Bio 111 Alternative Energy Options Week10

8/2/2019 Bio 111 Alternative Energy Options Week10

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Alternatives to Fossil

Fuels


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Nuclear Energy


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Atomic structure

all matter made of atoms

each atom composed of anucleus that contains protons(+ charge), and neutrons

(neutral) nucleus surrounded by a

cloud of orbiting electrons (-charge)

interesting factoid: orbitingelectrons moving at almostthe speed of light!


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Isotopes

in most atoms, # of protons = # of neutrons, butnot always

# of neutrons can vary

different forms of an element called isotopes

most elements a mixture of isotopes - some stable,but some not


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Radioactive decay

unstable isotopes throw off particles and emit

radiation from their nuclei as they decay

referred to as radioisotopes

over time, mass of radioisotopes actually

decreases measure of the decrease (rate of decay) called

half-life

half life - length of time it takes for 1/2 of theradioactive mass to decay to a stable form

half lives of isotopes vary from a fraction of asecond to tens of thousands of years


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Half life of isotopeslength of time until half of the material decays


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Chain reactions

nuclear fission gives off enormous amounts ofenergy

opportunity exists for a chain reaction - series ofsteps that occur one after the other, in sequence

example: forest fire if heat from one tree spreads to second tree and

second to third - fire burns at steady rate

but if one burning tree ignites two other trees and each

of these two ignite two more and so on, rate of burningwill speed up

acceleration called a branching chain reaction


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if a branching chain reactioncontinues rapidly, energy isreleased at an increasing rate

results in an atomic explosion

(see a movie of an atomic explosion at

http://www.youtube.com/watch?v=H1sS1TmXF38

if the chain reaction is carefully

controlled, energy can be releasedslowly for useful purposes
http://www.youtube.com/watch?v=H1sS1TmXF38http://www.youtube.com/watch?v=H1sS1TmXF38http://www.youtube.com/watch?v=H1sS1TmXF38http://www.youtube.com/watch?v=H1sS1TmXF38


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Nuclear fission

process starts when a neutron strikes a U-235nucleus

nucleus splits

kinetic energy released as fission products flyapart

flying fragments hit other atoms and transferenergy - releases heat

energy released by nuclear reactions muchgreater than amount released by chemicalreactions


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Nuclear power production

less than 1% of mineduranium contains theisotope needed fornuclear fission

processed (enriched)uranium formed intopellets

pellets inserted into

thin tubes called fuelrods (about 12' long,1/2" diameter)

pellets of enriched uranium

on palm of hand


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fuels rods are bundledand lowered into the

core of the reactor

control rods fitbetween the fuel rods

control rods can beraised or lowered tocontrol the rate offission


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fuel rods inserted intoposition in the reactorcore

the reactor core is

contained by a reactorvessel with 6" steelcasing

in most countries,

reactor vessel housedin a containmentbuilding with 4' thickcement walls


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Nuclear power plants

similar to coal plants in that heat is used toproduce steam to drive a turbine

energy released from nuclear fission in the fuelrods heats water bathing the reactor core

to avoid radioactive contamination, the wateris contained in huge pipes in the wall of thereactor vessel


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not all reactors havecomplete containment

buildings nuclear reactor at

Chernobyl had onlypartial containment

proved inadequate inthe accident in 1986

20 of the former

Soviet Union's 44reactors now inoperation have thesame design


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Radioactive waste about 1/3 of old fuel

rods (40-60 rods) arereplaced annually

entire assembly,

containing unuseduranium, newly formedplutonium, and wasteproducts, is removed

all components willcontinue to beintensely radioactivefor a long period of

time

storage of nuclear wasteremains a problem - oneproposed solution - storagetunnels under Yucca Mountain,

Nevada


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most people in the world stillget their energy from burningplant or animal products

people who burn wood indeveloped countries do so outof choice, but for most of theworld's poor, fossil fuels are

simply not available or tooexpensive

wood or cow dung are theonly possible alternatives

this has caused timberdepletion and deforestationaround the world

biomass is renewable only ifnot overharvested


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Problems with biomass fuels

wasted time and potential

in rural areas wood is scarce - people spend a large portion oftheir time simply finding the fuel needed to cook their meals

Africa - women and children often travel 50 km/day hunting forfuel wood (wasted time on this task prevents girls and womenfrom getting an education and seeing to other needs)

Asia - common for families to spend 1/4 of their income or 1/4 oftheir time obtaining fire wood

Andes Mountains of South America - families must support anextra donkey just to collect and haul fire wood

wasted resources when manure is burned instead of wood, this represents the loss

of a potential source of fertilizer

a conflict arises - when the dung is burned to cook today's dinner,there's less fertilizer available to grow food for the following

season


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biogas - creative, low-tech solution to both theenergy and fertilizer problems

manure from cattle dung and night soil is converted into a clean source of energy.helps in conservation of fuel wood, improves sanitation and generates

employment in rural areas.

