Is it best to install Wind Turbine or Solar Panels? Firstly let me tell you there is not a straight answer to this question, because it is going to be mainly dependent upon your location. What is the climate of that region? It should be noted that we can divide the world in 3 regions based on climate.
What is the best location for wind turbines?
- First are the regions where high atmospheric pressure dominates through out the year. These are high pressure regions. These are arid areas with high solar insolation. All the deserts of the world are based in this strip.
- Second are the regions where low atmospheric pressure remains for most part of the year. They are called low pressure regions. Wind is high in such regions and it remains mostly cloudy. Annual precipitation also is high. These areas include Britain, Northern Europe, the Philippines and New Zealand.
- Third are the areas which have a mixed climate. At times low pressure creeps in and at times high pressure dominates in such areas.
So if you are in the region of first kind then solar panels are more appropriate for you. In Pakistan interior, Sindh, Balochistan and South Punjab are areas where only solar technology can be used. Similarly in India, the area of Rajasthan is appropriate for Solar.
Which are the best countries for wind energy?
If you live in an area where low atmospheric pressure dominates through the year, than Wind turbines are better in such locations. If you live in the 3rd kind of region where Climate is varied, then you will have to see how much investment you can make and how much are the wind and solar resources of the area. Only with that knowledge it can be decided which technology would be better suited.
In the last decade there has been an exponential rise in both Solar Energy and Wind Energy Technology. Such has been the increase in both technologies that people have started to think that we can shutdown the power plants running on coal, oil and gas.
The total wind power capacity in the world is 486 GW, whereas total world capacity for solar energy is 303 GW. For comparison we can add that Pakistan’s total energy capacity is only 22 GW´.
The areas which have high speed wind are very feasible for wind turbines. However, the wind turbines of only large scale are the ones that are effective. We are talking about turbines that produce several hundred kW of electricity at a given time. Note that some even produce even more electricity than 5 mega watt. These turbines are taller than 10 storey buildings.
Such turbines are mostly purchased by large organizations. It is almost impossible for an individual to buy them. It should be noted that a turbine of 1 Mega watt costs around 1 million USD. However, if it is installed in an area which has high wind, then it can recover its costs within 3 to 4 years because of its high yield.
Video and transcript by kind permission Synergy Files
Are small wind turbines cost effective?
Note that a turbine life is around 15 to 20 years, and can be 25 years if maintained properly. Small scale turbines are not very efficient, in fact they are useless. Turbines that are 10 kW or less are inadequate because they don’t have the technology that is in the large scale turbines.
This is the reason why the output of small turbines is almost next to nothing. This is the reason that when you will look at a picture of a wind farm you will mostly see that there are large scale wind turbines in the farm. Compared to wind, Solar Energy is as efficient on small scale as it is on a large scale. That is why it is in the reach of a common person.
If you observe all the solar projects in the world you will note that they are largely small scale installations. Whereas if you look at wind power project then you will note that small scale installation of 10 kW or less are next to nothing.
If we look at Pakistan, than there are only few regions where wind turbines would recover their costs. These areas includes the southern coastal regions and some valleys in Balochistan and Khyber Pakhtoonkhwa.
What is the minimum wind speed for a wind turbine?
You can look at the world’s wind resource map the areas where the annual wind speed is less than 5.5 m/s at the altitude of 10 meters. Installing wind turbines in such regions is a waste of money. That is why in Pakistan, India and Afghanistan, Solar technology is the most suitable technology.
You can get 10 KW turbines in the market from 10,000 to 15,000 USD but wind turbines have to be installed in open areas and if possible have to be installed at highest of altitudes. You may have noticed in pictures that often they are installed on top of hills.
You cannot install them in built-up areas. Wind not only loses its speed and energy after it hits the buildings, but also the turbulence is increased. I have noted many people claiming that wind resources are high in their area
but I should mention that in most areas in Pakistan the annual wind speed is less than 3.5 m/s.
There are only a few areas where it surpasses 5.5 m/s speed. Compared to this, in Scotland speeds of 5.5 m/s to 7.5 m/s are fairly common. The final point is that, in engineering, there is a general rule of thumb that if there are moving parts in a machine, then its reliability is lower compared to a machine that is solid state and doesn’t have moving components, such as electronic products.
