renewable_energy_sources.ppt

7/30/2019 Renewable_Energy_Sources.ppt

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Renewable Energy

Sources

composed byDragica Vasileska


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In the last 100 years, the Earthwarmed up by ~1 C

100 years is nothing by geological time scales!


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Climate change dueto natural causes(solar variations,volcanoes, etc.)

Climate change dueto natural causes

and humangenerated

greenhouse gases

Can we predict the past?


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CO2 Concentration, Temperature, and Sea LevelContinue to Rise Long after Emissions are Reduced

100 years

1,000 years

Sea-level rise due to icemelting: several millennia

Sea-level rise due to

thermal expansion:centuries to millennia

Temperature stabilization:a few centuries

CO2 stabilization:

100 to 300 years

CO2 emissions

CO2 emissions peak

0 to 100 years

Today


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The possibility / likelihood of

global warming is disturbing but there may be a biggerproblem!

Chu


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Consumption of Energy Increased by 85%Between 1970 and 1999

20202015201020051999199519901985198019751970

700

600

500

400

300

200

100

0

Quadrillion Btu

History Projections

By 2020, Consumption will Triple


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World production of oil and gas ispredicted to peak within 10 - 40 years

2010


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Energy conservation and

efficiency can buy time(a factor of ~2)

but the fundamental problem remains


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Electrical generation

Switch from petroleum to coaland natural gas

Why has hydroelectric

declined?

When did nuclear go up?


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Numbers = how long it would last if all energy came from one source

Resource recoverable recoverable and hoped for

Coal 125 1300

Petroleum 5 50?

Natural gas 5 50?

Oil shale 0 2500

Conventional reactors 3 15

Breeder reactors 115 750

Fusion 106 to 109

Geothermal surface 0.2 60

deep rock 0 600

Estimates of depletable energy resources in the U.S.


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Numbers = proportion of current U.S. energy needs that could be supplied foran indefinite period.

Tidal energy 0.1

Organic Waste 0.1

Photosynthesis 0.23

Hydropower 0.14

Wind Power 5

Solar radiation 740

Estimates of renewable energy


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(in the U.S. in 2002)

1-4 2.3-5.0 6-8 5-7

Today: Production Cost of Electricity

6-7

25-50

Courtesy Nate Lewis

0

5

10

15

20

25

Coal Gas Oil Wind Nuclear Solar

Cost


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Energy Costs

0

2

4

6

8

10

12

14

$/GJ

Coal Oil Biomass Elect

Brazil E

urope

$0.05/kW-hr

www.undp.org/seed/eap/activities/wea

Courtesy Nate Lewis


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Potential Sources of Energy whenFossil Fuels Run Out

NuclearFission

Magnetic PlasmaConfinement,Inertial Fusion

Waste &Nuclear Proliferation

Nuclear

Fusion

10 TW = 10,000 new 1 GWreactors: i.e., a new

reactor every other day forthe next 50 years


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Solar, Wind and Water

We do not know how to store electricalenergy on a massive scale


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Geothermal

Heat near surface ofthe earth = geysers,volcanoes, hotsprings


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Photosynthesis Photovoltaic andelectricity to

chemical

H O

O H

2

22

sc M

e

sc

e

M

CO

Sugar

H O

O

2

2

2

Solar to Chemical Energy

Semiconductor/liquid junctions


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Energy gained in cornethanol production


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Total CO2 emissions


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From Summary of Renewable FuelOptions (NCEP)

Unlike corn ethanol, cellulosic ethanol has

potential to achieve near-zero net carbon

emissions.

Cultivation of cellulosic feedstocks requires

very low energy inputs and, if sustainably

managed, the carbon released during fuel

combustion is reabsorbed by the growth of

new feedstocks.


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Use heat to make steam to turn

turbine for electrical generationNote: deep hot waters arecorrosive to best to inject cleanwater in a closed system and bringit back to the surface as steam.

Geothermal Energy in More Details


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In U.S., much done onpublic land = cheap

Very little potential in eastand mid west


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World wide distribution ofvolcanos, hot springs, etc.

Japan, Iceland,New Zealandbig users of geothermal.


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Although hot areas near surface are limited, the earth is hot

everywhere if you go down far enough.


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Bright idea!? drill deep enough to find heat. Since rock is a poor conductor ofheat, set off a big bomb to crack the rock and allow heat to move then pump

down water to make steam.


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Hydropower in More Details


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Hydropower = dams

Not much used in world,

why??


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Norway,Zambia,Ghana bigusers


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Most unused hydropower in U.S. = Alaska,

In World = Canada, Russia


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Problems with hydroelectric

Location = unused rivers are in extremenorth or low population areas

Competition with recreational uses (U.S.)and environmental concerns

Hard to build dams in populated rivervalleys

Siltation of dams limited life.


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Tidal Power

1. In areas of large tides

2. Anywhere buildoffshore dam


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Highest tides in theworld = Bay of Fundy16 meters = 48+ feet!


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Tidal power anywhere

1. No dam but a turbine.

Problems:

1. Corrosion

2. Navigation

3. Appearance

4. Amount of energy availableis low

5. Best tides are near polesaway from people.


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Wind Power Generation


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Best wind location = Aleutian Islands,why no wind development there?
http://www.nrel.gov/wind/images/wherewind800.jpg


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Best U.S. localities

Midwest, mountains

And coastal areas.


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Netherlands =

coastaldevelopment


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England = off shore
http://www.power-technology.com/projects/blyth/index.html


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Wind energy problems

Location near population center

Bird migration

Visual Must be coupled with other sources ofelectricity (intermittent supply)


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Solar Energy in More Details

1. Solar Thermal


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At focal point = heat liquid steamto turn turbine


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S l R f C t ti


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Solar Resource for a ConcentratingCollector


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Big Plants


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2. Solar Photovoltaics


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hard vs soft energy paths

Hard =

1. Big plants

2. Centralized production

Soft =

1. Decentralized

2. units per household


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Big Plants
http://en.wikipedia.org/wiki/File:Nellis_AFB_Solar_panels.jpg


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Energy efficient house; windpower on roof. Solar panelsfor heat and electricity.

Decentralized


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Solar electricity generation


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Solar water heating solar air heating


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Solar house problems

The Los Angeles air = smog

Retrofitting- very expensive

Hard for big hotels, Walmarts, etc.


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Solar house economics

Add $16,000 to price of house

Pay back - $1500 per year in energy costs

15 years to break even

Federal tax incentive; 40% of investment can be written off. Discontinued in1986

City of Claremont solar energy ordinance. 60% of hot water solar

Exceptions for equivalent savings of energy = Colleges approach. Why nottrust solar?

renewable_energy_sources.ppt

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