Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth’s surface, and rotation of the earth. Wind flow patterns are modified by the earth’s terrain, bodies of water, and vegetation. Humans use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity.
The terms wind energy or wind power describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity.
So how do wind turbines make electricity? Simply stated, a wind turbine works the opposite of a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity.
This aerial view of a wind power plant shows how a group of wind turbines can make electricity for the utility grid. The electricity is sent through transmission and distribution lines to homes, businesses, schools, and so on.
Types of Wind Turbines
Modern wind turbines fall into two basic groups: the horizontal-axis variety, as shown in the photo, and the vertical-axis design, like the eggbeater-style Darrieus model, named after its French inventor.
Horizontal-axis wind turbines typically either have two or three blades. These three-bladed wind turbines are operated “upwind,” with the blades facing into the wind.
Sizes of Wind Turbines
Utility-scale turbines range in size from 100 kilowatts to as large as several megawatts. Larger turbines are grouped together into wind farms, which provide bulk power to the electrical grid.
Single small turbines, below 100 kilowatts, are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off-grid locations, where a connection to the utility grid is not available.
As already mentioned, wind turbines capture the energy of moving air and convert it to electricity.
Below shows the parts of a turbine.
Most turbines have three aerodynamically designed blades. These blades spin a shaft which connects to a generator that produces electricity.
The wind passes over the blades creating lift (just like an aircraft wing) which causes the rotor to turn.
The nacelles houses the low-speed shaft, the gearbox (or alternatively a slow rotating generator and no gearbox), the high-speed shaft and the generator.
The turning blades spin this shaft 30-60 times per minute.
The gears in this box connect the low-speed shaft to the high-speed shaft to 1000-1800 rotations per minute..
This rapidly spinning shaft drives the generator to produce electric power.
The generator’s electrical output goes to a transformer that converts it to the right voltage for the larger electricity grid.
How does it work?
Three main variables determine how much electricity a turbine can produce.
[How wind turbines work?
Stronger winds produce more energy. Wind turbines generate energy at wind speeds of 4-30 metres per second. If the wind reaches speed of over 30 metres per second, which happens rarely, the turbine is stopped because it can be damaged.
The larger the radius or "swept area" of the blades, the more energy can be produced. Doubling the blade radius can result in four times more power.
"Heavier" air exerts more lift on a rotor. Air density is a function of altitude, temperature and pressure. High-altitude locations have lower high pressure and "lighter" air so they are less productive turbine locations. The dense "heavy"air near sea level drives rotors relatively more effectively.
Before installing a wind turbine it is best to measure the wind at site. This will allow to accurately predict the payback period and output of a chosen wind turbine. Many people think they have a windy site, spend thousands, or tens of thousands, installing a turbine only to be disappointed by the output and return on their investment. Using a unique temporary mast, it's possible to survey the site for some weeks.
Getting a wind survey is a low risk and independent way to find out if a site is suitable for a wind turbine. A turbines payback period should be no more than 8 – 10 years. Beyond that the maintenance costs will start to negate the electricity produced. Published wind maps on the internet or from S.E.A.I., while useful, only go down to 50 metres from the ground and are not site specific.
It's possible to measure wind on site (for at least one month) and at 10 metres which is the normal hub height of a turbine in Ireland requiring no planning. There is a significant difference in wind speeds at 10 metres and 50 metres from the ground.
A 10 metre temporary mast is erected on site with wind measuring equipment. The mast is left on site for at least four weeks. Once the period of time has elapsed , the mast is removed, the collected wind data is analysed and compared against one of our 15 fixed Met Stations, over the same period. This allows to obtain a weekly or monthly predicted wind speed (in metres per second, m/s) for the site at 10 metres.
Wind turbines outputs are predicted using the manufactures published power curves. The power curve will give the power generated at given wind speeds. A sample of a power curve for a 5 KW turbine is shown below.
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The sun heats the earth unevenly, creating thermal air currents. In order to achieve equal temperatures around the earth these air pockets move about the earth as global wind. The energy that travels in the wind can be captured and converted to provide electricity.
Wind energy provides a clean, sustainable solution to our energy problems. It can be used as an alternative to fossil fuels in generating electricity, without the direct emission of greenhouse gases. And there will always be wind; it is inexhaustible and renewable.
It is envisaged that wind power will make the most significant contribution to the achievement of national and international targets for green electricity, due to its environmental benefits, technological maturity and competitiveness.
Where does wind come from?
It is possible to compare the earth's atmosphere to a thermal engine where air masses move due to their different thermal conditions. This large scale motion can be observed in the air streams which are the result of the transformation of thermal energy into kinetic energy. The source of this energy is the sun.
The motion of air in the atmosphere is evident as a global circulation with seasonal cycles or as a regional phenomenon. The movement can also be determined locally by orographic or surface conditions.
As the earth has a spherical form, the incident radiation at the equator is greater than that occurring at the polar regions. This energy imbalance created, with excess in the atmosphere around the equator and a deficit around the southern and northern latitudes, causes the heat to move by air masses into the cooler regions. These global movements are called geostrophic winds.
There may also be local imbalances in radiation, however these are mainly due to differences in the earth's surface. Local winds with site specific characteristics result. The most important local winds in an Irish context are the sea-land breeze and the mountain-valley wind.
