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Author: Smil, Vaclav
Wind turbines are the most visible symbols of the quest for renewable electricity generation. And yet, although they exploit the wind, which is as free and as green as energy can be, the machines themselves are pure embodiments of fossil fuels.
Large trucks bring steel and other raw materials to the site, earth-moving equipment beats a path to otherwise inaccessible high ground, large cranes erect the structures, and all these machines burn diesel fuel. So do the freight trains and cargo ships that convey the materials needed for the production of cement, steel, and plastics. For a 5-megawatt turbine, the steel alone averages [pdf] 150 metric tons for the reinforced concrete foundations, 250 metric tons for the rotor hubs and nacelles (which house the gearbox and generator), and 500 metric tons for the towers.
If wind-generated electricity were to supply 25 percent of global demand by 2030 (forecast [pdf] to reach about 30 petawatt-hours), then even with a high average capacity factor of 35 percent, the aggregate installed wind power of about 2.5 terawatts would require roughly 450 million metric tons of steel. And that’s without counting the metal for towers, wires, and transformers for the new high-voltage transmission links that would be needed to connect it all to the grid.
A lot of energy goes into making steel. Sintered or pelletized iron ore is smelted in blast furnaces, charged with coke made from coal, and receives infusions of powdered coal and natural gas. Pig iron is decarbonized in basic oxygen furnaces. Then steel goes through continuous casting processes (which turn molten steel directly into the rough shape of the final product). Steel used in turbine construction embodies typically about 35 gigajoules per metric ton.
To make the steel required for wind turbines that might operate by 2030, you’d need fossil fuels equivalent to more than 600 million metric tons of coal.
A 5-MW turbine has three roughly 60-meter-long airfoils, each weighing about 15 metric tons. They have light balsa or foam cores and outer laminations made mostly from glass-fiber-reinforced epoxy or polyester resins. The glass is made by melting silicon dioxide and other mineral oxides in furnaces fired by natural gas. The resins begin with ethylene derived from light hydrocarbons, most commonly the products of naphtha cracking, liquefied petroleum gas, or the ethane in natural gas.
The final fiber-reinforced composite embodies on the order of 170 GJ/t. Therefore, to get 2.5 TW of installed wind power by 2030, we would need an aggregate rotor mass of about 23 million metric tons, incorporating the equivalent of about 90 million metric tons of crude oil. And when all is in place, the entire structure must be waterproofed with resins whose synthesis starts with ethylene. Another required oil product is lubricant, for the turbine gearboxes, which has to be changed periodically during the machine’s two-decade lifetime.
Undoubtedly, a well-sited and well-built wind turbine would generate as much energy as it embodies in less than a year. However, all of it will be in the form of intermittent electricity—while its production, installation, and maintenance remain critically dependent on specific fossil energies. Moreover, for most of these energies—coke for iron-ore smelting, coal and petroleum coke to fuel cement kilns, naphtha and natural gas as feedstock and fuel for the synthesis of plastics and the making of fiberglass, diesel fuel for ships, trucks, and construction machinery, lubricants for gearboxes—we have no nonfossil substitutes that would be readily available on the requisite large commercial scales.
For a long time to come—until all energies used to produce wind turbines and photovoltaic cells come from renewable energy sources—modern civilization will remain fundamentally dependent on fossil fuels.
Exposure to Electromagnetic Fields (EMF) from Submarine Power Cables Can Trigger Strength-Dependent Behavioural and Physiological Responses in Edible Crab, Cancer pagurus (L.)
Author: Scott, Kevin; et al.
