Alternative Energy - Jayabalaji Sathiyamoorthi

Alternative Energy

Jayabalaji Sathiyamoorthi

INTERNATIONAL ENGINEERING CONGRESS

Alternative Energy Applications

Paper on

“PASSIVE SOLAR SYSTEM AS A SUSTAINABLE SOURCE OF ALTERNATIVE ENERGY”

Author: Mr. Jayabalaji Sathiyamoorthi Master Student University of Applied Science, Emden, Germany [email protected] 1|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

TABLE OF CONTENTS

1.

INTRODUCTION ....................................................................................................................................... 3

2.

NEED FOR ALTERNATIVE ENERGY................................................................................................... 4

3.

SOLAR ENERGY TECHNIQUES ............................................................................................................ 6 3.1. 3.2. 3.3. 3.4. 3.5.

4.

SOLAR ENERGY BASICS ......................................................................................................................... 6 UNITS OF SOLAR ENERGY .............................................................................................................. 7 SOLAR ENERGY FOR HEATING WATER ................................................................................................... 8 ACTIVE AND PASSIVE SOLAR SYSTEMS ..................................................................................... 9 ADVANTAGES AND DISADVANTAGES...................................................................................... 10

PASSIVE SOLAR SYSTEMS .................................................................................................................. 12 4.1. 4.2.

5.

PASSIVE SOLAR BUILDINGS .................................................................................................................. 13 PASSIVE HEATING SYSTEM CHARACTERISTICS ..................................................................................... 13

DAYLIGHTING ........................................................................................................................................ 16 5.1. 5.2. 5.3.

6.

WHY DAYLIGHTING? ..................................................................................................................... 16 DAYLIGHTING VS HUMAN PERFORMANCE ............................................................................. 17 WAYS TO CALCULATE DAYLIGHTING ...................................................................................... 18

TRANSPIRED SOLAR COLLECTOR .................................................................................................. 19 6.1. 6.2. 6.3. 6.4. 6.5.

WORKING PRINCIPLE .................................................................................................................... 19 SOLAR COLLECTOR SPECIFICATIONS ....................................................................................... 22 DESIGN HIGHLIGHTS ..................................................................................................................... 22 CASE STUDIES ................................................................................................................................. 24 ENVIRONMENTAL BENEFITS....................................................................................................... 25

7.

ENERGY MINIMIZATION TECHNIQUES ......................................................................................... 26

8.

FUTURE OF SOLAR ENERGY.............................................................................................................. 28

9.

DISCUSSION ............................................................................................................................................. 29

10.

CONCLUSION AND SUMMARY ...................................................................................................... 30

11.

REFERENCES ...................................................................................................................................... 31

2|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

Passive Solar System as a sustainable source of Alternative Energy 1. Introduction Nature has nurtured human race for centuries with its amazing resources as food, cloth and shelter. As the humans evolve from Stone Age to the Modern Age, the needs are multiplied and so the life style. This is evident from our day to day life, which is equipped with sophistication in terms of the houses we live, the cars we drive, the industries we have, the products we manufacture and the advancements in science and technology arena. The consumption rate of the energy resources has multiplied several folds. This eventually led to the rise in oil prices; reserves of oil, coal and natural gas are being depleted; and the continued use of non-renewable fuels poses threats to the environment. So the topic of exploring Alternative Energy gains enormous focus and attention. In-fact many world leaders, business leaders and environmentalists have recently encouraged the development of alternative energy resources.

Recent years the renewable energy resources like sun light, wind, rain, tides and geothermal heat are the important arenas of the alternative energy. In 2006, about 18% of global final energy consumption came from renewable energy sources as against 13% coming from traditional biomass. In this paper, the idea of using passive solar system as a sustainable source of alternative energy and the different methods of generating alternative energy using passive solar system will be discussed.

3|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

2. Need for Alternative Energy The world’s consumption of non-renewable energy sources have raised to a maximum threshold. As the business models are getting more and more globalised, making us to feel world is just a small village. So the goods and services are available to anyone from anywhere in the world, on an average these hi-tech goods and products travel twice the globe before it reach us. These phenomenons have gradually depleting the non-renewable energy source and migrate to renewable energy sources. Renewable energy in simpler terms is the energy generated from natural resources—such as sunlight, wind, rain, tides and geothermal heat. All these sources are renewable or naturally replenished with a least damage to the environment. The important question is will renewable energy sources will make an alternative energy source? Let us find out by evaluating both of these resources. When comparing the processes for producing energy, there remain several fundamental differences between renewable energy and fossil fuels. The process of producing oil, coal, or natural gas fuel is a challenging and demanding process that requires a great deal of complex equipment, physical and chemical processes. On the other hand, renewable energy can be widely produced with basic equipment and naturally basic processes. However, there needs some optimization techniques that needs to be done with these renewable energy production to maintain and utilize the generated energy. The necessity of finding sustainable alternative energy source for the future generation has come. Most of the nations have understood the need due to the climate change, increase in oil prices etc., hence the investment on alternative energy have multiplied several fold. For instance, Brazil has one of the largest renewable energy programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 18 percent of the country's automotive fuel.

