Bottom line is that India is in dire need of power (electricity). The cheap and dirty “solution” is to have coal fired Ultra Mega Power Plants (UMPP), which are being sanctioned and are being built. These UMPPs will emit humongous amount of greenhouse gases (GHG) aiding pollution and global warming. Also, economical coal supplies will not last long. Hence, it is mandatory for us to brace for sustainable energy solutions. Amongst various sustainable energy sources solar energy is basic, unlimited, freely available and guaranteed (available throughout the year in certain parts of our country) and this article discusses the same.

There are two solar technologies to produce electricity – Photovoltaic (PV) and Thermal. Currently, the PV technology that produces electricity directly from incident solar rays using special grade silicon is quite costly. Also, this technology is suitable for colder regions with ample sunlight as PV cells function better in cold conditions – not ideal for India. The solar thermal technology, on the other hand, is a multipurpose technology. Apart from producing electricity, the same plant can be used for desalination of water. This technology uses the heat component of the solar radiation. It is not very costly.

 Here’s how to get electricity from solar heat:

1. Solar rays are concentrated using various techniques like linear fresnel lens (cheapest) or solar tower (promising) or parabolic troughs (proven) or parabolic sterling dishes (ideal for non-grid small plants).
2. Water or oil (as heat transfer fluid) is heated using the concentrated solar rays. In case the oil is used then the oil further heats stored water and steam is produced.
3. This steam drives a steam turbine and electricity is generated.
4. The steam can be used as desalinated water or it can be re-circulated.

In order to maximize the power output, the plant must be located at a place that receives a “plenty” of sun throughout the year. One such place in India is Thar Desert in west Rajasthan. Following characteristics of Thar Desert make it an ideal location for a solar thermal power plant (STPP):

1. Area: 0.28 million km²
2. Solar Intensity: approx 6 kWh/m²/day
3. Sun Availability: 345-355 days in a year
4. Rains occur only for 10-20 days in a year

There are a few “Strategic Advantages” that Thar Desert presents, which would make it a NexGen Powerhouse of India. These are as follows:

1. Strategic Location:
   1. South Boundary of Thar Desert:

                                                             i.      Arabian Sea is just 80-90 kms away and hence a STPP located at the south boundary can double-up as a water desalination plant also providing clean water to local people.

                                                           ii.      Gujarat industrial cluster is also very near from the south boundary and hence the power generated can act as a peak power to these industrial units at a reasonable rate.

2. North-East Boundary of Thar Desert:

                                                             i.      Power hungry states of Punjab, Haryana and Delhi can get peak power especially during hot summers with a STPP located nearby.

2. As it is a desert, it is scantly populated and most of the land is government owned and hence land acquisition, relocation of local people and associated issues will be minimal.
3. The local people live a tough life as the land is arid and there is no industry. These local people can get a means of livelihood in constructing and maintaining the STPP. STPP will usher-in an era of all round development in this area.

Initially, the STPPs would provide only “Peak-hour Power” i.e. only during daytime when solar energy is available. Later on, when the cost is reduced, the solar energy storage (in the form of say molten salts) can be built to provide power after sunset.

So what are we waiting for? Let us make the Thar Desert the next clean and green energy hot spot!

A back-of-the-envelope calculation: As written in the article, the solar intensity is 6kwh/m²/day or 250w/m². Considering the cheapest and most inefficient method of linear fresnel lens having efficiency of 15%, the power produced would be 37.5w/m². i.e. 37.5MW/KM² or around 1GW/25 KM². ...and Thar desert area is 2.28 Lac KM² (0.28 Million KM²)! So now you can imagine the potential!!!