ABSTRACTOur country is facing a number of problems on power generation. The original target of increasing the generating capacity by 30,000 MW during eight plans got reduced to 20,000MW and fears are now being expressed about by achieving even this reduced target. This is ascribed essentially to a lack of sufficient financial resources. Privatization of generation with a view to attracting private investors, Indian and Foreign countries is now considered a remedy to overcome this difficulty. The load demands are increasing fast while the additions to generating capacities are slow and relatively small, and the reliabilities and quantity of power supply are deteriorating resulting in frequent interruptions and low voltages thus affecting industrial and agricultural production and causing inconvenience to the public in a variety of ways. Due to the demands outstripping availability, the grid systems are being operated at sub-standard frequencies resulting in serious systems disturbances and black - outs.

To overcome this sensible technology for the wide use of renewable energy must be simple and reliable, accessible to the technologically less developed and developing countries that are sunny and often have limited material sources. It should not need cooling water and it should be based on environmentally sound production from renewable or recyclable materials.

The solar tower meets these conditions. Economic appraisals based on experience and knowledge gathered so far have shown that large scale solar towers (>= 100 MW) are capable of generating electricity at costs comparable to those of conventional power plant. This is reason enough to further develop this form of solar energy utilization, up to large, economically viable units. In a future energy economy, solar towers could thus help assure the economic and environmentally benign provision of electricity in sunny regions.

INDEX

PAGE NO 1. INTRODUCTION

3-11

1.1WIND ENERGY

1.2 SOLAR ENERGY IN INDIA

1.3 ECONOMICS OF WIND FARMS

2. SOLAR CHIMNEY TECHNOLOGY

12-19

2.1 PARTS OF SOLAR CHIMNEY

2.1.1 THE COLLECTOR

2.1.2 THE CHIMNEY

2.1.3 THE TURBINES

3. FUNCTIONAL PRINCIPAL AND WORKING

20-22

4. A HYDROELECTRIC POWER STATION FOR

23-24

THE DESERT

5. SOLAR CHIMNEY ON THE INTERNATIONAL GRID

25-276. THE PROTOTYPE IN MANZANARES

28-396.1HOW THE PROJECT RAN

6.2 TESTS DURING THE NINE-YEAR PROJECT

8. CONCLUSION

40-41

7. REFERENCES

CHAPTER- 1

INTRODUCTION1. INTRODUCTION1.1WIND ENERGY

India is a country with diverse climate & vast potential, untapped resources. Abundant natural resources like wind, sun & water are available & can be made use of. Wind, being the most available of resources, has turned out to be the most popular & with the new thrust on generating power to meet the needs of tomorrow, there are a host of entrepreneurs willing to tap this form of energy. Being unlimited, renewable & pollution-free resource, there has been a movement world over, to develop highly sophisticated technology to convert this kinetic energy into its Mechanical & Electrical form. Winds result from differential heating of the earth & its atmosphere by the sun & are subjected to several forces altering their direction & speed of flow; about one per cent of total solar radiation that reaches the earth is converted into wind energy.

Wind poweris the conversion ofwindenergyinto a useful form of energy, such as usingwind turbinesto makeelectrical power,windmillsfor mechanical power,windpumpsforwater pumpingordrainage, orsailsto propelships.

Largewind farmsconsist of hundreds of individual wind turbines which are connected to theelectric power transmissionnetwork. For new constructions, onshore wind is an inexpensive source of electricity, competitive with or in many places cheaper than fossil fuel plants.Small onshore wind farms provide electricity to isolated locations. Utility companies increasinglybuy surplus electricityproduced by small domestic wind turbines.[3]Offshore wind is steadier and stronger than on land, and offshore farms have less visual impact, but construction and maintenance costs are considerably higher.

Wind power, as an alternative tofossil fuels, is plentiful,renewable, widely distributed,clean, produces nogreenhouse gasemissions during operation and uses little land.[4]Theeffects on the environmentare generally less problematic than those from other power sources. As of 2011,Denmark is generatingmore than a quarter of its electricity from wind and 83 countries around the world are using wind power to supply the electricity grid.[5]In 2010 wind energy production was over 2.5% of total worldwide electricity usage, and growing rapidly at more than 25% per annum.

Wind power is very consistent from year to year but has significant variation over shorter time scales. As the proportion of windpower in a region increases, a need to upgrade the grid, and a lowered ability to supplant conventional production can occur.[6]

HYPERLINK "http://en.wikipedia.org/wiki/Wind_power" \l "cite_note-abbess-7" [7]Power management techniques such as having excess capacity storage, geographically distributed turbines, dispatchable backing sources, storage such aspumped-storage hydroelectricity, exporting and importing power to neighboring areas or reducing demand when wind production is low, can greatly mitigate these problems.[8]In addition,weather forecastingpermits the electricity network to be readied for the predictable variations in production that occur

Wind power has been used as long as humans have putsailsinto the wind. For more than two millenniawind-powered machineshave ground grain and pumped water. Wind power was widely available and not confined to the banks of fast-flowing streams, or later, requiring sources of fuel. Wind-powered pumps drained thepolders of the Netherlands, and in arid regions such as theAmerican mid-westor theAustralian outback,wind pumpsprovided water for live stock and steam engines.

