Day-ahead energy production in small hydropower plants: uncertainty-aware forecasts through effective coupling of knowledge and data

Motivated by the challenges induced by the so-called Target Model and the associated changes to the current structure of the energy market, we revisit the problem of day-ahead prediction of power production from Small Hydropower Plants (SHPPs) without storage capacity. Using as an example a typical run-of-river SHPP in Western Greece, we test alternative forecasting schemes (from regression-based to machine learning) that take advantage of different levels of information. In this respect, we investigate whether it is preferable to use as predictor the known energy production of previous days, or to predict the day-ahead inflows and next estimate the resulting energy production via simulation. Our analyses indicate that the second approach becomes clearly more advantageous when the expert's knowledge about the hydrological regime and the technical characteristics of the SHPP is incorporated within the model training procedure. Beyond these, we also focus on the predictive uncertainty that characterize such forecasts, with overarching objective to move beyond the standard, yet risky, point forecasting methods, providing a single expected value of power production. Finally, we discuss the use of the proposed forecasting procedure under uncertainty in the real-world electricity market.

Quadriceps Muscle Fatigue Reduces Extension and Flexion Power During Maximal Cycling

Purpose: To investigate how quadriceps muscle fatigue affects power production over the extension and flexion phases and muscle activation during maximal cycling.Methods: Ten participants performed 10-s maximal cycling efforts without fatigue and after 120 bilateral maximal concentric contractions of the quadriceps muscles. Extension power, flexion power and electromyographic (EMG) activity were compared between maximal cycling trials. We also investigated the associations between changes in quadriceps force during isometric maximal voluntary contractions (IMVC) and power output (flexion and extension) during maximal cycling, in addition to inter-individual variability in muscle activation and pedal force profiles.Results: Quadriceps IMVC (−52 ± 21%, P = 0.002), voluntary activation (−24 ± 14%, P < 0.001) and resting twitch amplitude (−45 ± 19%, P = 0.002) were reduced following the fatiguing task, whereas vastus lateralis (P = 0.58) and vastus medialis (P = 0.15) M-wave amplitudes were unchanged. The reductions in extension power (−15 ± 8%, P < 0.001) and flexion power (−24 ± 18%, P < 0.001) recorded during maximal cycling with fatigue of the quadriceps were dissociated from the decreases in quadriceps IMVC. Peak EMG decreased across all muscles while inter-individual variability in pedal force and EMG profiles increased during maximal cycling with quadriceps fatigue.Conclusion: Quadriceps fatigue induced by voluntary contractions led to reduced activation of all lower limb muscles, increased inter-individual variability and decreased power production during maximal cycling. Interestingly, power production was further reduced over the flexion phase (24%) than the extension phase (15%), likely due to larger levels of peripheral fatigue developed in RF muscle and/or a higher contribution of the quadriceps muscle to flexion power production compared to extension power during maximal cycling.

Preserving and Presenting Heritage through Sustainable Energy Tourism: The Case of Kobarid in Slovenia

Energy tourism, which is quite recent despite the fact that the practice of tourists visiting power plants, very often for educational purposes, has a long tradition in Slovenia due to power plants on the Drava River. Particularly, the oldest Fala power plant is an area where the technical field of electric power production and transmission overlaps with tourism. The article that employs the methods of participant observation, interviews with some stakeholders and content analysis focuses on some possibilities of including electric power production and transmission infrastructure into various tourist and educational programmes, including through storytelling, which is a useful tool also when it comes to presenting sustainable and socially responsible project design, considering the needs of all stakeholders involved in the process and, consequently, raising awareness and responsibility towards the environment. Based on a case study of the Kobarid substation, which is a modern sustainably designed power facility built in a Natura 2000 protected area, this article focuses on the possibilities of creating new energy tourism products by employing storytelling, new media and new technologies.

Only the good die old? Ontogenetic determinants of locomotor performance in Eastern cottontail rabbits (Sylvilagus floridanus)

For many animals, the juvenile stage of life can be particularly perilous. Once independent, immature animals must often complete the same basic survival functions as adults despite smaller body size and other growth-related limits on performance. Because, by definition, juveniles have yet to reproduce, we should expect strong selection for mechanisms to offset these ontogenetic limitations, allowing individuals to reach reproductive adulthood and maintain Darwinian fitness. We use an integrated ontogenetic dataset on morphology, locomotor performance, and longevity in wild cottontail rabbits (Sylvilagus floridanus, Allen 1848) to test the hypothesis that prey animals are under selective pressure to maximize juvenile performance. We predicted that 1) juveniles would accelerate more quickly than adults, allowing them to reach adult-like escape speeds, and 2) juveniles with greater levels of performance should survive for longer durations in the wild, thus increasing their reproductive potential. Using high speed video and force platform measurements, we quantified burst acceleration, escape speed, and mechanical power production in 42 wild-caught S. floridanus (29 juveniles, 13 adults; all rabbits >1kg in body mass were designated to be adults, based on published growth curves and evidence of epiphyseal fusion). A subsample of 22 rabbits (16 juveniles, 6 adults) were fitted with radio-telemetry collars for documenting survivorship in the wild. We found that acceleration and escape speed peaked in the late juvenile period in S. floridanus, at an age range that coincides with a period of pronounced demographic attrition in wild populations. Differences in mass-specific mechanical power production explained ∼75% of the variation in acceleration across the dataset, indicating that juvenile rabbits outpace adults by producing more power per unit body mass. We found a positive, though non-significant, association between peak escape speed and survivorship duration in the wild, suggesting a complex relationship between locomotor performance and fitness in growing S. floridanus.

Ocean Energy

Until the middle of 20th century, there was a strong conviction that the next century would be the age of renewable and nuclear energy resources. However, at present, the whole world is dependent on fossil fuels to satisfy their energy need. Environmental pollution and global warming are the main issues associated with the use of fossil fuels for electricity generation. As per the report of US Energy Information IE Outlook 2016, coal, natural gas, and petroleum share nearly 67.2% of global electricity generation whereas renewable energy shares only 21.9%. This share is only one-fifth of the global electricity demand. According to the IEA 2016 Medium Term Renewable Energy Market Report, worldwide power production capacity of marine was only 539 MW in 2014, and to reach at a level of 640 MW, it will take 2021. The oceans cover about 70% of the Earth and acts as the largest thermal energy collector. A recent study reveals that global development capability of ocean energy is approximated to be 337 GW, and more than 885 TWH of electricity can be produced from this potential.