Energy in general is the ability to do work. Modern civilization is possible because people have learned how to change energy from one form to another and then use it to do work. We use energy to move cars along roads and boats through water, to cook food on stoves, to make ice in freezers, and to light our homes.
The main source of energy used for day to day life is from fossil fuels, and the demand of energy increases day by day due to population growth and modernisation. Fossil fuels are the finite sources of energy, which one day may get vanished.
Need for sustainable sources of energy:
1. Limited Fossil Fuels:
Fossil Fuel Energy Reserves in World
Coal: Coal contributes maximum energy source of energy with total 1035012 million tonnes of reserves in world, with R/P (Reserves to Production) ratio of 134.
Natural Gas:The total reserves of natural gas is 193.5 trillion cubic metres with R/P ratio 52.6
Oil: The total oil reserves in world are 1696.6 thousand million barrels with R/P ratio 50.2(one barrel of oil is equivalent to 158.9 litres).
The researchers have now set a year point when the current reserves run out, in according to increase in population, energy demand, total reserves, R/P ratio, but this point may not be the limit of fossil fuels because some new reserves may be found which will help fossil fuels last longer, but they wont last forever. New reserves of fossil fuels are becoming harder to find, and those that are being discovered are significantly smaller than the ones that have been found in the past.But instead of panicking, instead of asking how much oil is left and fretting about how long fossil fuels will last, we simply need to embrace the alternatives and there are much, much better alternatives to fossil fuels out there. The major reserves of fossil fuels are used for electricity generation.
Degradation of environment is due to the emission of Greenhouse gases (carbon dioxide, methane) and other pollutants (sulphur oxides, nitrogen oxides, particulate matter). The carbon dioxide emission at the end of 2017 was 33444 million tonnes with a growth rate of 1.6% from 2016. The pre-historic concentration of carbon dioxide was 280 ppm (parts per million) which has now increased to nearly 400 ppm. Carbon dioxide is not the any harmful gas but its behaviour shows adverse effects on environment like global warming which in turn is related to climate change. The earth is showing many signs of worldwide climate change, which are
Average temperature have climbed to 1 degree Celsius
Annual increase in temperature
Glaciers and mountain snows are rapidly melting: A recent study by British Antarctic Survey reveals. An iceberg twice the size of New York City is about to break off of Antarctica. A chasm and a crack on the Brunt Ice Shelf in Antarctica are creeping closer and closer to one another, and when the two finally meet, a slab of ice twice the size of New York City will break away and float out to sea.
Increase in the acidity in sea water, which affects the aquatic animals.
Other pollutants are sulphur oxides which reactwith water to form sulphuric acid causing acid rain, nitrogen oxides and other particulate matter, carbon monoxide causing problems in respiratory and nervous system organs. 100 ppm of Carbon Monoxide causes headache, 500 ppm of Carbon Monoxide causes collapse 1000 ppm of Carbon Monoxide is fatal. These particles are emitted from fossil fuel fired power plants and other processing industries. Carbon dioxide is mainly emitted from coal fired power plants and sulphur oxides (mainly from power plants) and nitrogen oxides are emitted from automobiles.
3. Energy Security and potential for Conflicts: Fossil fuel sources are not uniformly distributed in the world, this can lead to conflicts. The countries, where these resources are not available in sufficient quantity, will always feel insecure in terms of their supply and results in conflicts. The other insecurity comes from the pricing of these fossil fuels. It has been witnessed that the prices of a barrel are not stable. The increase in the oil prices is attributed to the fact that the oil producing countries are not able to increase their production as per the demand. Therefore security of the supply may not be guaranteed even if one is willing to pay the high price.
So the renewable sources of energy are the best alternative for above said problems, which means harvesting energy from solar photonic energy, solar thermal, wind, small hydro (up to 25MW), very low enriched nuclear energy, tidal energy, fuel cells, biogas etc.