With the development of electric power, wind power found new applications in lighting buildings remote from centrally-generated power. Throughout the 20th century parallel paths developed small wind plants suitable for farms or residences, and larger utility-scale wind generators that could be connected to electricity grids for remote use of power. Today wind powered generators operate in every size range between tiny plants for battery charging at isolated residences, up to near-gigawatt sizedoffshore wind farmsthat provide electricity to national electrical networks.

Wind energyWind energy is thekinetic energyof air in motion, also calledwind. Total wind energy flowing through an imaginary areaAduring the timetis:

[11] INCLUDEPICTURE "http://upload.wikimedia.org/math/2/0/a/20a1aea40d9f3be65347fb94ba08b337.png" \* MERGEFORMATINET

whereis thedensity of air;vis the windspeed;Avtis the volume of air passing throughA(which is considered perpendicular to the direction of the wind);Avtis therefore the massmpassing per unit time. Note that v2is the kinetic energy of the moving air per unit volume.

Power is energy per unit time, so the wind power incident onA(e.g. equal to the rotor area of a wind turbine) is:

Wind power in an open air stream is thusproportionalto thethird powerof the wind speed; the available power increases eightfold when the wind speed doubles. Wind turbines for grid electricity therefore need to be especially efficient at greater wind speeds.

Map of available wind power for theUnited States. Color codes indicate wind power density class. (click to see larger)

Wind is the movement of air across the surface of the Earth, affected by areas of high pressure and of low pressure. The surface of the Earth is heated unevenly by the Sun, depending on factors such as the angle of incidence of the sun's rays at the surface (which differs with latitude and time of day) and whether the land is open or covered with vegetation. Also, large bodies of water, such as the oceans, heat up and cool down slower than the land. The heat energy absorbed at the Earth's surface is transferred to the air directly above it and, as warmer air is less dense than cooler air, it rises above the cool air to form areas of high pressure and thus pressure differentials. The rotation of the Earth drags the atmosphere around with it causing turbulence. These effects combine to cause a constantly varying pattern of winds across the surface of the Earth.[ The total amount of economically extractable power available from the wind is considerably more than present human power use from all sources.[13]Axel Kleidon of the Max Planck Institute in Germany, carried out a "top down" calculation on how much wind energy there is, starting with the incoming solar radiation that drives the winds by creating temperature differences in the atmosphere. He concluded that somewhere between 18 TW and 68 TW could be extracted.[14]Cristina Archer andMark Z. Jacobsonpresented a "bottom-up" estimate, which unlike Kleidon's are based on actual measurements of wind speeds, and found that there is 1700 TW of wind power at an altitude of 100 metres over land and sea. Of this, "between 72 and 170 TW could be extracted in a practical and cost-competitive manner".[14]They later estimated 80 TW.However research atHarvard Universityestimates 1 Watt/m2on average and 210 MW/km2capacity for large scale wind farms, suggesting that these estimates of total global wind resources are too high by a factor of about 4.

Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed.

The strength of wind varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there. To assess the frequency of wind speeds at a particular location, a probability distribution function is often fit to the observed data. Different locations will have different wind speed distributions. TheWeibullmodel closely mirrors the actual distribution of hourly/ten-minute wind speeds at many locations. The Weibull factor is often close to 2 and therefore aRayleigh distributioncan be used as a less accurate, but simpler model. Wind farmsMain article:Wind farm

Wind turbines at the Jepirach Eolian Park inLa Guajira,Colombia.

A wind farm is a group ofwind turbinesin the same location used for production of electricity. A large wind farm may consist of several hundred individual wind turbines distributed over an extended area, but the land between the turbines may be used for agricultural or other purposes. A wind farm may also be located offshore.

Almost all large wind turbines have the same design a horizontal axis wind turbine having an upwind rotor with three blades, attached to a nacelle on top of a tall tubular tower. In awind farm, individual turbines are interconnected with a medium voltage (often 34.5 kV), power collection system and communications network. At a substation, this medium-voltage electric current is increased in voltage with atransformerfor connection to the high voltageelectric power transmissionsystem.

1.2 SOLAR ENERGY IN INDIA

If the vast expanse of the Thar Desert in Northwestern India was harnessed to produce solar energy, it could light up five of Asia's most populated cities. Scientists say the endless sands of Rajasthan State could well earn the distinction of being the "biggest" solar powerhouse by 2010, producing 10,000 MW of electricity. The Rajasthan Energy Development Agency (REDA) has started the spadework on an ambitious project. "A major chunk of the desert, about 13,500 square miles, will be declared a Solar Energy Enterprise Zone like the one in Nevada (in the United States)", says director Probhat Dayal. He thinks that if the state were to install solar collectors in just one Percent of its desert, which stretches over 77,200 square miles, "we could generate 6,000 megawatts of electricity".

A city the size of Delhi with 10 Million people needs 1,800 megawatts. "This solar bowl of the desert will become the world's biggest center for solar power generation, research and development", he declares. The earth receives some 4,000 trillion-kilowatt hours of electromagnetic Radiation from the sun- about hundred times the world's current energy consumption needs. At present, a 354 megawatt solar power project in southern California is the world's largest, providing 90 percent of global solar energy.

