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2nd International Conference on Energy Systems and Technologies 18 – 21 Feb. 2013, Cairo, Egypt

WELCOMING THE WIND: THE POTENTIAL FOR URBAN WIND TURBINES TO RESHAPE THE BUILT

ENVIRONMENT

*Naglaa Ali Megahed

*Port Said University, Faculty of Engineering, Architecture and Urban Planning Department, Port Said, Egypt

Wind energy is an important part of the diverse energy portfolio that is needed for a stabile energy sector. In recent years, the trend toward integration of urban wind turbines has increased gradually within urban elements in streets, bridges, highways or in other open spaces. The paper proposes the most integrated concepts to capture wind within the built environment. Conclusions are drawn on the suitability of urban wind turbines for utility new vision of creativity which can become works of art and may change the roles of principals of architecture and urban design. Keywords: Building augmented wind turbines, Revolutionary wind turbine, Urban bridge turbine, Urban street turbine, Urban wind turbine.

INTRODUCTION

It is clear that interest in innovative wind-power technology, from both governmental institutions and private companies, has increased dramatically in the last few years and will likely to continue for some time [1]. Realistically, how this technology is viewed, and how such feelings can affect the future of wind-power development everywhere. It presents historical and theoretical questions bearing on wind energy aesthetics. Along with the need for increased sustainability in the energy sector, wind-power technology is increasing its market share faster than any other renewable-power technologies with significant improvement in operating efficiencies, making them more economically competitive [2, 3, 4]. No one can ignore this but how can this technology affected on our surroundings.

The increasing interest among architects and planners in designing environmentally friendly built environment has led to a desire to explore and integrate wind-power technology with their projects [5]. Even though, architecture and urban design are becoming experimental investigations of technology, there are more to take architects and planners their part to express and evaluate the advantages and disadvantages of wind capture into urban sittings from their point of views. Architectural and urban projects that are based only on conceptual expression and sculptural form have become unrealistic and no longer of social relevance. It was not responsible to think only in terms of past design theories, but futuristic theories should be taken place, especially after the increasing of renewable-power technologies. The aim is to investigate the possibility of improving the integration of wind turbines, under low

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wind speed conditions and more turbulent in built environment. The paper covers the unique and revolutionary designs for the integrated approaches from building design to its urban surroundings, through the examples of current or futuristic concepts that will succeed in changing, enhancing and reshaping our urban built environment.

RENEWABLE WIND ENERGY FACTS

Energy has been the main issue for the mankind for long time, electrical energy consumption is expected to be doubled by the year 2053 compared with the year 2008. Today, utilization of fossil fuel resources of energy is becoming more restricted mainly because of declining in fossil fuel reservoirs, threatening global warming, and the increase of oil prices. Therefore harnessing clean and renewable sources of energy is becoming the main worldwide topic for many researchers. Especially, those offer the possibility of on-site generation for residential, commercial and industrial energy users, moreover, with new and continuous improvements in the urban environments [6, 7]. On-site renewable energy systems represent an important role in narrowing the electricity gap in rural parts of the developing world. Planning authorities are also required include policies in their development plans that require a percentage of the energy in new developments to come from on-site renewable resources [8, 9].

With the rapidly growing demand for electrical power in Egypt and the finite life of conventional fossil fuels coupled with their adverse effects on the environment. It is evidenced that Egypt continues to develop its renewable energy market with the aid of the World Bank and the Clean Technology Fund. According to the Egyptian Environment Action Agency (EEAA) and the Supreme Council of Energy (SCE), Egypt affirmed its commitment to increase the share of wind energy such that it would represent 12% of total electricity demand by the year 2020. As a result of these data, wind energy systems will present an important role in narrowing the electricity gap in Egypt where become one of the major wind users in the world [10, 11]. However, the question here what about our visual environment or what is the future of architecture and urban design within the new wind technological parameters. As a result, the paper tries to investigate the integrated approaches to capture the wind especially after that commitment to increase the percentage of wind-power technology.

