Perspectives on Alternative Energy

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					Perspectives on Alternative Energy
By David Bennett, Obi Nwachuku & Wei Chieh Wong

What we wish to learn
• What are the pros and cons of both renewable and nonrenewable energy? • Is the implementation of renewable energy in modern society realistic? • We will use coal as an example of renewable energy; solar and wind power for nonrenewable energy

World Energy Use

Coal Pollutes
• Coal’s combustion adds more carbon dioxide emissions to the atmosphere than any other resource (38.2% of ALL CO2 IN THE WORLD from coal plants in 1999) • Coal plants also emit toxins such as sulfur dioxide, nitrogen oxide, carbon monoxide, hydrocarbons, and the list goes on…

Coal: Health Effects /04/eng20051004_212470.html

Coal: Health Effects
• Coal mining deaths are common • In 2004, 6,434 Chinese miners died on the job • The pollution from nearby factories often enters houses and gets trapped inside due to poor ventilation

Coal: Pros
• The only thing that keeps some countries, such as China, using coal is because it’s • A) Cheap: about 4 cents for every kilowatthour of energy produced, or 3,600,000 J • B) Efficient: when coal is burned, about 40% of its energy is converted into electricity

So, is coal worth it?
• Pros • It’s cheap • It’s efficient • Cons • It pollutes • It releases lots of CO2 = lots of global warming • Mining it is dangerous • Strip mining destroys the environment • It’s non-renewable

an alternative form of energy is called for!

Wind Power?
• While coal is terrible for the environment, wind power is not only a renewable resource, but it also doesn’t pollute!

Wind Power?
• In fact, wind is also pretty cheap: it’s only 3-4.5 cents/kilowatt-hour (kWh) • BUT, that’s because it’s making it’s money back over time—that’s the bonus of renewable energy • Of course, it is expensive to install in the first place, around $800,000 for a big 750 kW turbine • But over time, it’ll get even more back

Wind Power?
• Wind power has about 20% conversion efficiency—only about half as much as coal power • There are two factors in determining how much power you’ll get: wind speed, and wind consistency

Wind Power?
• Of course, wind power does have its drawbacks:
• A) Wind farms take up a lot of space • B) They can dominate a landscape that might otherwise have aesthetic value • C) They can kill birds or interfere with television reception

So what?
• Overall, wind power looks good! • But, it’s hard to implement in a rapidly developing country without much money (like China or India) • And, wind power probably wouldn’t be able to meet such huge power demands • However, implementing it little by little, and hoping that it becomes more efficient and cheaper FAST seems logical

How about…Solar Power?
• Solar power is also a renewable form of energy

Solar Energy?
• But, it’s a little more expensive than the others, at 30 cents/kWh • In addition, while coal and wind power could operate all day (and night) long, solar energy is only effective during a few hours in the day

Solar Energy?
• The sun’s energy is typically harnessed through photovoltaic cells to convert the sun’s power into usable energy • These cells convert the sun’s energy into electricity at 10-15% (not the best) • Large, flat expanses of land are usually needed, BUT they can also be conveniently placed on rooftops

Solar Energy?
The good news is, there’s great payback over time!

So don’t sell it short…

Solar Energy?
• A common use of solar energy is to heat homes

Solar energy, good stuff?
• It might be a little too expensive and not cost-effective enough to replace coal power in developing countries yet, but they’re working on it!

So, which is the best?
For price, it’s two against one.

Comparison of Prices for Energy obtained

Cost (cents) per kilowatts per hour (kWh)

25 20 Photovalic Power 15 10 5 0 Coal Power Wind power on shore Wind power off shore

So, which is the best?
However, when we project into the future, things get closer!
Comparison of cost of different forms of energy, projected until 2010
60 50 coal wind (class 4) wind (class 6) photovalic (utility scale) photovalic (solar thermal)

Cents per kilowatt-hour

40 30 20 10 0 1995 2000 Year 2005 2010

• What’s important is that we STOP global carbon dioxide emissions, saving our lungs and stopping global warming. • We made a projection as to how much the carbon dioxide levels will go down as we start using more renewable energy…

As we use more renewable energy, carbon dioxide concentration goes down!
1: Atmospheric CO2 ppmv 1: 550

1: Atmospheric CO2 ppmv 1: 550


450 1 1 1


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90% Fossil Energy , 10% Renewable Energy

1: Atmospheric CO2 ppmv 1: 455

1: Atmospheric CO2 ppmv 1: 435

1 1: 405 1

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80% Fossil Energy , 20% Renewable Energy

70% Fossil Energy , 30% Renewable Energy

• It’s not easy to quantify exactly which renewable resource is better—each has its pros and its cons • The fact is: anything is better than coal! • Renewable energy may not replace fossil fuels overnight, but a push towards them is mandatory if we are to stop global warming

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