Affordable Wind Power for Anyone Anywhere
Wind power has the potential to provide affordable electrical power throughout much of the world, and there is certainly more than one way to do it. The patented revolutionary INVELOX wind technology, developed by the American company SheerWind, is providing an effective alternative to conventional propeller-driven wind-harvesting systems. In this article, Dr Daryoush Allaei notes some of the problems with conventional wind power generation and then goes on to describe how the innovative INVELOX wind technology could change the game.
Dr Daryoush Allaei, Chief Technical Officer, SheerWind, Inc.
In recent years there have only been limited incremental improvements in conventional wind power generating systems. Since its foundation SheerWind has considered wind power conversion from a totally different perspective in order to address the performance, cost and environmental issues. The system that has been developed looks very different to conventional systems – and performs with vastly more efficiency.
Conventional wind turbines use massive turbine-generator systems mounted on top of a tower. INVELOX, by contrast, funnels wind energy to ground-based generators. Instead of snatching bits of energy from the wind as it passes through the blades of a rotor, the INVELOX technology captures wind with a funnel and directs it through a tapering passageway that passively and naturally accelerates its flow. This stream of kinetic energy then drives a generator that is installed safely and economically at ground level.
Conventional Wind Power Generation
Conversion of wind power to electrical energy is controlled by two major factors: free-stream wind speed and blade radius. Because of these two design parameters, the tower height and blade sizes in conventional systems have grown to be massive. In terms of manufacturing, logistics, installation and maintenance challenges and costs, the heights of the towers and size of the blades are reaching their limits.
Manufacturers have incrementally improved conventional wind turbines in the last two decades – but the greatest energy output gains have come from building turbines with ever-larger blades, perched on ever-taller towers, built at ever increasing expense and with ever increasing areas of land required. As the size and height of turbines and towers increase, often reaching beyond 100 metres – wide enough to allow a 747 aircraft to fit within the sweep of the blades – the cost of wind-generated power continues to exceed the cost of power generated by hydropower plants, coal and natural gas. Turbines are often subjected to excessive downtime, and failure and repair costs are high. Moreover, complaints of harm to wildlife continue to plague the industry, as do complaints of harm to human health from high-decibel low-frequency sound waves from wind turbines, propeller noise and flickering of light through rotating turbines.
The visual nuisances of large wind farms are another cause of complaints. Most alarming is the increase in the number of unhappy investors and financial institutions funding utility scale wind power plants in recent years, because they do not believe their initial investment will ever be recovered.
In recent years, innovators across the globe have developed approaches showing promise for certain applications. For example, airborne units have been developed with turbines at 300 to 500 metres above the ground. A variety of single and multiple array ducted turbines have also been developed. The single-ducted turbines have been shown to be effective and economical for small wind applications. Attempts have been made to scale up the single-ducted turbines for utility scale applications. However, due to the required excessive size of the shroud as the turbines grow in size, and the required speed increase, they have been proven to be uneconomical. Even though an array of ducted turbines can generate more electrical energy, they suffer from complexity in actual implementation for utility scale. As a result, the industry has remained on the same track – using turbines mounted on the top of towers – for almost a century.
A Game-Changing Approach
In order to make wind power an acceptable mainstream electrical energy generation industry, a totally game-changing approach needs to be taken to the disruptive features of wind power generation mentioned above, even though such a new approach will no doubt initially, and naturally, generate huge resistance and opposition from current experts in the industry. A recently developed technology, INVELOX (increased velocity), has shown promise. INVELOX is simply a wind capturing and delivery system that allows more engineering control than ever before. The second field-tested model and a description of the system are shown in Figure 1 and Figure 2 respectively.
Even though the original idea of capturing and accelerating wind is based on a 100-year-old ducted turbine combining both Bernoulli and Venturi concepts, INVELOX has certain unique features that could make it the breakthrough technology that the wind industry desperately needs.