1- Wind-Power Technology: the Old and the New

For centuries, people have used the wind to sail ships, grind grains, run small sawmills

and pump water from wells. The history of wind-power technology can be traced back more than 7000 years to the first use of sails to propel reed boats in Southern Mesopotamia. The first windmills with a reliable historical record were vertical axis machines in Iran and Afghanistan early in the Islamic era. Horizontal axis windmills with four blades developed independently in England from waterwheels over the twelfth century and spread rapidly throughout Northern Europe. The main early applications were for pumping water and grinding corn but as soon as electrical power arrived, large wind machines were built to drive the generators [12]. By the time, there have been major advances in this technology.

Recently, wind turbines can be subdivided into different categories: large (>1 MW), medium (40 kW–1 MW), small (40-20 kW) and micro (20-0.4 kW) [13]. Large-scale wind installations have been advanced and investigated widely compared with small ones in urban areas. However, recent studies have identified that there are possible benefits from the theoretical augmentation of wind flow around buildings [9]. As a result, the development of

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innovative small wind turbine technologies is of growing interest with innovative design and new materials suitable for better performance in the built environment [7].

2-Types of Wind Turbines

Modern wind turbines fall into two basic groups: horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). Much historical developments of wind turbine technology have focused on HAWTs, although VAWT machines may be more appropriate to the urban context [14-16]. However, the recent applications of VAWTs provide even better results than horizontal ones, as they use all the different directions of wind flow and are quieter in operation; type designs include Savonius, Darrieus and H-rotor [3, 17, 18]. In general, VAWTs can produce electrical energy in separate unites or they can be used as integrated system for connecting to an electrical network [7]. Although VAWTs have shown to have advantages over HAWTs, their installation heights are limited, and their blades are prone to cyclic fatigue [14-16]. More practical experience is needed with VAWTs and HAWTs in the urban environment to verify their electricity production levels.

3-Wind Turbines Advantages and Disadvantages

Wind power is characterized as a clean and environmentally friendly technology, and this is one of the main benefits that make it such an attractive and promising energy supply solution [19]. Besides this positive side, it is important to study the negative impact of the wind turbine technology; wind turbines have fierce opponents and devoted supporters. There are some summarized points that should be taken into accounts before a wind turbine is erected.

- Environmental impacts; wind power does not produce waste products that require disposal or gas emissions that contribute to air pollution and global climate change. It does not consume or pollute water. But in some areas, people worry about the birds that may be injured by wind turbines [20]. Many birds can instantly be killed because the fast spinning blades of the turbines cannot be seen very well. This was discovered in 1994 in California, which experienced large numbers of such deaths. Consequently, several studies were conducted to determine how avian deaths could be reduced, and the lessons learned were incorporated into later and recent wind projects [21].

- Noise impact; recent wind turbines are quieter than the earlier models, but they still produce some noise. There is no completely satisfactory way to measure the subjective effects of noise or the corresponding reactions of annoyance and dissatisfaction. However, annoyance with the sound of large turbines is the major problem compared with small ones, particularly VAWTs which have less health effects. As a result, the research is carrying out to improve the mechanical structure of turbines to reduce the noise output and improving the standards of turbines design [21, 22].

- Wind turbine safety; it is a major concern because some potential dangers are related to the operation. Wind turbines are like most other engineering products as cars or aircraft; they are designed to operate to high standards of safety. However, there have been a number of injuries and fatalities to operational staff across the world and concerns have also been raised about the longevity of turbines within the urban environment or possible consequences of failure [21, 23].

- Aesthetic impact and public acceptance; in terms of integration within the built environment, aesthetic considerations are as important as the functional ones. One of the most common complaints about wind turbines is that they spoil the view. On the other hand, some

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people find wind turbines not only beautiful but also signs of hope for the future. Recently, turbines esthetics become a major focus, a new generation of wind turbines is now being produced with this concern specifically in mind [6]. Public acceptance has been a very strong barrier to the increase of wind-power technology but it varies by time and circumstance. Today, people naturally accept the presence of modern-life technologies like cars, telephone poles, antennas, electric lines, etc., because they recognize their benefits. But this was not the case about one or two hundred years ago when they first appeared [1, 24]. The best example was the criticism of Gustave Eiffel's plan to erect a great tower in the heart of Paris. By time Eiffel's tower won over its critics and symbolized Parisian architecture. The vision of modern wind turbines will also gradually become an accepted part of the cultural landscape [25].