Indiais densely populated and has high solarinsolation, an ideal combination for usingsolar power in India.. In the solar energy sector, some large projects have been proposed, and a 35,000km2(14,000sqmi) area of theThar Deserthas been set aside for solar power projects, sufficient to generate 700 to 2,100GW. Also India's Ministry of New and Renewable Energy has released the JNNSM Phase 2 Draft Policy,by which the Government aims to install 10 GW of Solar Power and of this 10 GW target, 4 GW would fall under the central scheme and the remaining 6 GW under various State specific schemes.

In July 2009, India unveiled aUS$19 billion plan to produce 20 GW of solar power by 2020Under the plan, the use of solar-powered equipment and applications would be made compulsory in all government buildings, as well as hospitals and hotels.On 18 November 2009, it was reported that India was ready to launch itsNational Solar Missionunder the National Action Plan on Climate Change, with plans to generate 1,000 MW of power by 2013.From August 2011 to July 2012, India went from 2.5 MW of grid connected photovoltaics to over 1,000 MW.

According to a 2011 report by BRIDGE TO INDIA and GTM Research, India is facing a perfect storm of factors that will drive solar photovoltaic (PV) adoption at a "furious pace over the next five years and beyond". The falling prices of PV panels, mostly from China but also from the U.S., has coincided with the growing cost of grid power in India. Government support and ample solar resources have also helped to increase solar adoption, but perhaps the biggest factor has been need. India, "as a growing economy with a surging middle class, is now facing a severe electricity deficit that often runs between 10% and 13% of daily need".[5]India is planning to install the World's largest Solar Power Plant with 4,000 MW Capacity nearSambhar LakeinRajasthan.[6]On 16 May 2011, Indias first 5 MW of installed capacity solar power project was registered under the Clean Development Mechanism. The project is in Sivagangai Village,Sivagangadistrict,Tamil NaduCURRENT STATUS

Solar Resource Map of India

With about 300 clear, sunny days in a year, India's theoreticalsolar powerreception, on only its land area, is about 5000 Petawatt-hours per year (PWh/yr) (i.e. 5,000 trillionkWh/yr or about 600,000GW).[8]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_power_in_India" \l "cite_note-9" [9]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_power_in_India" \l "cite_note-mnreSolar-10" [10]The daily average solar energy incident over India varies from 4 to 7 kWh/m2with about 1,5002,000 sunshine hours per year (depending upon location), which is far more than current total energy consumption. For example, assuming the efficiency of PV modules were as low as 10%, this would still be a thousand times greater than the domestic electricity demand projected for 2015.

Installed capacityThe amount of solar energy produced in India in 2007 was less than 1% of the total energy demand.[12]The grid-connected solar power as of December 2010 was merely 10 MW.[13]Government-funded solar energy in India only accounted for approximately 6.4MW-yr of power as of 2005.[12]However, India is ranked number one in terms of solar energy production per watt installed, with an insolation of 1,700 to 1,900 kilowatt hours per kilowatt peak (kWh/KWp).[14]25.1 MW was added in 2010 and 468.3 MW in 2011.[15]By January 2014 the installed grid connected solar power had increased to 2,208.36 MW,[16]and India expects to install an additional 10,000 MW by 2017, and a total of 20,000 MW by 2022.

1.3 ECONOMICS OF WIND FARMSThe Non-Conventional Energy sources wind energy is the best alternative for the following reasons. Since the raw material costs are almost negligible, it is economically viable. A cost analysis between available sources shows that the cost of producing one KW of power works out to:

Solar Rs. 1 Lakh,

Photo-voltaic Rs. 3 Lakh

Biomass Rs. 0.5 Lakh,

Wind Rs. 0.3 Lakh

Wind is the only raw material, which is free, abundant, & after setting up capital machinery the maintenance costs are minimal. Besides this the technology is uncomplicated & gestation period is short. It also has the advantage of generation of power immediately after installation. An analysis of the cost of power generation shows that conventional forms of thermal & diesel costs Rs.2.5 per KWh & in a period of four years, it escalates approximately Rs.6 & Rs.5 respectively. But in wind power it is the reverse as it reduces to about Rs. 0.30 per kW. With the viability & commercial benefits established, wind energy will soon be a thrust area to cater to an ever-increasing population. It does make a lot of sense when you consider the fact that a third of the oil produced in the world is burned for the production of power. Whereas the installation of one MW of wind saves close to 5000 barrels a day.

CHAPTER -2

SOLAR CHIMNEY TECHNOLOGY2. SOLAR CHIMNEY TECHNOLOGY

The new technology called Solar Chimney Technology; foresees to produce bulk electricity in sunny regions of the plant, by creating breeze of sufficient speed (more than 20 to 30 kph.) to run wind turbines coupled to electric generators of total o/p of 30 to 200 MW.

This Technology

Is simple & reliable.

Does not need cooling water or produced waste heat.

Is open to environmentally neutral.

It can be installed by the less developed countries technologically.

2.1 PARTS OF SOLAR CHIMNEY

Man learned to make active use of solar energy at a very early stage; greenhouses helped to grow food, chimney suction ventilated & cooled building & windmills ground corn & pumped water. A Solar - Thermal Chimney simply combines them in a new way. The Solar Chimney contains three essential elements: collector, chimney, wind Turbines.