4|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

It is to be noted that most renewable energy projects and production is large-scale, renewable technologies are also suited to small off-grid applications, sometimes in rural and remote areas, where energy is often crucial in human development. Alternative Energy has the advantages of being non-pollution, less cost (though there is an initial investment) and independent of a politically controlled energy sources such as the electric grid or oil. This self-sufficiency has important implications as the modern world comes to understand the eruptive danger of energy dependence.

5|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

3. Solar Energy Techniques Solar energy techniques use the sunlight as the principle source of energy. Solar energy has become very popular and grabbed public attention in recent years as it is understood that the picture of fossil fuel consumption is limited. It is apparent that the present energy equation is not balanced. Using up energy reserves is an untenable situation and the imbalance is reflected in our diseased biosphere. To be in balance, man cannot rely on energy that is not self-renewing. Alternate energy sources, aside from being self-renewing Solar heating systems may be either active or passive. Active systems use fans and pumps to move the heat about. Passive systems use no forms of energy other than sun power, they are more appropriate for developing countries.

3.1. Solar Energy Basics Solar energy is intense radiation energy produced by thermonuclear reaction in the sun. It takes approximately eight minutes for a “packet” of light to reach earth’s surface. This energy can be captured and converted into two major useful forms: Heat and Electricity •

The amount of energy captured depends on geographical location and amount of “radiation source” available

•

The amount of energy is greatest in afternoon compared to morning and evening times

•

No survival is possible without some sun light for all living organisms – reasons also why the water is transparent for helping aquatic animals

6|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

Courtesy: SunLine Transit Agency

3.2. UNITS OF SOLAR ENERGY

•

KILO WATT HOUR PER SQUARE METER Photo-Voltaic (PV) cells are used for generating electricity from solar radiation. It is often represented using kilowatt-hour per square meter (KWh/m2) or Watt per square meter (W/m2) – The energy collected by photo voltaic is generally in DC mode. Using an INVERTER, it is converted to AC mode for domestic applications. A single PV module can generate between 10 to 300 watts.

•

BRITISH THERMAL UNIT Solar energy used for water and space heating application is generally represented in British thermal units per square feet (BTU/ft2) – Based on type of collector used, the quantity of water (or space) to be heated varies – As a thumb rule 20 square feet (2 square meters) of solar panel is necessary for heating around 50 to 60 US gallons (190 to 230 litres) of water. For every additional family member, add 8 to 10 square feet (0.73 to 1 square meter) of solar panel. The tank size should be accordingly

7|Page

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

increased. For every square feet of panel area, consider 1.5 gallons (5.7 litres) to 2 gallons (7.7 litres)

3.3. Solar Energy for heating Water •

Two methods of heating water: Passive (no moving parts) and Active (utilizing pumps).

•

In both, a flat-plate collector is used to absorb the sun energy to heat the water.

•

The water circulates throughout the closed system due to convection currents.

•

Insulated tanks can be used for storing hot water throughout the day

HEATING WATER •

Efficiency of solar heating system is always less than 100% because:

•

Percentage of heat transmitted depends on angle of incidence

•

Number of glass sheets (single glass sheet transmits 90-95%), and

•

Composition of the glass

•

Solar water heating saves approximately 1000 megawatts of energy annually equivalent to eliminating the emissions from two medium sized coal burning power plants

•

By using solar water heating over gas water heater, more than 30% energy conservation can be achieved

8|Page

2009

Alternative Energy

•

Jayabalaji Sathiyamoorthi

Although the initial installation is a complex process, the heating system saves “conventional energy” in long run

SOLAR-THERMAL ELECTRICITY: POWER TOWERS

•

General idea is to collect the light from many reflectors spread over a large area at one central point to achieve high temperature.

•

Example is the 10-MW solar power plant in Barstow, California having 1900 heliostats, each measuring 400 square feet with a 295 feet central tower

•

An energy storage system allows it to generate 7 MW of electric power

•

Capital cost is greater than coal fired power plant, despite the no cost for fuel, ash disposal, and stack emissions

•

Capital costs are expected to decline as more and more power towers are built with greater technological advances

•

One way to reduce cost is to use the waste steam from the turbine for space heating or other industrial processes.

3.4. ACTIVE AND PASSIVE SOLAR SYSTEMS An active solar system is defined as one that relies to some extent on conventional energy to operate. This implies that the added conventional energy is needed to induce the elements in the system to perform in a way that is counter to their natural propensities, such as to make hot air flow downward and cold air upward. Active systems are not appreciably different in efficiency to passive ones and are almost always more complex, more expensive and more subject to breakdown because of moving parts and power failure. The justification for active systems of the past is that passive technology was not yet understood. And the main importance of active systems at present is for retrofitting many of the existing structures that may not be able to incorporate passive principles. Direct Conversion into Electricity •

Photovoltaic cells are capable of directly converting sunlight into electricity.

•

A simple wafer of silicon with wires attached to the layers. Current is produced based on types of silicon (n and p-types) used for the layers. Each cell=0.5 volts.

