Dr Rajiv Desai

THE ENERGY

January 23, 2010 by Dr Rajiv Desai

THE ENERGY
Energy is defined as a capacity/ability to do the work and it is measured in Joules.
Power is defined as the rate at which the work is done which means work divided by time and it is measured in Watts.
1 watt= 1 joule per second.
1 Giga-joule(GJ)= 1 billion joules
1 Exa-joule(EJ)= 1 billion GJ.
31.7 watts= 1 GJ per year.
1 kilo-calorie= 4.2 kilo-joules.
1 kilo calorie is the amount of energy required to raise the temperature of 1 kg of water by 1 degree celsius. Calorie is the unit of energy in nutrition. Human being needs 2000 kilo calories of energy through food for all activities per day which is equivalent to 90 watt light bulb.
Energy makes change and does things for us.Energy lights homes, cooks food,runs car/fan/AC/heater/machines/TV etc.We will go back to stone age if there is no energy.
First industrial revolution was launched in 18’th century by the chemical energy of coal.
Second industrial revolution was launched in 20’th century by the energy from petroleum and nuclear power.
GDP is the single important driver of energy demand and GDP per capita is a measure of standard of living and therefore population growth needs more energy to maintain quality of life.
World’s total energy consumption per capita per year is 73 GJ and developed countries use 198 GJ and developing countries use 41 GJ. America uses 327 GJ, China 48 GJ and India 21 GJ.
On average, 25% of world’s energy consumption is in electricity. The average electricity consumption of the world per capita is 721 watts and developed countries use 2224 watts, developing countries use 324 watts,America 3705 watts, China 494 watts and India 175 watts.
The human development index of the UN shows that countries with higher electricity consumption per capita have better human development record.
Energy are of 3 types,kinetic energy,potential energy and rest energy.
Kinetic energy is the energy possessed by an object due to its motion and includes electrical,radiant,thermal,motion and sound energy. Potential energy is the energy possessed by an object due to its position and includes gravitational,chemical and compressed mechanical energy. Rest energy is the energy possessed by an object by virtue of its mass.
Electrical energy is due to movement of electrical charge(electron)in a medium.Electricity is due to movement of electrons in a wire and lightening is due to movement of electrons in atmosphere.
Radiant energy is due to movement of electromagnetic waves like light,Gamma rays, X rays,radiowaves etc. Solar energy is an example of radiant energy.
Thermal energy(Heat)is due to vibration/movement of atoms/molecules in an object manifested as the temperature of an object.Geothermal energy is an example of thermal energy.
Motion energy is due to movement of an object from one place to another place.Wind/wave energy is an example of motion energy.
Gravitational energy is due to the position of an object above the surface of earth.Hydropower is due gravitational energy possessed by water stored in a reservoir behind a Dam.
Chemical energy is the energy stored in chemical bonds between atoms/molecules.Fossil fuel(oil,coal,natural gas)and Biomass are examples of stored chemical energy.Food we eat contain stored chemical energy for our daily activities. 1 gram sugar gives 4 kilo calories and 1 gram butter gives 9 kilo calories.
Stored mechanical energy is the energy possesed by an object due to application of force, for example,compressed spring,stretched rubber band.
Rest energy is the energy possessed by an object by virtue of its mass as per Einstein’s formula of E=MCsquare.This energy is released when the nuclear forces which bind protons and neutrons in a nucleus of an atom are broken with resultant loss of mass in the process of nuclear fission/fusion.Nuclear energy is obtained by fission of uranium in nuclear power plants.Sun releases energy by nuclear fusion of hydrogen atoms.
The law of energy conservation states that energy cannot be created or destroyed but converted from one form to another form and the sum total of all forms of energies in a system remains same.
Examples of energy conversion are plenty.A battery converts chemical energy into electrical energy,a Dam converts gravitational potential energy of water into kinetic energy of turbine which is converted to electrical energy, Sun converts nuclear energy into radiant energy which is converted by photosynthesis into chemical energy in plants, chemical energy of petroleum is converted into motion energy of a car etc.
However, energy conversion results in loss of usable energy due to inefficiency in the system. Human body uses only 5 % of energy obtained from food for usable work and rest is lost as heat.
