Energy Security and
Conservation
A Major Part of the Solution to
Energy Generation and
Environmental Degradation
Dr. R.P. Dahiya
Professor, IIT Delhi
Email: rpdahiya@ces.iitd.ac.in
8 April 2015
ENERGY SECURITY
8 April 2015
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Scientists in Energy
James Joule
First Law of
Thermodynamics
Sadi Carnot
Second Law of
Thermodynamics
Carnot Cycle
Thomas Edison
Light Bulb, etc.
Alexander
Graham Bell
Telephone
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Scientists in Energy
Albert Einstein
E=mc²
Enrico Fermi
First Nuclear
Reactor
William Shockley
Transistor
Bill Gates
Computers
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Topics
•
•
•
•
•
•
•
•
•
Energy Sources and Uses
Fossil Fuels
Nuclear Power
Energy Conservation
Solar Energy
Fuel Cells
Biomass
Energy From the Earth’s Forces
What’s Our Energy Future?
8 April 2015
PART 1: ENERGY SOURCES AND USES
• Work is the application of force through a distance.
• Energy is the capacity to do work.
• Power is the rate of flow of energy, or the rate at
which work is done.
– A small calorie is the metric measure of energy necessary to heat
1 gram of water 1oC, whereas a British Thermal Unit (BTU) is
the energy needed to heat 1 pound of water 1oF
– A joule is the amount of work done by a force needed to
accelerate 1 kilogram 1 meter per second per second. Another
definition for joule is the force of an electrical current of 1
amp/second through a resistance of 1 ohm.
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Measurements
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Worldwide Commercial Energy Production
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How We Use Energy
• What are the commercial uses of energy?
– Industry uses 38%;
– Residential and commercial buildings use 36%; and,
– Transportation uses 26%.
• Half of all energy in primary fuels is lost during conversion to more
useful forms while being shipped or during use.
– Nearly two-thirds of energy in coal being burned to generate
electricity is lost during thermal conversion in the power plant.
Another 10% is lost during transmission and stepping down to
household voltages.
• Natural gas is the most efficient fuel.
– Only 10% of its energy content is lost during shipping and
processing. Ordinary gas-burning furnaces are about 75% efficient.
High-economy furnaces can be 95% efficient.
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Per Capita Energy Use & GDP
Energy Use Trends
•
•
•
A general trend is for
higher energy use to
correlate with a
higher standard of
living
In an average year,
each person in the
U.S. and Canada
consumes more than
300 times the
amount of energy
consumed by a
person in one of the
poorest countries of
the world; however,
Several European
countries have
higher living
standards than the
U.S., yet they use
about half as much
energy.
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ENERGY RESOURCE AVAILABILITY IN INDIA
Source
Capital cost
(crores/MW)
Emissions
(t CO2-eq/Mwh)
Reserves
Longevity
Coal
4-5
1.1
10 5820 MT
70 years
Oil
2.5
0.62
1200 MT
~ 10 years
Gas
3.5
0.47
1.5 TCM
~ 20 years
Hydro
6- 20 (Site and
size dependant)
0
148.7 GW
NA
Nuclear
8-13
0
70,000 tonnes of
Uranium
~ 200 tonnes of Pu
40 years with Uranium
Source : BP statistical review report, NHPC,NTPC
8 April 2015
INDIA'S ENERGY ASPIRATIONS
• Annual GDP growth projection : 8 – 9%
• Elasticity of electricity : GDP ~ 0.95
• Net electricity generation required in 2020 : 1850 billion units
– per capita electricity consumption in 2020 : ~ 1200 kWh
– Still, well below world average of 2800 kWh
• India has announced intent to reduce CO2 intensity: GDP by 20-25% from
2005 levels by 2020
• Multiple objectives for Indian energy policy
– Access for all
– Reliability
– Low cost
– Low carbon
– Energy Security
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INDIA’S PRIMARY ENERGY CONSUMPTION :
A SNAPSHOT
In 2010 alone, India’s primary energy consumption grew by 9.2%
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Source : BP statistical review of world energy, 2011; CSTEP
ELECTRICAL ENERGY STATUS
IN INDIA
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ELECTRIC POWER
•
•
Current Capacity : 173,855 MW (utility)
– 5th largest in the world
Low per capita electricity consumption
–
–
–
–
•
•
India
US
China
World
717 kWh
14,000 kWh
2500 kWh
2800 kWh
Peak shortage ~ 15%
800,000 MW in 2030 – 40
– ~ 25,000 MW per year
•
Environmental concerns
– India 3rd largest emitter of CO2 behind China and US
– 38% of emissions from power sector
•
Energy security concerns
– 67% power from coal-based thermal plants - need to depend on imports
– Prototype breeder reactors to exploit thorium reserves
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SOURCE: CEA
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ENVIRONMENTAL CONCERNS :
GHG EMISSIONS IN INDIA (2007)
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ENERGY SECURITY CONCERNS
Source : Telegraph, FT
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PROJECTED FUEL MIX IN 2020
•
Required capacity in 2020 assuming 8% growth = 387,280 MW in BAU
scenario
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Source : Interim report, Planning commission 2011
HOW TO GROW AND BE SUSTAINABLE?
