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 electrons 5. Nuclear: energy stored in the nuclei of atoms. It is released by either fission (splitting) or Fusion (combining) of atoms 6. 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/Power Unit or PrefixDescription 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” HorsepowerPrimarily used in the auto industry. 1 horsepower (HP) = 746 watts Kilo-Means 1,000 or kW = 10 3 watts Mega-Means 1,000,000 or MW = 10 6 watts Watt (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 notation Use 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 p Barrons) 20 MW X (1 x 10 6 watts) X 1kW = 2 X 10 4 kW 1 1MW 10 3 watts 2 X 10 4 kW X 8,000 hours = 16,000 X 10 4 kWh/yr 1 1 yr = 1.6 X 10 7 kWh/yr  Remember : NO CALCULATORS in the exam

Laws of Thermodynamics  1 st law Energy cannot be created or destroyed  2 nd 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 20 th century and remains the primary source worldwide today  Natural gas and coal experienced rapid development in the 2 nd half of the 20 th 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

 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 time Biomass Geothermal Hydropower Solar energy Wind energy

US Energy Production vs. Consumption CommodityUS ProductionUS Consumption Oil18%39% Natural gas27%23% Coal33%23% Nuclear10%7% Renewable (geothermal, biomass, solar, wind)9%3.6% Hydroelectric5%4% US Energy Production by Sector Sector% Transportation27% Industrial38% Residential and commercial36%

Fossil Fuel Consumption by the US Commodity% of total world usage Oil40% Natural gas23% Coal23%

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 coal Includes: ○ washing the coal to remove impurities and minerals ○ capturing SO2 and CO2 from the flue gasses

1. O2 added to promote more complete burn 2. Coal is pulverized- more complete burn, and washed to remove contaminants 3. ash removal, via electrostatic precipitators 4. steam is condensed and returned to boiler 5. CO2 is recovered using lime, and sequestered

Methane Hydrates

Oil Shale

Tar Sands