INTEGRATED APPROACHES: READING THE SPACE FROM THE INTEGRATION OF URBAN WIND TURBINES

Growing awareness of rising levels of greenhouse gases, global warming and increasing

prices of fossil fuels have led architects, project developers and local governments to a shift towards investing into micro-generation technologies. Amongst these technologies, urban wind turbine is a comparative newcomer to this market place [26, 27]. Manufacturers improved performance for their devices at lower wind speeds [28- 30] with the minimum recommended average at the turbine location is 5.5 m/s. [31].

The definition of Urban Wind Turbines (UWTs) varies across jurisdictions, laws, and incentive programs, however the paper outlines UWTs to the turbines that are specially adapted for the wind regime in the built-environment as the shapes and sizes of the turbines have been well designed for this purpose. Furthermore, they have the potential to be integrated within buildings, roads, bridges, and cityscapes. These integrated approaches are more complex than rural or open ones, with a number of compound interactions involving human factors such as clients, designers, the public, legislative and statutory bodies, as well as technical issues such as turbulence, installation, safety and environmental impacts. Recently, there have been innovations in the design of wind turbines that can facilitate their deployment in urban environments. Some of these approaches are recently patented, some are patent-pending, and the rest may need more lab and field testing before reaching the final stage. Inspired by the broader perspective of the need to coexist with their natural surroundings. The following sections reviews the integrated approaches which selected as the most related to paper viewpoint and divided into capturing the wind by (1) building augmented wind turbines, (2) urban street turbines, (3) urban bridge turbines and (4) revolutionary wind turbines.

1-Building Augmented Wind Turbines (BAWTs)

A very promising category among current innovative wind-power concepts includes

systems purposefully designed to be integrated with functional building. It is a fact that there are many attempts about the capability of small wind turbine, because of compactness, portability, simple structure, low noise level in driving. In addition to technical benefits such as (i) electricity generation at the point of use, (ii) low cost mounting using the building as the fixing point and (iii) positive contribution to the carbon rating of a building [16].

One of the approaches being used, and investigated more frequently, is the incorporation of wind turbines into the design of the building. Wind turbines located at the high wind speed zones in buildings are called Building Augmented Wind Turbines (BAWTs), and the wind turbine makes use of buildings as a concentrator of wind. For retrofit applications BAWTs

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can only be positioned to invest any augmentation afforded by the existing building. Based on air naturally flows from areas of high pressure to areas of low pressure, the most effective locations for wind turbines will be either in the accelerated shear layers around the edge and top of the building, or in specially developed passages linking the areas of positive and negative pressure. By using one of the generic options (Side- mounted to building, roof- mounted on building, building integrated or between two building [9, 17, 32]. Thus, BAWTs are coming under increasing investigations as part of a group of technologies suitable for domestic micro-generation applications.

Roof-mounted wind turbines have been well studied by Computational Fluid Dynamics (CFD) simulations, the following summarized the results of different techniques.

- Vaulted roof is the optimum roof shape for mounting wind turbines while the lowest maximum wind velocity acceleration occurred on top of the wedged roof when the wind direction is parallel to the roof profile. - The optimum location for mounting the wind turbine on top of that roof is at the midpoint of the roof at a height of 1.3 times the height of the building. - Roof mounted wind turbines have higher potentials when mounted above tall buildings. - Staggered urban configuration has less effect on wind flow than canyon configuration [5] - Darrieus turbines are being considered as one of the most attractive solutions due to their low visual impact, the reduced acoustic emissions and their better response to a turbulent oncoming flow [26].