• How do we grow to ~ 2,000 billion kWh by 2020
• How do we get 3,00 billion kWh of low-carbon power?
• What fuel options & technologies?
•
•
•
•
•
•
•
•
Wind
Nuclear,
Solar
Hydro
Bio-fuels
Carbon Sequestration
Hydrogen & fuel cells
Hybrid cars
• Investments, research, policies?
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WIND POWER
•
•
Power proportional to V 3
India - 5th in wind capacity
Cost of generation reasonable: ~ Rs 3 per
kWh
– Economics sensitive to wind speeds
•
•
World total installed 194,000 MW
India:
– Potential: 50,000 MW based on hub height
of 50 m and 2% land usage
– Recent studies offer reassessed potential
at 80m 6-7% land usage
•
•
Onshore - 676, 000 MW
Offshore - 214,000 MW
– Intermittent; grid stability is a concern
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China
44, 733 MW
US
40,180 MW
Germany
27,215 MW
Spain
20,676 MW
India
13,000 MW
SOLAR POWER
• JNNSM launched in 2010 targets 22,000 MW by 2022
– Phase 1 ( until March 2013)
• Target of 1300 MW : 800 MW PV and 500 MW CSP
• 25 years of guaranteed feed in tariff
– Off-grid PV
• Target of 2000 MW by 2022
• Rural applications where grid is unviable or unreachable
– Challenges
• High nominal cost of generation : ~ Rs 15 per kWh
• Water scarcity issues for CSP
• Requirement of skilled personnel
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NUCLEAR POWER
•
•
Installed Capacity
Generation
•
Domestic Uranium reserves
– Poor quality ore
•
4780 MW
~ 23 Billion kWh
(2.5 % of total)
~ 61,000 Tons
(0.01% - 0.05% Uranium)
Large Thorium deposits
– But, Thorium is fertile and has to be converted to fissile U233 in a reactor
•
Phase Nuclear Program
– Phase I
– Phase II
– Phase III
•
Build Pressurized Heavy Water Reactors using domestic Uranium
Reprocess spent fuel from Phase I to get Plutonium for Breeder Reactors
Use U233 (obtained from Thorium) and use it with Plutonium
Domestic Uranium reserves can sustain 10,000 MW PHWR for 40 years
– Low capacity factors due to Uranium mining constraints
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INDIAN NUCLEAR POWER PROGRAM
Type
Operating
Projections
(2020)
Projections
(2030)
Heavy Water
Reactors
4,460 MW
10,000 MW
10,000 MW
Light Water
Reactors
320 MW
9,300 MW
22,000 MW
Fast Breeder
Reactors
-
1,500 MW
1,500 MW
4780 MW
20,800 MW
33,500 MW
Total
Nuclear capacity presently under construction : 5300 MW
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ELECTRICITY GENERATION COSTS :
COMPARISON
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Source : LBNL, CERC , CSTEP & NPCIL
POTENTIAL R&D DOMAINS
• New and affordable materials for photovoltaic
• Clean coal technologies; carbon capture and
sequestration
• Low-speed wind power
• Cellulosic ethanol
• Efficient and affordable hybrids, electric vehicles
• Energy storage – efficient batteries and condensers
• Demand side management of power
• Trained human resource
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Conservation of Energy
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PART 4: ENERGY CONSERVATION
Hybrid gas-electric automobile
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ENERGY CONSERVATION
– Most potential energy in fuel is lost as waste heat.
