Solar Energetics In Space

Solar Energetics in Space

INTRODUCTION The demand for energy has been continuously increasing in the country. Electricity demand is growing at rate about 8% per annum with present energy and peaking shortages about 7% andl6% respectively. On the basis of 15th Electric power survey, the required power generation capacity addition during 9th plan is estimated to be 44,730 MW. This is addition to an additional capacity of about 13,000 MW required for meeting the peak short ages. But, the world oil supplies could perhaps last only for another 75 years, those of natural gases and coal for 250 years or more. While these are global figures, the actual energy situation in many individual country like India, is quite serious. With 6 billion tonnes of carbon emission each year, global warming at unprecedented rates, danger of acid rain and climate changes not to speak of the finite and exhaustible nature of fossil fuel resources, it is clear that end of the fossil fuel age is in sight and the transition to a solar energy economy has begun all over the world. The search for alternative sources of energy has lead to the development of solar power. Compared to fossil fuels, the SUN promises to be infinite source of energy. Technology has already created the ability to harness the power of sun cheaply and efficiently without the drawbacks of fossil fuels. Each year the earth receives an energy input from the sun equal to 15,000 times the world's commercial energy consumption and over 100 times the world's proven coal, gas, oil reserves . The annual global energy consumption can be supplied by the sun's ray falling on less than 0.1% of the earth's surface harvested with a conversion efficiency of not more than 10%. India receives solar energy equivalent to over 5,000 trillion KW/year which is far more than the total energy consumption of the country. The daily average solar energy incident varies from 4.7 kw/ sqm. depending upon the location. There are 250-300 sunny days in most parts of Govt. Polytechnic, Washim.

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Solar Energetics in Space the country If 1% of the total land area is used to generate electricity from this radiation at a net efficiency of only 1%, it will be possible to produce about 300,000 MW power. Putting above in the different way, it has been estimated that a plot of 100 Hectares in Rajasthan can deliver 30 MW of grid quality electricity. Now in context of above, if we think the space solar power over terrestrial solar systems, the advantage is that the magnitude of the space solar power is one order of magnitude larger than terrestrial solar systems and efficient working of the system is likely to take place at space rather on earth because of climate conditions. Hence, there are a lot of research is going on this respect which is followed in the next contents of the report.

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Solar Energetics in Space

2. SOLAR ENERGETICS IN SPACE : PLACE AND PROSPECTS Using power resources of the outer space and it's industrialization have become an urgent task in the development of present day civilization. Solar energy is the most suitable basis for power supply for the majority of projects in the near-Earth space. Passing on to the large scale space based system of power supply requires putting into life demonstration experiments in which power transmission by electromagnetic emission is supposed. Now a day's when traditional energetic is confronted with in separable difficulties and causes the threat of the global ecological catastrophe, when nuclear energetic has turned into a source of new danger, it becomes clear that the only radical way to the solution of the mankind's global energetic problems consists in going over from two dimensional industry to the earth surface to three dimensional industry. This means partial transfer of power production with great power consumption to the near-Earth Space. It is believe that in 40-50 yr, the space - solar power-energy part in the global energetic balance will make up 26%, including half of electric power consumption and high - potential heat for industry. Using power from space on Earth can be realized in different ways illumination of cities, regions of farming and civil engineering work, increase of bio-mass production on earth through light day prolongation, rising energy production by on-ground solar power plants due to additional illumination. The most universal way of obtaining solar power from space is the transmission of converted energy from solar power station through electromagnetic radiation passing easily through the atmosphere namely microwave or LASER emission. Thus, the in exhaustible space power source becomes accessible without restrictions imposed by on-ground conditions i.e. dependence upon season and meteorological Factors. Govt. Polytechnic, Washim.

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Solar Energetics in Space Power consumption is space grows year by year. Prisniakov (1991) has proposed the formula describing the growth of the maximum power of space power plants. N = 10τ ⁄ Θ where, τ = t -1968(yr.)

&

Θ = 11 yrs. t = counting year N = Number of space power plants. Space

vehicle

program

is

divided

into

information

technological and transport ones. Information satellite and meteorological supply, the Earth surface observation. The development of information space vehicles goes by way of improving special equipment, enhancing its reliability and service life. Their terms of active functioning and working orbit heights increase. This results in the growth of power expense connected with the arrangement of the satellites in space and their operation causes the increase of electric power consumed on the board the space vehicles. Nevertheless, power consumption for majority of information satellites is not great and will not exceed several tons of kilowatts of electric power in future. The exception is space vehicles intended the help of radar apparatus and for direct broadcasting and television. Their on-board power consumption will again hundreds of kilowatts. Space technological system construction and operation will demand considerable energy outlay. Their levels of power consumption will exceed that of information systems by 2-3 orders on avg.Power transmission from an external source to the vehicle should be conducted by the direct flux of electromagnetic emission.