•

Battery needed as storage – Higher the power, higher will be the battery capacity

9|Page

2009

Alternative Energy

•

Jayabalaji Sathiyamoorthi

No moving parts mean they don’t wear out. But because they are exposed to the weather, their lifespan is about 20 years.

3.5. ADVANTAGES AND DISADVANTAGES •

Efficiency is far lass than the 77% of solar spectrum with usable wavelengths.

•

Efficiency drops as temperature increases (from 24% at 0°C to14% at 100°C.)

•

With proper designing, the electricity generated from solar energy can light up entire house

•

The solar energy is noise free, pollution free, and maintenance free

•

Does not reflect the true costs of burning coal and its emissions to the non-polluting method of the latter.

•

Underlying problem is weighing efficiency against cost.

•

Crystalline silicon-more efficient but expensive to manufacture

•

Amorphous silicon- Half as efficient but expensive to produce

•

The cost of power generation will be three to four times conventional method with present day technologies

•

At present, solar heating system components are expensive

10 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

•

Argument that sun provides power only during the day is countered by the fact that 70% of energy demand is during daytime hours. At night, traditional methods can be used to generate the electricity

•

Goal is to decrease dependence on fossil fuels

•

Currently, 75% of electrical power is generated by coal-burning and nuclear power plants

•

Solar energy reduces the effects of acid rain, carbon dioxide, and other impacts of burning coal and counters risks associated with nuclear energy

•

Pollution free, indefinitely sustainable

•

The primary source – SUNLIGHT – is available, free, throughout life!

11 | P a g e

2009

Alternative Energy

4.

Jayabalaji Sathiyamoorthi

Passive Solar Systems

A passive system is defined as one which operates entirely on the renewable energy available in the immediate environment. Aside from the manufacture of the original equipment, which in most cases will require at least some non-renewable energy, the passive systems are in balance. They don’t use up resources. In most cases the systems can be constructed of environmentally clean materials such as glass, adobe, rock, water and iron. The operation of passive systems takes advantage of the natural characteristic of materials, such as the convective flow of air and water, the absorbing capacity of dark colours and dense materials, heat-sorting properties of dense materials and water, and the poor heat conductivity of insulating materials. Understanding these properties allows the designer to arrange them in such a fashion that they perform according to the heating and cooling requirements of the house given the sun as a heat source and the night sky as a heat sink. From the earliest development of solar technology it was understood that to heat a house adequately one must perform these functions; collect the sun's heat, store it, and release it in a useful way. This prompted the development of solar collectors, heat storage units and radiators or hot air controls as separate units. Since the collectors were usually on the roof, and the heat storage units in the house below, a fan or pump was required to motivate the circulation of the heat transporting fluid. Thus these systems became unduly complex, expensive, unsightly and dependent on the energy grid to operate. A more sophisticated and far cheaper solution presented itself as the nature of heat and its relationship to building materials was better understood. The three functions of collecting, storing and using the sun's heat were integrated into and were indistinguishable from the very structure of the house. Since such a system requires no further devices or power to operate, it is termed as passive Solar energy has been defined as a "Soft" technology as opposed to; say for instance, "hard" nuclear technology. Passive solar heating is at the soft end of solar technology. Another way of putting it is: passive solar technology is the type most directly coupled to the sun and is least damaging to the environment, because it takes the principle of using renewable energy to its logical extreme. 12 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

4.1. Passive solar buildings A passive solar building is one that derives a substantial fraction of its heat from the sun using only natural processes to provide the necessary energy flows. Thermal conduction, free convection, and radiation transport therefore replace the pumps, blowers, and controllers associated with active solar heating systems. The elements of a passive solar heating system tend to be closely integrated with the structure for which heat is provided. South facing windows, for example, may serve as apertures through which solar energy is admitted to the building, and thermal storage may be provided by inherent structural mass. Solar radiation absorbed inside the building is converted to heat, part of which meets the current heat load whereas the remainder is stored in the structural mass for later use after the sun has set. Because of the integral nature of passive solar buildings, it is not possible to design the structure independent of the heating system as is usually done with active systems. Instead, it is necessary to consider the solar characteristics of the building from the initial phases of the design process to completion of the construction documents. A well designed passive solar building is comfortable, energy efficient, and very reliable because of its inherent operational simplicity. However, a poor design, lacking some or all of these desirable characteristics, may be very difficult to modify after construction is complete and the problems become manifest. It has therefore been necessary to develop a new approach to building design that couples solar/thermal considerations with the more traditional concerns of form and structure.

4.2. Passive heating system characteristics The interaction between a passive heating system and its environment is a complex process that involves many subtle phenomena. The complexity of the interaction makes it difficult to determine exactly what type of passive system will perform best in a given climate. Ultimately, detailed design analysis calculations of the type to be described later in these procedures may be required to make the final decision. However, a few generalizations may be cited that are useful for selecting candidate systems during the schematic phase of design.

