Review topics for Test 3
Fossil Fuels
Natural gas – global reserves, geologic occurrences (with coal and with oil), drawbacks of natural gas
Marcellus shale
Hydraulic fracturing – how it works, key considerations, potential for contamination
Methane hydrate – definition, characteristics, energy potential and possible implications for climate
Tar sands, oil shale, coal-bed methane – formation, locations, environmental impacts
Climate change
How we know Earth’s climate history:
O18 (oxygen isotope) ratios from organisms’ shells give temperature for last 540 million years
O18 ratios from ice cores give temperature for last 740,000 years
Characterize Earth’s current climate on different time scales:
Millions of years: cold
Hundreds of thousands of years: 100,000-year-cycles of glacial periods and warm interglacials
Thousands of years: current interglacial since ~10,000 years ago
Decades: dramatic warming of last century (with mid-20th century plateau)
Causes of long-term climate change:
Tectonic: positions of continents, rates of movement
Shifts in Earth’s orbit: Milankovitch cycles, 100,000-year ellipticity cycle, angle of axial tilt,
precession
Earth’s atmosphere: composition, greenhouse effect, greenhouse gases – their characteristics and
relative importance
Climate modeling: temperature increases of end 20th century, correlation between CO2 levels and
temperature for last million years, forcing mechanisms (solar, volcanic, anthropogenic)
Atmospheric CO2 levels: typical glacial period, typical interglacial, today (in ppm)
Estimate of temperature increase over next century
Expected effects of 21st century warming: pattern of warming, precipitation changes, sea level rise
(Efforts to remove CO2 from atmosphere)
Renewable Energy
Names and examples for types of solar energy: passive, photovoltaic (individual panels and large plants)
low- and high-temperature thermal
Hydropower – characteristics, advantages and disadvantages of large hydroelectric dams, run of the
river dams, wave converters, tidal and current power
Advantages, disadvantages, innovations of wind power
Examples of bio-energy: plant waste, urban waste, methane gas, bio-diesel, ethanol (corn or sugar cane),
algae (absorbs CO2 and forms hydrocarbons)
Characteristics of geothermal electricity, enhanced geothermal, geothermal heating
Definition of ocean-temperature energy conversion (OTEC)
Nuclear fission: recent decline, abundant but non-renewable uranium
Chain reaction of fission, proportion of U-235 and U-238
Accidents at Chernobyl 1986, Fukushima 2011
Fusion – definition, hydrogen → helium, pressure/temperature (Sun)
Reactor shapes – tokamak, stellator
Hydrogen use in fuel cells
Grey, blue, green, white hydrogen