Energy crisis is defined as the shortage/disruption of energy supply resulting in the rise of energy price which adversely affects the economy/security of the world with lowering standard of living and poor quality of life. Energy crisis occurs due to labour strike,accident,war,terrorist strike,overconsumption of energy,depletion of energy sources, business corruption,severe weather,energy theft etc.
Primary energy source in the world can be divided in Renewable and Non-Renewable energy source, which is converted into secondary energy source like electricity and hydrogen.Secondary energy source is energy carrier which stores,transports and delivers energy to home in usable form.For example, coal is the primary energy source in a thermal power plant which generates electricity which is energy carrier, which is delivered in our home to cook food or cool home.
Non-Renewable energy(NRE) is defined as the energy source which cannot be replenished naturally in a relatively short time includes fossil fuel(coal,oil,natural gas,propane) and uranium ore.
Renewable energy(RE) is defined as the energy source which is derived from natural sources replenished constantly.It includes solar energy,wind power,hydropower,ocean energy, geothermal energy, biomass/biogas/biofuel and hydrogen derived from renewable sources.
Today, 85 % of world’s energy need is met with NRE and 15 % with RE.It is estimated that NRE will be depleted in 200 years,and then, world’s energy need ought to be met with RE to sustain standard of living and quality of life.Also, RE is better than NRE because it is cheap,unlimited supply,environment friendly,less pollutant,less global warming,generate employement and stabilize energy price.
NRE: Fossil fuel were formed millions of years ago due to actions of the heat of the earth’s core and the pressure from rocks and soil over the remnants of dead animals and plants. Coal supplies 25 %, oil 37 % and natural gas 23 % of the world energy need.At the present rate of energy consumption in the world, coal will be over in 133 years,oil in 48 years and natural gas in 61 years.
Average oil consumption of the world per capita per year is 4.7 barrels with america using 25 barrels, China 1.8 and India 0.8 barrel. World’s total oil reserve is 1238 billion barrels with yearly consumption of 32 billion barrels and new oil found 6 billion barrels per year.So oil will be over in 48 years as per mathematics and even if there is an error, still oil will never last 100 years.America is biggest energy waster because it has 5 % world population and uses 25 % of world oil.
Nuclear energy consumption in Tera-watt-hour per 1 million population shows France using 4.2 twhr,America 2.7, India/China 0.01 twhr.World’s uranium ore reserve is 5.5 million tons with yearly consumption of 65000 tons of uranium in nuclear power plants to generate electricity. So uranium will be over in 85 years.
Looking at all figures, it is clear that the assumption of NRE lasting for 200 years is wrong and considering population explosion, the NRE will be over in less than 150 years and we are heading for energy disaster.
World’s energy problem has 2 solutions,energy conservation and RE.
Energy conservation is defined as a practice of reduced quantity of energy utilisation by either energy efficiency or reduced energy consumption.Energy efficiency is defined as the total energy developed in usable work divided by the total energy available from the source fuel for that work.Every year America loses 130 billion dollars due to inefficient energy consumption and can save 23 % of energy by year 2020 by energy efficiency.
ENERGY SAVED IS ENERGY PRODUCED.
Examples of energy efficiency:
1) Fluorescent light bulb uses only 25 % energy as compared to incandescent bulb. Replacing conventional light bulbs with LED lighting can cut energy consumption by as much as 90%. 

2) Paint the wall of your house with light colour because dark colour will absorb light and more electricity will be consumed for same effect.
3) Switch off all electrical appliances at the source when not in use because ‘switching off’ on the appliance itself would still consume 75 % electricity.
India can save 25000 MW electricity by efficient energy consumption.
Electrical distribution loss in rural India is 35 % as compared to 7 % in Britain. Also, 42 % of electricity is stolen in India as compared to 3 % in China. Also,theft of electricity costs 4.5 billion dollars to India every year.
Co-generation is a concept of generating 2 forms of energy from one fuel to increase energy efficiency.The conventional power plant has only 35 % energy efficiency. However, in co-generation power plant, low pressure exhaust steam coming out of turbine is used for heating purpose in homes which increases energy efficiency to 75 % because electricity and heat are produced from one fuel.