Fig1. ELEMENTS OF SOLAR CHIMNEY POWER PLANT

Air is heated by solar radiation under a circular glass roof open at the periphery, this and natural ground below it form a hot air collector. In the middle of the roof is a vertical chimney with large air inlets at its base. The joint between the roof and chimney base is airtight. As hot air is too lighter than cold air it rises up the chimney suction from the chimney then draws in more hot air from the collector and cold air comes in from the outside. Thus, solar radiation causes a constant up draught in the chimney. The energy this contains is converted into the mechanical energy by pressure stepped wind turbines at the base of chimney and into electrical energy by conventional generators.

The main parts of the solar chimney are

a) Collector

b) Turbine

c) Tower (or) Chimney

a) THE COLLECTOR

Hot air for the chimney is produced by greenhouse effect in a simple air collector consisting only of a glass of plastic film covering stretched horizontally 2 to 6 m above the ground. Height increases only adjacent to the chimney base, so that the air can be diverted to vertical movement without friction loss. This covering admits short wave solar radiation component and retains long wave radiation from the heated ground. Thus, ground under the roof heats up and transfers its heat to the air flowing radially above it from the outside to the chimney, like flow heater. The air temperature rise could be 350C in a well-designed collector. The total radius requires for 5MW, 30MW, 100MW is 500, 1000 and 1800 m respectively.

Peripheral area of the collector can be used as greenhouse or drying plants, at no extra cost and without significant performance loss. A collector roof of this kind is of long span and continuous maintenance can give service up to 60 years or more. Collector efficiency is improved as rise in temperature decreases. Thus, a solar chimney collector is economic, simple in operation and has a high-energy efficiency level.OPTICAL PARAMETER OF VARIOUS GLASS ROOF MATERIALS

greenwhiteIR REFLEX

Glass thickness (mm)444

Long waves absorption0.9180.9180.15

Long wave transmission0.0000180.0000180.000018

Short wave absorption0.050.010.07

Short wave transmission0.8860.970.81

Refractive index1.501.501.50

Specific heat capacity (J/kg oc)481481481

Density (kg/m3)258025802580

Thermal conductivity (W/mK)0.90.90.9

b) THE CHIMNEY

The chimney itself is the plant's actual thermal engine. It is a pressure tube with low friction and loss (like a hydroelectric tube) because of its optimum surface-volume ratio. The up-thrust of the air heated in collector is approximately proportional to air temperature rise DT in collector and volume (i.e. height and diameter of the chimney). In a large solar chimney the collector raises the temp. of air by DT=350C. This produces an up-draught velocity in chimney of about V=15 m/s. The efficiency of the chimney (i.e. conversion of heat into kinetic energy) is practically independent of DT in collector and determined by outside temp. To (lower the better) and height of chimney (higher the better).

Power = K. (Hc/To)*(Solar radiation at location)*(Area of collector)

Thus, solar chimneys can make particularly good use of the low rise in air temp. Produced by heat emitted by the ground during the night and even the meager solar radiation of a cold winter's day! However, compared with the collector and the turbines, the chimneys efficiency is relatively low, hence the importance of size in its efficiency curves. The chimney should be as tall as possible e.g.: at 1000m height can be built without difficulty. ( Let it be remind that T.V. Tower in Toronto, is almost 600m height and serious plans are being made for 2000 m skyscrapers in earthquake ridden Japan.)

C) THE TURBINES

Mechanical output in the form of rotational energy can now he derived from the vertical air-current in the chimney by turbines. Turbines in a solar chimney do not work with stepped velocity like a free-running wind energy converter, but as a cased pressure-stepped wind turbo-generator, in which, similar to a hydroelectric power station, static pressure is converted into a pipe. The energy yield of a cased pressure-stepped turbine of this kind is about eight times greater than that of the same diameter. Air speed before and after the turbine is about the same. The output achieved is proportional to the product of volume flow per time unit and the fall in pressure at the turbine. With a view to maximum energy yield the aim of the turbine regulation concept is to maximize this product under all operating conditions.

The turbine regulates air speed and air flow by means of blade tilt. If the blades are horizontal, the turbine does not turn. If the blades are vertical and allow the air to flow through undisturbed, there is no drop in pressure at the turbine and no electricity is generated. Between these two extremes there is an optimum blade setting; the output is maximized if the pressure drop at the turbine is about two thirds of the total pressure differential available. If the air stream is throttled the air takes longer to heat up. This increases the rise in temperature in the collector. This in its turn causes increase ground storage and thus enhanced night output, but also greater loss from the collector (infrared emissions and convection). Turbines are always placed at the base of the chimney. Vertical axis turbines are particularly robust and quiet in operation. The choice is between one turbines whose blades cover the whole cross-section of the chimney or six smaller turbines distributed around the circumference of the chimney wall, here the blade length of each turbine will a sixth of the chimney diameter. The diversion channel at the base of the chimney is designed for one or six turbines as appropriate. But it is also possible to arrange a lot of small turbines with horizontal axes (as used in cooling tower fans) at the periphery of the transitional area between canopy and available technology. Generator and transmission are conventional, as used in related spheres

.

In a solar chimney there are no critical dynamic loads on blades, hubs and setting equipment of the kind met in free-running wind energy converters due to gustiness of the natural wind as the canopy forms an effective buffer against rapid pressure and speed changes. This makes these components structurally simple and cheap to manufacture, and they also have a long life span.