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Solar Energetics in Space As object put into space become more complicated, space system for assembling and constructing are supposed to be created. Robotic system with power consumption of tens and hundreds of kilowatts order will be widely used for assembling and repairing large scale space objects. Quantitative characteristics of power consumption levels at different stages of space industrialization is shown in following table.

Stage

Main consumer and kinds of activities in space

Power consumption

1. 2.

Modern information satellites and orbital stations. Radar apparatus of information satellite,

level (Kw) 1-10 102 - 103

transmitting

apparatus

of

communication

satellites for direct broadcasting. Experimental production 3.

of

new

materials.

Interorbital

transport vehicles with electric propulsion. Industrial material production assembling large

103 - 104

scale structure interorbital transportation using 4.

external power sources. Placing harmful industry in space using the bowls of

moon

and

asteroids

space

105 - 106

construction.

Transportation from Earth to low orbits based on space power sources. To the context of above a brief discussion regarding to above needs may be resolved by means of a limitless power demonstrating system which was suggested by Glaser in 1968. He published a paper which gave a broad vision over the transmission of solar power in form of microwave which should be ultimately used for consumer electric as well as industrial purpose.

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Solar Energetics in Space Glasefs original idea was to build a photovolatic solar power station in geostationary earth orbit, which converts generated electric power to microwave to be beamed to a receiving attend on the Earth where the microwave are rectified and transformed utility power for public use. The above idea clicks the most affective revolutionary path for the utilization of the space solar power which gave birth to ‘SATELLITE POWER SYSTEM' generally termed as SPS. This SPS reference system was designed and developed by NASA which studying the features of above programme under the name 'CONCEPT DEVELOPMENT EVALUATION PROGRAM (CDEP)' The idea of space solar power satellite is revolutionary as it converts the limitless solar energy into high quality sustainable energy for humankind. The solar power satellite will provide a clean, reliable source of energy source for mass consumption. The system will use satellites in gesostationary orbits around the Earth to capture the sun's energy. The intercepted sunlight will be converted to laser or microwave according to merit. Ground system on earth will convert the transmission from space into electric power. In addition to this the idea indicates a direction for productive space activities which would be able to recover the huge investments in early space exploration and technology development for space flight by supplying part of the world electricity market which is many times larger than space industry. Thus this new system was expected to interest the two parties of energy development and space activities. However, both parties have been indifferent to SPS.

3. FEATURES OF PAST SPS RESEARCH

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Solar Energetics in Space After Glaser, many concepts of power system rising space solar energy have been proposed mainly by planners of space projects. They stressed various aspects of solar power from space, some discussed the system design of the space section of power other discussed specific technical areas such as the method of power conversion, power transmission and reception. These efforts were devoted to filling the gap between the refines system and present day space technology from various view points such as demonstration of principle, early phase development, alternate system configuration and different application from power from space. All above points may be discussed or categories as follows.

3.1 IDEAS AND CONCEPTS One of the biggest issues is concerned with the location of solar power stations and customer Glaser's original idea and CDEP chose Geostionally Orbit (GEO) for space solar power stations. Both systems consist of solar panels actively controlled to face the sun and transmitting antenna beaming microwave power to power receiving stations on the earth. In this case, the positions of the space power stations relative to the receiving stations can practically be fixed, so that these power stations serve exclusively for rectanas just like power station built in the territory of the India. However, the distance of power Transmission is very long, more than 36,000 Kn, that is the height of the orbit above the equator. Many derivative ideas and concepts proposing to use low Earth Orbit (LEO) instead of GEO are intended to avoid the difficulty of wireless power transmission over this long distance and also to ease the difficulty of wireless power transmission over this long distance and also to ease the difficulty of transportation of materials from earth.

