◽

Cited By ~ 6

Author(s):

S. J. Allin ◽

J. C. Laube ◽

E. Witrant ◽

J. Kaiser ◽

E. McKenna ◽

...

Keyword(s):

Isotope Fractionation ◽

Isotope Composition ◽

Stratospheric Ozone ◽

Standard Uncertainty ◽

Gas Chromatography Mass Spectrometry ◽

Sources And Sinks ◽

Chlorine Isotope ◽

Tropospheric Measurements ◽

Single Detector

Abstract. The stratospheric degradation of chlorofluorocarbons (CFCs) releases chlorine, which is a major contributor to the destruction of stratospheric ozone (O3). A recent study reported strong chlorine isotope fractionation during the breakdown of the most abundant CFC (CFC-12, CCl2F2, Laube et al., 2010a), similar to effects seen in nitrous oxide (N2O). Using air archives to obtain a long-term record of chlorine isotope ratios in CFCs could help to identify and quantify their sources and sinks. We analyse the three most abundant CFCs and show that CFC-11 (CCl3F) and CFC-113 (CClF2CCl2F) exhibit significant stratospheric chlorine isotope fractionation, in common with CFC-12. The apparent isotope fractionation (&varepsilon;app) for mid- and high-latitude stratospheric samples are respectively −2.4 (0.5) and −2.3 (0.4) ‰ for CFC-11, −12.2 (1.6) and −6.8 (0.8) ‰ for CFC-12 and −3.5 (1.5) and −3.3 (1.2) ‰ for CFC-113, where the number in parentheses is the numerical value of the standard uncertainty expressed in per mil. Assuming a constant isotope composition of emissions, we calculate the expected trends in the tropospheric isotope signature of these gases based on their stratospheric 37Cl enrichment and stratosphere–troposphere exchange. We compare these projections to the long-term δ (37Cl) trends of all three CFCs, measured on background tropospheric samples from the Cape Grim air archive (Tasmania, 1978–2010) and tropospheric firn air samples from Greenland (North Greenland Eemian Ice Drilling (NEEM) site) and Antarctica (Fletcher Promontory site). From 1970 to the present day, projected trends agree with tropospheric measurements, suggesting that within analytical uncertainties, a constant average emission isotope delta (δ) is a compatible scenario. The measurement uncertainty is too high to determine whether the average emission isotope δ has been affected by changes in CFC manufacturing processes or not. Our study increases the suite of trace gases amenable to direct isotope ratio measurements in small air volumes (approximately 200 mL), using a single-detector gas chromatography–mass spectrometry (GC–MS) system.

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Inter-annual variability of wind climates and wind turbine annual energy production

10.5194/wes-2018-48 ◽

2018 ◽

Author(s):

Sara C. Pryor ◽

Tristan J. Shepherd ◽

Rebecca J. Barthelmie

Keyword(s):

Standard Deviation ◽

Wind Energy ◽

Wind Turbine ◽

Energy Production ◽

Wind Farm ◽

Wind Farms ◽

Wind Speeds ◽

Annual Variability ◽

Eastern Usa

Abstract. Inter-annual variability (IAV) of expected annual energy production (AEP) from proposed wind farms plays a key role in dictating project financing. IAV in pre-construction projected AEP and the difference in 50th and 90th percentile (P50 and P90) AEP derives in part from variability in wind climates. However, the magnitude of IAV in wind speeds at/close to wind turbine hub-heights is poorly constrained and maybe overestimated by the 6 % standard deviation of annual mean wind speeds that is widely applied within the wind energy industry. Thus there is a need for improved understanding of the long-term wind resource and the inter-annual variability therein in order to generate more robust predictions of the financial value of a wind energy project. Long-term simulations of wind speeds near typical wind turbine hub-heights over the eastern USA indicate median gross capacity factors (computed using 10-minute wind speeds close to wind turbine hub-heights and the power curve of the most common wind turbine deployed in the region) that are in good agreement with values derived from operational wind farms. The IAV of annual mean wind speeds at/near to typical wind turbine hub-heights in these simulations is lower than is implied by assuming a standard deviation of 6 %. Indeed, rather than in 9 in 10 years exhibiting AEP within 0.9 and 1.1 times the long-term mean AEP, results presented herein indicate that over 90 % of the area in the eastern USA that currently has operating wind turbines simulated AEP lies within 0.94 and 1.06 of the long-term average. Further, IAV of estimated AEP is not substantially larger than IAV in mean wind speeds. These results indicate it may be appropriate to reduce the IAV applied to pre-construction AEP estimates to account for variability in wind climates, which would decrease the cost of capital for wind farm developments.