13 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

Direct gain buildings are passive solar heating systems in which sunlight is introduced directly to the living space through windows or other glazed apertures. As with all passive solar systems, it is important that the apertures face south or near south in order to achieve high solar gains during the winter heating season and low solar gains during the summer cooling season. Thermal storage mass is essential to the performance and comfort of direct gain buildings. A building that has inadequate mass will overheat and require ventilation, which entails a loss of heat that might otherwise have been stored for night time use. Generally, it is desirable to employ structural mass as a storage medium in order to take advantage of the improved economics associated with multiple uses. Insulation should always be placed on the outside of massive elements of the building shell rather than on the inside in order to reduce heat Losses without isolating the mass from the living space. Concrete floor slabs can contribute to the heat capacity of a building provided they are not isolated by carpets and cushioning pads. Heat losses from the slab can be limited by placing perimeter insulation on the outside of the foundation walls. If the structure is fairly light, the heat capacity can be effectively increased by placing water containers in the interior. A variety of attractive containers are available commercially. An overhang is used to shade the solar aperture from the high summer sun while permitting rays from the low winter sun to penetrate and warn the inside of the building. In climates having particularly warm and sunny summers, an overhang may not be sufficient to prevent significant aggravation of the summer cooling load. Sky diffuse and ground reflected radiation enter the living space despite the presence of an overhang and must be blocked by external covers or internal shades. Using movable insulation on direct gain apertures has the advantage of reducing night time heat losses during the winter-as well as eliminating unwanted solar gains during the summer. Direct gain buildings involve less departure from conventional construction than other types of passive solar systems and are therefore cheaper and more readily accepted by most occupants. However, they are subject to overheating, glare, and fabric degradation if not carefully designed; these problems can be minimized by distributing the sunlight admitted to the building as uniformly as possible through appropriate window placement and the use of diffusive blinds or glazing materials. When properly designed for their location, direct gain 14 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

buildings provide an effective means of reducing energy consumption for space heating without sacrifice of comfort or aesthetic values. ADVANTAGES •

All chemical and radioactive polluting by-products of the thermonuclear reactions remain behind on the sun, while only pure radiant energy reaches the Earth.

•

Energy reaching the earth is incredible. By one calculation, 30 days of sunshine striking the Earth have the energy equivalent of the total of all the planet’s fossil fuels, both used and unused

•

The heat energy produced by sun, if ever captured completely, can satisfy entire mankind’s energy requirement for hundreds of years

DISADVANTAGES •

Sun does not shine consistently throughout the season and varies across geographical locations – Also the 23 ½ degree tilt of earth axis ensures non-uniform distribution of solar energy

•

Solar energy is a diffuse type of heat source. To harness, it must be concentrated into an amount and form that we can use such as heat and electricity. The diffusion occurs due to various environmental factors like clouds, moisture, dust, pollutant and altitude of the location

•

The intensity of solar radiation after diffusion can vary from 10% to 100%

15 | P a g e

2009

Alternative Energy

5.

Jayabalaji Sathiyamoorthi

Daylighting

The use of sunlight to provide illumination within a building, especially in order to supplement or replace electric lighting is sometimes called daylighting or passive solar. Solar lighting may involve a variety of techniques and technologies, ranging from efficient window placement, to the use of special window coatings that minimize reflection or can alter the window's transmittance depending on the weather, to the use of solar collectors and fibre optics to transmit sunlight into a building. The early 21st century as seen active research on hybrid solar lighting, combining daylight piped in by optical fibre with electric lighting. Through this approach, consistent illumination can be provided at a lower cost than with conventional electric light.

5.1. WHY DAYLIGHTING? Daylighting is the use of light from the sun and sky to complement or replace electric light. Appropriate fenestration and lighting controls are used to modulate daylight admittance and to reduce electric lighting, while meeting the occupants' lighting quality and quantity requirements. Daylighting is a beneficial design strategy for several reasons: •

Pleasant, comfortable daylighted spaces may increase occupant and owner satisfaction and may decrease absenteeism. Productive workers are a valuable business asset.

•

Comfortable, pleasant, daylighted spaces may lease at better-than-average rates.

•

Comfortable, pleasant spaces typically have lower tenant turnover rates.

•

Lighting and its associated cooling energy use constitute 30 to 40% of a commercial building's total energy use. Daylighting is the most cost-effective strategy for targeting these uses. Both annual operating and mechanical system first costs can be substantially reduced.

•

The Uniform Building Code, BOCA, and State Energy Codes regulate the "proper" use of windows in buildings.

•

Energy-efficient buildings generally provide higher returns on developer investment and yield higher cash flows.

•

Smart decisions up front save retrofit dollars later.

16 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

•

Energy-efficient, daylighted buildings reduce adverse environmental impacts by reducing the use and need for power generating plants and their polluting by-products.

•

Daylight contributes to a more sustainable design approach.

