Copyright Baylor University 20061 Lecture 36: Alternate Energy Sources Approximate Runtime: 38 minutes Introduction to Engineering

Copyright Baylor University 2006 1

Lecture 36:Alternate Energy Sources

Approximate Runtime: 38 minutes

Introduction to Engineering


Introduction

Steven Eisenbarth, Ph.D. Associate Dean of

Engineering and Computer Science

Baylor University


Alternative Energy Sources

Alternative energy refers to any type of energy which is not derived from fossil fuels.

Significant alternative energy sources: Bioenergy Nuclear Solar Wind Geothermal Hydroelectric Ocean Current H2 Fuel Cells


Global Energy Production by Fuel Type

from: http://www.iea.org/textbase/papers/2006/renewable_factsheet.pdf; copyrighted by the OECD/IEA, September 2006.


Basic Building Blocks of the Universe

Basic building blocks of matter Electrons, muon, and tau Neutrinos (one corresponding to electron, muon, and tau) Quarks (six types; up and down most common)

Four fundamental forces of nature: Electromagnetic (photons) Strong Nuclear (gluons) Weak Nuclear (W+, W-, Z) Gravitation (Higgs boson?)


What is Energy?

Broad definition: The ability to do work.

Comes in a wide variety of forms, for example: Nuclear Energy Chemical Energy Electrical Energy Thermal Energy Radiant Energy

Potential energy – a reservoir from which energy can be extracted.


Energy’s Manifestations

Energy related to movement of matter:

Kinetic Energy: where m is mass and v = velocity of the mass.

Kinetic Energy of Rotation: where I is the moment of inertial and ω is the angular velocity.

Thermal Energy: where k is the Boltzmann constant and T is absolute temperature.

2

2

1mvE

kTE2

3

2

2

1 IE



Energy related to position:

Gravitational Potential Energy: Where m is mass, g is the acceleration due to local gravity at the earth’s surface, and h is height.

Gravitational Potential Energy: Where E is energy, G is the gravitational constant, m and M are the two masses, and r is the distance between the masses’ center of gravity.

mghE

r

GmME



Energy related to position:

Electrostatic Potential Energy: Where q and Q are electric charges, r is the distance between the charges, and ε0 is the permittivity of free space.

Magnetostatic Potential Energy: Where μ is the magnetic dipole moment an B is the magnetic field strength. (This is a scalar product of two vector quantities.)

r

qQE

04

E



Energy related to nature of matter:

Radiant Energy (photons): Where h is Planck’s constant, and ν is frequency.

Rest Mass Energy: Where m = mass and c is the speed of light.

Chemical Energy: related to the chemical bonds between atoms within a molecule.

hvE

2mcE

No simple formula, primarily electrostatic in nature.



Energy related to nature of matter:

Nuclear Energy (fusion): The result of strong and weak nuclear forces that bind nuclear particles.

Nuclear Energy (fission): The result of strong and weak nuclear forces that bind nuclear particles.

2mcE

2mcE



Potential energy related to elastic properties of materials.

Elastic potential energy of a compressed spring: Where k is the force constant and x is the displacement from mechanical equilibrium.

2

2

1kxE


Energy Conversion Efficiency

Energy Conversion Efficiency = (Energy Input / Energy Output) * 100.

EnergyConversion

ProcessEnergy Input Usable Energy Output

EnergyLost


Combustible Renewables

Bio-energy refers to any type of energy derived from bio-mass. Bio-energy energy derived from the Sun which is stored within biomass Biomass includes:

Agriculture and forest wastes Public wastes Animal wastes

Bio-energy is considered a renewable energy because its production and use operate in a cycle.


Bio-Energy Production

Organic fuels are produced via the photosynthesis of sunlight.

Water and Oxygen is used by Chlorophyll to convert sunlight to NADPH and ATP.

Cell respiration converts water, CO2, NADPH and ATP to sugar with O2 as a bi-product.

Energy associated with the forming or breaking of chemical bonds.

Figure from: http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookPS.html

Overall Photosynthesis reaction:

6H2O + 6CO2 + light --> C6H12O6+ 6O2


Energy Crops

Energy crops are bioengineered to grow bigger and faster than regular crops making them useless for any other type of application.

http://www.nrel.gov/data/pix/Jpegs/10470.jpg

http://www.nrel.gov/data/pix/Jpegs/12672.jpg

Energy crops include plants, trees and other vegetation which are processed for energy.