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AMPK and vacuole-associated Atg14p orchestrate μ-lipophagy for energy production and long-term survival under glucose starvation

eLife ◽

10.7554/elife.21690 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 64

Author(s):

Arnold Y Seo ◽

Pick-Wei Lau ◽

Daniel Feliciano ◽

Prabuddha Sengupta ◽

Mark A Le Gros ◽

...

Keyword(s):

Energy Source ◽

Energy Production ◽

Alternative Energy ◽

Yeast Cells ◽

Survival Strategies ◽

Glucose Starvation ◽

Term Survival ◽

Long Term Survival ◽

Glucose Depletion

Dietary restriction increases the longevity of many organisms, but the cell signaling and organellar mechanisms underlying this capability are unclear. We demonstrate that to permit long-term survival in response to sudden glucose depletion, yeast cells activate lipid-droplet (LD) consumption through micro-lipophagy (µ-lipophagy), in which fat is metabolized as an alternative energy source. AMP-activated protein kinase (AMPK) activation triggered this pathway, which required Atg14p. More gradual glucose starvation, amino acid deprivation or rapamycin did not trigger µ-lipophagy and failed to provide the needed substitute energy source for long-term survival. During acute glucose restriction, activated AMPK was stabilized from degradation and interacted with Atg14p. This prompted Atg14p redistribution from ER exit sites onto liquid-ordered vacuole membrane domains, initiating µ-lipophagy. Our findings that activated AMPK and Atg14p are required to orchestrate µ-lipophagy for energy production in starved cells is relevant for studies on aging and evolutionary survival strategies of different organisms.

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Application fields of wood as a renewable energy source in Europe

Acta Agraria Debreceniensis ◽

10.34101/actaagrar/47/2423 ◽

2012 ◽

pp. 31-35

Author(s):

Nándor Csatári

Keyword(s):

Energy Source ◽

Renewable Energy ◽

Energy Production ◽

The European Union ◽

Eu Member States ◽

Short Rotation ◽

Renewable Energy Production ◽

Application Fields ◽

The Eu

Fuelwood, and wood wastes provide almost half of the renewable energy production of the European Union. Enhancing the use of wood in renewable energy production has more constraint than wind- or solar energy. Forests in the EU member states are sustainably used, they are increasing both in terms of area, and growing stocks. There are possibilities to enhance the fallings and use more fuelwood. Short rotation coppices could fulfill the long term demand for fuelwood; because these plantations surpass the dendromass yield of forests.

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Study on the production and use of biomass energy in the Timis County

ROMANIAN BIOTECHNOLOGICAL LETTERS ◽

10.25083/rbl/26.2/2434.2440 ◽

2021 ◽

Vol 26 (2) ◽

pp. 2434-2440

Author(s):

CRISTINA BACĂU ◽

◽

NICOLETA MATEOC-SÎRB ◽

RAMONA CIOLAC ◽

TEODOR MATEOC ◽

...

Keyword(s):

Renewable Energy ◽

Energy Production ◽

Nuclear Energy ◽

Renewable Energy Sources ◽

Biomass Energy ◽

Renewable Energy Resources ◽

Continuous Increase ◽

Fossil Energy ◽

Term Energy

The use of renewable energy resources is gaining more and more ground, thanks to the continuous increase in the price of fossil energy and the decrease in stocks, and the management of waste from nuclear energy production, respectively. The implementation of an energy strategy to harness the potential of renewable energy sources (RES) is part of the coordinates of Romania’s medium – and long-term energy development and provides the appropriate framework for the making of decisions on energy alternatives and the inclusion in the Community acquis in the field. In this respect, a study on the biomass potential of Timiş County and on the possibilities of producing unconventional energy from biomass has been carried out. The study is based on research, data collection from the literature, as well as from official documents or official websites, the processing and interpretation of the data and their quantitative and qualitative analysis. It was concluded that biomass is a promising renewable energy source for Romania, both in terms of potential and in terms of usability.

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