Generally, simulation studies have used CFD methods to model wind flow around

buildings. In built environment, vertical axis machines are more reliable in residential zones, while in commercial, office parks and manufacture zones a combination between horizontal axe on roofs and vertical axe on walls could be achieved to reach maximum efficiency of generating electricity. Machines between 1 and 5 kW are mainly confined to the domestic level. The larger machines are suitable for commercial, industrial buildings and groups of houses [27, 33]. However, unlike the mapped wind regimes for coastal large-scale wind farms, there is still no universal, comprehensive design code of practice for the use of BAWTs through the normal planning mechanism.

2-Urban Street Turbines (USTs)

The following concepts intend for the turbines to be used along urban streets and highways, where constant and steady traffic would provide plenty of wind to turn the turbines. The turbines are turned by cars as they move by in the urban environment as presented in Fig.1. The turning of the turbines creates clean electricity that can be stored and used to power the lights and service areas lining streets and highways.

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Figure 1. Urban street turbines, Adapted from Refs. [34-38].

- Voltair vertical turbine; the system makes double use of the fuel already being used to power vehicles. The fuel is used first by the vehicles, but is then used again as the air disturbance created by the vehicles’ passing is transformed into electricity. Vehicles are some of the worst environmental offenders, so doubling the use of the fuel that runs them without doubling their emissions could be a huge environmental benefit [35].

- E. Turbine; many turbines are located between lanes, each turbine stores the produced energy into a battery then distributes it to the grid, or it can also act like a normal wind turbine that uses the natural wind [37].

- The turbine-light; the system aims to illuminate roadways, by using the wind-power to light up the city with harvesting renewable energy contained in the air turbulence generated by passing traffic [36].

- Wind-solar hybrid streetlamp; the design of the solar lamp integrates a vertical axis wind turbine and a solar panel to extend lighting power to the lamp all through the year. This lamp does not require expensive wired connected to the grid for receiving power. This Streetlamp can be easily customized to meet the lighting, color and design requirements [38].

- Highway mounted wind turbine; a student at Arizona State University has proposed overpass-mounted turbines. The concept wind turbines powered by the passing vehicles rushing at the average speed of 70 mph. The idea uses the space above our highways as wind farms shaped like an axis [34]. This proposed concept could be considered also as urban bridge turbines which will be illustrated in the following point.

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3-Urban Bridge Turbines (UBWs)

The following concepts intend for the turbines to be used in the unused higher open spaces as shown in Fig. 2; they are designed to be constructed in various types to be architectural attractions or dynamic landmarks to enhance the cityscape sitting.

Figure 2. Urban bridge turbines at higher open spaces: a) the wind tunnel footbridge [39], b) solar wind bridge [40] and c) city speed turbine [41].

- The wind tunnel footbridge; as the wind blows, the five wind turbine wheels (made of

steel and aluminum) turn at different speeds around the people who are walking through to reach the other side. Three of the five wheels turn in one direction while the other two turn in the opposite direction. As the wind driven wheels turn in different directions and at different speeds, they can produce different electronic corresponding sounds [39].

- Solar wind bridge; Southern Italy is dotted with unused viaducts, and rather than spending millions to tear them down, town officials held a competition asking to re-use the existing structures in an environmentally conscious way. The solar wind concept was proposed as a new bridge incorporates wind and solar energy into its design, and looks fantastically sleek. The concept would use the space between existing viaducts to install 26 wind turbines [40].

- City speed turbine; the concept was the winner of the Mini Design Award proposed by Italian based industrial designer Giacomo Sanna. This futuristic wind turbine is designed for offers a new way to harness energy for urban settings that producing energy by harnessing the air flowing produced by the vehicle speed [41]. This future project can be applied in future city setting for producing sustainable electricity for generating LED light placed inside the architecture construction.

4-Thinking out of the Box: Revolutionary Wind Turbines (RWTs)

One of the biggest complaints against the wind turbine is that having an ugly view, so aesthetic value has recently tried to adapt with renewable energy. In terms of integration with built environment, the psychological aspects of aesthetics and functionality seem to be increasingly important in promoting public acceptance of wind-power technology systems [1], by giving them a sculptural appearance can fulfill to the functions quite simply. The following concepts intend for the turbines to be used as attractive urban turbines as shown in Fig. 3.

