Renewable Energy Sources

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Renewable Energy Sources

• SUN!
• What is the distribution of fuel use in the
  world?
• Petroleum 34
• Coal 25
• Natural gas 21
• Renewables 14
• Nuclear 6

2
How can we use energy from the sun directly?

• Solar Heat
• Passive designs
• Active designs
• Solar Thermal Electricity
• Trough collection
• Tower collection
• Dish collection
• Photovoltaic Electricity
• Using the photoelectric effect explained by
  Einstein

3
Solar Heating

• Passive Design
• Maximizes the capture of direct solar energy
• Direct gain (the simplest system) stores and
  slowly releases heat energy collected from the
  sun shining directly into the building and
  warming materials such as tile or concrete. Care
  must be taken to avoid overheating the space.
• Indirect gain (similar to direct gain) uses
  materials that hold, store, and release heat the
  material is located between the sun and living
  space (typically the wall).
• Isolated gain collects solar energy remote from
  the location of the primary living area. For
  example, a sunroom attached to a house collects
  warmer air that flows naturally to the rest of
  the house.
• According to US-DOE Buildings with passive
  heating design require 1/2 heating requirements
  of conventional new buildings.

4
Solar Heating

• Active Design
• Called active because a source of energy other
  than solar is required to drive the system.
• Solar hot water heat
• Radiative building heat

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Solar Heating Active design
Flat-plate collectors are used for residential
water heating and hydronic space-heating
installations.
Consult Fig. 4.2 from text
Energy Star Residential Water Heaters Available
January 1, 2009 http//apps1.eere.energy.gov/news/
news_detail.cfm/news_id12159
6
Solar Thermal Electricity
Generating electricity from sunlight -
Advantages 10,000 mi2 of Nevada desert could
supply the TOTAL electricity needs of the US
using flat-plate solar collectors (at 10
efficiency)! It can complement existing systems
and is becoming more attractive for peak power
additions Disadvantages Its very
costly Sunlight is an intermittent
source However, as costs diminish price of
fossil fuels increase, solar electricity will
become very competitive
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Solar Thermal Electricity (Fig. 4.3)

• Trough system
• Oil in pipe is heated to 400C
• Heat is used to generate electricity in
  conventional generator.

This solar thermal power plant located in the
Mojave Desert in Kramer Junction, California, is
one of nine such plants built in the 1980s.
During operation, oil in the receiver tubes
collects the concentrated solar energy as heat
and is pumped to a power block (in background)
for generating electricity.
For a picture of how this works
see http//www1.eere.energy.gov/solar/review_meet
ing/pdfs/prm2008_cohen_acciona.pdf
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Solar Thermal Electricity (Fig. 4.3)

• Power Tower
• Uses molten salt at 565C
• Heat is used to generate electricity in
  conventional generator.
• Can operate 65 of year without backup

This 1996 photo shows the solar tower and
surrounding field of mirrors for Solar Two, a
demonstration project located near Barstow,
California.
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Solar Thermal Electricity (Fig. 4.3)

• Dish
• Energy is directed to focal point
• Powers an engine generator directly at 800C
• Good for remote power needs

This solar dish-engine system is an electric
generator that "burns" sunlight instead of gas or
coal to produce electricity. The dish, a
concentrator, is the primary solar component of
the system, collecting the energy coming directly
from the sun and concentrating it on a small
area. A thermal receiver absorbs the concentrated
beam of solar energy, converts it to heat, and
transfers the heat to the engine/generator.
(Credit Sandia National Laboratories)
10
Photovoltaic Electricity

• Sunlight can also be transformed directly into
  electricity via the photovoltaic effect.
• When light is absorbed by certain materials,
  electrons get excited and move.
• Advantages
• Simple and versatile
• Portable (road signs)
• Can be much less expensive than grid extensions
• Disadvantages
• Its still more expensive than conventional
  power (3 times)

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Photovoltaic Electricity

• Semiconductors a look at bonding
• Metals (conductors)
• Nonmetals (insulators)
• Semimetals (semiconductors)
• Photocell Design
• How do we get the electrons to move?

12
Photovoltaic Electricity
n-layer is doped with As p-layer is doped with
Ga
This results in an electric potential the cell
acts like a battery
13
Hydroelectricity Uses running water to turn a
turbine and generate electricity. Provides about
20 of worlds electricity needs. Advantages   
  Disadvantages

• No CO2 or other emissions
• Small facilities can utilize riverflow directly
• Large facilities require a dam (which can be
  beneficial)
• Riverflow is variable
• Dams can be harmful to environment
• Future development is very limited

Beauharnois DamThe Beauharnois Dam on the St
Lawrence Seaway harnesses some of the river's
enormous electric potential (photo by J.A.
Kraulis). Produces 1658 MW.
14
Wind Power The technology has been around for
2000 years to harness the power of the wind.
15
Fastest-Growing Energy SourceTaking Off Worldwide
Wind Leaders 1. Germany (2.3) 2. United
States(.2) 3. Spain (2.4) 4. Denmark (13) 5.
India (0.6)
World Total (at the end of 2001) Nearly 24,000 MW
Based on information supplied by International
Energy Agency and the American Wind Energy
Association.
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Cost of Wind Energy
12
10
8
Low wind speed sites
COE (/kWh constant 2000 )
6
Bulk Power Competitive Price Band
High windspeed sites
4
2
0
1990
1995
2005
2010
2015
2020
2000
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An All American Resource
World Class Wind Potential
Germanys Potential 100 GW North Dakotas
Potential 250 GW
Slide Courtesy of the American Wind Energy
Association.
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The Community Energy Wind Farms
The 15-MW Mill Run Wind Farm Fayette County,
PA On-Line October 2001
The 31-MW Fenner Wind Farm Madison County,
NY On-Line June 2002
The 9-MW Somerset Wind FarmVisible From the PA
Turnpike On-Line October 2001
The 61-MW Pocono Wind Farm Northeast of
Scranton, PA Expected On-Line Fall 2003
The 66-MW Mountaineer Project Allegheny Plateau,
WV On-Line December 2002
The 7.5-MW Jersey Atlantic Project Atlantic
City, NJ Expected On-Line Spring 2004
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Who uses wind?
Allegheny College 7.5
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Wind Powers Low Environmental Impact
Rating -- Power Scorecard
21
Ocean Energy

• Tidal Energy in the research stages
• Using Temperature Gradients
• In Hawaii Ocean Thermal Energy Conversion
  (OTEC) integrated power, air conditioning, water
  and farming activities

22
Geothermal Energy Using the earths molten core
(hot springs, volcanos) Currently supplies 0.3
of worlds electricity (high T - 150C) Can also
be used for space heating, industrial process
steam, greenhousese, and aquaculture (medium T
90 - 150C) Low T (lt90C) can be coupled with
heat pumps for home heating and cooling.
The first modern geothermal power plants were
also built in Lardello, Italy. They were
destroyed in World War II and rebuilt. Today
after 90 years, the Lardello field is still
producing.