The current study investigated the effects of different strength Electromagnetic Field (EMF) exposure (250 µT, 500 µT, 1000 µT) on the commercially important decapod, edible crab (Cancer pagurus, Linnaeus, 1758). Stress related parameters were measured (l-Lactate, d-Glucose, Total Haemocyte Count (THC)) in addition to behavioural and response parameters (shelter preference and time spent resting/roaming) over 24 h periods. EMF strengths of 250 µT were found to have limited physiological and behavioural impacts. Exposure to 500 µT and 1000 µT were found to disrupt the l-Lactate and d-Glucose circadian rhythm and alter THC. Crabs showed a clear attraction to EMF-exposed (500 µT and 1000 µT) shelters with a significant reduction in time spent roaming. Consequently, EMF emitted from MREDs [Marine Renewable Energy Devices] will likely affect crabs in a strength-dependent manner thus highlighting the need for reliable in-situ measurements. This information is essential for policy making, environmental assessments, and in understanding the impacts of increased anthropogenic EMF on marine organisms.
Kevin Scott, Petra Harsanyi, Blair A.A. Easton, Althea J.R. Piper, Corentine M.V. Rochas, and Alastair R. Lyndon
St Abbs Marine Station, UK.
School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Edinburgh, UK.
Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
Journal of Marine Science and Engineering 2021, 9(7), 776; doi: 10.3390/jmse9070776
Download original document: “Exposure to Electromagnetic Fields (EMF) from Submarine Power Cables Can Trigger Strength-Dependent Behavioural and Physiological Responses in Edible Crab, Cancer pagurus (L.)”
Author: Chiu, Chun-Hsiang; et al.
Abstract: Wind turbines generate low-frequency noise (LFN, 20–200 Hz), which poses health risks to nearby residents. This study aimed to assess heart rate variability (HRV) responses to LFN exposure and to evaluate the LFN exposure (dB, (LAeq) inside households located near wind turbines. Thirty subjects living within a 500 m radius of wind turbines were recruited. The field campaigns for LFN (LAeq) and HRV monitoring were carried out in July and December 2018. A generalized additive mixed model was employed to evaluate the relationship between HRV changes and LFN. The results suggested that the standard deviations of all the normal to normal R–R intervals were reduced significantly, by 3.39%, with a 95% CI = (0.15%, 6.52%) per 7.86 dB (LAeq) of LFN in the exposure range of 38.2–57.1 dB (LAeq). The indoor LFN exposure (LAeq) ranged between 30.7 and 43.4 dB (LAeq) at a distance of 124–330 m from wind turbines. Moreover, households built with concrete and equipped with airtight windows showed the highest LFN difference of 13.7 dB between indoors and outdoors. In view of the adverse health impacts of LFN exposure, there should be regulations on the requisite distances of wind turbines from residential communities for health protection.
LFN exposure has been found to cause a variety of health conditions. Exposure to LFN from wind turbines results in headaches, difficulty concentrating, irritability, fatigue, dizziness, tinnitus, aural pain sleep disturbances, and annoyance. Clinically, exposure to LFN from wind turbines may cause increased risk of epilepsy, cardiovascular effects, and coronary artery disease. It was also found that exposure to noise (including LFN) may have an impact on heart rate variability (HRV). HRV is the variation over time of the period between adjacent heartbeats, which is an indicator of the activities of the autonomic nervous system, consisting of the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS). Autonomic imbalance usually represents a hyperactive SNS and a hypoactive PNS and results in reduced HRV. An autonomic imbalance may increase the morbidity and mortality of cardiovascular diseases. A review paper indicated that road traffic noise may overactivate the hypothalamic-pituitary-adrenocortical axis (HPA) and sympathetic-adrenal-medullar axis (SAM), increase the blood pressure and reduce HRV, and finally affect the cardiovascular system. A recent study analyzing 658 measurements of HRV obtained from 10 healthy males (18–40 years old) indicated reductions in HRV due to environmental LFN exposure. However, few studies have specifically examined the effect of LFN from wind turbines on HRV in healthy individuals; thus, this was the aim of this study. …
Besides distance from turbines, building materials also affect indoor LFN exposure. This work assessed the indoor LFN levels for several recruited households with different building materials and open/closed windows to illustrate their potential impacts. It is known that materials have different sound absorption coefficients. The overall sound pressure level and spectrum of external noise change when transmitted to the interior of a building. Mid- and high-frequency noises are selectively attenuated by roofs and walls, causing the building structure to function like an LFN pass filter. Outdoor to indoor noise reduction generally decreases with frequency, [but variations exist] related to housing construction and room dimensions. [Below 2.5 Hz, the outdoor to indoor noise reduction is zero. (“Outdoor to indoor reduction of wind farm noise for rural residences,” Kristy Hansen, Colin Hansen, and Branko Zajamšek)] Factors contributing to indoor/outdoor noise reduction also include structural resonances, room modes, and coupling between the air volume inside the residence and the stiffness of the walls, roofs, and ceilings.