5.2. DAYLIGHTING VS HUMAN PERFORMANCE New buildings, no longer optimized for daylight, were constructed with lower ceilings and lower skin to volume ratios. Older buildings were often retrofitted with dropped ceilings, heavily tinted glass or insulating panels designed to reduce heat gain from windows. The net result has been a dramatic reduction in the amount of daylight available in our schools and workplaces during the past half-century. Two forces are working to reverse this trend. First, when lighting electricity consumption is considered along with heating and cooling as part of a whole building energy equation, daylighting typically provides a net energy benefit. Daylight is intrinsically more efficient than any electric source because it provides more lumens per unit of heat content. If appropriate daylighting techniques are used to displace electric illumination, the savings for lighting and cooling can be dramatic. Secondly, a growing interest in the influence of indoor environments on health and productivity has resurrected interest in the potential health and productivity benefits of daylighting. Reductions in worker absenteeism, higher retail sales, and better student health were associated with increases in daylight in anecdotal reports. However, few formal scientific studies have addressed These types of statistical studies show strength of association between variables, but cannot prove a causal relationship, such as between daylight and improved human performance. Other types of studies are necessary to prove a causal mechanism. Daylight is actually quite a complex phenomenon, involving variations in the intensity, spectrum, distribution, duration, and timing of light exposure. A number of potential mechanisms (alone or combined) that may have been responsible for the positive association between daylight and improved performances of students are: •

Improved visibility due to higher illumination levels;

•

Improved visibility due to better light quality;

17 | P a g e

2009

Alternative Energy

•

Mental stimulation; and

•

Improved mood, behaviour or well-being.

Jayabalaji Sathiyamoorthi

The potential energy savings from daylighting can be substantial. While 25% of the existing non-residential building stock in the United States is amenable to side-lighting from perimeter windows, an additional 60% could potentially be reached from above, via skylights or roof monitors. If the link between increased daylight and improved human performance holds true with additional studies, it strongly suggests that we should act to reverse our current building trends that are reducing the presence of daylight in the workplace.

5.3. WAYS TO CALCULATE DAYLIGHTING DAYLIGHTING CALCULATIONS BY HAND. This is an alternative to photometry in a scale model, when it’s important to quantify daylight illumination levels. Several standard procedures exist. A lighting designer should be familiar with them or find from many instructional literatures are available COMPUTER DAYLIGHTING MODELS. Daylighting software typically delivers faster, more accurate results than illumination calculations done by hand. Consult a lighting designer or request a “Daylighting Design Tool Survey” from the Windows and Daylighting Group at Lawrence Berkeley National laboratory (510-486-5605). ENGINEERING SOFTWARE. Refine window sizing, early glazing decisions, building form, and sitting with preliminary mechanical load calculations. See the list of energy analysis software in the Mechanical Coordination section of these guidelines.

18 | P a g e

2009

Alternative Energy

6.

Jayabalaji Sathiyamoorthi

Transpired Solar Collector

The transpired solar collector is a thin sheet of dark perforated metal. The dark wall absorbs solar radiation and heats fresh air drawn through its perforations by a building's ventilation fans. As green building practices become more important — not only for environmental reasons, but also for cost savings and tax credits — new products supporting this philosophy are popping up everywhere. This wealth of product information and “green wash” can be tedious for the building professional to sort through. The transpired solar collector, however, is one that deserves the attention of the savvy building envelope consultant. The U.S. Department of Energy (DOE) has called transpired collectors “the most reliable, best-performing, and lowest-cost solar heating for commercial and industrial buildings available on the market today.” The concept has received numerous honours and awards from DOE, the American Society of Heating, Refrigeration, & Air Conditioning Engineers, Inc. (ASHRAE), R&D Magazine, and many others worldwide.

6.1. WORKING PRINCIPLE The concept is simple: perforated metal wall cladding is attached approximately 4 to 8 inches from a south-facing wall to a support grid of vertical and horizontal channels. The system may be applied vertically or horizontally over any non-combustible wall substrate, over or around existing wall openings. The grid system vertical channels are attached to the building wall, the horizontal channels are attached to the vertical channels, and the perforated metal sheets are through-fastened to the horizontal channels. The transpired solar collector wall may be mounted to the wall in several different ways, depending on the volume of air required. In some cases, only a portion of the south wall is needed, or even a penthouse wall may be suitable. The sun heats the metal panel and the heated air is drawn through tiny holes into the cavity between the panel and the wall by fans mounted at the top of the wall. The fans then distribute the heated air into the building through flexible ducts mounted from the ceiling, or through standard ducts connected to the heating and ventilating system. In the winter, the heated air removes a substantial load from the building’s conventional heating system, thus saving considerable energy and money. In 19 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

the summer, the panel is shading the inner wall, thus reducing the cooling demands of the building. When heating is not required, a controlled damper can be opened to allow air to bypass the solar collector, providing a continual supply of fresh air into the building. The transpired solar collector wall is also effective on cloudy days, although at a reduced level.