RE: Total investment in RE in the year 2008 was 120 billion dollars which produces 168 watts per capita of electricity which is much less than the 721 watts per capita of the world’s electricity need.
Solar energy: The total solar energy absorbed by the earth’s atmosphere,land and ocean per year is 3850000 Exa-joules which is twice of total NRE on earth.The amount of solar energy absorbed by earth in an hour is same as the total energy need of the world per year.Solar energy can be captured using solar photovoltaic(SPV)cells,solar thermal power station,solar cooker/heater/pond/car etc. SPV cells convert solar energy into eletricity and 10 % of solar energy can be harnessed into electricity.Annual solar electricity generation is only 6900 MW in the world. 1 square meter of solar panel can generate 130 watts and it can last 20 years and 1 kilo-watt-hour of electricity will cost 3.8 cents in America and 2.8 rupees in india.
Wind energy: It is a form of solar energy. When sunlight falls on earth, it heats up land faster than ocean and the warm air over land rises and the cold air over ocean rushes over to take its place producing wind and the process is reversed at night.The total amount of wind energy that can be harnessed is 285 GJ per capita per year.Wind turbine converts kinetic wind energy into electricity.Denmark produces 21 % of electricity from wind turbines.Worldwide installed wind power capacity is 120000 MW per year.
Hydropower: It supplies 15 % of world’s electricity need and 3 % of world’s energy need. Canada gets 61 % of its electricity from hydropower.
Biomass :It is defined as biodegradable matter produced by all living organisms which includes trees,crops,manure etc. Photosynthesis by plants capture 3000 Exa-joules of solar energy every year which can be converted to electricity/fuel. 13 % of world’s energy need is met by biomass.Burning wood for cooking/heating is an inefficient way of using biomass but 3 billion people use it. America produces 7800 MW electricity from biomass.Biogas is methane gas produced by actions of anaerobic bacteria on sewage like manure,garbage,crop remnant etc.Biofuel like bio-ethanol,bio-diesel can be used in automobiles instead of petroleum.Brazil uses alcohol from sugarcane crop in 50 % of its vehicles.
Ocean energy is converting kinetic energy of water waves into electricity and also,using thermal energy of the ocean surface water which is warmed up due to solar heat.
Geothermal energy is using very hot core of the earth to generate electricity.World produces 8000 MW electricity from geothermal energy.
Hydrogen gas is an energy carrier like electricity and releases energy when combines with oxygen to produce water.Hydrogen fuel cell converts chemical energy of hydrogen into electricity.However, it requires more energy to produce hydrogen than the energy carried by it.Electrolysis of water needs 50 kilowatthour of electricity to produce 1 kg of hydrogen.The cheapest way to get hydrogen is from fossil fuel extraction.It is not a convenient carrier of energy because it must be liquefied/compessed in a tank which is expensive.
The discussion on energy is incomplete unless it is correlated with water.We need energy to produce water and we need water to produce energy.Saving water saves energy and saving energy saves water.Biofuel alcohol needs 20 times more water to run a car because sugarcane farms need lot of water.Cars run on electricity needs lot of water as compared to petroleum based cars because thermal/nuclear power plants need lot of water.
THE MORAL OF THE STORY:
1) Non-Renewable energy will be over in less than 150 years.
2) Today,Renewable energy is not sufficient to meet the energy need of the world.
3) The amount of solar energy absorbed by the earth in one hour is the same as the energy consumed by the world in one year.
4) Every house must be fitted with solar panel SPV cells and every field must be fitted with wind turbine to generate electricity.
5) Every community must have a sewage disposal plant converted into Biogas plant.
6) Energy efficiency saves 25 % of energy consumed.
7) Research must be funded on controlled nuclear fusion to overcome difficulties to generate electricity.
8) Hydrogen gas is an expensive, inconvenient and inefficient energy carrier as compared to electricity.
9) Saving water saves energy and saving energy saves water.
10) Clean energy and energy efficiency must be made a motto of 21’st century.
Dr.Rajiv Desai. MD.