India’s renewable energy sector will offer investment opportunity of $30 billion every year for the next decade and beyond, but the country cannot wish away conventional sources of energy like oil and coal as demand is forecast to gallop in the next few decades, the Economic Survey said.
The cumulative renewable power installed capacity has more than doubled to 78 GW in March 2019 from 35 GW in March 2014. In addition, around 27 GW renewable power capacity is under installation and over 38 GW under bidding to achieve an installed capacity of renewable based power of 175 GW by 2022
Non-conventional sources of energy are those which have been developed in the recent past as an alternative to conventional sources of energy.
These include solar energy, wind energy, tidal energy ,geothermal energy, nuclear energy and biogas. They are renewable and therefore, inexhaustible, non-polluting, less expensive and easy to maintain.
These sources of energy are considered as the energy resources of the future. Considering their benefits, many countries of the world, including India, have started producing these sources of energy on a large scale. Besides, continuous research is this field to reduce the cost of production and to make them more cost-effective.
Sun is the ultimate source of energy. Traditionally, we have been using solar energy for drying clothes and food grains, preservation of eatables and for obtaining salt from sea-water. India is fortunate enough to receive higher amount of solar energy, equivalent to5,000 trillion kWh per year This is because of India’s location on the Tropic of Cancer. Most parts of the country have 300 clear sunny days in a year and per hour per square km availability of solar energy is between 5 to 7 kW.
GENERATION OF SOLAR ENERGY
Several techniques have been developed in India for harnessing solar energy, as given below:
(i) Solar cells:They are known as photovoltaic cells. Solar cells are made of thin wafers of semi-conductor materials from silicon and gallium. When the sun’s radiations strike on them, the sun’s energy is converted into electricity. Solar cells are widely used in calculators, electronic watches, street lighting, traffic signals, water pumps, etc.
A group of solar cells joined together in a solar panel can give out a large amount of solar energy and can produce electricity enough to run street-light, irrigation water pump, heating of house, etc.
(ii) Solar Cooker:Solar cookers use solar heat by reflecting the solar radiations using a mirror on to a glass sheet which covers the black insulated box. The raw food is kept in the box. The inside walls of the sides are painted black for efficient absorption of light. The box is insulated on the outside so that the heat cannot escape. The heated inside of the box emits infra red radiation to which to the glass window is opaque. In this way a significant amount of the energy entering the oven is retained. The cooking pot is placed inside the box and cooking is made possible. A new design of solar cooker is now available which involves spherical reflector instead of plane mirror that has more heating effect and greater efficiency.
(iii) Solar Water Heater:One of the most successful applications of solar energy has been in the field of water heating. Sunlight is allowed to fall on flate-plate collectors, which are shallow rectangular trays filled with water and properly inclined so that the efficiency of collection is highest. It consists of an insulated box painted black from inside and having a glass lid to collect and store solar heat. Inside the box it has black painted copper coil through which cold water is made to flow in. The coil gets heated and the water gets heated and flows into the storage tank.
(i) Solar energy is a renewable source of energy which can be harnessed in most of the areas of the world.
(ii) It can be used for diverse purposes- to produce electricity in areas without access to the energy grid, to distill water in regions with limited clean water supplies and to power satellites in space.
(iii) Solar energy systems do not require a lot of maintenance. Most reliable solar panel manufacturers give 20-25 years warranty. Also, as there are no moving parts, there is no wear and tear, So, after covering the initial cost of the solar system, it requires little spending on maintenance and repair work.
(iv) It saves fossil fuels like coal and petroleum, used to produce electricity and also reduces electricity bills,
2. WIND ENERGY
Wind is an inexpensive, reliable, and non-polluting source of energy for generating electricity.
GENERATION OF WIND ENERGY
The wind energy is obtained by making use of windmills. The blades of the windmill rotate due to the force of the wind. The rotational motion of the blades drives a number of machines like water pumps, flourmills and electric generators.
A number of windmills are installed in a definite pattern in clusters called wind farms. They generate a large amount of electricity. Wind farms are installed in coastal regions, open grasslands or hilly regions.
The Indian wind energy programme is the fifth largest in the world after Germany, Denmark, the USA, Spain and the UK. In India, the largest wind farm cluster is situated from Nagarcoil to Madurai in Tamil Nadu.
Besides, Andhra Pradesh, Gujarat, Karnataka, Kerala. Lakshadweep and Maharashtra have important wind farms.
(i) Wind energy is a renewable source of energy which can be produced again and again.
(ii) It is the cleanest form of renewable energy which produces no pollution.
(iii) It reduces our dependence on the fossil fuel.
(iv) Land owners can look for additional income by installing wind turbines on land that can even be used for agriculture purposes. The electricity generated by wind power can be used for domestic consumption and reduce monthly electricity bills, and the surplus power can be sold back to the local grid which can result in more savings.