Source: http://www.energysavers.gov/your_home/space_heating_cooling/index.cfm/mytopic=12510

Additional Benefits In addition, the use of this preheated fresh air system eliminates stratification of the air inside industrial buildings, where hot air raise to the ceiling and is lost through the roof or drawn out with exhaust fans. Since the air is constantly being replaced, the system is ideal for vehicle repair shops, machine shops, chemical storage plants, and industrial applications where fumes are present. The system also provides positive pressure for the building. When a door or window is opened, the heat from indoors exits, but the cold outside air does not rush in. New ventilation codes specify minimum ventilation rates and indoor air quality, depending on the type of building and the number of occupants. Inadequate fresh air may lead to “Sick Building Syndrome,” which results in headaches; eye, nose and throat irritations; and fatigue 20 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

and/or difficulty in concentration for its inhabitants. This system replaces the air constantly and is ideal for manufacturing plants, hazardous waste storage buildings, gymnasiums, airplane hangars, schools, office buildings, apartment buildings and warehouses requiring ventilation. The system also provides process heat for agricultural or industrial purposes. Environmentally, the transpired solar collector wall is using natural energy that is clean, thus lowering the need for fossil fuel heat and reducing production of greenhouse gases. Payback of the system is relatively short, and state and federal grants, as well as tax credits, are given as incentives for solar energy use. The installation may qualify for Leadership in Energy and Environmental Design points and credits. The cost of conventional energy can vary greatly, depending on the area and the season of the year. With soaring energy prices, the use of free solar heat will reduce the need for conventional energy sources. Any existing non-combustible south-facing exterior wall in need of repair could be covered with the energy-saving transpired solar collector wall panel. For a uniform appearance, the other exterior walls can be covered with a similar panel system in the same colour. For variety and aesthetics, coordinating or contrasting colours may be used. Use of the perforated panels on a vertical, southern exposure wall is recommended to collect the most solar energy. A vertical surface will give more reflected radiation, with no snow build-up and low wind loads. Research has proven that each square foot of panel will supply 150 to 200 BTUs per hour. Intake air is preheated by up to 65°F (36°C) above ambient air temperature, reducing annual heating costs by $1 to $5 per square foot of collector wall, depending on the type of fuel displaced. U.S., Canadian, and German governments have independently monitored installations of this type. The International Energy Agency (IEA) Solar Heating and Cooling Program are reporting efficiencies of over 70%. The National Renewable Energy Laboratory, a division of the Department of Energy (DOE), is currently monitoring some projects and is continually researching the transpired solar collector system.

21 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

6.2. SOLAR COLLECTOR SPECIFICATIONS Transpired solar collectors are typically manufactured from aluminium and, to a lesser extent; zinc, in two-wide, ribbed configurations. Thickness varies from .032-in. aluminium to .028in. zinc. Panels are approximately 40 in. wide and are available in many colours and with a PVDF (polyvinylidene fluoride) finish. Darker colours with high solar absorption rates are recommended for maximum effectiveness. The systems are virtually maintenance free, since there are no liquids or moving parts other than the fan system or optional filters. The paint finish is warranted for 30 years. Most industrial and commercial buildings require large quantities of ventilation air to maintain a healthy work environment. In many regions, this ventilation air needs to be heated throughout the fall, winter, and spring to provide a comfortable work environment. Transpired solar collectors, developed jointly during the last decade by researchers at the National Renewable Energy Laboratory (NREL) are a reliable, low-cost technology for preheating building ventilation air. With simple payback periods ranging from 3 to 12 years and an estimated 30-year life span, transpired collector systems offer building In a typical application, a large portion of a building’s south-facing wall is clad with darkcoloured, perforated metal sheeting, which performs as a large solar collector. The sheeting is mounted to the building’s structural wall, creating a 4- to 6-inch gap between the two. As outside air is drawn through the collector’s perforations by ventilation fans, its temperature increases by as much as 40°F (22°C). The heated air flows to the top of the wall, where it is distributed to the building’s interior through conventional ductwork.

6.3. DESIGN HIGHLIGHTS •

Converts as much as 80% of available solar radiation to heat

•

Ideal for use in sunny climates with long heating seasons

•

Installed cost: $6 per square foot in new construction; $10 in retrofit applications

•

Payback periods range from 3 to 12 years depending on climate and type of fuel being displaced

•

Estimated 30-year system life

22 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

As a result, the transpired collector is one of the most efficient solar collectors, converting as much as 80% of the solar energy striking it into usable heat. Ford, General Motors, Federal Express, and McDonnell Douglas are on the growing list of industrial users of this technology. With the exception of the fans, the transpired collector has no moving parts and requires no maintenance. A solar collector that is about 70 percent efficient compared to 30 to 40 percent for conventional collectors. Unlike most solar collectors, there's no glazing. Solarwall is a solar preheated for ventilation air. The heat captured by the collector is drawn into the house by a ventilation fan. Preheating reduces the energy needed to bring the incoming air up to comfortable temperatures. Passing through the collector boosts air temperature by as much as 54°F. As air flows through the panels, it picks up heat that would normally escape through the wall to the outside. This boosts building performance even more. Solarwall is ideal for commercial and industrial buildings with large ventilation requirements. Residential applications can also be practical in colder climates where ventilation increases space heating loads. For homes, the panels can be sized to the amount of ventilation air needed. One to two sq. ft. of panel would be needed for each cubic foot per minute (cfm) of ventilation requirement. For example, an 1800 sq. ft. house might need 84 cfm to maintain 0.35 air changes per hour. That would require an 84-sq.-ft. to 168-sq.-ft. Solarwall. Each panel is 2-1/2 ft. x 8 ft. For residential jobs, the panels are mounted about four inches off the weather tight exterior wall with dimensional lumber. An axial fan pulls air through the panel and blows it into the house. Air can flow directly into the living space or be connected to a forced air heating system for distribution. One control option is a differential temperature control that turns the solar fan on when the air in the panel is higher than outside. Panel cost is about $5 per sq. ft. Aesthetics could limit Solarwall for residential applications. Colour selection is limited to dark blue, dark brown, dark green and black. Some homeowners may not want large areas of their house covered with dark, perforated aluminium. Solarwall systems offer an alternative to heat recovery ventilators for sunny building sites in cold climates. 23 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

