The power of windmills

Ever found yourself frustrated during scorching summer months, enduring endless power outages and lengthy load-shedding sessions? Ever wondered why we can’t have electricity all the time like many other countries of the developed world do?

The answer lies in the stark reality that our electricity production falls short of the ever-growing demand, prompting the urgent need for more power plants. While makeshift solutions like generators, UPS and solar panels offer temporary relief on an individual level, the broader picture demands robust, long-term solutions to fuel not only our homes, but also vital industries and businesses crucial for our economy.

Electricity is produced in different ways in Pakistan — by hydroelectric power, by fossil fuel or coal generated power plants, but they are not good for the environment. Due to increasing concern for global warming, it is important that while looking for alternative means of generating electricity, it should be kept in mind that they are environment-friendly as well.

One such environment-friendly alternative is wind energy. Yes, those gusty winds that sometimes bother us can be, and are being, used to produce electricity. You may not know, but in 2022, wind energy sources accounted for nearly 7.33 percent of electricity generation worldwide.

Wind energy has been used for centuries in various ways such as in sail boats, windmills and wind pumps to crush grains and draw water. But today, wind power is widely used to generate electricity through wind turbines, which are the modern version of the windmills which have been in use since the mediaeval times.

The earliest known windmills were built in western Asia more than a thousand years ago, and were used to grind grain and pump water. It is believed that the first practical wind-powered machines, the windmill and the wind pump, were invented in the ninth century in the region which is now Afghanistan, Iran and Pakistan. The windmills soon arrived in India, China and Europe, where they went through a number of improvements.

As a source of electrical power, the windmill was first used in 1890 when P. La Cour built one in Denmark. Interest in the use of windmills for electric power generation revived in the 1970s.

The modern windmills, called wind turbines, use the power of the wind to create electricity. They are becoming more and more popular throughout the world as wind power is considered a sustainable and renewable source of energy, and has a much smaller impact on the environment as compared to traditional sources of power, as it causes less pollution. Windmills or wind turbines consumes no fuel and emit no air pollutants, unlike power sources using fossil fuel.

It is believed that the cost of per unit of electricity produced through wind power is one of the lowest among the various other sources. Wind turbines have currently been installed throughout the world, both onshore and offshore.

A group of wind turbines working together is called a wind farm. Individual turbines are interconnected with a voltage power collection system and communications network. A large wind farm may consist of several hundred individual wind turbines spread over an extended area. These are connected to the electric power transmission network to provide electricity to a town or city.

Windmills in Pakistan

Under its Renewable Energy Policy, the Pakistan government plans to generate 60 percent of energy from renewable resources by 2030. Pakistan has immense wind potential in Sindh, Balochistan and Khyber Pakhtunkhwa (KP). Various regions have been identified as wind corridor regions such as the Karachi-Hyderabad region, especially on hilltops, ridges in the northern Indus valley, wind corridor areas in western Pakistan, high mountainous regions and hills and ridges in south-western Pakistan. The coastal belt of Pakistan has a 60km wide and 180km long wind corridor, which has the potential to produce up to 50,000 MW of electricity through wind turbines.

Pakistan’s first wind power project, the Jhimpir Wind Power Plant, is located in the Gharo-Jhimpir wind corridor in Sindh, which is considered the most profitable site for wind power plants. The wind power potential covers an area of 9,700 km square, with a gross wind power potential of 43,000 MW.

The project was conceived in 2012 and achieved commercial operation in March 2018 and produces 55 MW energy. Based on state of the art and highly efficient wind turbine technology, Jhimpir power plant is designed to inject approximately 200 GWh into the national grid every year.

Jhimpir is just one of the 26 private wind projects that are currently operating in the country, producing approximately 1,335 MW, while 10 wind projects with cumulative capacity of 510 MW are under construction.

Hopefully when all the wind power plants planned are connected to the national grid we will not have to face power outages and load-shedding.

How windmills work

The design of earlier windmills was derived from the earliest water mills. These windmills were of the horizontal type, with sails attached to a vertical axis in a building, which had openings for the wind to enter and exit. The openings were diametrically opposite to each other. Each mill drove a single pair of stones directly, without the use of gears. Some old style windmills are still functioning, among them are those in Iran’s, which are one of the oldest windmills still in use.

Over the years, the designs changed and the later windmills had a number of blades that were mounted on a tall tubular tower. The blades spin around when wind blows on them. The turning blades provide power to a generator, which produces electricity.

Wind turbines are of two types — horizontal-axis wind turbines and vertical-axis wind turbines. Horizontal-axis wind turbines are the most familiar type of electricity-producing windmills. Most have three large blades that spin parallel to their towers, where the main rotor and generator are located. They stand about 60 to 90 metres tall, and the blades rotate at 10 to 20 rotations a minute. The blades on a horizontal-axis wind turbine usually face the wind (upwind).

The blades of vertical-axis wind turbines have varied, unusually shapes and rotate in complete circles around their tower. The main rotor and generator are located near the ground, making maintenance easier and less expensive. Vertical-axis wind turbines can be much smaller than their horizontal counterparts. Standing only five metres (15 feet) tall, these turbines can be installed on the roofs of buildings.

Asbads, the windmills of Iran

Asbads (windmills) of Iran, built in the town of Nashtifan, are said to be the oldest windmills in the world and are in use since centuries. Made of natural clay, straw and wood, these windmills have vertical wood blades and horizontal rotation. These were used to grind grains for flour for approximately a thousand years. Each windmill of Nashtifan comprises eight chambers, with each chamber housing six blades. As strong steady wind enters the chambers, it turns the blades, which then turn the grindstones. The structures reach up to about 65 feet in height.

Now only 15 ancient windmills remain in Iranian province of Sistan and Baluchistan. Considered a national heritage, some of these historical structures are being restored.

In the eastern parts of Iran strong northern winds blow throughout the year. The area is popular for the wind that blows 120 days in a year, the speed of which sometimes reaches 100 km/hour. Because of the strong winds, Nashtifan was originally known as “Nish Toofan” which means “storm’s sting”.

Interesting facts about windmills

• The oldest mill in the Netherlands dates back to the eight century.

• Today, there are between 1,000 and 1,150 windmills in Holland. Some are still actively used to grind grain or for water drainage.

• Holland celebrates “National Mills Day” every second Saturday in May.

• Earliest mills were not made only to process grain, but also to be used as automated stations that can route water from flooded areas or pump water from the depths to water agricultural areas.

• During the peak of windmill popularity in 18th and 19th century, Europe housed around 200 thousand of them.

• First windmill in America was created in 1888 by Charles Brush in Cleveland, Ohio.

• Early windmills used fan shaped objects made from wood. Modern windmills are using metal or other modern composite material.

• World’s largest wind turbine that is 20 stories high and has rotors that have length of entire football field. It is built and stationed in Hawaii.

• One megawatt of wind energy can prevent creation of 2,600 tonnes of carbon dioxide that is made by fossil-powered engines.

• The popularity of wind power turbines quadrupled between the years 2000 and 2006.

• Modern wind turbine is a complicated machine with over 8,000 parts.

• Modern wind turbines strive to place their blades at highest altitude possible so that they could access to stronger winds.

• United Kingdom is home to over 130 windmill energy farms.

• The average size of a wind turbine rotor reached a diameter of 97 metres in 2013.

• The country that has most wind turbines is not USA, it is China.

• Twenty percent of the energy production in Portugal and Denmark comes from wind turbines.