3. TIDAL ENERGY
The term ‘tide’ is used for the periodic rise and fall of waters of the ocean and produced by the attraction of the Moon and the Sun This rise and fall of water produces a large amount of energy called tidal energy.
GENERATION OF TIDAL ENERGY
The tidal energy can be harnessed by constructing a tidal barrage. During high tide, the sea-water flows into the reservoir of the barrage and turns the turbine, Which in turn produce electricity by rotating the generators. The reverse process takes place during the low tide, when the sea level is low, the sea water stored in the barrage reservoir flows out in the sea. During the process, eth flowing water turns the turbines. There are only a few sites in the world where tidal energy can be suitably harnessed. In India, the prospective sites for exploitation of tidal energy are Gulf of Kutch, Cambay and Sunderbans. Other suitable sites are near Lakshadweep Islands and Andaman and Nicobar Island.
(i) Massive amounts of water in the oceans move in extremely predictable patterns. This make sit easy to harness the tidal energy.
(ii) Tides are controlled by the gravitational pull between the earth, sun and moon. This means that as long as the earth is being orbited by the moon, the tides will continue to be there producing energy and tidal energy is an inexhaustible source of energy.
(iii) After the initial construction costs, there are very few additional costs to keep the tidal energy plant running, They require little maintenance and minimal personnel as well.
(iv) Tidal energy can be produced even if the water moves at low speed.
(v) There are no carbon emissions from tidal energy plant, making it an energy source that does not negatively affect the global environment.
Geothermal energy is the heat energy contained in the rock and fluid that fills the fractures an pores within the rock in the earth’s crust. It is clean and sustainable.
The surface temperature of the hot springs ranges from 350C to as much as 98oC. These hot springs have been grouped together and termed as different geothermal provinces. different regions are-Himalayan geothermal province, Naga-Lushai geothermal province and Cambay graben, Son-Narmada-Tapti graben, West coast, Damodar valley, Mahanadi valley, Godavari valley.
Geothermal Energy is heat stored in earth crust and being used for electric generation and also for direct heat application worldwide since beginning of last century. USA, Philippines, Indonesia, Turkey, and New Zealand are leading countries availing commercial exploitation with worldwide installation of 12800 MW at end of 2017
GENERATION OF GEOTHERMAL ENERGY
Resources of geothermal energy range from the shallow ground to steam, hot water and hot rock accessed by drilling wells up to thousands of feet beneath the earth’s surface. The extremely high temperatures in the deeper geothermal reservoirs are used for the generation of electricity. The high-pressure steam spine a turbine that rotates a generator and produces electricity.
Hot water is pumped from deep underground through a well, under high pressure. When the water reaches the surface, the pressure is dropped, which causes the water to turn into steam. The steam spins a turbine, which is connected to a generator that produces electricity. The steam cools off in a cooling tower and condense back to water. The cooled water is pumped back into the Earth to begin the process again.
The general characteristics of geothermal energy that make it of significant importance for both electricity production and direct use include:
- It is easily accessible because of its extensive distribution.
- It is environment-friendly in nature; ha slow emission of sulphur, carbondioxide and other Greenhouse effect.
- It is independent of external supply and demand effects and fluctuations in exchange rates.
- It is independent of weather and season.
India has about 12,000 MW of geothermal power potential that can be harnessed for various purposes. In India, geothermal plants are located in Manikaran in Himachal Pradesh and Puga valley in Ladakh.
(i) Power Production
Geothermal electricity generation is site and technology specific and India is in Low Geothermal Potential Region with low/medium heat enthalpy. Government is planning to encourage the industry lead demonstration projects at the first stage to assess the technical viability of the project before going to the commercial models.
Various resource assessments carried out by GSI, NGRI & CEA estimated the potential of approx. 10000 MW spread over 300 hot springs across seven geothermal provinces/11 states.
The worldwide average capital cost for geothermal energy power plants is around Rs. 30 – 35 crore per MW (@ power purchase tariff of around Rs. 10-12 per KWhr). This is due to high drilling cost, uncertainty of project specific exploration, etc. Interested stakeholders may look into secondary products like space cooling & heating, desalination, etc. for achieving reasonable rates.
(ii) Ground Source Heat Pumps (GSHP’s)/ Geo-exchange Pumps.
Ground Source Heat Pumps (GSHP’s) use the earth’s relatively constant temperature between 16 – 240C at a depth of 20 feet to provide heating, cooling, and hot water for homes and commercial buildings. GSHP harvests heat absorbed at the Earth’s surface from solar energy. The temperature in the ground below 6 metres (20 ft) is roughly equal to the mean annual air temperature at that latitude at the surface. It uses the earth as a heat source (in the winter) or a heat sink (in the summer)
The National Building Code 2016 has included new and energy efficient options of air conditioning, heating and mechanical ventilation, such as variable refrigerant flow system, inverter technology, district cooling system, hybrid central plant using chilled beams, radiant floor components, and geo-thermal cooling and heating.