6.4. CASE STUDIES United States Measure on Transpired Air Collector System Transpired air collector systems are successfully being used by both private and governmental sectors. Installations in automotive, manufacturing, aviation, education, and distribution facilities have shown substantial energy savings. Transpired solar collector systems have been installed on many buildings throughout the United States. A 3,600 sq. ft. Classic Bronze collector (solar absorptive capacity 0.91) faces 16 degrees west of due south. The total airflow rate is 18,000 cubic feet per minute (cfm), which is delivered by two 30-in diameter fans. For each square foot of collector wall, the flow rate is 5 cfm. The annual renewal energy delivered is 650 million BTUs. The average air temperature rise is 13°F at 5 cfm/sq ft during daylight hours for the 9-month use season. The rise of the temperature over ambient air on a sunny afternoon is typically 55°. The annual greenhouse gas reduction for this installation was 98,000 pounds per year. The annual projected energy savings for this project was $16,500, with an actual savings of $22,086, translating to a savings of $4.60 per sq ft of collector wall. The total projected energy savings for this installation over a 30-year project life is approximately $700,000. The simple payback period, with accelerated MACRS depreciation, is less than 3½ years. Greenwood Elementary School The Greenwood Elementary School in Millerstown, PA, was recently renovated to include 730 sq. ft. of black-coloured collector wall. The annual greenhouse gas reduction is 19,000 pounds. The annual heating cost savings is $2,553, with a simple payback of five years (based on 2008 natural gas costs). Expected savings over the 30-year project life are $115,000. Schools are not eligible for tax credits. However, when using on-site renewable energy, there is a possibility of additional grants from state governments.

24 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

6.5. ENVIRONMENTAL BENEFITS •

Fuel is sunlight

•

Displaces fossil fuels

•

Saves ≈ 40 lbs / ft ft2 2 / annum of CO CO2

•

Average Energy Savings: o 1.5 - 3.5 therms / ft ft2 (of solar collector) /annum o $1 - 6 / ft ft2 / annum (depending on fuel costs)

•

Typical Payback Periods: o New construction: 0 - 3 years o Retrofit: 3 - 7 years

•

Panel cost comparable to a brick wall

25 | P a g e

2009

Alternative Energy

7.

Jayabalaji Sathiyamoorthi

Energy Minimization Techniques

The following are a few techniques that can be followed for energy utilization, Minimize conventional air conditioning We don't use conventional air conditioning and we encourage everybody else to abandon it too. There is an art to living without air conditioning that has largely been lost. People used to know how (and when) to open their houses at night for ventilation, and when to close them up in the day time to keep out the heat of the days. Decrease use of heating appliances … oven, stove, toaster oven, hairdryer, clothes dryer. Replace heat producing incandescent lighting with compact fluorescent lighting. Night time cooling Open windows and doors to admit cool night air. Close them again as the sun rises. A wellinsulated building will retain “cool” for many hours. Exterior window shades or awnings Once the sun hits the window, the heat gets in the house by conduction, even if there is a shade and a curtain on the inside of the window. Hang tightly-woven screens or bamboo shades outside the window during the summer to stop 60-80% of the sun’s heat from getting to the window. Weatherization Weatherization is the plugging and sealing of air leaks. Usually emphasized for northern climates in wintertime to keep heat in, it can also effectively keep heat and humidity out. Weather stripping doors, windows and attic openings; sealing around plumbing vents; insulating around electrical wire penetrations; sealing holes between the living space and the attic/crawlspace Personal cooling solutions Proper clothing, hats, cool drinks, proper hydration, hand fans, and the wisdom of the siesta time are common sense solutions we often overlook. Ceiling and table fans can move the air around inside (thereby knocking about 10 degrees Fahrenheit off the apparent temperature).

26 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

Insulation Slows heat transfer from outside to inside your home and vice versa in the winter. Landscaping for shade and passive cooling Plant deciduous trees and other vegetation and place structures (trellises, vines, large shrubs, etc.) appropriately so that your sunny exposures are shaded in the summer, but open to sunlight in the winter. People with flat roofs should definitely consider a green roof. Deciduous trees planted to the south or west of your building block summer sun, but drop their leaves to allow half or more of the winter sun’s energy into your home to warm you on clear winter days. The valuable summertime shading will reduce unwanted heating as much as 50%. Those are better results than we get from more expensive projects like window and insulation upgrades Radiant Barriers Thin metal films, typically stapled to the underside of attic rafters, will reflect approx. 97% of long-wave infrared heat radiation. Install awnings on south-facing windows where there’s insufficient roof overhang to provide shade. Roof whitening If you’re replacing a roof, choose white or reflective surface. Coating existing roofs with white elastomeric paint specifically designed for roof whitening will reduce your heat load on the house. Re-modelling and new construction Integrate the principles of passive cooling into the basic design of the structure. If you’re planning a remodel or other construction Adjust your Expectations Understand that our future will be quite different from the trajectory of our historic and economic past. It must be. To reduce greenhouse gas emissions 70-80% over the next few decades, and to create a graceful solution to Peak Oil, we must re-think and redesign all of our fossil-fuel intensive habits.

