Resource Documents: Technology (160 items)
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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.
Water droplet erosion of wind turbine blades: mechanics, testing, modeling and future perspectives
Mohamed Elhadi Ibrahim and Mamoun Medraj
Department of Mechanical and Industrial Engineering, Concordia University, Montréal, Québec, Canada
[Abstract] The problem of erosion due to water droplet impact has been a major concern for several industries for a very long time and it keeps reinventing itself wherever a component rotates or moves at high speed in a hydrometer environment. Recently, and as larger wind turbine blades are used,erosion of the leading edge due to rain droplets impact has become a serious issue. Leading-edge erosion causes a significant loss in aerodynamics efficiency of turbine blades leading to a considerable reduction in annual energy production. This paper reviews the topic of water droplet impact erosion as it emerges in wind turbine blades. …
A probabilistic long-term framework for site-specific erosion analysis of wind turbine blades: a case study of 31 Dutch sites
Amrit Shankar Verma, Zhiyu Jiang, Zhengru Ren, Marco Caboni, Hans Verhoef, Harald van der Mijle-Meijer, Saullo G.P. Castro, and Julie J.E. Teuwen
Faculty of Aerospace Engineering, University of Technology, Delft, The Netherlands; Department of Ships and Ocean Structures, SINTEF Ocean, Trondheim, Norway; Department of Engineering Sciences, University of Agder, Grimstad, Norway; Department of Marine Technology, Norwegian University of Science and Technology, Trondheim, Norway; TNO Energy Transition, Petten, The Netherlands
[Abstract] Rain-induced leading-edge erosion (LEE) of wind turbine blades (WTBs) is associated with high repair and maintenance costs. The effects of LEE can be triggered in less than 1 to 2 years for some wind turbine sites, whereas it may take several years for others. In addition, the growth of erosion may also differ for different blades and turbines operating at the same site. Hence, LEE is a site- and turbine-specific problem. In this paper, we propose a probabilistic long-term framework for assessing site- specific lifetime of a WTB coating system. Case studies are presented for 1.5 and 10 MW wind turbines, where geographic bubble charts for the leading-edge lifetime and number of repairs expected over the blade’s service life are established for 31 sites in the Netherlands. The proposed framework efficiently captures the effects of spatial and orographic features of the sites and wind turbine specifications on LEE calculations. For instance, the erosion is highest at the coastal sites and for sites located at higher altitudes. In addition, erosion is faster for turbines associated with higher tip speeds, and the effects are critical for such sites where the exceedance probability for rated wind conditions are high. …
RADAR-derived precipitation climatology for wind turbine blade leading edge erosion
Frederick Letson, Rebecca J. Barthelmie, and Sara C. Pryor
Department of Earth and Atmospheric Sciences and Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, New York
[Abstract] Wind turbine blade leading edge erosion (LEE) is a potentially significant source of revenue loss for windfarm operators. Thus, it is important to advance understanding of the underlying causes, to generate geospatial estimates of erosion potential to provide guidance in pre-deployment planning and ultimately to advance methods to mitigate this effect and extend blade lifetimes. This study focuses on the second issue and presents a novel approach to characterizing the erosion potential across the contiguous USA based solely on publicly available data products from the National Weather Service dual-polarization RADAR. The approach is described in detail and illustrated using six locations distributed across parts of the USA that have substantial wind turbine deployments. Results from these locations demonstrate the high spatial variability in precipitation-induced erosion potential, illustrate the importance of low probability high impact events to cumulative annual total kinetic energy transfer and emphasize the importance of hail as a damage vector.
Rain erosion maps for wind turbines based on geographical locations: a case study in Ireland and Britain
Kieran Pugh and Margaret Stack
Department of Mechanical Engineering, University of Strathclyde, Glasgow, Scotland
[Abstract] Erosion rates of wind turbine blades are not constant, and they depend on many external factors including meteorological differences relating to global weather patterns. In order to track the degradation of the turbine blades, it is important to analyse the distribution and change in weather conditions across the country. This case study addresses rainfall in Western Europe using the UK and Ireland data to create a relationship between the erosion rate of wind turbine blades and rainfall for both countries. …
[Introduction] … One common advance is to install much larger blades, however, this is coupled with substantially greater tip velocities of the blades. These increased velocities create a higher risk of degradation of the leading edge due to impacts from rain erosion. With tip speeds from turbines reaching 300mph, the repeated impact of raindrops is sufficiently energetic to erode the material. The erosion rates of wind turbines have a direct relationship to the environment they are erected. More rainfall will result in more erosion of turbine blades. Typically wind turbine farms are constructed in barren locations due to land availability, wind speeds and away from local beauty spots; however, this results in turbines being subjected to harsh conditions and in some locations heavy rainfall. …
Mapping hail meteorological observations for prediction of erosion in wind turbines
Hamish Macdonald, David Infield, David H. Nash, and Margaret M. Stack
Wind Energy Systems CDT and Mechanical and Aerospace Engineering, University of Strathclyde, Glasgow, Scotland
[Abstract] Wind turbines can be subject to a wide range of environmental conditions during a life span that could conceivably extend beyond 20 years. Hailstone impact is thought to be a key factor in the leading edge erosion and damage of the composite materials of wind turbine blades. Using UK meteorological data, this paper demonstrates that the rotational speed is a crucial factor in determining the magnitude of the kinetic energy associated with singular impact and is likely to be significant for incidents of hail. …
Forurensing fra vindturbinvinger
[Leading edge erosion and pollution from wind turbine blades]
Asbjørn Solberg, Bård-Einar Rimereit, and Jan Erik Weinbach
The Turbine Group, Stavanger, Sogndal, and Trondheim, April 22, 2021 [in Norwegian]. Download.