Other Biomass

Agriculture and forest waste may be used to create fuels instead of allowing to it decompose.

Public wastes that can be used as biomass include paper, trimmed grass, landfill gas, etc.

Animal wastes, obtained mainly from farm animals, can be used for bio-energy production. In some remote locations it is used as a cooking fuel.

All of these different forms of bio-mass may be used for electric energy production.

http://www.repp.org/bioenergy/link4.htm


Bio-Energy Conversion

Biomass may be used traditionally to produce heat which can provide heating and cooking energy.

Alternatively, biomass can be transformed into liquid fuels such as ethanol, bio-diesel, and methanol.

These liquid fuels may be used in conjunction with other fuels to create a high-energy-content fuels.

These liquid fuels produce lower levels of pollutants than traditional fossil fuels.




Direct Firing Method:

biomass is taken as a solid and fired to produce hot gases. The hot gases are passed through a heat exchanger which boils water to produce steam which powers turbine-driven generators.

Co-Firing Method:biomass is combined with coal and used as feed to a existing coal-fired power plant. Bio-mass can represent 1 to 15% of total energy output.

From: http://www.tva.gov/power/coalart.htm


Bio-Energy Conversion (Gasification)

PartialOxidationGasifier

H2, CO, CO2

Bio-mass

Oxygen

Oxygen

Ash

PowerGeneration

or Syn-gas

Production

850º C, 1/3 O2



Anaerobic Digestion:

• This method uses biomass such as manure and solid waste. The biomass is broken down with bacteria to release methane which is then used as a fuel for gas engines powering generators.



Bio-Energy’s Future

Future plans involving bio-energy include drilling into landfills and capturing methane instead of letting it escape to the atmosphere.

Advantages

• Good way of recycling waste.

• May be less expensive than energy derived from fossil fuels.

• Positive impact on environment.

Disadvantages

• Hard to keep a huge amount of waste at all time.

• Release and burning of methane causes greenhouse gases.

• Without proper management bio-energy plants can pollute the environment.


Nuclear Energy Production

http://www.greendiary.com/images/nuclear_power_plant5.jpg


Nuclear Power Plants within U.S.

From: http://www.solcomhouse.com/nuclear.htm


Nuclear Power Plants Worldwide

From: http://www.solcomhouse.com/nuclear.htm


Nuclear Reaction

The most common nuclear fuel is U-235.

The nuclear fission process starts when U-235 atoms absorbs slow neutrons to become U-236.

U-236 is unstable and breaks apart releasing two fission products and three fast neutrons.

The mass of the fragments and released neutrons is about 0.1% less than original U-236 mass.

This mass has been converted to kinetic energy.

A moderator slows the released neutrons so that a chain-reaction can be sustained.

From: http://www.atomicarchive.com/Fission/Fission1.shtml


Pressurized Water Reactor (PWR)

• In a Pressurized Water Reactor, water heated by the nuclear fuel is kept in a primary closed loop.

• The pressure raises the boiling point of the water in the loop.

• The primary-loop water passed through heat exchangers which transfers heat from the water in the primary loop to the water in the secondary loop which boils creating steam which powers turbine generators.

http://www.solcomhouse.com/nuclear.htm


4/26/86 Chernobyl, Ukraine.

http://en.wikipedia.org/wiki/Image:Chernobyl_Disaster.jpg

• Reactor No. 4 after fire/meltdown.

• 130,000 evacuated

• 1.5 M exposed to radioactive fallout

• 600,000 involved in clean-up

• Increased cancer rates


Nuclear Power’s Future

Future development of nuclear technology will involve releasing energy through fusion instead of fission.

In fusion two nuclei would be joined to create a heavier one. Although it is already possible, it takes more energy than is released.

Advantages

1. More efficient than traditional fossil fuels.

2. Does not contribute to greenhouse effect.

3. Produces a small amount of waste.

Disadvantages

1. Waste is extremely dangerous.

2. Accidents can be catastrophic

3. Can be used to create nuclear weapons.

Documents

Copyright Baylor University 20061 Lecture 36: Alternate Energy Sources Approximate Runtime: 38 minutes Introduction to Engineering