Importance of Energy Efficiency60% of Coal and other Fossil
Fuels have been consumed in last 200 years85% of world industrial
need met from non-renewable sourcesExploration, transportation and
burning of Fossil fuels creates irreversible environmental
damageAll Energy Efficiency Measures leads to reduction of GHG
emission ultimately
Ask participants to define energy. Ask them to provide examples
of energy use. What would happen if here were no energy at all ?Ask
participants to provide examples of energy use in their homes.
Discuss the convenience of electrical energy over heat energy.
Before putting this slide ask the participants to list the
various steps in electricity production till the stage it reaches
the light bulb and lights up the lamp.
Describe the process as shown in the slide above
Primary Energy are derived from nature. Examples are Coal, oil,
natural gas and biomass (wood) Solar energy, nuclear energy
etc.Secondary energy is derived from primary energyAsk participants
to list a few more examples of primary energy such asHydro
energyWind energy (but basically caused by sun)Ocean energy
Etc.Other secondary energies include steam which is derived by
combustion of fuel
Though renewable energy sources are inexhaustible, their
commercial exploitation has been limited.Any of you here use
renewable energy in your industry ?Agro residues such as rice husk,
paddy husk, coconut shell are now being progressively used.How
about in your homes ! Drying of clothes !!!!We still need non
renewable energy to run our automobiles, to fuel our
industries.Energy content in an organic matter (Calorific Value)
can be measured by burning it and measuring the heat released. This
is done by placing a sample of known mass in a bomb calorimeter, a
device that can be completely sealed and is insulated to prevent
heat loss. A thermometer is placed inside (but it can be read from
the outside) and the increase in temperature after the sample is
burnt completely is measured. From this data, energy content in the
organic matter can be found out.
The heating value of fuel is the measure of the heat released
during the complete combustion of unit weight of fuel. It is
expressed as Gross (or High) Calorific Value (GCV) or Net (or Low)
Calorific value. The difference between GCV and NCV is the heat of
vaporization of the moisture (hydrogen to water vapour) contained
in the fuel. Typical GCV and NCV for heavy fuel oil is 10,500
kcal/kg and 9,800 kcal/kg
As different energy is sold in different units, it must be
converted into common units for comparison purpose. In practice,
energy is expressed in either kiloJoules or kilocalories
(kcals).
As different energy is sold in different units, it must be
converted into common units for comparison purpose. In practice,
energy is expressed in either kiloJoules or kilocalories
(kcals).
Ask the participants to work out the following problemExample:
An Industry consumes 900 kiloliter of fuel oil, 5,00,000 units
electricity in an year for the production. Determine the total
energy used in the plant in million Kcals/year.
(5,000,000 Units x 860 kcal/unit) = 516,000,000 kcals(900 x 1000
L x 10200 kcal/litres) = 9,180,000,000 kcalsTotal Energy in kcals =
9,696,000,000Total energy in kiloJoules = 9,696,000,000 x 4.186 =
405874560000 kJ
Ask the participants the difference between energy and power. A
person jogging 5 kms uses the same energy as a person walking 5
kms. But on who jogs does the job in lesser time. So he needs more
power than the one who walks, though the energy required is the
same.Ampere:(A) Current is the rate of flow of electricity. The
ampere is the basic unit of electric current. It is that current
which produces a specified force between two parallel wires, which
are 1 metre apart in a vacuum.Voltage (V): The volt is the
International System of Units (SI) measure of electric potential or
electromotive force. A potential of one volt appears across a
resistance of one ohm when a current of one ampere flows through
that resistance.1000 V = 1 Kilovolts (KV)Alternating current (AC).
A current which reverses in regularly recurring intervals of time
and which has alternately positive and negative values, and
occurring a specified number of times per second. Direct current
(DC). A non-varying, unidirectional electric current. Frequency:
The supply frequency tells us the cycles at which alternating
current changes. A unit of frequency is hertz .(Hz :cycles per
second).