Typical dimensions and electricity output

1.Capacity MW 5 30 100 200

2.Tower height m 550 750 1000 1000

3.Tower diameter m 45 70 110 150

4.Collectordiameter m 1250 2900 4300 7000

CHAPTER -3 FUNCTIONAL PRINCIPAL AND WORKING3. FUNCTIONAL PRINCIPAL AND WORKING

Heated air-->rises up-->gains momentum-->flows through chimney-->rotates turbine.The principle is when air is heated by solar radiation under a low circular translucent roof open at the periphery; the natural ground below it form an air collector. In the middle of the roof and the natural ground below it form an air collector. In the middle of the roof is a vertical tower with large air inlets at its base. The joint between the roof and the tower base is airtight.

As hot air is lighter than cold air it rises up the tower. Suction from the tower then draws in more hot air from the collector, and cold air comes in from the outer perimeter. Continuous 24 hours operation can be achieved by placing tight water filled tubes or bags under the roof. The water heats up during day time and releases its heat at night. These tubes are filled only at once, no further water is needed. Thus solar radiation causes a constant updraft in the tower. The energy contained in the updraft is converted into mechanical energy by pressure-staged turbines at the base of the tower, and into electrical energy by conventional generator.

Solar chimneys are constructed to actively promote ventilation of unwanted heated or stale air by drawing fresh cooler air from vents at lower levels. The exchange and movement of air cools the building by driving heat to the outside. The process by which this movement of air occurs is called natural convection . Natural convection is created by solar energy heating air within the chimney. The heated air escapes out the top of the chimney and is replaced by air from the outside (through windows or vents elsewhere in the building).In winter the chimney vents to the outside can be closed and heated air in the chimney forced (using fans, or other air handling system) into the building for heating purposes.

CHAPTER -4 HYDROELECTRIC POWER STATION FOR THE DESERT4. A HYDROELECTRIC POWER STATION FOR THE DESERT

Solar chimneys are technically very similar to hydroelectric power stations- so far the only really successful renewable energy source, the collector roof is the equivalent of the reservoir, & the chimney of the pressure pipes. Both power generation systems work with pressure-stepped turbines, & both achieve low power production costs because of their extremely long life span & low running costs. The collector roof & reservoir areas required are also comparable in size for the same electrical output. But the collector roof can be built in arid deserts & removed without any difficulty whereas useful (often even populated) land is submerged under reservoirs.

Solar chimneys work on dry air & can be operated without the corrosion & cavitations typically caused by water. They will soon be just as successful as hydroelectric power stations. Electricity yielded by a solar chimney is in proportion to the intensity of global radiation, collector area & the chimney height. Thus, there is no physical optimum. The same output can be achieved with a higher chimney & a small collector or vice-versa. Optimum dimensions can be calculated only by including specific component costs (collector, chimney, and turbines) for individual sites. And so plants of different sizes are built from site to site-but always at optimum cost, if glass is cheap & concrete dear the collector will be large with a high proportion of double glazing & a relatively low chimney, and if glass is dear there will be a smaller, largely single-glazed collector and a tall chimney.

CHAPTER -5 5. SOLAR CHIMNEY ON THE INTERNATIONAL GRID5. SOLAR CHIMNEY ON THE INTERNATIONAL GRID

Generally speaking solar chimneys will feed the power they produce into a grid. The alternating current generators are linked directly in the public grid by a transformer station. The thermal inertia of solar chimneys means that there are no rapid abrupt fluctuations in output of the kind produced by wind parks and photovoltaic plants (output fluctuations up to 50% of peak output within a minute causing the familiar frequency and voltage stability problems in the grid. Solar chimney output fluctuation is a maximum of 30% of the rated load within 10 to 15 minutes; this means that grid stabilization can be easily handled by the appropriate regulation stations.

In the case of island grids, without conventional power sources and no linkage with other grids, a connection of solar chimneys to pumped storage stations is ideal. These stores the excess energy produced by the solar chimney by the day or year and releases it when needed. Thus available energy in independent of varying amounts of sunshine by day and night, and throughout the year.

Many countries already have hydroelectric power stations, and these can also be used as pumped storage stations, if necessary their reservoirs can be covered with membranes to prevent water evaporation. The rpm of solar chimney turbines and pumps can be uncoupled from the rigid grid 50 Hz frequency by frequency converters of the kind already used by a Badenwerk hydroelectric plant in South-West Germany.

The import of solar-produced energy, from North Africa to Europe, for example, will soon be perfectly cheap and simple, as the European grid is to be extended to North Africa. Transfer costs to Europe will then be only a few cents/kWh. A large extended grid will itself also optimize energy flow between the various producers and consumers and thus need hardly any storage facilities.

If distances between solar energy stations and consumers are large, as for example from North Africa to Europe, low loss, high voltage D.C. transmission is also available. Transfer losses over a distance of 3500 km from the Sahara to central Europe will be less than 15%.

On the other hand, hydrogen technology converting solar power into hydrogen by electrolysis, transporting this and then converting it back into electricity-makes no sense, and is conceivable only for mobile use in vehicles and aircraft.

Thus, there is no technical reason why a global solar energy economy cannot be achieved. Transfer and distribution of solar energy generated in deserts no longer presents serious problems, even of an economic nature.