Rotating and moving components over time have wear and tear and require maintenance. In a wind turbine there are rotating components, whereas solar panel is a solid state device
Are Small Scale Wind Turbines Worth It For The Home?
Almost a decade ago small-scale turbines of one to five kilowatt power rating were driven out of business when it transpired that their output was next to nothing, even during the time when they were spinning.
Over time, both the performance has improved and the costs have slid down. The performance increased mainly due to the trickle-down of technology from larger turbines to smaller ones. We will discuss four major technological advancements that is boosting the small-scale wind turbine industry.
Small wind turbine blade dimensions
As a rule, turbine with blade diameters of 1 meter or less should be avoided. the reason being the low amount of energy that they intercept in the first place. This low intercepted energy then has to go through a poorly efficient conversion process to be converted into electricity.
As a result the output is not high enough to be of any use. Now let’s turn our attention to the turbines in the 1 kilowatt to 210 kilowatt category and see how they have upped their game.
What are wind turbine blades made out of?
The first improvement is in the quality of the blades. It was a common practice among the small turbine manufacturers that in order to reduce the cost they would use polymer blades, or use die-cast single piece metal blades. Each had its own problem. The wear in plastic and the fatigue in metal blades rendered many of the turbines useless a little while after their installation.
Carbon or glass fiber reinforced polymer blades are becoming common in smaller turbines giving them strength and durability. Furthermore, the blade shape for smaller turbines has improved, making them much more efficient and quieter.
The improved blade shape also allows the turbine to get going at a lower cutting speed. The second important development for small turbines is the availability of telescopic masts and guide masts that now allow turbines to be mounted at heights of 10 metres or above.
It’s common knowledge that the further the distance from the ground, the higher is the wind speed and there is a cubic relationship between power and wind speed. The slightest increment in wind speed results in a huge improvement in power.
How high does a wind turbine need to be?
Today, taller masts are available for smaller turbines, which gives their performance a huge boost. Previously we’ve noted that wind turbines, particularly on the lower end, were mounted on masts which were much shorter than 10 metres. This reduced their performance substantially.
We now move to another advancement in small turbines, which is the direct drive technology. Now large-scale direct drive turbines can be identified with their shorter nacelle. Instead of having a gauge system, they have permanent magnet generators and an inverter.
In a normal large-scale turbine, a complex mechanical system is at work for increasing the speed in the generator. A sophisticated gating system is used. In a direct drive the complexity of that system is taken out by electrical and power electronic systems.
Gearboxes in turbines result in huge maintenance costs, while the majority of small scale turbines do not feature a gearing system, but they also don’t have the direct drive system as found in some large scale turbines. Bear in mind that large-scale direct drive systems have flatter electrical generators and complex inverter circuits to generate that 50 or 60 Hertz output, which is required.
The direct drive circuit allows the 50 or 60 Hertz AC output to be generated at a wide range of rotational speeds of the blade. On the other hand, in most small-scale AC wind turbines, such circuits do not exist. They don’t have to just spin, but have to spin above certain speeds to have a usable output.
Can wind turbines spin too fast?
As of today however, quite a few small-scale turbines are offering the same electrical system as their large direct drive counterparts and this is one of the biggest reasons why small turbines are making a comeback. This brings us to reason number four, which is the variable pitch system used in the blades.
It was common practice that small turbines had to be pulled down when wind speed went up to gale-force range. Some slightly better systems in small turbines would be a carrot brake which would stop the turbine completely at very high speeds.
This is different to what we see in larger turbines, where the variable pitch system allowed the blades to rotate at an angle that would minimize the lift force imparted on the blades, thus reducing the rotational speed of the blades even in very high winds.
Do wind turbines change speed?
This technique is called feathering and allowed the turbines to still make use of that high energy in the wind whereas the braking system strategy would mean no output when the energy in the wind was at its peak.
Another important thing to note about these variable-pitch systems is that they are very complicated, with separate small motors housed in the cell to provide the rotational force to tilt the blades. This arrangement is difficult to accommodate in smaller turbines.
However, some turbine manufacturers have found a clever solution. They have introduced a spring-based mechanism which allows the blades to be rotated back by extreme wind loads, and as the wind load reduces, the spring forces the blade back to their original position.
In effect, it is a simple self-regulating system that doesn’t require any electrical components to operate. In other words, the turbine’s effectiveness is increased with minimal increase in costs.