In contrast to older designs of ducted turbines, INVELOX separates the location of the shroud and turbine-generator system; the intake is on the top while the turbine-generator is placed at ground level inside the ducted pipe carrying captured wind towards the turbine. This unique feature allows the engineers to design the size of the intake wind delivery system for any speed increase required, depending on local wind speeds, without increasing the turbine size. In fact, the turbine size may be selected based on the ability of the INVELOX to increase wind speed. For example, assuming wind speed can be increased by a factor of two, remarkably, one can reduce the size of turbine by a factor of three and yet generate the same amount of power.
The turbine-generator system is installed at ground level and inside the optimum location of the horizontal section of INVELOX resulting in significant cost savings at the time of installation, and during operation and maintenance for the entire 15- to 20-year life of the system.
Because there is no moving component on the top of the tower, most adverse environmental impacts are eliminated or minimised. Moreover, radar interference and optical flickering are no longer issues. The absence of a large rotating turbine on the top allows INVELOX towers to be installed closer to each other, reducing land requirements by as much as 90%.
Turbines inside INVELOX, or any ducted turbine, have a higher power coefficient than those installed in an open-flow environment. Standard horizontal or vertical turbines can be installed inside INVELOX and generate superior energy when compared with open-flow systems. This feature allows a much faster commercialisation, because there is no immediate need to develop new turbine-generator systems. However, in the future, the turbine-generator systems could be designed specifically for INVELOX in order to optimise the power output at higher wind speeds.
INVELOX allows a much lower cut-in speed because it can increase wind speed at the location of the turbine. For example, if INVELOX is designed to increase free-stream wind speed by a factor of four at the turbine location, and it uses a traditional turbine that has a cut-in speed of 4m/s, the cut-in speed of the INVELOX-turbine system will be 1m/s. Having a low cut-in speed is one of the most important features offered by INVELOX. This feature not only allows an increase in annual energy production and capacity factor but also increases wind power availability. It allows installation of INVELOX in wind class 1 and 2 areas. It also allows INVELOX to be installed nearer the end user, thereby significantly reducing transmission losses and added costs.
In total, INVELOX has the potential to reduce the net cost of utility scale wind power generation by 30 to 50%.
INVELOX is a true game-changing technology. Along with all new technologies come strong sceptics with opposite views on their viability. A reason to be sceptical of INVELOX is the fact that in the past ducted turbines have not made any significant headway in the industry due to financial viability, even though positive performance was in general demonstrated. It is also reasonable to question whether, once a turbine is placed inside an INVELOX system, the increase in speed might no longer be maintained, making the promise of superior performance no longer valid. It should be noted, however, that the same is true for traditional open-flow systems. The free-stream wind reduces speed when approaching the blades; it could reduce to a half to two-thirds, depending on the environmental and blade profile factors. In the case of turbines inside INVELOX, the increased wind speed also reduces when approaching the blades, but the level of decrease is no worse than with open flow. But since it starts at a much higher speed, it will end up with a relatively higher speed, too.
The performance of the system was validated by recent measured field data from the model shown in these datasets. It has been shown that the increase in wind speed was maintained even when a turbine was installed inside INVELOX and thereby the daily energy production was significantly improved. This measured data is shown to be consistent with that obtained through laboratory and wind tunnel tests, and full-scale computational fluid dynamics (CFD) models.
INVELOX technology has the potential to provide affordable electrical energy from micro to mega scale to anyone, anywhere around the globe.
Biography of the Author
Dr Daryoush Allaei has over 25 years of research, development and business experience. His technical expertise is in dynamic systems with emphasis on vibration and noise control. Since 1992, Dr Allaei has founded, or co-founded, six companies. He currently serves as the Chairman and Director of Research and Development of QRDc, Inc. in Minnesota as well as being Chief Technical Officer for the QRDc spin-off company, SheerWind.
Co-authors
Professor Jorge E. Gonzalez, NOAA CREST Professor of Mechanical Engineering, City College of New York
Professor Ali M. Sadegh, Director of the Center for Advanced Engineering Design/Development, Department of Mechanical Engineering, City College of New York.
Professor Yiannis Andreopoulos, Michael Pope Professor of Energy Research, Grove School of Engineering, City College of New York
David Tarnowski, VP of Operations, QRDc, Inc.