– In response to 1970’s oil prices, average US automobile gasmileage increased from 13 mpg in 1975 to 28.8 mpg in 1988.
Falling fuel prices of the 1980’s, however, discouraged further
conservation.
Energy Conversion Efficiencies
•Energy Efficiency is a measure of energy
produced compared to energy consumed.
–Household energy losses can be reduced by one-half to threefourths by using better insulation, glass, protective covers, and
general sealing procedures. Energy gains can be made by
orienting homes to gain passive solar energy in the winter.
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Definition
Conservation of energy refers to
efforts made to reduce energy
consumption and to increase
efficiency of energy use.
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Conservation of Energy
P.E  K.E.  P.E.  K.E. … Is energy lost?
No!
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Energy is converted!
What does conserve energy mean?
Conserve Electricity
Conserve Natural Gas
Conserve Water
So On ………...
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Energy Conservation
Safety First!
Consider safety first
Saving energy is important, but avoid measures
that have negative impacts on people and
communities
All existing and potential health and safety issues
should be evaluated prior to implementing any
conservation measures
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Law of Conservation of Energy
• Energy can be neither created nor destroyed.
• The total energy in a “closed” system is always
the same.
• The energy may be in different forms, but the
amount will be equal.
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Conservation of Energy
• Thermal Energy produced by friction is not
useful energy-Why?
• It IS NOT used to do work.
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8 April 2015
Perpetual Motion
• A machine that would run forever without
the addition of energy.
• Some energy is wasted due to the thermal
energy produced, so perpetual motion is
not possible.
• So how does the “drinking bird” work?
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ANATOMY OF A HAPPY DRINKING BIRD HOW IT WORKS - The techie stuff.
Technically, the Drinking Bird is a type of "Heat Engine". But thankfully you won't
need a degree in physics or thermodynamics to understand the basics of how it
works!
The body of the bird comprises 2 glass "bulbs", one for the head and The glass
tube which interconnects the two bulbs dips deep into a special liquid (usually
coloured methylene chloride) in the body.
An important fact is that the bird will "drink" providing the head bulb is slightly
cooler than the body bulb (i.e. there is a "temperature differential").
8 April 2015
ANATOMY OF A HAPPY DRINKING BIRD HOW IT WORKS - The techie stuff.
Technically, the Drinking Bird is a type of "Heat Engine". But thankfully you won't need a degree in physics or thermodynamics to
understand the basics of how it works!
The body of the bird comprises 2 glass "bulbs", one for the head and The glass tube which interconnects the two bulbs dips deep into
a special liquid (usually coloured methylene chloride) in the body.
one for the lower body.
An important fact is that the bird will "drink" providing the head bulb is slightly cooler than the body bulb (i.e. there is a "temperature
differential").
The head is usually coated in a red felt-like material which absorbs water when the bird "drinks". Evaporation of water from the head
causes the head to become cooler than the body. By lucky coincidence, the swaying motion of the bird assists the evaporation.
Although the head and upper part of the glass tube appear to be "empty", they are actually full of invisible vapour from the methylene
chloride. Methylene chloride is good for this because it doesn't take much heat energy to turn it into a vapour (It has a "low latent heat
of evaporation").
Because the head is cooler than the body, some of this vapour condenses inside the head, like steam when it touches a cold window.
As this vapour "shrinks" into minute droplets of fluid, it takes up a lot less space. This makes the pressure inside the head slightly
lower than the body, causing the liquid to be sucked up the tube. You could also think of it as the "hot" fluid in the body making
"steam" above itself, which blows the liquid up the tube (vapour pressure); it's all relative. The main thing is, the body is always
warmer than the head. It's not the same a thermometer, though, because it does not rely on expansion of the liquid itself, which is
insignificant. It's the pressure of the vapour that does the work.
