Prof. Dr. P. K. Jena* in Bhubaneswar, April 8, 2017 : Energy resource has become very important and is one of the basic needs for socio economic development of mankind. Energy security is therefore, imperative for sustained growth of our economy. It is well known that, fossil fuels have been a major source of energy required for the socio economic developments of mankind in most parts of the world since the early industrial revolution.

At present, nearly 80% of global energy consumption is from various types of fossil fuels. Except the hydropower which is a renewable and clean energy, the rest of the conventional fuels like coal, oil, wood and natural gas during their combustion cause pollution and mostly responsible for global warming due to release of large amounts of the oxides of carbon, sulphur and nitrogen to the atmosphere.

The oil crisis of 1973, with increasing demand of fossil fuels all over the world and the concern for the environment due to their excessive use, various global efforts are being made in harnessing alternate clean energy resources like sun, wind, biomass and small hydro power.

Solar Energy

Solar energy is a viable alternative for power generation and has the highest global warming mitigation potential amongst the available clean energy sources. Further, it is the single largest source of energy available on this planet. The effective solar energy reaching earth’s surface ranges from about 0.06 /m2 at higher latitudes to 0.25 /m2 at lower latitudes. The recent technologies have been able to encourage the use of solar energy in small scale in the form of concentrated solar power (CSP) and also the large scale photovoltaic (PV) system which is able to feed into electricity grids.

It is reported that, the cost of high power band solar modules has decreased from about US $ 27000 per KW in 1982 to about $4000 per Kw in 2006. Similarly, the installd cost of a PV system has declined from $16000 per Kw in 1992 to about $6000 per Kw in 2008. The solar energy’s market has gained momentum since early 2000. The total installed capacity for generating electricity through solar energy has become only 40 GW by the end of 2010.

The research and mass production have led to a dramatic drop in prices and the solar cells now cost about $20 per watt. This huge cost savings has opened up the use of solar cells in railroads, lighthouses, offshore oil rigs, buoys, and remote houses and even in watches, calculators and toys. It is suggested that, in order to achieve increased market potential of solar photovoltics, the development of high performer flat plate PV and concentrator PV modules with efficiencies of 25% and 40% respectively, is necessary. At present, the major PV cell producers are USA, Germany, Japan, China and Taiwan. However, some developing countries are gearing up their R & D effort in this direction.

Biomass Energy

Biomass consists of all organic materials that stems from plants, algae, trees, crops including all land and aquatic vegetation and also the organic wastes such as agricultural and domestic wastes, animal’s dung, human excreta etc. Biomass is the plant material produced through reaction of carbon dioxide present in the air with water, moisture and sunlight. This process is known as ‘Photosynthesis’. Biomass as an energy and heat source has been in use since the dawn of human civilization.

If the biomass is burnt efficiently, oxygen in the atmosphere will combine with carbon present in the biomass to produce carbon dioxide and water. This carbon dioxide and water through photosynthesis will produce new biomass. It is accepted that, biomass absorbs the same amount of carbon dioxide while growing that it releases when it is burnt. Assuming this in the outset, we may consider biomass as a fuel which will add negligible amount of carbon dioxide to the atmosphere.

In recent time, a lot of developments have taken place to extract energy and heat from various types of biomass including the organic wastes in an environment friendly manner. In order to choose any thermo-chemical or bio-chemical process, it is necessary to know the type and the quantity of biomass feed stock available. The thermo-chemical conversion of biomass to bio-energy can be carried out in four different ways namely, Combustion, Pyrolysis, Gasification and Liquefaction.

The bio-chemical conversion to bio-energy can be carried out in two different ways namely, anaerobic digestion to produce methane along with carbon dioxide and fermentation to produce methanol. Liquid bio fuels include ethanol produced from the fermentation of sugars and biodiesel through transesterification of vegetable oils. It is reported that, 57 kilotonnes (Kt) of production capacity is in operation, and a good number of plants each with a capacity of between 50,000 tons and 300,000 tons are coming up in different parts of the world.
Wind Energy

The scope of wind power to supply clean energy to replace the fossil fuels is one of the important ones. Wind power is the conversion of wind energy into a useful form of energy such as using wind turbine to make electrical power, wind mills for mechanical power, wind pumps for water pumping and wind power to propel ships.

The modern wind turbine is based on the principle of converting energy of the wind into electrical energy. In 2013, the global wind energy investment ranged from 70 billion to 130 billion US dollars and it is expected to rise between 101 billion and 250 billion dollars in 2020. There is a great scope for the production and utilization of wind energy particularly in countries like Mexico, Brazil, South Africa, India, China and USA. The merits of wind power are, it is plentiful, renewable, widely distributed, clean, no cost for the fuel and uses little land.

At present, the five main wind power producing countries are China, USA, Germany, Spain and India, and together share nearly 73% of the total global wind energy capacity of about 297000 Mw.

Small Hydro Power

Hydro Power can be harnessed easily from flowing water from higher altitude to the lower ones. When water is falling by the force of gravity it can be used to turn turbines and generators that produce electricity. The hydro power projects have long life. Further, hydro electric generators respond quickly to the changing system conditions. In view of this, hydro electricity generated from hydro power has become attractive. Harnessing energy from hydro power can be more consistent by supplying water through dams. Dams store water for producing hydro power as well as it can be utilized for irrigation, domestic and industrial purposes.

The water reservoir is very much like a battery storing energy in the water and utilizing whenever required to generate power. In this, a pipe carries the water from the reservoir to the turbine. The fast moving water helps in rotation of turbine blades. The water forces on the turbine blades turn the rotor. The moving part of the electric generator’s coils of the wire on the rotor when sweeps past the generator’s stationary coil (starter), electricity is produced. From environment protection point of view the small hydro power is being encouraged all over the world. The world’s estimated potential of small hydro power is about 180,000 Mw of which India has got only 15,000 Mw. The different types of small hydro power system include Run-of-the-river schemes, Canal fall based scheme and Dam-toe based scheme.

At present only 16% of the total energy used in the world is obtained from renewable energy sources. Better technology should be developed to make renewable energy more competitive to fossil fuels. Various incentives and public awareness programme should be given to replace fossil fuels by renewable energy at a faster rate to save our planet.

With respect to use of renewable energy resources, India is very much lagging behind many countries like USA, Germany, Japan and even China. It should take further necessary steps to harness and utilize the abundant renewable resources available in the country, so that the limited fossil fuels resource can be selectively utilized with better technology to drastically minimize the green house gasses and particulate matters in our environment.

* (Former Director General, Council of Scientific & Industrial Research, India)