CHAPTER-6

THE PROTOTYPE IN MANZANARES6.THE PROTOTYPE IN MANZANARESObjective:-

Detailed theoretical preliminary research and a wide range of wind tunnel experiments led to the establishment plant with a peak output of 50 kW on a site made available by the Spanish utility Union Electricity Fenosa in Manzanares (about 150 km south of Madrid) in 1981-82 with funds provided by the German Ministry of Research and Technology (BMFT) The aim of this research project was to verify theoretical data established by measurement & to examine the influence of individual component on the plant's output and efficiency under realistic engineering and meteorological conditions. To this end a chimney 195m high and 10 m in diameter was built, surrounded by a collector 240 m in diameter. The plant was equipped with extensive measurement data acquisition facilities. The performance of the plant was registered second by second by 180 sensors.

Since the type of collector roof primarily determines a solar chimney's performance costs, different building methods and materials for the collector roof were also to be tested in Manzanares. A realistic collector roof for large-scale plants has to be built 2 to 6 m above ground level. For this reason the lowest realistic height for a collector roof for large-scale technical use, 2 m, was selected for the small Manzanares Plant. (For output a roof height of only 50 cm would in fact have been ideal.) Thus only 50 KW could be achieved in Manzanares, but this realistic roof height also permitted convenience access to the turbine at the base of the chimney. This also meant that experimental planting could be carried out under the roof to investigate additional use of the collector as a greenhouse.

Solar updraft tower

Schematic presentation of a solar updraft tower

Thesolar updraft tower(SUT) is arenewable-energypower plantfor generating electricity fromsolar power. Sunshine heats the air beneath a very wide greenhouse-like roofed collector structure surrounding the central base of a very tallchimneytower. The resultingconvectioncauses a hot air updraft in the tower by thechimney effect. This airflow driveswind turbinesplaced in the chimney updraft or around the chimney base to produceelectricity. Plans for scaled-up versions of demonstration models will allow significant power generation, and may allow development of other applications, such as water extraction or distillation, and agriculture or horticulture.

As a solar chimney power plant (SCPP) proposal for electrical power generation, commercial investment is discouraged by the high initial cost of building a very large novel structure, and by the risk of investment in a feasible but unproven application of even proven component technology for long-term returns on investmentespecially when compared to the proven and demonstrated greater short-term returns on lesser investment in coal-fired or nuclear power plants. Likewise, the benefits of 'clean' or solar power technologies are shared, and the widely shared harmful pollution of existing power generation technologies is not applied as a cost for private commercial investment. This is a well-describedeconomic trade-off between private benefit and shared cost, versus shared benefit and private cost. If it is in the public interest, then some form of public investment or subsidy to share cost and risk will be required to demonstrate SCPP feasibility at scale.

DesignPower output depends primarily on two factors: collector area and chimney height. A larger area collects and warms a greater volume of air to flow up the chimney; collector areas as large as 7 kilometres (4.3mi) in diameter have been discussed. A larger chimney height increases the pressure difference via thestack effect; chimneys as tall as 1,000 metres (3,281ft) have been discussed.[1]Heat can be stored inside the collector area. The ground beneath the solar collector, water in bags or tubes, or asaltwater thermal sinkin the collector could add thermal capacity and inertia to the collector. Humidity of the updraft and condensation in the chimney could increase the energy flux of the system.[2]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-Schlaich-3" [3]Turbineswith a horizontal axis can be installed in a ring around the base of the tower, as once planned for an Australian project and seen in the diagram above; oras in the prototype in Spaina single vertical axis turbine can be installed inside the chimney.

Carbon dioxideis emitted only negligibly[citation needed]as part of operations. Manufacturing and construction require substantial power, particularly to producecement. Net energy payback is estimated to be 23 years.[3]Since solar collectors occupy significant amounts of land, deserts and other low-value sites are most likely.

A small-scale solar updraft tower may be an attractive option for remote regions in developing countries.[4]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-5" [5]The relatively low-tech approach could allow local resources and labour to be used for construction and maintenance.

Locating a tower at high latitudes could produce up to 85 per cent of the output of a similar plant located closer to the equator, if the collection area is sloped significantly toward the equator. The sloped collector field, which also functions as a chimney, is built on suitable mountainsides, with a short vertical chimney on the mountaintop to accommodate the vertical axis air turbine. The results showed that solar chimney power plants at high latitudes may have satisfactory thermal performance.[6]Solar updraft towers can be combined with other technologies to increase output.Solar thermal collectorsorphotovoltaicscan be arranged inside the collector greenhouse. This could further be combined with agriculture.[citation needed]

Solar Chimney Manzanares view through the polyester collector roof

In 1982, a small-scale experimental model of a solar draft tower[15]was built inManzanares, Ciudad Real, 150km south ofMadrid, Spain at390234.45N31512.21W. The power plant operated for approximately eight years. The tower'sguy-wireswere not protected against corrosion and failed due to rust and storm winds. The tower blew over and was decommissioned in 1989.[16]

SUT as seen from La Solana

Inexpensive materials were used in order to evaluate their performance. The solar tower was built of iron plating only 1.25 millimetres (0.049in) thick under the direction of a German engineer,Jrg Schlaich. The project was funded by the German government.[17]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-18" [18]The chimney had a height of 195 metres (640ft) and a diameter of 10 metres (33ft) with a collection area (greenhouse) of 46 hectares (110 acres) and a diameter of 244 metres (801ft), obtaining a maximum power output of about 50kW. Various materials were used for testing, such as single or double glazing or plastic (which turned out not to be durable enough). One section was used as an actual greenhouse. During its operation, 180 sensors measured inside and outside temperature, humidity and wind speed data was collected on a second-by-second basis.[19]This experiment setup did not sell energy.