As the liquid rises up the tube, it gradually changes the centre of gravity of the bird. This makes it tip over more and more until
eventually it tilts into the water. If everything is adjusted just right, then as it tilts over, the end of the tube inside the body comes out of
contact with the liquid. Instead of pushing the liquid up the tube, the vapour above the liquid in the body can now quickly rush up the
tube, equalising the pressures in head and body. As this happens, the liquid which has moved up towards the head now gurgles back
down into the body. This rapidly moves the centre of gravity back to the lower body, and the bird swings back away from the glass.
When you understand how the bird works, you will see how you can even "trick" it to "dip" with no water at all:
If you shine a lamp towards only the bottom part of the bird, this slightly warms it (compared to the head), so there is the necessary
"temperature differential" and it should "dip".
If you have just shown your friends how the bird works (with water), then you may perhaps puzzle them again by removing the glass,
and watching it continue to drink long even though the head has become dry, secretly using the warmth from a lamp nearby (which
may have been on before). Take care, though, because excessive heat will burst the glass and make a terrible mess! (Thanks to Jan
at "Arabesk" for this interesting trick
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“Zero energy” new homes
8 April 2015
Household Energy Use for Entertainment Electronics
Plasma HDTV
Primary TV
DVD/VCR
HD set top box
Analog CRT
Secondary TV
DVD/VCR
Digital cable set top box
Combined energy use0
~ 1200 kWh per year
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200
400
Annual Energy Use (kWh)
600
Lighting
• Compact Fluorescents or Long Fluorescents using plasma
discharges use only 1/3 of the energy and heat of
incandescent lights, which derive their light from heating
filaments hot enough to emit visible light.
• If every home changed their five most used lights, they
would save $60 per year in costs.
• This would also be equal to 21 power plants.
• The fluorescents also last up to 10 times as long.
• Replacing one bulb means 1,000 pounds less CO2
emitted over the compact fluorescent’s lifetime.
• Traffic signal LEDs use 90% less energy and last 10 years
rather than 2 years.
8 April 2015
Additional Advantages of Energy Conservation
(Moralizing)
• Less need to secure oil overseas with attendant military
and civilian casualties while costing hundreds of billions
of dollars
• Fewer power plants and liquid natural gas ports are
needed
• Less air pollution
• Less drilling for oil in Alaska and near national parks
• Less global warming and attendant environmental
destruction
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Conclusions on Energy
Conservation
• Energy conservation has saved the need for many power plants and
fuel imports.
• It has also avoided CO2 and environmental pollution.
• Regulations on efficiency work, but voluntary efforts lag far behind.
• Much has been done, but much more can be done
• In this new era of global warming and high energy costs and energy
shortages, the public must be informed and politicians sought who are
sensitive to these issues.
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PART 6: FUEL CELLS
•
•
•
•
•
•
•
8 April 2015
Fuel cells use ongoing electrochemical
reactions to produce electrical current
Fuel cells provide direct-current electricity
as long as supplied with hydrogen and
oxygen.
Hydrogen is supplied as pure gas, or a
reformer can be used to strip hydrogen
from other fuels.
Fuel cells run on pure oxygen and hydrogen
produce only drinkable water and radiant
heat.
Reformer releases some pollutants, but far
below conventional fuel levels.
Fuel cell efficiency is 40-45%.
Positive electrode (cathode) and negative
electrode (anode) separated by electrolyte
which allows charged atoms to pass, but is
impermeable to electrons. Electrons pass
through external circuit, and generate
electrical current.
PART 7: BIOMASS
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Fuelwood Crisis
• Currently, about half of worldwide annual wood harvest is used as fuel.
– Eighty-five percent of fuelwood is harvested in developing countries.
• By 2025, worldwide demand for fuelwood is expected to be twice current
harvest rates while supplies will have remained relatively static.
• About 40% of world population depends on firewood and charcoal as
their primary energy source.
– Of these, three-quarters do not have an adequate supply.
• Problem intensifies as less developed countries continue to grow.
– For urban dwellers, the opportunity to scavenge wood is generally
nonexistent.
8 April 2015
Fuelwood Crisis in Less-Developed Countries
• About 40% of the
world’s population
depends on firewood
and charcoal as their
primary energy source.