manure

biogas generator


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Biogas

when sewage, garbage, manure, or cropresidues decompose in the absence of oxygen,methane (natural gas) is released

methane produced in this manner is calledbiogas

methane produced from wastes is identical tomethane extracted from underground deposits

Basics of biogas conversion


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Basics of biogas conversionNote: this would be a great time to review the action

of decomposers in ecosystems!

fermentation of manure generates methane

anerobic bacteria feed on the undigestedvegetation in the manure and perform cell

respiration to convert food energy to ATP energy because cell respiration in occurring in a low

oxygen environment, the waste product producedis methane (instead of carbon dioxide)

the methane gas is used for cooking, lighting andelectricity generation


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Biogas residue makes excellent fertilizer

review: mineral nutrients contain no foodenergy and aren't biodegradable

after the biogas is released, the decomposed

manure is removed and spread on farm fields asa high quality fertilizer

construction costs are returned in 1-3 years byfuel savings

tens of thousands of units have been built inChina and elsewhere through Asia


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manure to energy projects work in developedcountries too! example: dairy farm operated oncow manure


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Waste to energy

about 300 plants worldwide burn municipalgarbage to generate electricity or produce steamto heat homes and offices

largest facility - Rotterdam, Germany - 550

megaWatt plant (about half the output of alarge nuclear reactor) operates entirely onrefuse

Munich, Germany - generates 12% of itselectricity by burning garbage

North America - is a largely unexploited resource


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conversion of municipal solid waste to energy


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Cost/benefit analysis from U.S. projects

Modesto, CA - methane from sewage treatment iscollected and used in city vehicles

cost of setting up the system and maintenance is equivalent tobuying gasoline at 30 cents/gallon

Brooklyn, NY - drilled more than 100 gas wells into thecore of an extensive landfill outside the city

about 3.5 million cubic feet of methane are collected every dayfrom decomposing garbage

city realized a profit of $600,000 in the first year of operation of

the wells 25,000 homes are supplied with heating and cooking gas from a

source that otherwise would have been wasted

Bi f l t l t i it d


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Biofuels can generate electricity andpower vehicles

fermentation of vegetation producesethanol

energy conversion from crop to fuel is quitelow - some plants more efficient than

others the higher the % of cellulose in the

vegetation, the better the conversion, butcorn is quite low in fiber

sources with the potential for higherefficiency: lumber waste (from sawmills),reeds and other marsh plants, algae, fungi

Drawbacks to biofuel production to


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Drawbacks to biofuel production topower vehicles

methane isclean in regardto many airpollutants, butstill releasescarbon dioxide(majorgreenhousegas)

FYI - methaneis a greenhousegas too

Drawbacks to biofuel production to


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ethanol from corn, sugar beets, sugar cane, and biodieselfrom oil seeds, all require high-quality agricultural land forgrowth

in U.S, large quantities of fossil fuels used to plant, harvest,

and transport the corn that's used to produce ethanol additional fossil fuels used to manufacture fertilizers and

pesticides

more fuel needed to cook the grain, warm the sugar as itferments, and distill the mixture to obtain pure alcohol

therefore, when the whole process is taken into consideration,there's little real conservation of fossil fuels

in less industrialized countries, such as Brazil, farmers usemore manual labor and less fuel to raise crops, so the energybalance in ethanol production is more favorable


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ethanol productionhas raised world foodprices

more difficult to raisethe money forimported food indeveloping countries

Source: USDA NationalAgricultural Statistics Service


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Solar Energy


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Passive solar design

simplest way to use solar energy - design andorient a house so that the structure itself collectsand stores heat from the sun

many ancient civilizations used passive solar

design was standard in ancient Greece and Rome - in

Vesuvius, Romans had solar bath houses

Greek playwright Aeschylus believed onlyuncivilized barbarian societies didn't understandthe concept of solar design

what do you think?


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passive solar used inthe Americas sincethe Anasazi built cliffdwellings in the

American Southwest

they chose southfacing cliff sites fortheir homes

Gila cliff dwellings New Mexico


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Canyon de Chelly, Arizona


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in winter, the sun shines directlyinto the buildings providing heat

in summer, the sun is higher in

the sky

the edge of the cliff acts as anawning to provide cooling shade


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Gila cliff dwellings New Mexico

view from inside the cliff dwellings

H l d f th t?


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Have we learned from the past?

today many

people in theSouthwest livein rectangularhouses

oriented andconstructed sothat largeamounts offossil fuels areneeded toprovide heat

and cooling


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basics of passivesolar design

use heat-absorbingconstructionmaterials

south facingwindows maximize

sunlight capture inwinter

plant trees and othervegetation around

buildings

H d l k?


