Physics and Society Lecture 2 October 25, 2004 Richard J. Plano

October 25; Lecture 2/5 Physics and Society 1

Physics and SocietyLecture 2 <> October 25, 2004

Richard J. Plano

Today: Energy

• First a little physics

• The magnitude of the problem

• Solutions (?)

1. Continue? NO!

2. Coal, Oil, Gas? NO!


Agenda (Cont)

1. Wind? Will help.

2. Solar? A possibility (expensive).

3. Nuclear Power? Great idea!

4. Hydrogen economy? Forget it!



Thermodynamics(A dismal science)

No Perpetual Motion Machines!!!

First Law: Energy is Conserved

You can’t win!Second Law: You can’t just take energy from a reservoir and produce an equivalent amount of work.

You cannot break even!Third Law: Entropy (disorder) always increases.

Things are getting worse!


Clean and efficient coal burning

Secretary Abraham Announces $235 Million for Florida Clean Coal Plant

Project Expected to Create More Than 1,800 Jobs

ORLANDO, FL -- Secretary of Energy Spencer Abraham, joined by Governor Jeb Bush, today announced a $235 million grant from the U.S. Department of Energy that will aid in the development of one of the cleanest coal-fired power plants in the world. The project is a team effort led by Southern Company.

The grant comes as part of President George W. Bush’s 2002 Clean Coal Power Initiative (CCPI) to invest $2 billion over 10 years to advance technologies that can help meet the Nation's growing demand for electricity while providing a secure and low-cost energy source and protecting the environment.


The Exxon Valdez in trouble


Typical yield from one barrel of crude oilProduct GallonsFinished Motor Gasoline 19.69Distillate Fuel Oil 9.70Kero-Type Jet Fuel 3.99Residual Fuel Oil 1.76Still Gas 1.89Petroleum Coke 2.14Liquefied Refinery Gas 1.76Asphalt and Road Oil 1.34Naptha for Feedstocks 0.63Other Oils for Feedstocks 0.50Lubricants 0.46Special Naphthas 0.13Kerosene 0.17 Miscellaneous Products 0.17Finished Aviation Gasoline 0.04Waxes 0.04 Total 44.41 One barrel = 42 gallons


The most efficient possible heat engine is

described by the Carnot Cycle.

hT

cT

hQ

cQ

W hchc

hch

TTQQ

TTQWe

/

/1/

Typically hot = 500K; cold=350K

e = 30%

hc QQ 7.0

ch QQW


Energy Usage at the Plano HouseholdElectricity Natural Gas

24 kWh/day=>1 kW average 3.1 Th/dy = 90 kWh/day=>3.8 kW

Annual: 9000 kWh @ $0.12/kWh

$1100

33,000 kWh @ $0.034/kWh

$1150Gasoline: Camry + Prius

15 gal/wk = 780 gal/y @ $2.00/gal = $1560

780 gal => 28,000 kWh


Numbers, Conversion Factors, etc.Energy: kWh, Joule, BTU, Hp-h

Power: kW, Watt, BTU/s, Hp

1 kWh = 3.6E6 Joules = 3413 BTU = 1.3 Hp-h

1 Therm = 1E5 BTU = 29.3 kWh

1 gal gasoline => 49 Hp-h=36.6 kWh .

=>8 lb = 3.6 kg => 3.6E-3 m^3

Natural Gas = 0.30 kWh/ft^3; Coal = 5860 kWh/ton

H2 gas = 39 kWh/kg = 0.09 kWh/ft^3 (STP)

1 m^3 = 35.3 ft^3; 1 Barrel (bbl) = 42 gal

1 tanker carries 250,000/500,000 tons of oil(Seawise Chant is 1504ft x 226ft – 500,000 tons)


Electricity

Total USA: 3.7E12 kWh

Note: 4E8 times Planos

USA Pop 295,000,000 = 3E8

Gasoline

4.7E12 kWh =1.3E11gal

Note: 1.7E8 times Planos

Total Annual Energy Usage in the USA

This is a lot of energy!

One year’s supply of gasoline would fill a tank

30 ft high by 4.5 miles x 4.5 miles!

Need 12 supertankers/day to supply <1/2 of petroleum.


Population!Note that if the U.S. population were the same as when I graduated from high school in 1947 (144 M),

we would NOT have to import ANY oil!

U.S. population is now 295 M and growing!

When I was born in 1929, US pop was 122M and world pop was 2B; in 1900 US was 76M and world was 1.6B. World now: 6.4B.

Much less stress on environment…


Capacity and Production by Fuel

Note that gas, coal, and, especially, nuclear produce more relative to their capacity.


Coal and Natural Gas

One TVA plant uses 14,000 tons of coal/day = 140 railroad cars!

Generates 1E10 kWh/yr; Average of 1200 MW (700,000 homes)

Need 370 such plants to meet USA needs.

If powered by natural gas (0.30 kWh/ft^3), need about 2.74E8 ft^3 each day. A rectangular tank to hold this much at STP would be 30 ft high by 3000 ft on a side.

Both, esp. coal, generate a LOT of CO2 and other junk, leading to global warming and many forms of pollution.


WindmillsWind has kinetic energy:

2

2mv

Must stop the air to get all the energy;

But then no air passes so m=0, so no energy.

Most efficient if leaving air has 30% of its initial speed.

Therefore, windmills must be spaced rather far apart.

Typically 7*D in wind direction and 4*D perpendicular,

D = diameter of propellers


Windmills are

BIG!To supply our electrical needs, about 4,000,000

1 MW windmills are needed!

They need an area 350 miles on a side.

Some dislike them as neighbors.


Could windmills provide all our electrical needs. ???

Use 1 MW windmills; diameter of rotor is 54 m.

Each needs an area:

4D x 7D = 216 m x 378 m = 0.08 km^2 = 0.03 mi^2

A 1 MW windmill generates about 0.2 MW on average, so we need:

8E5 MW/0.2 MW/windmill = 4E6 = 4,000,000 windmills.

These would cover an area of at least 120,000 mi^2 =>

An area at least 350 miles on a side!!!

They are also a danger to birds (and bats),

but cell phone towers pose a much larger hazard.


Wind Power available by state

Note: 1billion kWh = 1E12 kWh

We use 3.7E12 kWh of electricity each year, 3E13 kWh of all kinds of energy.


Problem: Bats in the windmills!

Unusual Alliance Hopes to Keep Bats out of Wind Turbines

•4 March 2004 - Conservationists, industry officials and federal agencies are joining forces to address an unexpected side effect of renewable wind energy. Bats in some parts of the country show an unexplained tendency to collide with the blades of wind turbines. AWEA News Release

http://www.awea.org/news/news040303bat.html

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Physics and Society Lecture 2 October 25, 2004 Richard J. Plano

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