KVAR is the reactive power. Reactive power is the portion of
apparent power that does no work. This type of power must be
supplied to all types of magnetic equipment, such as motors
transformers etc. Larger the magnetizing requirement larger the
KVAR.
For a company, it is the amount of electrical units in kWh
recorded in the plant over a month for billing purpose. The company
is charged /billed based on kwh consumption.
Example: A 100 kW motor running for 3 hours will consume 100 kW
* 3 hours = 300 kWh of electrical energy. A 1000 Watt light bulb
operating for one hour would use one kWh ( 1 unit of
electricity).
Make the participants work out the energy requirements for
lighting for this five day programme in the room .
Power Factor (PF) is the ratio between the actual or useful
power and apparent power (KW) being consumed by the plant
electrical loads to the power drawn or apparent power (KVA) from
the main supply (Grid). The inductive loads such as induction
motors, transformers, discharge lamp etc absorb reactive power
(KVAR). Electrical Authority may insist on the consumers to
maintain a PF at a minimum of 0.9 and penalty will be charged if PF
falls below 0.9. Lower the power factor, electrical network is
loaded more and more. It would be advisable to have highest power
factor (closed to 1) so that network carries only active power
which does real work. PF improvement is done by installing
capacitor near the equipment. Power factor is also denoted as
Cos.Contract Demand
Contract demand is the amount of electricity that a customer
demands from utility in a specified interval. Unit used is KVA or
KW. It is the amount of electricity that the consumer agreed upon
the utility and user for assured supply. This would mean that
utility has to plan for the specified capacity.
Billing DemandBilling Demand is the highest average KVA recorded
during any one demand interval within the month. The demand
interval is normally 30 minutes but may vary from utility to
utility from 15 minutes to 60 minutes. The demand is measured using
a tri-vector meter.Maximum Demand?The maximum KW/ KVA requirement
over a billing cycle is called as Maximum Demand.
Some electric utilities have a differential tariff for energy to
encourage / discourage users to use energy.
For example on utility found the peak usage will be between 6-9
A.M. and P.M. Other periods of the day there was less drawl,
especially during nights. So the utility decided to charge the
consumers additional 20 % for the energy used during peak hours.
The effect was consumers tried to do shuffling of operations to
mnimise energy consumption during peak hours and maximise during
non-peak hours.This is similar to the tariffs of telecom
operators.Most of the motive drives such as pumps, compressors,
machines etc. operate with 3 phase AC Induction motor. Power
consumption can be determined by using the relation.Power = 3 x V x
I x CosMeasuring instruments used are power analysers or meters.
Alternatively, knowing the Volts (V) and Amps (I) and assuming the
power factor from nameplate details or suitably, power can be
determined.Example: A 3-phase AC induction motor (20 kW capacity
)is used for pumping operation. Electrical parameter such as
current, volt and power factor were measured with power analyzer.