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How does solar power work?

active solar -

photovoltaic (PV)cells contain siliconand other elements

sunlight excites

electrons which areejected from thesilicon atoms

ejected electronsflow out of the PVcells through awire, producing

electricity


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passive solar home

active solar home


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i t lli l l k fl t f


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installing solar panels - works on any flat surface


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PV cells Georgetown University Intercultural Center

can supply half of the building's electricity needs


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PV panels can be fragile and expensive

new, improved products are on the market

these are solar shingles (thin film solar cells)

less fragile, much cheaper, more durable


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this is the coolest thing since sliced bread - solar paint!

several years in development, seems to be about ready to

hit the market http://news.nationalgeographic.com/news/2005/01/0114_

050114_solarplastic.html
http://news.nationalgeographic.com/news/2005/01/0114_050114_solarplastic.htmlhttp://news.nationalgeographic.com/news/2005/01/0114_050114_solarplastic.htmlhttp://news.nationalgeographic.com/news/2005/01/0114_050114_solarplastic.htmlhttp://news.nationalgeographic.com/news/2005/01/0114_050114_solarplastic.html


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these examples and thefollowing are just for fun, butthey can be useful


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I saw this guy in the airport andasked if I could take his photo - thebackpack charges his laptop(plugged in inside) while he walksaround

I have a radio similar to thisand they work great -especially for a day at thebeach

solar car race from DC to California - colleges and universities entered


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solar car race from DC to California colleges and universities enteredcarsthe race started at L'Enfant Plaza a few years ago, so I was able to getthese photos


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New solar technologieslearn more at

http://www.nanosolar.com/

G th l
http://www.nanosolar.com/http://www.nanosolar.com/


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Geothermal energy energy from the heat in the earth's crust

core of the earth is a large mass of moltenmaterial called magma - temperature upto 800F.

in most places, magma is many miles

below ground, but some locations, itcomes close to the surface and createshot spots

when groundwater comes in contact withhot spots, the water turns to steam

example: geysers in Yellowstone NationalPark

see some cool video athttp://www.yellowstonenationalpark.com/

geysers.htm

Geothermal
http://www.yellowstonenationalpark.com/geysers.htmhttp://www.yellowstonenationalpark.com/geysers.htmhttp://www.yellowstonenationalpark.com/geysers.htmhttp://www.yellowstonenationalpark.com/geysers.htm


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Geothermalpower

Geothermal power


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Geothermal power the steam is used to spin

turbines that drive

electric generators

problem: the steam oftencontains minerals thatcan clog and corrode the

generating equipment U.S. has 1.8 million acres

of land wheregeothermal energy is

known to exist has potential to become

an important source ofelectricity

geothermal power plant - Iceland

H d l i


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Hydroelectricpower

turbine hydroelectric power

Interesting wind power factoids


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Interesting wind power factoids

since ancient times, people

have harnessed wind energy over 5,000 years ago,

Egyptians used windmills to sailships on the Nile River

later, people built windmills togrind wheat and other grains

earliest known windmills usedin Persia (present day Iran)

American colonists usedwindmills to grind wheat andcorn, to pump water, and tooperate sawmills

Wi d


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Wind power

fastest growingenergy sector

estimated that windgeneration could

produce about 40%of the country'spresent energy needs

technology needed to

build infrastructure isrelatively simple andcommerciallyavailable


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just wanted you tosee the real size ofcommercialwindmills

use the person onthe top for size

comparison

of course they comein small, residentialsizes too


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here's a coolcombinationof wind andsolar

when the sunisn't shiningthe wind isprobablyblowing


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The Pickens Plan

T. Boone Pickens, founder/chairman of BP Capital Mgmt.(huge energy-oriented investment fund - $4 billion - and

heavily invested in the oil industry)

despite this, he has a plan to help make the U.S. energy

independent that involves, wind, solar, and natural gas

what do you think of his ideas?

http://www.pickensplan.com/theplan/

(scroll down to see the details of the plan)

Hydroelectric Power
http://www.pickensplan.com/theplan/http://www.pickensplan.com/theplan/


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Hydroelectric Power

water turns

the blades ofthe turbine

the turbinedrives the

generator


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water over the dam

(sorry - I couldn't help myself)

Co-generation


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Co generation(also called combined heat and power - CHP)

simultaneousgeneration ofheat and power

instead of

releasing the heatas a wasteproduct, thereleased heat

provides spaceheating or heatswater to producesteam

the diagram in the following slide represents an idealized co-


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the diagram in the following slide represents an idealized cogeneration and energy sharing system

generation of electricity (blue lines) and steam heat (red

lines) comes from multiple sources besides traditional power plants that supply electricity to

substations for distribution, incineration plants and combinedheat and power plants (CHP) would play a larger role inenergy production

both of these plants could also supply steam for heat and forindustrial processes

waste heat from industrial plants can be piped throughturbines to create additional electricity

small individual CHP generators are now available and can beinstalled in homes and offices to provide both heat and power- they feed any excess electricity back into the grid

Source: Scientific American, January 2009


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Bio 111 Alternative Energy Options Week10