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Solar Energetics in Space Summary of past ideas and concepts of SPS, featured by design factors; where, who and when. The arrows indicate directions of wireless power transmission from the locations of solar power stations on the moon, GEO (geostatonary orbits) or LEO (low earth orbits) to use is locations of S/c (spacecraft), GEO, LEO or earth. Fig. shows summary of proposed locations of space solar power stations and receiving stations is schematically shown by arrows. The arrow directions indicate the direction of power transmission. Is seen in fig. some space power system are intended to beam power not to the ground but to other space systems in space. Here, we focus our discussion from space to earth for detailed study. In fig. three space power stations locations GEO, LEO & MOON are identified. "GEO To Earth" is represented by the CDEP which was intensively studied to conceptualize a system to be used as reference for evaluation. "LEO To EArth" is a compromise to ease the difficulty of the "GEO TO EARTh APPROACH" for which technical and economic risks are predicted.

3.2 ENERGY LEVEL REQUIREMENT FOR SPACE PROGRAMME Space vehicle COSMOS-1

Year of

Operation

Electric power

Solar array

Launching 1962

time ( Days) 60

(W) 3.5

area ( m2) --

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Solar Energetics in Space COSMOS-6 AUOS-EARTH OCEAN OREOL-3 AUOS-SM OCEAN-O

1962 1976 1979 1981 1994 1995

60 180 180 2000 365 365

30 250 250 200 850 1500

4 12 12 12 18 32

4. PRACTICAL APPROACHES TO SPACE SOLAR POWER RESEARCH In addition to having realistic targets, space solar power research should be practical, not theoretical. Assuming that we were to prepare a business plan for space solar power research. When we give a practical approach to above subject following are some important thing to be considered. *

Technology available from industries concerned. It will be most favorable for industry to participate because the project should be a joint venture and it should have low project cost.

*

Low cost space Transportation which should reduce project cost.

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Solar Energetics in Space *

Cost is not a design parameter.

*

Launch failure rate is 1%

*

Weight growth factor of 15% should be reflected in final mass estimates. The following are the basic system requirements of the

established by the request for proposal by CDEP. 1.

The SPS will supply 5 GW to ground site

2.

Damage to Earth and space environment is minimal

3.

System debris from construction/ operation is minimal

4.

System life is 30 yrs. SPS working group, which engaged in above activities which

may be described as follows. The solar power satellite was proposed (by Glaser) to solve future problems caused by activities of human beings on global scale. The research areas of SPS are concerned with not only technology and engineering, but also big problems such as "Global Energy Production" and "Exploitation of extra-terrestrial resources" as well as economical problems such as "project cost" & risk factors. The working group is divided into 13 subgroups by specialized research fields Nine of them are concerned with studies on SPS subsystems & technologies and other four subgroups are for studies on the effects of interaction of SPS operation with the environment. The individual research guilds of 13 subgroups are listed as follows.:

4.1 STUDY ON SUB-SYSTEMS AND TECHNOLOGIES i.

Microwave Transmission

ii.

Microwave Reception

iii.

Large Space structures

iv.

Guidance And control

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Solar Energetics in Space v.

Large Space Structures

vi.

Photovolatic Technology

vii.

Thermodynamic power generator

viii.

Propulsion

ix.

Space Robotics

4.2 STUDY ON ENVIRONMENTAL INTERACTION x.

Space craft environment

xi.

Space electromagnetic environment

xii.

Communication system

xiii.

Biology and Ecology. The SPS working group from Japan has practically

constructed such type of solar satellite under above mentioned features whose technical specifications are discussed as follows. The general configuration of SPS 2000 has the shape of a triangular prism with a length 800 m and sides of triangle of 100m as shown in above fig. The prism axis is in North-south direction. The transmitting antenna is fixed to the bottom surface facing to Earth and other two sides surfaces are used to deploy solar arrays. No Energy storage for power transmission during eclipse is provided. The reason this configuration is adopted is easiness of construction of the system in orbit as well as of orbital operation under the gravity gradient force which is larger in low earth orbit (LEO) than in Gesostationary orbit (GEO) on the other hand requirement of high efficiencies interms of power conversion and mass reduction, which have been generally accepted for space system design are not considered to have high priority in this study.

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Solar Energetics in Space

4.3 STRUCTURE DESIGN: A conventional rigid beam structure is assumed for main structure of pyramid shape the function of the structure is to deploy the solar array and phased array antenna and to provide the subsystems with reference of geometrical locations. The strength of structure is more important then it's accuracy. A stander beam of the structure is 100m long and cross section is triangular with sides of 3 m. The fundamental element of the structure is aluminum pipe. With outer diameter 12mm and 0.5 mm wall thickness. The total mass of structure is 4 ton. Solar allays consist or 1500 rolls of I m x 100m strips. Each strips generates about 1 KV x 20A

D.C electrical power at maximum with

conversion efficiency 14%

4.4 TRANSMITTING ANTENNA Transmission is possible only when a rectenna is in field of view of the controllable microwave beam which is assumed to be movable as much as 30° in any direction from centre equator can receive power from a single satellite in 1000 km equatorial orbit for 200 sec. in one orbit and about 1600s in a day.

