ENERGY RESOURCES AND

CONSUMPTION

Sources, Concepts and Conservation

Energy Concepts Forms of Energy

1. Mechanical: 2 types; mechanical potential (energy of position) and kinetic (energy of motion)

2. Thermal: Heat is the internal energy in substances- the vibration and movement of atoms and molecules within a substances

3. Chemical: energy stored in bonds between atoms in a molecule

4. Electrical: results from the movement of electrons5. Nuclear: energy stored in the nuclei of atoms. It is released

by either fission (splitting) or Fusion (combining) of atoms6. Electromagnetic: Electromagnetic energy travels by waves

Power and Units Power: the amount of work done per time.

Work done/ time The most common unit is kilowatt-hour

(kWh)

Units of Energy/PowerUnit or Prefix Description

Btu ( British Thermal Units)

•Unit used in US, most countries use – joule.• the amount of heat required to raise the temp of 1 pound of water by 1 degree F.•1 watt is approximately 3.4 Btu/hr•1 horsepower is approximately. 2,540 Btu/hr•12,000 Btu/hr is called a “ton”

Horsepower •Primarily used in the auto industry.•1 horsepower (HP) = 746 watts

Kilo- •Means 1,000 or 103

• 1kW = 103 wattsMega- •Means 1,000,000 or 106

•1 MW = 106 wattsWatt (electrical) •A kilowatt-hour(kWh) is the amount of energy expended by a 1

kilowatt (1000 watts) device over the course of 1 hour.•Measured in the context of power plants and energy bills

Watt (thermal) •Nuclear power plants produce heat measured in thermal watts

Energy Conversion Problems These conversion problems are often on the AP

exam!Use scientific notationUse the factor-label method:

○ The factor-label method: the sequential application of conversion factors expressed as fractions and arranged so that any dimensional unit appearing in both the numerator and denominator of any of the fractions can be cancelled out until only the desired set of dimensional units is obtained

Scoring these problems by steps: 1 point correct set-up, 1 point correct calculations, No points if work is not shown!

Conversion of MW to kW Example Problem (Handout p283-285 Barrons)

20 MW X (1 x 106 watts) X 1kW = 2 X 104 kW

1 1MW 103 watts

2 X 104 kW X 8,000 hours = 16,000 X 104 kWh/yr 1 1 yr = 1.6 X 107 kWh/yr

Remember : NO CALCULATORS in the exam

Laws of Thermodynamics 1st law

Energy cannot be created or destroyed 2nd law

When energy is transformed, a less useful form is the result (lower quality energy)

Energy cannot be recycled to a higher quality○ Only 20% of energy in gasoline is converted

to mechanical energy○ 80% is lost as heat (a low quality energy)

Energy Consumption Wood (a renewable source) was the

predominant form of energy up until the Industrial Revolution.

Coal (non-renewable) then surpassed wood’s usage

Coal was overtaken by petroleum in the middle of the 20th century and remains the primary source worldwide today

Natural gas and coal experienced rapid development in the 2nd half of the 20th century

US Energy Consumption by Source

US Energy Consumption US was energy independent, self sufficient until

the late 1950’s Then energy consumption began to outpace

domestic production This led to oil imports The largest energy consumers have always

been industry, followed by transportation, then residential, and commercial uses

Rapid increases in petroleum consumption continued through the 1970’s

Energy Consumption vs. Production

Energy Consumption vs. Production Beginning 1998, net imports of oil

surpassed the domestic oil supply in the US

The US consumes 25% of the worlds petroleum production

Energy Consumption in US by End Use

Leading Petroleum Consumers

Present Global Energy Use In the US most of the energy comes

from nonrenewable energy sources (limited supplies) such as:coal, petroleum,natural gas,Propane and uranium

Global Renewable Energy Sources Renewable sources: relatively short

replenishment timeBiomassGeothermalHydropowerSolar energyWind energy

US Energy Production vs. Consumption

Commodity US Production US ConsumptionOil 18% 39%

Natural gas 27% 23%

Coal 33% 23%

Nuclear 10% 7%

Renewable (geothermal, biomass, solar, wind) 9% 3.6%Hydroelectric 5% 4%

US Energy Production by SectorSector %

Transportation 27%

Industrial 38%

Residential and commercial 36%

Fossil Fuel Consumption by the US

Commodity % of total world usageOil 40%

Natural gas 23%

Coal 23%

Future Energy Needs Outlook for next few decades

Continued growth and reliance on the three major fossil fuels○ Petroleum○ Coal○ Natural gas

Realistic, economical viable resources for the future○ Clean coal○ Methane hydrates○ Oil shale○ Tar sands

Clean Coal Coal is abundant, able to meet global

needs for many years to come Clean Coal: Process which reduces

negatives of burning coalIncludes:

○ washing the coal to remove impurities and minerals

○ capturing SO2 and CO2 from the flue gasses

1. O2 added to promote more complete burn2. Coal is pulverized- more complete burn, and washed to remove contaminants3. ash removal, via electrostatic precipitators4. steam is condensed and returned to boiler5. CO2 is recovered using lime, and sequestered

Methane Hydrates

Oil Shale

Tar Sands