Wind power has the potential to provide affordable electrical power throughout much of the world, and there is certainly more than one way to do it. The patented revolutionary INVELOX wind technology, developed by the American company SheerWind, is providing an effective alternative to conventional propeller-driven wind-harvesting systems. In this article, Dr Daryoush Allaei notes some of the problems with conventional wind power generation and then goes on to describe how the innovative INVELOX wind technology could change the game. Dr Daryoush Allaei, Chief Technical Officer, SheerWind, Inc.
In recent years there have only been limited incremental improvements in conventional wind power generating systems. Since its foundation SheerWind has considered wind power conversion from a totally different perspective in order to address the performance, cost and environmental issues. The system that has been developed looks very different to conventional systems – and performs with vastly more efficiency.
Conventional wind turbines use massive turbine-generator systems mounted on top of a tower. INVELOX, by contrast, funnels wind energy to ground-based generators. Instead of snatching bits of energy from the wind as it passes through the blades of a rotor, the INVELOX technology captures wind with a funnel and directs it through a tapering passageway that passively and naturally accelerates its flow. This stream of kinetic energy then drives a generator that is installed safely and economically at ground level.
Conventional Wind Power Generation
Conversion of wind power to electrical energy is controlled by two major factors: free-stream wind speed and blade radius. Because of these two design parameters, the tower height and blade sizes in conventional systems have grown to be massive. In terms of manufacturing, logistics, installation and maintenance challenges and costs, the heights of the towers and size of the blades are reaching their limits.
Manufacturers have incrementally improved conventional wind turbines in the last two decades – but the greatest energy output gains have come from building turbines with ever-larger blades, perched on ever-taller towers, built at ever increasing expense and with ever increasing areas of land required. As the size and height of turbines and towers increase, often reaching beyond 100 metres – wide enough to allow a 747 aircraft to fit within the sweep of the blades – the cost of wind-generated power continues to exceed the cost of power generated by hydropower plants, coal and natural gas. Turbines are often subjected to excessive downtime, and failure and repair costs are high. Moreover, complaints of harm to wildlife continue to plague the industry, as do complaints of harm to human health from high-decibel low-frequency sound waves from wind turbines, propeller noise and flickering of light through rotating turbines.
The visual nuisances of large wind farms are another cause of complaints. Most alarming is the increase in the number of unhappy investors and financial institutions funding utility scale wind power plants in recent years, because they do not believe their initial investment will ever be recovered.
In recent years, innovators across the globe have developed approaches showing promise for certain applications. For example, airborne units have been developed with turbines at 300 to 500 metres above the ground. A variety of single and multiple array ducted turbines have also been developed. The single-ducted turbines have been shown to be effective and economical for small wind applications. Attempts have been made to scale up the single-ducted turbines for utility scale applications. However, due to the required excessive size of the shroud as the turbines grow in size, and the required speed increase, they have been proven to be uneconomical. Even though an array of ducted turbines can generate more electrical energy, they suffer from complexity in actual implementation for utility scale. As a result, the industry has remained on the same track – using turbines mounted on the top of towers – for almost a century.
A Game-Changing Approach
In order to make wind power an acceptable mainstream electrical energy generation industry, a totally game-changing approach needs to be taken to the disruptive features of wind power generation mentioned above, even though such a new approach will no doubt initially, and naturally, generate huge resistance and opposition from current experts in the industry. A recently developed technology, INVELOX (increased velocity), has shown promise. INVELOX is simply a wind capturing and delivery system that allows more engineering control than ever before. The second field-tested model and a description of the system are shown in Figure 1 and Figure 2 respectively.
Even though the original idea of capturing and accelerating wind is based on a 100-year-old ducted turbine combining both Bernoulli and Venturi concepts, INVELOX has certain unique features that could make it the breakthrough technology that the wind industry desperately needs.