These winds are mainly influenced by temperature differentials as well as the surface structure. For example, in the case of sea-land breezes, when the solar radiation heats the land during the day the temperature over the sea is lower resulting in an exchange of air masses as the land air rises. The wind may be noticed up to 40km inland and reach speeds of 10m/s.
In analysing potential sites and yield from wind energy the geostrophic winds are less important than the surface winds. When a fluid, in this case air, flows over a surface it interacts with that surface creating a boundary layer. The visualisation of this boundary layer depicts a velocity of zero at the surface rising to a maximum at some point in the atmosphere. Wind turbines always operate in this boundary layer, as it varies between tens and hundreds of meters.
In addition to the interaction of the air stream with a plain surface of the earth, in reality there are changes in orography, landscapes, buildings and natural obstacles which locally effect the wind speed profile by causing turbulence, degraded velocity and backflows.
For these reasons the only way to get a realistic assessment of the wind resource and energy yield from a prospective turbine site is to erect instruments such as anemometers and vanes over long periods, typically not less than a year to record full seasonal variations, and to use this data with the nearest met station's historical data.
Since the days of Admiral Sir Francis Beaufort (1774-1857), who introduced the Beaufort scale of wind force, the knot (one nautical mile per hour) has been used as a unit of wind speed. Modern meteorological practice however is to use metres per second (1 metre per second = 1.94 knots = 2.24 miles per hour).
Given its strength, the wind in Ireland represent a great potential and can be exploited.
The West coast of Ireland, along with Scotland, has the highest wind speeds in Europe. Wind speed is all important e.g. a turbine on a site with average wind speed of 8 m/sec will produce 80% more electricity than one on site with wind speed of 6m/sec.
Ireland could presently generate 25 % of its electricity from the wind with no increase in electricity prices to the consumer. If this was done, there would be wind turbines scattered across only ½ of one percent of the country, assuming no offshore development.
As already mentioned, the wind at a particular location can be influenced by a number of factors such as obstruction by buildings or trees, the nature of the terrain and deflection by nearby mountains or hills. For example, the rather low frequency of southerly winds at Dublin Airport is due to the sheltering effect of the mountains to the south. The prevailing wind direction is between south and west. Average annual wind speeds range from 7 m.p.h. in parts of south Leinster to over 18 m.p.h. in the extreme north. On average there are less than 2 days with gales each year at some inland places like Kilkenny but more than 50 a year at northern coastal locations such as Malin Head. Indeed the north and west coasts of Ireland are two of the windiest areas in Europe and have considerable potential for the generation of wind energy.
One of the most frequently asked questions that probably for all those individuals and organisations dealing with CSR issues is the obvious, is just what does “Corporate Social Responsibility” mean anyway?
First of all, what is CSR?
“CSR is the integration by companies of social and environmental concerns in their business operations and in their interaction with their stakeholders on a voluntary basis.” The concept of social responsibility means going beyond the fulfillment of legal requirements by investing more in human capital, the environment, and relations with stakeholders. It is a voluntary instrument, but must be implemented reliably so that it fosters trust and confidence among stakeholders.
The concept of CSR encompasses the ways in which a business contributes to a better society by actively engaging with and consulting stakeholders, including customers, employees, shareholders and the local community, in a manner that goes beyond the company’s financial and legal obligations. Through CSR, companies are working voluntarily to integrate social and environmental concerns into their everyday business operations.
CSR has been shown to result in a number of business benefits, including: customer attraction and retention; increased value and reputation; attraction and retention to of staff; better corporate governance; increased revenues; and improved efficiency.
Energy Sense Ireland has partnered with DonQi windmills to promote this concept to organizations in Ireland the launch of DonQi’s unique venture wind turbine. The DonQi Venturi Windmill is a high performance windmill using modern aero-dynamic techniques. It performs in light breezes and violent storms with practically no noise and an outstanding energy production. With every part designed to function maintenance free for at least 15 years, it features a silencer and a unique venture design that can generate up to 50% more electricity than traditional windmills.
New technologies are making “microwind” a reality and, in Europe, Dutch companies have developed small turbines that can be easily installed on rooftops today. It is the case of donQi, a young company started in the Netherlands with the intention of providing decentralized power generation for urban and rural areas.
DonQi’s urban turbines are easy to install and can be ready in a couple of hours; also, they can be connected to the grid. Prices are affordable, and both the EU and the different countries are putting several financial instruments in place to help businesses to green. Their unique style, appearance and option for company logo really stand out at client’s premises.
The DonQi wind turbine gives several benefits to clients when looking at Corporate Social Responsibility. It can boost your organisation’s corporate image and identity; have a high impact with local residents and high visibility from its premises. The project can also contribute to attracting positive media coverage, both nationally and locally.
Over the past 100 years, human activities have triggered a series of resources and environmental problems. Our planet is faced with severe challenges. Every country and nation, every enterprise and individual, should feel duty-bound to take actions and unswervingly promote green development
Site surveys, wind surveys and pricing proposal can be arranged by contacting:
Energy Sense Ireland
Unit C2, Donnybrook Commercial Centre, Douglas, Cork, Ireland
Phone number: +353 (0)21 4368581
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Some Information about the Donqi Wind Turbine