Find power consumption of motor in one hour? (Volts. = 440 V,
current = 25 amps and PF = 0.90). Measured Power consumption = 3 x
0.440 x 25 x 0.90 = 17.15 Kwh
Motor loadingA look at the name plate details of motor, KW or HP
indicates the OUTPUT of the motor at full load .The other
parameters such as volt, amps ,pf are the INPUT condition of motor
at full load.Example :A 10 kw motor has the name plate details as
415 v,18.2 amps and 0.9 PF. Actual input measurement shows 415 v,
12 amps and 0.7 PF which was measured with power analyzer during
motor running.Rated output at full load =10 KWRated input at full
load = 1.732x0.415x18.2x0.9 = 11.8 KWThe rated efficiency of motor
= 10/11.8 = 85%Measured (Actual) input power = 1.732x 0.415 x 12x
0.7 = 6.0 KWMotor loading(%) = Measured Kw = 6.0 x 100 = 51.2 %
Rated Kw 11.8 Problem 1: A 100 Watt mercury vapor lamp was switched
on for 12 hours per day. The supply volt is 230 V. Find the power
consumption per day? (Volt = 230 V, Current = 5 amps, PF =
0.8)Power consumption (kWH) = V x I x Cos x No of Hours = 230 x 5 x
0.8 x 12 = 11.04 kWH or UnitsProblem 2: An electric heater of 5 Kw
rating is used for hot water generation in an industry during one
shift ( 8 Hours operation). Find Power consumption per month?Power
consumption (kWH) = 5 Kw x 8 hours. x 30 days = 1200 Kwh/monthIf a
fuel fired to generate hot water, by 1st law all the heat in the
fuel is transferred to water. So the efficiency is 100%
But in actual practice there are always some losses such as flue
losses, radiation losses etc. So only a certain percentage of fuel
alone is transferred to water.Take the case of a boiler. Say, we
send 1000 kgs of water into the boiler.
Ask the participants:
How much quantity of steam will we get from the boiler ?1000,
less than 1000 or more than 1000.
We will actually get 1000 kgs, as all the mass going in has to
come out.
This principle is used in energy and material balance
calculations
High Grade EnergyLight energy and chemical energy are high-grade
energy, because the energy is concentrated in a small space. A
little bit of light or chemical energy can do a great deal of work.
The molecules or particles that store these forms of energy are
highly ordered and compact and thus considered as high grade
energy. High-grade energy such as electricity is used for
high-grade use such as melting of iron, aluminum etc.
Heat is low grade energy. It can still be used to do work
(example of a heater boiling water), but rapidly dissipates. The
molecules in which this kind of energy is stored (air and water
molecules) are more randomly distributed than the molecules of
carbon in a coal. This disordered state of the molecules and the
dissipated energy requires a classification of low grade energy.
CHP stands for Combined Heat and Power Plant. A typical process
industry needs both power and steam. Instead of separate
procurement of electricity and generation of steam from boiler, a
combined electricity and steam generation is resorted in a CHP
plant for maximizing energy efficiency and economic
perspective.When we drive a car chemical energy stored in petrol is
converted into mechanical energy and used to create motion. When we
use an electric stove, a power plant first converts chemical energy
stored in coal to electrical energy, which is transported through
the electrical distribution system. Then the stove converts
electrical energy to heat energy. The proportion of the original
energy, which ends up being, used for the final purpose (motion,
cooking) measures the energy efficiency. Nature sets some basic
limits on how efficiently energy can be used, but in most cases our
products and manufacturing processes are still a long way from
operating at this theoretical limit. Very simply, Energy efficiency
means using less energy to perform the same function. For example,
replacing traditional light bulbs with Compact Fluorescent Lamps
(CFLs) means you will use only 1/5th of the energy to light a room.
Can you think of any energy efficiency measures in this room.How
about switching off lights in this room ? Is it energy efficiency
?
No. Energy efficiency is using the needed energy more usefully.
It not denial of comforts nor decreasing production or quality.Why
is energy efficiency becoming more and more important? Coal and
other fossil fuels which have taken three million years to form are
likely to deplete soon. In last two hundred years, we have consumed
60% of all resources. For sustainable development, we need to adopt
energy efficiency measures.Today, 85% of raw energy comes from
non-renewable, fossil sources (coal, oil, etc.). The reserves are
continually diminishing and will not exist for future generations.
In addition, the exploration, transport and burning of these fuels
cause considerable or even irreversible environmental problems
(green house effect, etc.). As a result, the public and legal
demands for an efficient use of these energy sources are becoming
more stringent. It is hoped that such pressures would reduce the
damage, more often, blamed on the parties responsible, and the
supply shortage. All the above measures lead to reduction of
consumption of fossil fuels such as coal, oil or gas and ultimately
lead to reduction of greenhouse (CO2) emissions.