• Supplies diminishing
• Half of all wood
harvested worldwide is
used as fuel.
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Using Dung as Fuel
• Where other fuel is in short
supply, people often dry and
burn animal dung.
• When burned in open fires,
90% of potential heat and most
of the nutrients are lost.
• Using dung as fuel deprives
fields of nutrients and reduces
crop production.
• When cow dung is burned in
open fires, 90% of the potential
heat and most of the nutrients
are lost.
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Using Methane As a Fuel
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Alcohol from Biomass
• Ethanol (grain alcohol) production could be a solution to
grain surpluses but thermodynamic considerations
question it being practical on a sustainable basis. Gasohol
(a mixture of gasoline and alcohol) reduces CO emissions
when burned in cars. Ethanol raises octane ratings, and
helps reduce carbon monoxide emissions in automobile
exhaust.
• Methanol (wood alcohol)
• Both methanol and ethanol make good fuel for fuel cells.
8 April 2015
PART 8: ENERGY FROM EARTH'S FORCES
Wind
Geothermal
Tidal
Wave
Hydropower
• Water power produces 25% of
the world’s electricity and it is
clean, renewable energy.
• Dams cause social and
ecological damage.
8 April 2015
• Hydropower
– By 1925, falling water generated 40% of world’s electric power.
• Hydroelectric production capacity has grown 15-fold, but fossil fuel use
has risen so rapidly that now hydroelectric only supplies one-quarter of
electrical generation.
• Total world hydropower potential estimated about 3 million MW.
– Currently use about 10% of potential supply.
• Energy derived from hydropower in 1994 was equivalent to 500 million
tons of oil. Much of recent hydropower development is in very large
dams.
• Drawbacks to dams include:
– Human Displacement
– Ecosystem Destruction
– Wildlife Losses
– Large-Scale Flooding Due to Dam Failures
– Sedimentation
– Herbicide Contamination
– Evaporative Losses
– Nutrient Flow Retardation
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Wind Energy
• Wind power - advantages and disadvantages
• Wind farms - potential exists in Great Plains, along seacoasts and Eastern
Washington
http://www.awea.org/projects/washington.html
8 April 2015
Geothermal Energy
This energy source
involves the use of
high-pressure, hightemperature steam
fields that exist below
the earth’s surface.
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Tidal & Wave Energy
•Ocean tides and waves
contain enormous amounts
of energy that can be
harnessed.
–Tidal Station - Tide
flows through turbines,
creating electricity. It
requires a high tide/lowtide differential of
several meters.
–Main worries are
saltwater flooding
behind the dam and
heavy siltation.
–Stormy coasts with
strongest waves are often
far from major
population centers.
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Part 9:An Alternative Energy Future?
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THANK YOU
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DEMAND-SIDE MEASURES : SMART GRIDS
• Indian Institute of Science & CSTEP
– “Smart grid” test bed in IISc campus
– Consortium of technology provider companies
• Ministry of Power (under R-APDRP)
8 April 2015
BIOFUEL POTENTIAL
• India’s total land area
–
–
–
–
Cultivated
Cultivable wasteland
Rice
Wheat
328 million hectares (mha)
142 mha
30 mha
40 mha
26 mha
• Hazardous to divert agricultural area for bio-fuels.
• If entire wasteland used for growing bio-fuels,
– Produce about 30 million tons of bio-oil
– 10% of oil demand by 2031.
• Advisable to cultivate on such a large area?
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ETHANOL OPPORTUNITIES
• Increase yield of sugarcane using drip irrigation & fertigation
– Present average yield
– Using drip irrigation & fertigation
~ 80 tons per ha
150 tons per ha
• Sweet sorghum:
– Less water intensive than sugarcane
– Two crops a year
• Cellulosic ethanol from agro-forest residues such as bagasse,
rice husk, wood chips, crop residues.
– Technology needs to be developed
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WHAT CAN 1 HECTARE DO?
