BIOLOGY 157: LIFE SCIENCE: AN

ENVIRONMENTAL APPROACH (Energy needs: Fuel)

ENERGY

• Energy is the ability to do work

• Humans use energy of two types

Internal (= food)

External or Auxiliary (= fuels, etc.)

EXTERNAL (= AUXILLARY) ENERGY

• This includes all those energy sources we do not use directly to fuel our bodies.

• On the average during the 20th century population doubled every 37 years (about 1.9% per year).

• HOWEVER, on the average, External Energy use doubled every 20 years during the 20th century. This amounts to a 3.5% increase per year.

• Why the difference?

ENERGY QUALITY

IMPORTANCE OF AUXILIARY ENERGY

RELATIVE INPUTS OF MAJOR TYPES OF AGRICULTURAL SYSTEMS (I)

RELATIVE INPUTS OF MAJOR TYPES OF AGRICULTURAL SYSTEMS (II)

RELATIVE INPUTS OF MAJOR TYPES OF AGRICULTURAL SYSTEMS (III)

RELATIVE INPUTS OF MAJOR TYPES OF AGRICULTURAL SYSTEMS (IV)

U.S. ENERGY SOURCES (I)

U.S. ENERGY SOURCES (II)

U.S. ENERGY SOURCES (III)

U.S. ENERGY SOURCES (IV)

USE OF ENERGY IN THE U.S.

CLASSES OF ENERGY SOURCES

• Renewable solar, wind, hydropower, hydrogen

• Potentially Renewable wood and other biomass sources, alcohol,

methane (from present day organic matter)

• Non-renewable fossil fuels, uranium

ENERGY: MDC / LDC; RENEWABLE vs. NON-RENEWABLE

ENERGY: WORLD / U.S.; RENEWABLE vs. NON-RENEWABLE

ENERGY WASTE

STATUS OF FOSSIL FUELS (I)

• OIL• Estimated total -------- 2 trillion barrels

(of recoverable oil) (2,000,000,000,000)

• used to date ------------- 0.465 trillion• proven reserves -------- 1.15 trillion• anticipated reserves --- 0.530 billion

• AT CURRENT RATE OF USE:• proven reserves will last 40 years• anticipated reserves will last 19 years

STATUS OF FOSSIL FUELS (II)

• NATURAL GAS• Estimated recoverable total ---- 10,000 trillion ft3

• used to date ------------- 2,500 trillion

• proven reserves -------- 6,200 trillion

• anticipated reserves --- 1,300 trillion

• AT CURRENT RATE OF USE:

• proven reserves will last 60 years

• anticipated reserves will last 16 years

STATUS OF FOSSIL FUELS (III)

• COAL• Estimated total -------- 10,000 billion tons

(= 10 trillion)• used to date ------------- 1,000 billion• proven reserves -------- 1,200 billion• anticipated reserves --- 7,800 billion (IF all

is recoverable)

• AT CURRENT RATE OF USE:• proven reserves will last 200 years• anticipated reserves will last 1,300 years

STATUS OF FISSIONABLE NUCLEAR FUELS

• U235 and Pu239

• Current rate of use ----- 100 to 200 years

• Extended by Breeder Reactors ----- by 10x ???????????????????

HOW A NUCLEAR REACTOR WORKS (I)

• A ‘controlled’ atomic bomb

• most reactors use the fissionable U235

• fission - the splitting of atoms

• splitting of atoms releases energy

• the released energy is normally used to heat water (or some other liquid) and this heated liquid can be used to heat water to steam to run turbines to generate electricity

HOW A NUCLEAR REACTOR WORKS (II)

• small pellets of the fuel (U235) are embedded in fuel rods

• fuel rods are bundled in clusters

• between each cluster are damper rods (usually of boron or cadmium) which absorb neutrons

• the reaction rate is controlled by how far the damper rods are inserted between the fuel rod assemblies

HOW A NUCLEAR REACTOR WORKS (IV)

NUCLEAR FISSION (I)

NUCLEAR FISSION (II)

NEW AND / OR ALTERNATIVE FUELS (I)

* = renewable or potentially renewable# = not renewable and reasonably limited@ = not renewable but extremely abundant = does not produce CO2

• # TAR SANDS AND OIL SHALE

• * GEOTHERMAL ENERGY

• * WIND ENERGY

• * TIDE ENERGY

• * SOLAR ENERGY PASSIVE, ACTIVE, PHOTOVOLTAIC

NEW AND / OR ALTERNATIVE FUELS (II)

• * HYDROGEN

• * WOOD & other BIOMASS MATERIALS

• * METHANE and ALCOHOL (from organic materials) = ‘Biofuels’

• * HYDROCARBONS (‘OIL’) FROM PLANT SAP

NUCLEAR• # Fission• @ Fusion

Is it ‘worth’ it?

NUCLEAR FUSION

CONSERVING ENERGY (I)

• It costs only 1/4 to 1/3 as much to ‘save’ a unit of energy as to mine, extract, produce, etc. a ‘new’ unit.

• 1) EDUCATION to be less wasteful, to do things differently & more efficiently

• 2) More AND / OR better insulation in buildings

• 3) Less lighting AND / OR more efficient lighting

• 4) Less heating-cooling AND / OR more efficient heating-cooling

CONSERVING ENERGY (II)

• 5) More efficient gas and electric appliances, motors, engines

• 6) More efficient transportation systems (mass transit & shipping; carpooling)

• 7) More efficient production and transmission of energy

• 8) Restructuring of population centers (layout and size)

• 9) Better (longer lasting) products (cars, appliances, furniture, etc.)

SOME QUESTIONS FROM CHAPTER 12

• In what country do the people use the most energy per capita? Is this surprising?

• What is the most efficient (in use of fuel) way to transport freight: truck or train?