Chun-Hsiang Chiu, Shih-Chun Candice Lung, Nathan Chen, Jing-Shiang Hwang, & Ming-Chien Mark Tsou
Research Center for Environmental Changes and Institute of Statistical Science, Academia Sinica; Department of Atmospheric Sciences and Institute of Environmental Health, National Taiwan University, Taipei, Taiwan
Scientific Reports volume 11, article number: 17817 (2021)
Download original document: “Effects of low-frequency noise from wind turbines on heart rate variability in healthy individuals”
Author: Nguyen, Phuc; Hansen, Kristy; Zajamšek, Branko; and Catcheside, PeterNguyen, Phuc; Hansen, Kristy; Zajamšek, Branko; and Catcheside, Peter
Abstract – Wind farm noise amplitude modulation (WFNAM) is a major contributor to annoyance and could cause sleep disturbance. In laboratory listening experiments assessing its annoyance and sleep disturbance potential, WFNAM stimuli are commonly synthesised and can thus suffer from a lack of ecological validity. Here, five stimuli synthesis methods were compared with measured noise in terms of their perceived similarity. An ABX discrimination listening test and one-third octave band spectra were used for evaluation of the aural and visual similarity, respectively, between the synthesised and measured noise spectra. The results showed that synthesising WFNAM using a simple method can be ecologically valid as listeners could not accurately differentiate between measured and synthesised WFNAM. However, time varying features of WFNAM do play a small but significant role in human perception and therefore hearing test evaluation of synthesis is recommended for obtaining the most ecologically valid synthesised WFNAM.
Duc Phuc Nguyen, Kristy Hansen, College of Science and Engineering, Flinders University, Adelaide, Australia
Branko Zajamsek, Peter Catcheside, Adelaide Institute for Sleep Health, Flinders University, Adelaide, Australia
Applied Acoustics, Volume 166, September 2020, 107349.
Download original document: “Evaluation of wind farm noise amplitude modulation synthesis quality”
Wind farm infrasound detectability and its effects on the perception of wind farm noise amplitude modulation
ABSTRACT – Some residents attribute adverse effects to the presence of wind farm (WF) infrasound. However, dominant features of windfarm noise such as infrasound, tonality and amplitude modulation span the average human hearing threshold, so attribution to infrasound is problematic. This study used a combination of pre-recorded noise stimuli, measured at 3.2 km from a wind farm, in laboratory-based listening tests to investigate human perception of infrasound and amplitude modulation at realistic sound pressure levels in a group of 14 participants. Although a small sample size warrants cautious interpretation, preliminary results suggest differential effects between self-reported non-sensitive versus noise-sensitive participants, where the latter detected infrasound above chance. Infrasound did not affect the perception of amplitude modulation. Larger studies remain needed to clarify these findings.
Duc Phuc Nguyen, Kristy Hansen, College of Science and Engineering, Flinders University, Adelaide, Australia
Branko Zajamsek, Gorica Micic, Peter Catcheside, Adelaide Institute for Sleep Health, Flinders University, Adelaide, Australia
Presented at the Australian Acoustical Society Annual Conference, Acoustics 2019.
Download original document: “Wind farm infrasound detectability and its effects on the perception of wind farm noise amplitude modulation”