5. NUCLEAR POWER
Nuclear power is obtained from energy stored in the nuclei of atoms of naturally occurring radioactive elements like Uranium, Thorium and Plutonium.
GENERATION OF NUCLEAR ENERGY
When atoms of these radioactive substances react, they split apart. This process of splitting of atoms is called nuclear fission.
Nuclear fission produces heat, and this heat is used to heat water and make steam. The steam powers turbines which is turn are used to run generators which produce electricity. The two main types of nuclear reactors used to generate electricity are the pressurised (PWR) and boiling water (BWR) reactors. In the pressurized, it doesn’t boil. This hated water is circulated through tubes in steam generators allowing the water in the steam generator to turn to steam ,which then turn the turbine. In the boiling water reactor, the water comes to a boil due to the heat produced by nuclear reaction and turns into steam to turn the turbine. The water from the reactor powers turbine. In both systems, the water is reused.
Nuclear power is the fourth-largest source of electricity in India after thermal, hydroelectricity and renewable sources of electricity. India has 21 nuclear reactors in operation in seven nuclear power plants, having an installed capacity of 5780 MW and producing a total of 30,292.91 GWh of electricity.
Ukranium and Thorium, which are available in Jharkhand and the Aravali ranes of Rajasthan are used for generating atomic or nuclear power. The Monazite sands of Kerala is also rich in Thorium. India has a flourishing and indigenous nuclear power programme and aims to supply 25 per cent of electricity from nuclear power by 2050.
(i) Nuclear energy reduces the amount of energy generated from fossil fuels (coal and oil) and therefore, reduces the use of fossil fuels and lowers Greenhouse Gas emissions.
(ii) It saves on raw materials but also in transport, handling and extraction of nuclear fuel. The cost of nuclear fuel (overall uranium) is 20% of the cost of energy generated.
(iii) The production of electric energy is continuous. A nuclear power plant generates electricity fro almost 90% of annual time. It reduces the price volatility of other fuels such as petrol.
To meet the increasing energy needs of the country and to provide Energy Security, National Policy on Biofuels was announced in December 2009. The major goals of the policy are Development and utilization of indigenous non-food feed stocks raised on degraded or waste lands, thrust on research and development on cultivation, processing and production of biofuels and a blending mandate of 20% Ethanol and Bio-diesel by 2017. The Policy can be seen at National Policy on Biofuels
The objective of biofuel programme is to support R&D, Pilot plant/Demonstration projects leading to commercial development of 2nd Generation biofuels. The ministry supports R & D projects for development of technologies for production of biofuels through Biogas, Pyrolysis and Gasification, besides promoting deployment of technologies for pilot and full-scale projects on biofuels in general.
Hydrogen is a clean fuel and an energy carrier that can be used for a broad range of applications as a possible substitute to liquid and fossil fuels. The Ministry has supported research, development and demonstration projects on various aspects of hydrogen energy including its production, storage and use as a fuel for generation of mechanical/thermal/electrical energy. The application of hydrogen in fuel cells for power generation has been demonstrated as a result of initiatives taken by this Ministry. Hydrogen fuelled small power generating sets, two wheeler (motor cycles), three wheeler and catalytic combustion systems for residential and industrial sectors and fuel cell buses have also been developed and demonstrated.
Biogas is composed of methane, carbon dioxide, hydrogen and hydrogen sulphide. It is produced by anaerobic degradation of animal and plant wastes in the presence of water. Anaerobic degradation means breaking down of organic matter by bacteria in the absence of oxygen. The fermentation ofg the waste products is carried out by bacteria, which produces hydrocarbon gas, predominantly methane and alcohol. The residue left behind in the tank is rich in nutrients and can be used a valuable manure. The plants which use cattle dung are called ‘Gobar Gas Plants’. These plants, using cattle dung, have been set up in many villages. They provide twin benefits to the farmers in the form of energy and good quality manure. The gas is used for cooking, lighting and pumping water from wells.
GENERATION OF BIOGAS
A digester tank is placed underground. The digester tank receives the dung-water mixture through inlet pipe while the other side discharges the spent slurry through the outlet which is controlled by a pipe. Waste Recycling and resource Recovery Programmes (WRRSE) are now being used from the organic plant waste and night soil. This helps in improving the sanitary conditions in our cities and villages. The plants generate enriched organic manure useful for supplementing chemical fertilisers.
(i) Biogas is a clean, non-polluting and cheap.
(ii) There is direct supply of gas from the plant. Therefore, there is no storage problem.
(iii) The sludge left behind is a rich fertiliser containing bacteria biomass.
The Ministry of New and Renewable energy has been promoting the biogas Programme in India. It has set up a number of biogas plants across the country.