Solar Power – A Distant Dream or a Reality?
With growing fuel prices and depleting sources of energy, People all over the world have started looking at alternate ways of generating energy which they use in their daily life. Given the population and the rate of consumption of these non renewable sources of energy, The day when we could run out of it is not too far.
Electricity is the most common form of energy that we use on a daily basis.Power these days is generated using Thermal Energy, Hydro Energy and Nuclear energy. Hydro energy and Nuclear energy have proven potential in generating electricity, but have their own set of problems. Thermal energy plants can be setup wherever there is supply of coal. The setup cost and the production cost of these plants is low. However these plants are the major contributors to pollution, Coal being a non-renewable source, we are one day going to finish all of it. Finding an alternative to coal has become the need of the hour. World over, companies are investing billion of dollars to help aid research in all possible methods of generating electricity. A never ending source of energy, something that is available in plenty, something that is pollution free, and that something happens to be Solar energy. The concept of using solar energy to generate power is not new to us.
Use of Solar Panels( Photovoltaic ) for generating electricity is one of the known methods world over. But given the size, weight and the cost of these solar panels, Looks like using them on a large scale could generate problems. Not only the size, These solar panels make use of only a small amount of sun’s energy. The rest of it, Lost as heat. Therefore efficiency becomes a big question. It could however work well on a small scale, Setup is easy and the generated electricity could be stored on batteries. So if you are looking to power your house with Solar power, Solar panels is the way to go. Proven and easy to setup, one can generate electricity in hours. At least till there are developments in this space.
One such development comes in the name of ‘Concentrated Solar Power‘.
From Solar cookers to Solar power plants the basic design is all about reflecting the solar energy from the sun onto a particular object, The energy is then transferred to the object. This method of concentrating the incoming rays from the sun onto an object is called ‘Concentrated Solar Power’ or CSP.
Two huge examples of the CSP systems are :
Nevada Solar One: Kilometers of Concave mirrors placed side by side focusing energy on to a pipe carrying synthetic oil. This oil is heated continuously and passed through a water tank, The oil heats up to over 800 degree centigrade. This heat is then used to convert the water into steam, the steam to run the turbine, Turbine producing electricity.
This plant now produces electricity to power 55000 houses.
Solar Power Tower:
While the Nevada plant uses pipe to carry the oil, The Solar power tower has oil in a huge tank that is placed over 10 Stories high. Mirrors placed in a semi circular manner at the base of the tower are controlled in such a way that all of the energy incident on them is reflected towards the tank to heat up the oil. The heat is then used to convert water into steam and then the same method to generate electricity like any other plant. The mirrors at this plant are flat.
The Solar Power Tower has that slight edge over the Nevada system because of the lesser space per watt of power generated. Both these projects have their advantages and disadvantages, But both have proven successful. It is now up for us to decide. Given the nature and the size of the project, The Cost however becomes a very huge factor. The company that manufactured the concave mirrors for the Nevada plant had to use one of its 8 huge factories completely dedicated 24/7 only for this project, which obviously is a demand for more money. With more such projects coming in, the prices will fall as more companies will then step in.
With less than 10 hours of daily sunlight available,powering the rest of the night is a huge challenge. As one may understand, storing this high power electricity is impossible. Electricity is only generated depending on the demand, if generated in excess or remains unused, It is lost as heat. So is there a solution to this potential problem? The answer comes from a research group in some country( I don’t remember the actual name, google didn’t help either 😦 )
Molten Salt – The simplest example of a molten salt would be to take sodium chloride (“table salt”) and heat it to a red heat (greater than 801°C, or 1474° F)1 where it would melt into a liquid. This liquid is stable, has a heat capacity similar to water (by volume) and flows much like water does. Molten salt has the capacity to store heat, and this heat could be used to power the steam turbines during nights.
But it has a drawback too. Unlike water which starts to expand on cooling, Molten salt starts to contract or solidify if temperatures goes below 700 deg centigrade. This may block the pipes, Eventually bringing the plant to a halt. The Solar Tower however has started testing it. It has so far been successful in maintaining temperatures over 700 deg Celsius, thereby generating electricity through the night.
Solar power the way to the future?
Well, It could be. The US claims that it would power a major amount of its population by solar power by the year 2011. If proven to be the best and cost effective option, It could become a reality.
“If we compare the expenses of setting up a solar power plant to that of a thermal station, maintaining it to generate electricity. Solar power plants would start producing profits from the end of 13th year as all the investment that is required lies with setting up the plant, and since all the required power is available for free, It will be an economic option compared to the thermal power plants. Also given the fact that it is pollution free, Its worth the investment 🙂 ” says Gilbert E Cohen, the man behind the Nevada Solar One.
India, Anywhere close to using the technology?
With about 200 clear sunny days in a year, India’s theoretical solar power reception, just on its land area, is about 5 EWh/year (i.e. = 5000 trillion kWh/yr ~ 600 TW). The daily average solar energy incident over India varies from 4 to 7 kWh/m2 with about 2300 – 3200 sunshine hours per year, depending upon location. This is far more than current total energy consumption.
India is heavily dependent on coal and foreign oil – a phenomenon likely to continue until non-fossil / renewable energy technology become economically viable in the country. The cost of production ranges from Rs 15 to Rs 30 per unit compared to around Rs 2 to Rs 6 per unit for conventional thermal energy. India, an emerging nation trying to build an economy stronger than the other countries is in no state of investing such huge amounts of money in solar power.
With over 80000 Non electrified villages, Solar power looks like a distant dream. Private companies could however step in as help, if the government offers no or less subsidies to the company venturing in this field. India however is looking at generating power using solar energy for small villages and town and then moving to a higher level of powering the nation. For now, Its fossil fuel, we can only help the country by saving it.
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