Earth’s Resources Chapter 4

Energy and Mineral Resources Renewable – replenished over fairly short time spans (months, years, decades) Plants, animals, natural fibers trees, water, wind, sun Nonrenewable – takes millions of years to form and accumulate Coal, oil, natural gas, iron, copper, uranium, gold

Fossil Fuels Any hydrocarbon that may be used as a source of energy Coal, oil, natural gas Coal – forms when heat and pressure transform plant material over millions of years. Stages: Peat Lignite Bituminous coal anthracite

Coal Continued Uses: Disadvantages Power plants Enormous reserves Surface mining - scars land Underground mining - dangerous Burning – produces sulfuric acid

Coal in the United States

Petroleum and Natural Gas Form from remains of plants and animals that were buried in ancient seas Steps: Large # of plants & animals buried in ocean-floor sediments Continual sediment build-up causes organic remains to transform into petroleum and natural gas Oil and gas move into nearby rock beds Less dense than water – so migrate upwards through water-filled spaces

Petroleum and Natural Gas Oil trap – structure that allows large amounts of fluid to accumulate Anticline – uparched series of sedimentary rock layers

Tar Sands Tar sands – mixtures of clay and sand combined with water and black tar Can be refined into oil Disadvantages: Causes huge land disturbance Requires large amounts of water Contaminated water and sediment accumulate in toxic disposal ponds

Oil Shale Oil Shale – rock that contains waxy mixture of hydrocarbons called kerogen Processes: Can be mined and heated to vaporize kerogen Vapor processed to remove impurities Disadvantages: Heat energy 1/8 that of crude oil More expensive to mine, process, and dispose of

Formation of Mineral Deposits Ore – useful metallic mineral that can be mined at a profit Natural concentration of many minerals is small

Mineral Resources and Igneous Processes Igneous Processes produce deposits of: Gold Silver Copper Mercury Lead Platinum Nickel

Hydrothermal Solutions Most form from hot, metal-rich fluids left during late stages of movement and cooling of magma Examples: Gold deposits in Homestake Mine, South Dakota Lead, zinc, silver ores in Idaho

Placer Deposits Formed when eroded heavy minerals settle quickly from moving water while less dense particles remain suspended and continue to move Common sites: inside bends of streams, cracks, depressions Sparked California gold rush

Nonmetallic Mineral Resources All are used for specific chemical elements or compounds Divided into two broad groups: Building materials Crushed stone, sand, and gravel) Industrial minerals Limestone Not nearly as abundant Require considerable processing before use

Alternate Energy Sources Solar Energy Nuclear Energy Wind Energy Hydroelectric Energy Geothermal Energy Tidal Power

Solar Energy Direct use of the sun’s rays to supply heat or electricity Two advantages “fuel” is free Non-polluting Draw-backs Equipment and installation is not free Supplemental energy is needed on cloudy days, in winter, and at night Example: Solar collector Passive or active

Nuclear Energy Fuel for nuclear plants comes from radioactive materials that release energy through nuclear fission: Heavy atoms bombarded with neutrons; split into smaller nuclei and emit neutrons and heat energy Produces a chain reaction Energy drives steam turbines that turn electrical generator

Nuclear Energy Obstacles: Cost of building safe facilities Hazards associated with disposal of nuclear wastes Possibility of a serious accident could allow radioactive materials to ascape Three Mile Island; 1979 Substantial damage to reactor; little harm to public Chernobyl; 1986 Reactor out of control; 10 days to put out fire High levels of radioactive material as far as Norway

Wind Energy Estimate – all winds of N. and S. Dakota could provide 80% electrical energy in U.S. Wind turbines used to collect wind energy Experiments by U.S. Department of Energy since 1980 Altamont Pass near San Fransisco Next 50-60 years: 5-10% of country’s demand Needs: technical advances Noise pollution Cost of land

Hydroelectric Power Drives turbines that produce electricity Produce about 5% of the country’s electricity Dams – allow for controlled flow of water Water held in a reservoir behind a dam is a form of stored energy that can be released through the dam to produce electric power Disadvantages: Sediment is deposited behind dam and builds up – eventually fills reservoir Availability of suitable sites

Geothermal Energy Harnessed by tapping natural underground reservoirs of steam and hot water Used directly for heating and to turn turbines to generate electric power First one in U.S. built in 1960 Disadvantages Clean, but not inexhaustible Cannot be recharged

Tidal Power Harnessed by constructing a dam across mouth of a bay or estuary in coastal areas with a large tidal range Strong in-and-out flow that results drives turbines and electric generators Is not economical if tidal range is too big or too small

Renewable Energy Some of the renewable energies we will look at: Biomass Wind Hydroelectric Solar Geothermal Which is the most advantageous???...