Option 1
Sugarcane
Option 2
Corn Ethanol
Option 3
Jatropha
Option 4
Option 5
Sweet Sorghum Solar
Sugarcane:
80 tons
Corn Yield:
7500 Kg per
hectare
2000 to 3000
Trees per
hectare
Stalk yield:
Averageuse
daily
Bio-Fuels indirectly
35 – 50
tonsenergyradiation:
solar
per hectare
5- 6 kWh/m2
days of
Why not do 250
it directly?
sunshine
Juice Extraction
Solar
45 – 50%
50% area
covered by PV
panels
No Sugar
Ethanol:
Cane juice used 0.37 Liter per
to make
kg
ethanol.
Seed yield:
1 to 2 Kg per
tree
Ethanol:
6000 Liter per
hectare
Oil Yield:
Ethanol:
1 to 1.5 Ton per 2500 to 3500
hectare
Liters per
hectare
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2800 Liter per
hectare
10% Efficiency
of solar cells
LAND REQUIRED(HA/1000 MW)
Source : NPCIL & CSTEP
8 April 2015
PART 2: FOSSIL FUELS
•
•
Fossil fuels are organic chemicals created by living organisms that were buried
in sediments millions of years ago and transformed to energy-rich compounds.
Because fossil fuels take so long to form, they are essentially nonrenewable
resources.
 Coal
 Oil
 Natural Gas
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Coal
Oil
Natural Gas
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Coal Extraction and Use
•
•
•
•
Mining is dangerous to humans
and the environment
Coal burning releases large
amounts of air pollution, and is
the largest single source of acid
rain in many areas.
Economic damages are billions
of rupees
Billions of tons of coal are
burned the world over for electric
power generation. As a result,
multiple pollutants are released
such as:
–
–
–
–
–
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Sodium Dioxide (18 million metric
tons)
Nitrogen Oxides ( over 5 million
metric tons)
Particulates (over 4 million metric
tons)
Hydrocarbons (over 600,000
metric tons)
Carbon Dioxide (over 1 trillion
metric tons)
Oil Extraction and Use
• The countries of the Middle East control two-thirds of all
proven-in-place oil reserves. Saudi Arabia has the most.
• The U.S. has already used up about 40% of its original
recoverable petroleum resource.
• Oil combustion creates substantial air pollution.
• Drilling causes soil and water pollution.
• Often oil contains a high sulfur level. Sulfur is corrosive, thus
the sulfur is stripped out before oil is shipped to market.
• Oil is primarily used for transportation providing > 90% of
transportation energy.
• Resources and proven reserves for the year 2000 are 650
billion barrels (bbl). 800 bbl remain to be discovered or are
currently not recoverable.
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Natural Gas Consumption
•World’s third largest commercial fuel (23% of global energy used).
•Produces half as much CO2 as equivalent amount of coal.
•Most rapidly growing used energy source.
•
•
•
8 April 2015
Proven world reserves and
resources of natural gas
equal 3,200 trillion cubic
feet. This equals a 60 year
supply at present usage
rates.
Natural gas produces only
half as much CO2 as an
equivalent amount of coal.
Problems: difficult to ship
across oceans, to store in
large quantities, and much
waste from flaring off.
PART 3: NUCLEAR POWER
• President Dwight Eisenhower, 1953, “Atoms for
Peace” speech.
– Eisenhower predicted that nuclear-powered electrical generators would
provide power “too cheap to meter.”
– Between 1970-1974, American utilities ordered 140 new reactors, but
100 were subsequently canceled.
• Nuclear power now produces only 7% of the U.S.
energy supply.
• Construction costs and safety concerns have made
nuclear power much less attractive than was
originally expected.
– Electricity from nuclear power plants was about half the price of coal
in 1970, but twice as much in 1990.
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How Do Nuclear Reactors Work
•
•
•
•
•
•
•
The common fuel for nuclear reactors is U235 that occurs
naturally (0.7%) as a radioactive isotope of uranium.
U235 is enriched to 3% concentration as it is processed into
cylindrical pellets (1.5 cm long). The pellets are stacked in
hollow metal rods (4 m long).
100 rods are bundled together into a fuel assembly. Thousands
of these fuel assemblies are bundled in the reactor core.
When struck by neutrons, radioactive uranium atoms undergo
nuclear fission, releasing energy and more neutrons.This result
triggers a nuclear chain reaction.
