A few years back, the country's power generation depended mainly on coal-based super thermal power plants where each cluster could generate up to 4000 to 5000 MW. The power generated would then be fed to the national grid for widespread distribution. There are several such super thermal power plants across the country. In plants like these, coal is burnt to produce heat, which then boils water, generating superheated steam. This steam would pass through a turbine, connected to a generator. Lastly, the power generated would be dispatched to the switchyard for transmission to the power grid. In some plants, oil or natural gas is tapped as a substitute for coal. However, coal, oil and gas, all the three are dwindling resources.
The burning of coal, oil and natural gas is accompanied by waste flue gases, harmful to the environment as these contain toxic chemicals. Apart from polluting the environment, heat to the extent of 60% is released into the atmosphere, contributing to the elevating global warming levels. Approximately one ton of CO2 is emitted per MWh (Megawatt-Hour) of energy. It means that a super thermal power station of 2000MW would generate 2000 tons of CO2 every hour or 48,000 tons of CO2 every day. Thermal power plants have an installed capacity of 234GW, out of which 124GW is by coal-based plants. This can release up to 2976 thousand tons of CO2 per day into the atmosphere.
Schematic diagram of Solar PV based utility power plant- Totally pollution-free
There are several renewable sources of energy that nature provides in plentiful. Already several countries have made plans to take measures for damage control. Many countries have decided to go for mega-scale solar and wind-based power stations and replace the aged Super thermal power plants.
As of now, Solar power generation in India is 40.09GW. Contribution by Karnataka (7.1GW), Telangana (5GW), Rajasthan (4.4GW), Andhra (3.47GW), Gujarat (2.654GW) and the remaining by other states are significant. The target for renewable energy by 2022 is 175GW which includes 100GW for Solar, out of which 40GW is earmarked for rooftop grid-tied Solar and off-grid. In addition to that, work is in progress for setting up several Ultra mega Solar power plants on the PPA model in many states with investment by the private sector.
To take care of fluctuations of power generation by Solar and wind which vary with time and season large scale energy storage systems are being installed along with ultra mega Solar/wind parks for grid stability.
Renewable energy use not only replaces conventional power but also reduces it to the extent of 40%. This is because solar and electrical-based systems are more efficient than conventional fuel-based systems.
The efficiency improvement is of the order of 50% of the traditional systems. Renewable electricity energy use is 80% efficient compared to fuel-based combustion systems, which are only 40% efficient. No fuel can be used in raw form. It has to be processed before use. Then it has to be transported to the point of use. This requires a lot of effort and energy.
Converting to renewable energy may create several million more permanent, full-time jobs than jobs lost. Among renewable energy sources, the usage by 2050, as per a study, is likely to be about 30000 TWh by Solar, 9100 TWh by wind and 800 by hydropower. The contribution by other forms like wave, geothermal, tidal etc., would not be significant.
By: Challapalli Narayan Rao is a former scientist with Nuclear power Corp.; former Project engineer, NDDB; former senior technical director NIC; former advisor, ASA NGO; currently acting as an IT consultant , MP Pollution control board.