In December 2010, a tower inJinshawaninInner Mongolia,Chinastarted operation, producing 200kilowatts.[20]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-21" [21]The 1.38 billionRMB(USD208 million) project was started in May 2009 and intends to cover 277 hectares (680 acres) and produce 27.5 MW by 2013. The greenhouse is expected to improve the climate by covering loose sand, restraining sandstorms.

SUT powerplant prototype in Manzanares, Spain, seen from a point 8 km to the South

A proposal to construct asolar updraft towerinFuente el Fresno,Ciudad Real, Spain, entitledCiudad Real Torre Solarwould be the first of its kind in theEuropean Union[23]and would stand 750 metres (2,460ft) tall[24] nearly twice as tall as the continent's tallest structure, theBelmont TV Mast[25] covering an area of 350 hectares (860 acres).[26]It is expected to produce 40MW.[27]

Solar Chimney Manzanares-view of the tower through the collector glass roof

In 2001,EnviroMission[28]proposed to build a solar updraft tower power generating plant known asSolar Tower BuronganearBuronga, New South Wales.[29]The company did not complete the project. They have plans for a similar plant in Arizona,[30]and most recently (December 2013) in Texas,[31]but there is no sign of 'breaking ground' in any of Enviromission's proposals.

In December 2011, Hyperion Energy, controlled byWestern AustraliansTony SageandDallas Dempster, was reported to be planning to build a 1-km-tall solar updraft tower nearMeekatharrato supply power to Mid-West mining projects.[32]

View from the tower on the roof with blackened ground below the collector. One can see the different test materials for canopy cover, and 12 large fields of unblackened ground for agricultural test area.

Based on the need for plans for long-term energy strategies,Botswana's Ministry of Science and Technology designed and built a small-scale research tower. This experiment ran from 7 October to 22 November 2005. It had an inside diameter of 2 metres (6.6ft) and a height of 22 metres (72ft), manufactured from glass-reinforced polyester, with an area of approximately 160 square metres (1,700sqft). The roof was made of a 5mm thick clear glass supported by a steel framework.[33]In mid-2008, theNamibiangovernment approved a proposal for the construction of a 400 MW solar chimney called the 'Greentower'. The tower is planned to be 1.5 kilometres (4,900ft) tall and 280 metres (920ft) in diameter, and the base will consist of a 37 square kilometres (14sqmi) greenhouse in which cash crops can be grown.[34]A model solar updraft tower was constructed in Turkey as a civil engineering project.[35]Functionality and outcomes are obscure.[36]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-37" [37]A grade-school pupil's home do-it-yourself SUT demonstration for a school science fair was constructed and studied in 2012, in a suburban Connecticut setting.[38]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-39" [39]With a 7 metre stack and 100 square metre collector, this generated a daily average 6.34mW, from a computer fan as a turbine. Insolation and wind were the major factors on variance (range from 0.12 to 21.78mW) in output.

EfficiencyThe solar updraft tower has a power conversion rate considerably lower than many other designs in the (high temperature)solar thermalgroup of collectors. The low conversion rate is balanced to some extent by the lower cost per square metre of solar collection.[16]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-40" [40]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-41" [41]Model calculations estimate that a 100 MW plant would require a 1,000 m tower and a greenhouse of 20 square kilometres (7.7sqmi). A 200MW tower with the same tower would require a collector 7 kilometres in diameter (total area of about 38km).[3]One 200MW power station will provide enough electricity for around 200,000 typical households and will abate over 900,000 tons of greenhouse producing gases from entering the environment annually. The collector area is expected to extract about 0.5 percent, or 5W/m of 1kW/m, of the solar energy that falls upon it. Concentrating thermal(CSP)or photovoltaic(CPV)solar power plants range between 20% to 31.25% efficiency (dish Stirling). Overall CSP/CPV efficiency is reduced because collectors do not cover the entire footprint. Without further tests, the accuracy of these calculations is uncertain.[42]Most of the projections of efficiency, costs and yields are calculated theoretically, rather than empirically derived from demonstrations, and are seen in comparison with other collector or solar heat transducing technologies.

The performance of an updraft tower may be degraded by factors such as atmospheric winds,[44]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-45" [45]by drag induced by the bracings used for supporting the chimney,[46]and by reflection off the top of the greenhouse canopy.

Related ideas and adaptations Theatmospheric vortexproposal[47]replaces the physical chimney by a controlled or 'anchored' cyclonic updraft vortex. Depending on the column gradient of temperature and pressure, or buoyancy, and stability of the vortex, very high-altitude updraft may be achievable. As an alternate to a solar collector, industrial and urban waste-heat could be used to initiate and sustain the updraft in the vortex.

Telescopic or retractable design may lower a very high chimney for maintenance, or to prevent storm damage. Hot-air balloon chimney suspension has also been proposed.