This reaction is moderated in a power plant by neutronabsorbing solution (Moderator).
Control Rods composed of neutron-absorbing material are
inserted into spaces between fuel assemblies to control reaction
rate.
Water or other coolant is circulated between the fuel rods to
remove excess heat.
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Nuclear fission occurs in the core of a nuclear reactor
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Kinds of
Reactors
• 70% of nuclear power plants are pressurized water reactors
(PWRs). Water is circulated through the core to absorb heat from
fuel rods. The heated water is then pumped to a steam generator
where it heats a secondary loop. Steam from the secondary loop
drives a high-speed turbine making electricity.
• Both reactor vessel and steam generator are housed in a special
containment building. This prevents radiation from escaping and
8 provides
April 2015 extra security in case of accidents. Under normal
operations, a PWR releases little radioactivity.
Reactor Design
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Radioactive Waste Management
•
•
•
Production of 1,000 tons of uranium fuel typically generates 100,000
tons of tailings and 3.5 million liters of liquid waste.
– Now approximately 200 million tons of radioactive waste exists in
piles around mines and processing plants in the U.S.
About 100,000 tons of low-level waste (clothing) and about 15,000
tons of high-level (spent-fuel) waste in the US.
– For past 20 years, spent fuel assemblies have been stored in deep
water-filled pools at the power plants. (designed to be temporary).
– Many internal pools are now filled, and a number plants are storing
nuclear waste in metal dry casks outside.
A big problem associated with nuclear power is the disposal of
wastes produced during mining, fuel production, and reactor
operation.
– U.S. Department of Energy announced plans to build a high-level
waste repository near Yucca Mountain Nevada in 1987.
– Cost is $10-35 billion, and earliest opening date is 2010.
– This allows the government to monitor & retrieve stored uranium.
8 April 2015
PART 5: SOLAR ENERGY
•
•
•
Photosynthesis
Passive solar heat is using
absorptive structures with
no moving parts to gather
and hold heat. Greenhouse
design
Active solar heat is when a
system pumps a heatabsorbing medium through
a collector, rather than
passively collecting heat in a
stationary object. Water
heating consumes 15% of
US domestic energy budget.
Mean solar energy striking the upper atmosphere is 1,330 watts per
square meter. The amount reaching the earth’s surface is 10,000 times
> all commercial energy used annually. Until recently, this energy
8source
April 2015has been too diffuse and low intensity to capitalize for electricity
production.
High-Temperature Solar Energy
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•Parabolic mirrors (left) are
curved reflective surfaces that
collect light and focus it onto a
concentrated point. It involves
two techniques:
–Long curved mirrors focus
on a central tube containing a
heat-absorbing fluid.
–Small mirrors arranged in
concentric rings around a tall
central tower track the sun
and focus light on a heat
absorber on top of the tower
where molten salt is heated to
drive a steam-turbine electric
generator.
Photovoltaic Solar Energy
• During the past 25 years, efficiency of energy
capture by photovoltaic cells has increased from less
than 1% of incident light to more than 10% in field
conditions, and 75% in laboratory conditions.
– Invention of amorphous silicon collectors has allowed
production of lightweight, cheaper cells.
• Photovoltaic cells capture solar energy and convert it
directly to electrical current by separating electrons
from parent atoms and accelerating them across a
one-way electrostatic barrier.
– Bell Laboratories - 1954
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• 1958 - $2,000 / watt
• 1970 - $100 / watt
• 2002 - $5 / watt
Photovoltaic energy solar energy converted
directly to electrical
current
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Transporting & Storing Electrical Energy
• Electrical energy storage is
difficult and expensive.
– Lead-acid batteries are
heavy and have low energy
density.
• Typical lead-acid battery
sufficient to store electricity
for an average home would
cost $5,000 and weigh 3-4
tons.
– Pumped-Hydro Storage
– Flywheels
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Promoting Renewable Energy
•Distributional Surcharges
–Small charge levied on all utility customers to help finance research and
development.
•Renewable Portfolio
–Mandate minimum percentage of energy from renewable sources.
•Green Pricing
–Allow utilities to profit from conservation programs and charge
premium prices for energy from renewable sources.
8 April 2015