[Foreword] We have put together a report on an undercommunicated topic: microplastic emissions and possible toxic compounds in them. … Already in 2013, rotor blades for wind turbines accounted for 27% of Europe’s consumption of fiberglass-reinforced epoxy. Depending on the production method for the rotor blades, the epoxy contains as much as ~33% bisphenol A. … Bisphenol A is on the «Norwegian priority list of dangerous substances». (Vi har satt samme en rapport om et underkommunisert tema; utslipp av mikroplast og mulige giftige forbindelser i disse. Allerede i 2013 utgjorde rotorblad til vindkraftverk 27 % av Europas forbruk av glassfiberarmert epoksy. Avhengig av produksjonsmetode for rotorbladene så inneholder epoksyen så mye som ca. 33 % Bisfenol A. Bisfenol A står på «Den norske prioritetslista over farlige stoff».)
Author: Power the Future
On Earth Day, President Biden pledged under the Paris Climate Agreement that the United States would reduce greenhouse gas emissions by 50 percent in ten years (below 2005 levels). This goal is as preposterous as it is impractical. It’s clear that the Biden Administration is misleading the American people to impose the Green Agenda which includes stifling bureaucratic manipulation in every sector of the economy. Power The Future’s latest study, “Lights Out: How Green Mandates Are Undermining the Affordability and Reliability of Electricity,” explores the real costs and benefits of Biden’s plan.
Biden’s Climate Envoy John Kerry has himself admitted: “Almost 90 percent of all of the planet’s global emissions come from outside of U.S. borders. We could go to zero tomorrow and the problem isn’t solved.”
On this, as in little else, Kerry is right: Even assuming every signatory to the Paris Agreement (the US included, as pledged under President Obama) fulfilled its emissions commitments, the climate impact “is minuscule.” In measuring the temperature impact of every nation fulfilling every promise by 2030, the total temperature reduction would be 0.048°C (0.086°F) by 2100. Carry those assumptions out another 70 years, and Paris would reduce temperatures by just 0.17°C by 2100.
So what can we realistically expect from the types of proposals Biden is pushing? PTF looked at the results of renewable mandates in Texas, California, and New Mexico to find out.
Based on data from those states, it is clear that Biden’s pledge under the Paris Agreement sets the country on a dangerous trajectory. Green radicals will use it to push their fever dream of a 100 percent “clean” grid, powered by sources that don’t work at night or on cloudy days. These policies destroy good-paying jobs and raise energy prices. It’s time to wake up to these realities with policies that promote fuel diversity, reliability, and affordability—before it’s too late for all of us.
Download original document: “How Green Mandates Are Undermining the Affordability and Reliability of Electricity”
Author: Deroover, Marc
An electrical power network is all about power: at any moment, the network must deliver the power called upon by its customers. But wind turbines produce only variable power. Therefore the networks have to transform this variable power into a fixed guaranteed power in order to integrate it into their production plan.
This transformation requires backup generators, backdown generators, and, supposedly, various other exotic means like backup batteries or hydrogen storage. The costs of these tools are difficult to evaluate because they are hidden in the daily network’s operations. But we can have an idea of the type and magnitude of the problems encountered if we force the wind power plant to provide a fixed and guaranteed power and look at what has to be done to reach that goal.
The behavior of a wind power plant that has to provide a fixed and guaranteed power is illustrated in the following figure that shows, for each guaranteed power level, the average value of the various power flows in and out of the system.
The figure is drawn for a 1000 MW power plant, with a wind load factor of 28%, coupled with backup power generators and 4GWh batteries. The values are calculated for each guaranteed power value based on the day by day simulation of the system. The resulting daily values are then aggregated over the period to show the average power flows. Looking at the figure, one can see that:
- For all levels of guaranteed power, the wind turbines need some backup power to be able to provide the guaranteed power – except if this one is very low, which wouldn’t make much sense.
- A wind turbines power plant cannot even sell all the energy it produces if it must guarantee a power equal to its average power. In our example, about 25% of the wind energy produced by the wind turbines will need to be discarded and replaced by the production of some backup generators.
- Once the guaranteed power reaches the wind power average power, nearly all additional power will be provided by the backup generators, except for a few percent more of the wind power surplus that could finally be used to feed the load.
- The batteries can only be filled using a fraction of the wind power surplus: with or without batteries, the fraction of the wind power that can directly feed the load remains unchanged<./li>
- In our example, 4 GWh of batteries will allow for the saving of 9% of the wind power produced, thereby reducing the wind power surplus from 25% down to 16% of the wind power produced – probably at a huge price.
- The batteries are totally useless when they are full and there is too much wind, or when they are empty and there is not enough wind. This happens up to 50% of the time in our example. This is mainly due to the fact that the batteries are always too small with respect to the installed wind power (because of their cost).
- When the guaranteed power increases, the batteries become useless, because there is no enough wind power surplus to fill them. They remain empty most of the time.
- More surprisingly, the batteries become also useless when the guaranteed power decreases. This time it is because there is not enough wind power deficit to use the energy stored in the batteries. They remain full most of the time.
If you understand how a wind power plant forced to produce a guaranteed power works, you will also understand that any time someone promises you that wind turbines will provide some “magic things” that are not shown in the previous figure, what they really mean is that they intend to use the resources of the network to let you think that wind power is, well, “magic”.
You can try to add batteries in the customer houses, or use some hydrogen storage. But, because these things need to be filled with some power before being useful, they will behave as the main batteries of our example – very inefficiently.
That wind turbines are some kind of magic engines that could violate the laws of thermodynamics is one of the great illusions of our time. Only by pumping for free the resources of the network can wind turbines pretend to provide useful services.
There comes a time when people will realize that the laws of physics apply even if they don’t know them …
Download original document: “Wind Power is only Energy, no guaranteed power even with batteries”