27 | P a g e

2009

Alternative Energy

8.

Jayabalaji Sathiyamoorthi

Future of solar Energy

The following aspects could be considered by the Government of Kuwait in order to promote and nurture the solar energy technology. INCENTIVES. Due to the uncompetitive economics of solar power, incentives will be necessary to make it more attractive for commercial development. ECONOMY Solar power is still expensive, but high growth in manufacturing of photovoltaic cells and the construction of larger capacity sites is creating economies of scale. FOCUS ON TECHNOLOGY Several technologies are still at the experimental stage including solar towers, parabolic troughs and solar chimneys. Commercial solar power generation has yet to be dominated by one best in class technology. So finding the best power generation technique and focussing on it to be the first in the market. ENERGY STORAGE Widespread uptake of commercial solar power generation will require significant investment in energy storage. These technologies remain quite immature although new thermal solar power plants feature storage systems to retain generated heat.

28 | P a g e

2009

Alternative Energy

9.

Jayabalaji Sathiyamoorthi

Discussion

Through this paper the importance of the alternative energy are discussed. There can be many solutions and sources available for the alternative energy development, however the strong arguments to support Passive Solar Energy Technique is the optimal solution the following points need to be considered, •

Solar Fuel (Sun) is renewable and it is completely non-polluting and environmental friendly

•

Less Maintenance cost or almost free maintenance

•

Lifetime of free heating

•

Improved indoor air quality

•

Cost effective in compared with other techniques

•

Socially responsible technique

29 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

10. Conclusion and Summary Of all the sources of alternative energy available to the mankind in its pursuit of a sustainable future, solar power is a pivotal one. It is Plentiful, free and absolutely clean, the main challenge to fully tap its huge potential is to harness and distribute it. We have made considerable progress with solar power, but future uses of solar energy will be spawned by innovations still to come. At present, solar power is used in three main ways, that is, to heat air, water and space. Photovoltaic cells are also one of the most popular forms whereby sun energy is converted into power. In general it can be said that even though these principles appear to be self-evident once they are known, it has taken this long to understand them because of their holistic nature. The passive systems are directly coupled to the sun and the three functions of collection, storage and distribution of heat are carefully integrated into the architectural whole. What is needed is to understand the characteristics of the materials used and the physics of sunlight and heat transfer. The daylighting and transpired solar collector are a few of the evident techniques that proved very confident with the solar power generation. Hence the passive solar systems are very promising because they are effortless; they take advantage of the natural propensities of heat and materials to achieve the desired results without the need for added conventional energy.

30 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

11. References “Various techniques to minimize energy utilization”, http://www.energybulletin.net/primer.php accessed on 2nd August 09.

“Passive Solar Retrofit for North Carolina Homes,” by the North Carolina Solar Center, http://www.ncsc.ncsu.edu/information_resources/publications.cfm, accessed on 12th August 09.

“The Low-carbon Lifestyle,” an online index of practical resources, plus philosophical guidance for the transformation of society to a more sustainable existence. http://www.LegacyLA.net/LowCarbonLifestyle.htm accessed on 27th July 09.

ASHRAE Journal, June, 2002, American Society of Heating, Refrigerating and AirConditioning Engineers, Inc.

“Re-analysis report: daylighting in schools”, Analysis report by Heschong Mahone Group. 2001 available at www.newbuildings.org/pier, accessed on 25th August 09.

“DESIGN: PASSIVE SOLAR BUILDINGS”: USACE Publication Depot: US state defence specification documentation document id: MIL-HDBK-1003/19

Article on solar buildings by U.S. Department of Energy Conserval Systems, Inc. National Renewable Energy Laboratory, www.eren.doe.gov/solarbuildings, accessed on 28th August 09.

Ander, Gregg D., “Daylighting Performance and Design”, Van Nostrand Reinhold, New York, 1995

“ASHRAE Handbook of Fundamentals”, American Society of Heating, Refrigerating, and Air-Conditioning Engineers, 1993. 31 | P a g e

2009

Alternative Energy

Jayabalaji Sathiyamoorthi

Jennifer O’ Connor, “Tips for daylighting - the integrated approach” – published at Ernest Ortlando Lawrence Barkeley National Laboratory

Cara Smusiak, “How to Find Green Energy anywhere” available at http://planetgreen.discovery.com/home-garden/find-green-energy.html accessed on 2nd September 09.

“Solar Thermal Power”, article at http://science.howstuffworks.com/earth/greentechnology/energy-production/solar-thermal-power.htm/printable accessed on 1st September 09.

“Future uses of Solar Energy” article at, http://www.energyrefuge.com/archives/future-usesof-solar-energy.htm, accessed on 14th August 09.

32 | P a g e

2009