Solar Power : Sun is Ascending
Intro : Real utility of solar power at least in near future lies in improving the quality of life of 67 per cent population still living in villages. Half of the families do not have power connection.
Sun is the ultimate source of all energy – physical, chemical and biological. We are using its energy in various ways particularly in villages. On our electricity scenario
however its place has been quite insignificant.
Considerable progress has been made in the area of wind power generation and we have already built 22.5 Giga Watts (GW) of installed capacity from that source. We may take it further to 60 GW by 2022. As of March 24, 2015 the installed capacity for solar power is just 3.3 GW. We had earlier planned to increase it to 20 GW by 2022. This has now been raised to phenomenal -100 GW at an investment of $100 billion. Just for the perspective our total capacity from all sources currently is 257 GW.
There are two broad ways of harnessing solar energy. One is simple capture and concentration of solar irradiation using reflectors to heat up liquids or gases to generate steam with which to run the turbines and generate electricity. These are called Concentra-ted Solar Thermal (CST) or Concentra-ted Solar Power (CSP) systems depending upon whether they are used just for heating water or for generating electricity. The second is the use of Photo Voltaic Cells (PV) where photons kick out electrons and holes and the resulting charge is collected through wires. These are called solar panels and arrays.
There are many types of solar thermal power plants viz. parabolic trough, enclosed parabolic trough, power towers, dishes, fresnels and micro CSP etc. The idea is the same–to use mirrors to concentrate and direct solar irradiation on to insulated pipes etc to heat the medium such as synthetic oil with which steam is generated and the same fed into turbines. Parabolic trough has been in use in USA, Germany and in Spain for many years.
Under our JNN Solar Mission phase-I we have awarded blocks to private companies for various types of CSPs. Thus, although parabolic trough with storage is the most popular, we will have experience in different types which can be useful as we go forward in deciding for ourselves as to what suits where?
We have also adopted a 50:50 policy between CSP and PV solar. Also we have in place RPOs and RECs on the lines of carbon credits. RPOs are the commitments of electricity providers in different areas to purchase a fraction of their supply from renewable. This is going to be raised from 0.25 per cent to 3 per cent by 2,022.
The advantage of solar generation is that it is inexhaustible and does not require any fuel, hence it has little operating cost and it is on peak when the demand is also on its peak for refrigeration and air conditioning. India is particularly well placed to utilise solar insulation for generating power. We have 1,500-2,000 sunny hours per year and insulation of 1,700 to 2,150 Kilo Watt hours per Kilo Watt Peak (KWH/ KWP). We also have vast open areas with high solar insulation and wind velocity like the 35,000 sq kms Thar Desert and 7,500 kms long sea coast, not to talk about all the river banks. However, our DNI database needs to be built up so that investors may decide where exactly to set up
Phase I companies are reported to have suffered delays on this account. Curiously, solar cells work best at low temperature and don't work in shade. And CSPs require water which is scarce in deserts. We should also think seriously about the 7,500 kms long coastline and the river banks for generating power from both solar systems and wind.
Solar panels can also be installed on terraces, roofs, walls of buildings or on empty land nearby. Solar devices like lights, fans, lantern, cooker and water heater etc. can make a big difference to the rural families who do not yet have a power connection or have a very scanty and erratic power supply. Chinese mini solar systems are flooding Delhi's Lajpat Rai market. Incidentally Kenya tops in the uses of such systems. Not to worry if you are not connected to a grid. If there is sunshine, you can have light, heat and cooling, regardless. When an aeroplane can fly around the world on solar power, then sky is literally the limit to what else can be done with its help.
Intro: Once, the Thin Film Solar Cell bags the required efficiency, it will mark the dawn of a solar power revolution, because one kilowatt module is going to cost only Rs 10,000 making it suitable for energy budget of an average Indian house.
Dr KP Vijayakumar, a scientist in the Department of Physics, Cochin University of Science and Technology (CUSAT), Kochi, has been trying to find out a viable energy alternative at the lowest possible cost. He started his endeavour in 1984 just after completing his PhD in the varsity. He pursued it even during his stint as a lecturer in a city college for few years. Later on when he joined CUSAT, his alma mater, as a Reader in Physics, he got ample opportunity to continue the research in added vigour.
(July 19, 2015 Page : 14)
Like wind sunlight is also an intermittent source. Generation is therefore, dependent upon the vagaries of nature. Sun, however, follows a predictable pattern during the day and over the year. There is a need therefore, to store electricity generated by these methods. Concentrated Solar Powers (CSPs) have their storage systems for instance insulated tanks of molten salt which can store heat for 9 hours or so. These may therefore, be used for the base load by themselves. They can also be used as supplementary or a part of a hybrid system for regular 24 x7 supply or only for the peak load.
One rather easy way is to use them in combination with hydro-electricity by building pumped storage hydro power plants i.e. elevated reservoirs, which can be filled up during lean hours and used when the water table in the main dam falls down. PV solar systems use batteries and inverters togenerate first direct then alternating current.
Cost of PV cell has plummeted since 1977 when it was USD 77 to USD 0.36 in 2014. With the number of installations well past one hundred thousand in the USA the cost of installing 1 Watt peak capacity has fallen to $3.3. It is just $1.5 in China. Given the precipitous fall in the prices of PV cells at the compound rate of 20 per cent per year solar power is going to achieve grid parity in a few years.
Efficiency of PV cells is also on the upswing. For the Multiple Junction Concentrated PV cells, which use magnifying glass to focus light on the cells, it has already reached 47 per cent. Given the band gap, the maximum otherwise is 30 per cent. Thin film modules, which are much in use may have it in the range of 14-22 per cent. Overall the efficiency of PV systems is 15-20 per cent. That of CSPs is somewhat higher.
Real utility of solar power at least in near future lies in improving the quality of life of 67 per cent population still living in villages. Half of the families do not have power connection. For cooking fuel they still use crop and animal residue and for some light, the kerosene lamp. For drawing water from tube well they use diesel pump set or steal power. This can be easily changed with the help of solar devices like solar chulhas, solar geysers, solar water pumps and solar panels for a few lights and fans. We may put in our best R&D forward to improve the efficiency of such devices. We may also build groups to share the cost and use. One of the most shining examples of solar systems is found at Brahmakumaries at Mount Abu. If we can organise villagers to run solar powered community kitchens like them or solar powered pump sets, we can make a big difference in the way they live.
JP Dubey (The writer has expertise on developmental issues)
(July 19, 2015 Page : 12-14)