4.5 GUIDANCE AND CONTROL Reduction of the operating cost has been selected as the primary requirement of the guidance and control system design. To make this approach possible, the heavy lift launching should be operable over a ide range of conditions of relocated factor. The slander orbit attitude is 4000km for this study, although it may be subject to change to 800 or 1200 km to avoid the most crowded attitude of 1000 km.

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Solar Energetics in Space The mass of total satellite systems may be as follows. Item

Mass (ton)

Transmitting antenna

5

solar array

3

Main structure

0.5

cable and bus

1.5 -10 tons

Related to SPS-2000 design solutions for power satellite and working may be accomplished with Occurrence AUOS-SM. Following photo pictures gives a brief out look. Above space vehicle contains more solar arrays as compared to SPS-2000. Hence, Efficiency is more regarding to above. Regarding to same under guidance and control the satellite may be placed in the desired orbit with appropriate Fashion by launching in single stage if it's weight is considerably accessible. Following fig.s shows two different ways to establish the solar power satellite in the GEO or LEO orbit with proper control. Above unfolding mechanism is not for SPS-200 but it may be the one of the guide line for it. The process of unfolding occurs in following way. The bar with the panel unit is turned to 90° in respect to transport state. Then the packets joined through the root panels of the sections are unfolded in regard to the longitudinal grider axis then next step is the packets are unfolded in air. Given by the hinges of the two contingeous root panels coupled by smaller sides, (to angle 180°) after this end panels are unfolded successively (each tot he angle 180°). These panels having been coupled along the longer sides. The total array area is 63.4 m2, and mass is 243 kg. Govt. Polytechnic, Washim.

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Solar Energetics in Space EXPLANATION FOR FIG. C All unit sections are fastened by the root panel to the turning bar which takes the position 1st to vehicle axis after the unit liberation. A section deployment is provided by the special device including the drive of sliding rod, the rod itself and the transverse bar fastened to the free panel of the section. The drive is installed on the cantilever of turning bar. The area of array is 95 m\ mass is 370 kg.

5. PROBLEM AREAS FOR FURTHER STUDY As a result of the system analysis, several points requiring to be scrutinized for further sturdy.

5.1 SOLAR PHOTOVOLATIC TECHNOLOGY The selection of solar to electrical conversion method is primary consideration in realizing the SPS concept. The study research to options for energy conversion i) Solar dynamic system ii) Solar photovolatic cells. Out of this solar based upon the relative advantageous and Disadvantageous of the two conversion methods. It is also suggested that, to reduce the cost of the solar array by using plastic lenses to concentrate sunlight onto small area single crystals so, there is a lot of futuristic scope regarding to the conversion technology so to increase its efficiency.

5.2 POWER TRANSMISSION

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Solar Energetics in Space The power transmission subsystems studies selected a CO2 laser based system. Laser and microwave were compared on five different criteria. i.

Size of Transmission optics.

ii.

Efficiency

iii.

Flexibility of system.

iv.

Development of Technology

v.

Area of ground station required. Comparing

to

above

parameter

the

Laser

is

more

advantageous than microwave but the conversion efficiency of Laser is 30% to 80% where microwave has 80% to 90%. This is only area where laser concepts leags behind. There is a lot of futuristic scope in this regard.

5.3 GROUND SEGMENT Rectenna must be located in the relatively limited zone where the SPS is visible at an elevation angle of at least 60°. This is a zone between latitude of 5.5 degree north and south or 1200 km wide equatorial zone for an orbital altitude of 1000 km. Reception efficiency is directly proportional to distance of orbit. Since the orbit latitude is nearly proportional to serviceable zone width of latitude and minimum distance will serve better for rectenna working also the mass which carried by launch vehicle to higher orbit will be reduced significantly. If orbital altitude is 1000 km the maximum number of SPS will 33 and then all reactance can receive the nominal power from space almost constantly from early morning to early evening ever day.