In contrast to older designs of ducted turbines, INVELOX separates the location of the shroud and turbine-generator system; the intake is on the top while the turbine-generator is placed at ground level inside the ducted pipe carrying captured wind towards the turbine. This unique feature allows the engineers to design the size of the intake wind delivery system for any speed increase required, depending on local wind speeds, without increasing the turbine size. In fact, the turbine size may be selected based on the ability of the INVELOX to increase wind speed. For example, assuming wind speed can be increased by a factor of two, remarkably, one can reduce the size of turbine by a factor of three and yet generate the same amount of power.
The turbine-generator system is installed at ground level and inside the optimum location of the horizontal section of INVELOX resulting in significant cost savings at the time of installation, and during operation and maintenance for the entire 15- to 20-year life of the system.
Because there is no moving component on the top of the tower, most adverse environmental impacts are eliminated or minimised. Moreover, radar interference and optical flickering are no longer issues. The absence of a large rotating turbine on the top allows INVELOX towers to be installed closer to each other, reducing land requirements by as much as 90%.
Turbines inside INVELOX, or any ducted turbine, have a higher power coefficient than those installed in an open-flow environment. Standard horizontal or vertical turbines can be installed inside INVELOX and generate superior energy when compared with open-flow systems. This feature allows a much faster commercialisation, because there is no immediate need to develop new turbine-generator systems. However, in the future, the turbine-generator systems could be designed specifically for INVELOX in order to optimise the power output at higher wind speeds.
INVELOX allows a much lower cut-in speed because it can increase wind speed at the location of the turbine. For example, if INVELOX is designed to increase free-stream wind speed by a factor of four at the turbine location, and it uses a traditional turbine that has a cut-in speed of 4m/s, the cut-in speed of the INVELOX-turbine system will be 1m/s. Having a low cut-in speed is one of the most important features offered by INVELOX. This feature not only allows an increase in annual energy production and capacity factor but also increases wind power availability. It allows installation of INVELOX in wind class 1 and 2 areas. It also allows INVELOX to be installed nearer the end user, thereby significantly reducing transmission losses and added costs.
In total, INVELOX has the potential to reduce the net cost of utility scale wind power generation by 30 to 50%.
INVELOX is a true game-changing technology. Along with all new technologies come strong sceptics with opposite views on their viability. A reason to be sceptical of INVELOX is the fact that in the past ducted turbines have not made any significant headway in the industry due to financial viability, even though positive performance was in general demonstrated. It is also reasonable to question whether, once a turbine is placed inside an INVELOX system, the increase in speed might no longer be maintained, making the promise of superior performance no longer valid. It should be noted, however, that the same is true for traditional open-flow systems. The free-stream wind reduces speed when approaching the blades; it could reduce to a half to two-thirds, depending on the environmental and blade profile factors. In the case of turbines inside INVELOX, the increased wind speed also reduces when approaching the blades, but the level of decrease is no worse than with open flow. But since it starts at a much higher speed, it will end up with a relatively higher speed, too.
The performance of the system was validated by recent measured field data from the model shown in these datasets. It has been shown that the increase in wind speed was maintained even when a turbine was installed inside INVELOX and thereby the daily energy production was significantly improved. This measured data is shown to be consistent with that obtained through laboratory and wind tunnel tests, and full-scale computational fluid dynamics (CFD) models.
INVELOX technology has the potential to provide affordable electrical energy from micro to mega scale to anyone, anywhere around the globe.
Biography of the Author
Dr Daryoush Allaei has over 25 years of research, development and business experience. His technical expertise is in dynamic systems with emphasis on vibration and noise control. Since 1992, Dr Allaei has founded, or co-founded, six companies. He currently serves as the Chairman and Director of Research and Development of QRDc, Inc. in Minnesota as well as being Chief Technical Officer for the QRDc spin-off company, SheerWind.
Co-authors
Professor Jorge E. Gonzalez, NOAA CREST Professor of Mechanical Engineering, City College of New York
Professor Ali M. Sadegh, Director of the Center for Advanced Engineering Design/Development, Department of Mechanical Engineering, City College of New York.
Professor Yiannis Andreopoulos, Michael Pope Professor of Energy Research, Grove School of Engineering, City College of New York
David Tarnowski, VP of Operations, QRDc, Inc.