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Figure 3. Revolutionary Wind Turbines; (a), Treelike urban turbines [42]; (b), Floral Wind Turbines [43], (c), Simplenergy Domestic Turbine [44]; and (d), Multifunctional Wind Turbine [45].

- Treelike urban turbines; proposed by NL Architects’ Power Flowers to offer a way to bring such contraptions into cities without so many complaints from citizens. Treelike urban turbines are composed of smaller vertical axis turbines brought together as if on big bleached boughs. Branches of the turbine are ordered in the shape of a spiral, this creates natural design resembling a flower [42].

- Floral wind turbines; a revolutionary wind turbine designed to create wind power at speeds as low as 2 mph with a look like an actual flower. The typical wind speed that a wind turbine needs to produce power at is 7 mph, this combination of good looks and ease-of-use should help to make the concept a go-to choice for residential and small-scale wind power projects [43]. Based on so-called biomimicry principles, they embrace a natural form that can add to the urban aesthetics and create revolutionary wind turbines.

- Simplenergy domestic wind turbine; designed by Paul Mcluckie, the Simplenergy micro wind turbine is a vertical axis with Savannius design that will ask architects to incorporate into their designs, with complements and enhances the urban surroundings [44].

- Multifunctional wind turbines; it is known as Savannius that designed by industrial designer, Hirotaka Matsui, to generate small amounts of electricity and act as a bench at the same time. The interest of the Savonius rotor is that works in wind speeds as low as 1 m/s and it possesses a very high starting torque. In addition, it is rustic and little technology required in constructing it compared to other turbines that tries to create more functional eco-friendly designs [17, 45]. Despite such a certain number of advantages of Savonius wind rotors; they are not preferred so much due to their low aerodynamic performance levels. To eliminate this disadvantageous, several studies have been done in recent years in order to improve their aerodynamic performance; lot of theoretical and experimental studies have been carried out to increase the performance of Savonius wind rotors [46-48]. However, the proposed concepts are good-looking turbines developed for domestic use.

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LESSONS LEARNED AND FUTURE DIRECTION

The increase of environmental pollution, global warming and similar phenomena

indicate the necessity to diversify wind energy technologies. Technologies for wind energy conversion have significantly advanced during the past few decades. As a result, the wind power industry is fast growing and wind energy is widely accepted as the renewable energy resource which can be exploited in a commercial scale today [49]. There is widespread opinion that the government's policies should promote the adoption of widespread distributed wind-power technology particularly in the urban environment that will require change in the network infrastructure but this is the next step. In attempts to provide electricity generation at point of use thus eliminating transmission losses, strengthening of the grid reducing the need for upgrades and visibility in the highly populated urban environment leading to raised awareness of sustainability and renewable technologies [50]. Integrated approaches will become critical long-term research issues for industrial designers, planner, and architects. Designers still design and innovate out of the box and create wind turbines that look like no others turbines; they can play with their surroundings a new tool for creativity.

CONCLUSION

It is not responsible to think of successful architecture and urban design only in terms of

past design theories, but futuristic theories must be taken place, especially after the increasing of renewable energy technologies. The technology applications will change the historic methods of design creativity and roles of principal of architecture and urban design. Thus, It is important to identify local and distant viewpoints to choose the most appropriate site, shape, type and scale for the turbine in relation to its surroundings. The architect and planner must employ fine skills in seeking compatibility between urban built and this technology to reshape our built environment, the engineer also must create designs that are reliable and safe for this integration.

The integrated approaches can generate not only power, but public opinions. For this reason, the public should understand and discover the environmental benefits of wind-power to ensure the final public acceptance. It is gradually realized that they demand a holistic, systematic and accurate integrated approach to deal with. Finally, much more research of thoughtful and well-planned government legislation to foster the widespread implementation of UWTs are needed. So, it is very important that legislation define new planning guidelines for the wind turbines installation. The rules should fix the maximum height including the blade, diameter of blades, noise and vibration especially when integrated in conservation areas or world heritage sites.

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