5.4 ECONOMY Economy is the fundamental motivation for people to accept a new system in society when a new system like a space solar power system is Govt. Polytechnic, Washim.

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Solar Energetics in Space introduced in society, finance is the key factor. In the past the space solar power system which was large collection electric power system to be deployed over a huge territory from earth to space. As result, the project was predicted to be so big that it was unrealistic for interested parties except, Govt. to invest in it. The cost estimation suggests that electrical power would be economically competitive with conventional power system. However, the estimation is based on low cost transportation system. In the modem era of industrialization, transportation service should be provides by space infrastructure so SPS may reduced the space transportation cost Assuming the cost is 10 US $/W, the appx. figure for 10 MW model is 100 M US $. This will regards the lowering of future SPS plans. The cost content of the sps system may be summarized by flow chart.

6. SAFETY AND ENVIRONMENTAL CONCERNS 6.1 SAFETY The above term regarding to power transmission with respect to Laser so there are many safety concerns associated with beaming lasers to earth. The primary concern is effect laser beams might have on humans vicinity of the reception site. This problem is avoided by locating the receiving site in an area of sparse population and building fenced buffer zone around target area. Another concern is whether air planes will be able to fly through this beam. A radiation levels is as high as 1.5 W/cm2 is permitted for aircraft, but our system will beam as much as 10 W/ cm2 to the ground. Thus, it will have to restrict airplane flight in the vicinity of beam.

6.2 ENVIRONMENTAL CONCERNS The primary environmental effect of beaming lasers to earth is the effect the wasted heat (energy at ground station not converted to electricity) Govt. Polytechnic, Washim.

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Solar Energetics in Space may have on the climate. It has been found that this atmospheric phenomenon occurs only in a confined area of 200 acres around the receiving sites. The global or regional climate will not be affected, secondly, animals, birds, will be protected by controlling beam intensity. This is done in such a way that inner high power beam is surrounded by lower power ring region in which the birds will able to sense the increase in temp. and fly a way from central beam. Rain clouds also present a problem. The inability of laser beams to penetrate rain cloud reduces their overall operating efficiency so this may be minimized by locating the ground site in such a area which have max. clear days in a year placing ground site as high so that weather phenomenon is below:

7. CONCLUSIONS There are many concepts of space solar power systems that have been proposed for space solar energy to be used for human kind. However, most of them are theoretical and not evaluated on the basis of becoming practical power system. The SPS-2000 study was made on practical assumptions and demonstration and has indicated a realistic approach to space solar power research and development for terrestrial use. 1.

The advantage of space solar power over terrestrial solar system is one order of magnitude larger solar power in space than on earth. The disadvantage is the high cost of transportation of the required facilities in space. Even if reusable space transportation system under development realize lower cost.

2.

To faciliate research on this power system as future energy source to compete with other sustainable energy candidates it is necessary to consider the space solar power system as a variation of solar power systems now under research and development for terrestrial use.

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Solar Energetics in Space 3.

It is practical to apply concept of microwave fuel as the interface between space power suppliers and buyers, as utility power suppliers and consumer are related to each other by standard of commercial electric power. Considering that properly selected microwave frequency makes it possible for users to plan and even build their rectenna.

4.

To reduce transportation cost, we should choose LEO rather than GEO.

5.

The SPS-2000 can serve exclusively the equatorial zone especially benefiting zeographically isolated lands. This will be a aspect of societal issues which wasn't discussed in CDEP.

BIBLIOGRAPHY I)

MAKOTO MAGATOMO- An Approach to develop space solar power as a new energy system for developing Countries.

II)

PRISNIAKOV V.,F. LYAGUSMN S.F., STATSENKO I.N. & DRANOVSKY on the way to creating a system of distant power supply for space vehicles , (page 97-108), solar energy vol.56, (year 1996).

III)

VED MITRA, S.K. GUPTA, and K.R.S. ACHARY Role of Solar Energy in Indias Energy Future. "Indian Journal of power and River Valley Development (179-182), (Year 1997).

IV)

M.NAGATOMO, I Kiyonhiko, An evolutionary satellite power system for international Demonstration in Developilgn nations, SPS-91 (1991).

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Solar Energetics in Space V)

Clara V. Enriquez, et al. Satellite Power system, (May 9,1991).

VI)

www.Feedback@ spacefuture.com.

VII)

CSR/TSGC Team web.

VIII)

vro) http://observe.iw.nasa.gov.

IX)

www.science mag.org.

X)

www.kalmbach.com/astro/

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