A saltwater thermal sink in the collector could 'flatten' the diurnal variation in energy output, while airflow humidification in the collector and condensation in the updraft could increase the energy flux of the system.[2]

HYPERLINK "http://en.wikipedia.org/wiki/Solar_updraft_tower" \l "cite_note-Schlaich-3" [3] Release of humid ground-level air from an atmospheric vortex or solar chimney at altitude could form clouds or precipitation, potentially altering local hydrology.[48]Local de-desertification, or afforestation could be achieved if a regional water cycle were established and sustained in an otherwise arid area.

Thesolar cyclonedistiller[49]could extract atmospheric water by condensation in the updraft of the chimney. Thissolar cyclonicwater distiller with asolar collector pondcould adapt the solar collector-chimney system for large-scale desalination of collected brine, brackish- or waste-water pooled in the collector base.[50] Fitted with a vortex chimney scrubber, the updraft could be cleaned of particulate air pollution. Alternately, particulate air pollution caught in the updraft could serve as a nucleation stimulus for precipitation[51]either in the chimney, or at release altitude ascloud seeds.

A form ofsolar boilertechnology placed directly above the turbine at the base of the tower might increase the up-draught.[citation needed] If the chimney updraft is an ionized vortex, then the electro-magnetic field could be tapped for electricity, using the airflow and chimney as a generator.[citation needed] Energy production, water desalination[50]or simple atmospheric waterextractioncould be used to support carbon-fixing or food-producing local agriculture,[52]and for intensiveaquacultureandhorticultureunder the solar collector as a greenhouse.

6.1HOW THE PROJECT RAN

YEAR

PROGRESS

1980

Design

1981

Construction

1982

Commissioning

1983/84 Experimental phase & structural Optimization of the roof

1985/86 in operation, further improvements to collector & electric's.

1986-89

completely automatic long-term operation phase.6.2 TESTS DURING THE NINE-YEAR PROJECT

The experimental plant in Manzanares ran for about 15000 hours from 1982 onwards. The following tests were run in the course of the projects: Different collector roof covering were tested for structural stability, durability and influence on output. The behavior of the plant as whole was measured second by second (ground temperature, air temperature, speed and humidity, translucency of the collector, turbine data, meteorology etc. The ground's storage capacity was tested in terms of collector temperature and soil humidity. In order to investigate heat absorption and heat storage it was in turn left as it was, sprayed with black asphalt and covered with black plastic. Various turbine regulation strategies were developed and tested; Maintenance and running costs for individual components were investigated; The thermodynamic plant simulation program developed in all details in the mean time was verified with the aid of the experimental results and accompanying wind tunnel experiments, in order to make reliable calculations for any individual site data, meteorology and plant dimensions for daily & annual energy production by large solar chimneys.

TYPICAL PLANT OPERATING PARAMETERS FOR PLANT OF RATING 5, 30 AND 100 MW ARE GIVEN BELOW

5 MW 30 MW 100 MWCivil Engineering

Chimney height (m)

445

750

950

Chimney radius (m)

27

42

57.5

Collector radius (m)

555

1100

1800

Collector height, external (m)

3.5

4.5

6.5

Collector height, internal (m)

11.5

15.5

20.5

Mechanical Engineering

Type of turbine

propeller Type

5 MW 30 MW 100 MW

Number of turbine

33

35

36

Distance of turbine from

53

84

115

Chimney Centre (m)

Airflow rates (m/s)

8

10.4

13.8

Shaft power rating of

190

1071

3472

Individual turbines (KW)

Blade tip-to-wind speed ratio

10

10

8

Rotational speed (1/min) 153

132

105

Torque (kNm)

11.9 77.5

314.5

Operating data at rated load

5 MW 30 MW 100 MW

Upward air draught speed (m/s)

9.07

12.59

15.82

Total pressure difference (pa)

383.3 767.1

1100.5

Pressure drop over turbine (pa)

314.3 629.1

902.4

Friction (N)

28.6

62.9

80.6

Temperature in collector (oC)

25.6

31.0

35.7CHAPTER -6

CONCLUSION6. CONCLUSION

1) The collector of solar chimney plant can use all solar radiation both direct and diffused. So, this plant technique is also helping hands to those countries where the sky is frequently overcast.

2) There are many regions in country which are deserts and soil doesnt bear any crop. And thus no contribution to mankind. But installing plant there give excellent results.

3) The technology and the material to build such plants are available in the country. Hence, such power plants are very attractive in India for bulk power generation even in deserts. The capital cost is high, nearly 7crore/MW, which can be reduced. However, the cost of generation could be as low as Rs.1.62 per KWH in long run.

A 200MW power plant is being built at Thar (Jaisalmar) by a consortium of Srilanka and Germany at the cost of US$ 450 million which is going to commissioned in year 2000, according to Rajasthan Energy Development Agency (REDA).

REFERENCES1. www.sciencedirect.com/renewable/energy volume 17 issue 1-4

2. www.science.com/Energy&buildings Volume 32 issue 1

3. www.wikepedia.com

4. N. K. Bansal, M Kleeman & M. Meliss. Renewable energy source and conversion technology Tata McGraw Hill

5. www.eere.energy.gov/redirects/troughnet

6. Schlaich, J., 1995, "The Solar Chimney: Electricity from the Sun". C. Maurer, Geislingen

7. www.ibookdb.net/isbn/

8. "Solar chimney power plants for high latitudes". Solar Energy 79 (5): 449-458

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