Mining and Energy Resources Ch 8, 12 and 13

Mineral Resources Concentration of naturally occurring material in or on the earth’s crust. can be extracted and processed into useful materials at an affordable cost they are classified as nonrenewable resources because they take so long to produce

Formation of mineral Resources Hydrothermal processes divergent boundaries allow magma to superheat seawater dissolving metals from rock and magma Sedimentary sorting minerals settle out in streams on the basis of density (Gold panning) Evaporative mineral deposits as water evaporates it leaves behind minerals (salt, borax, sodium carbonate)

Reserves Reserves- the known quantity of a resource that can be economically recovered. 4

Types of Mining Surface mining- removing minerals that are close to Earth’s surface. Strip mining- removing strips of soil and rock to expose ore. Open pit mining- the creation of a large pit or hole in the ground that is visible from the surface. Mountain top removal- removing the entire top of a mountain with explosives. Placer mining- looking for metals and stones in river sediments. 5

Types of Mining Subsurface mining- mining for resources that are 100 m below Earth’s surface. 6

Surface Mining Restoration Difficult and usually incomplete Most surface mining is in arid/semiarid regions Damage to these biomes is almost always permanent

Environmental Effects of Mining Land Surface: scarring and disruption fires in coal mines land subsidence causing houses to tilt, cracked sewer lines, broken gas mains and disrupted groundwater systems erosion of spoil heaps and tailings by water and wind air and water pollution

Environmental Effects of Mining Rainwater seeping through a mine or mine waste can carry sulfuric acid to nearby streams Smelting—used to separate metals from other elements in the ore mineral Emit enormous quantities of air pollutants SO2, soot, tiny particles of arsenic, cadmium, lead and other heavy metals Other mining wastes: radioactive uranium compounds, compounds of lead, mercury, arsenic and cadmium

Mining the oceans Most minerals in seawater occur at very low concentrations – not economically practical to recover them. Only minerals that can be profitably extracted are magnesium, bromine and sodium chloride Continental Shelf – sand, gravel, phosphates, sulfur, tin, copper, iron, tungsten, silver, titanium, platinum, and diamonds.

Mining The Oceans Deep ocean floor – future site for sources of manganese and other metals; uncertainty who owns the mineral rights in international waters. Hot volcanic springs – sources of sulfide deposits of gold, silver, zinc and copper Environmental effects of deep-sea mining are unclear and debatable

Economics of Mining Economic Depletion - Occurs when it costs more to find and extract the deposit than it is worth Depletion time—time it takes to use up a certain proportion (80%) of the reserves of a mineral at a given rate of use Then our choice becomes recycling, reusing, wasting less, using less, finding a substitute or doing without

U.S. Energy Use United States is the world’s largest energy user History of energy use in U.S. Coal - 1885 Oil - 1915 Oil overtook coal in 1950 Hydroelectric power overtook wood in 1968 Nuclear overtook wood and hydro in 1973

Net Energy Net Energy—total amount of energy available from an energy resource minus the energy needed to find, extract, process, and get that energy to consumers Net energy ratio—ratio of useful energy produced to the useful energy used to produce it Oil has a high net energy ratio because much of it comes from large accessible deposits in the Middle East Nuclear energy has a low net energy ratio due to the costs associated with power generation

Nonrenewable Energy Nonrenewable energy resources- fossil fuels (coal, oil, natural gas) and nuclear fuels.

Energy Use Commercial energy sources- those that are bought and sold, such as coal, oil and natural gas. Subsistence energy sources- those gathered by individuals for their own use such as wood, charcoal and animal waste.

Process of Energy Use

Overall Fuel Efficiency of U.S. Automobiles

Electricity Generation

Electricity Generation The burning fuel from coal transfers energy to water, which becomes steam. The kinetic energy contained within the steam is transferred to the blades of a turbine, a large device that resembles a fan. As the energy in the steam turns the turbine, the shaft in the center of the turbine turns the generator. This mechanical motion generates energy.

Energy Efficiency Most coal burning power plants are about 35% efficient.

Coal Coal- a solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved 280-360 million years ago. Four types of coal ranked from lesser to greater age, exposure to pressure, and energy content. These four types are: lignite, sub-bituminous, bituminous, and anthracite. The largest coal reserves are in the United States, Russia, China, and India.

Coal

Advantages and Disadvantages of Coal Energy-dense Contains impurities Plentiful Release impurities into air when burned Easy to exploit by surface mining Trace metals like mercury, lead, and arsenic are found in coal Technological demands are small Combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere. Economic costs are low Ash is left behind Easy to handle and transport Carbon is released into the atmosphere which contributes to climate change Needs little refining

Petroleum Petroleum- a mixture of hydrocarbons, water, and sulfur that occurs in underground deposits. Oil and gasoline make this ideal for mobile combustion, such as vehicles. Formed from the remains of ocean-dwelling phytoplankton that died 50-150 million years ago. Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico.

Petroleum

Advantages and Disadvantages of Petroleum Convenient to transport and use Releases carbon dioxide into atmosphere Relatively energy-dense Possibility of leaks when extracted and transported Cleaner-burning than coal Releases sulfur, mercury, lead, and arsenic into the atmosphere when burned

Natural Gas Natural gas- exists as a component of petroleum in the ground as well as in gaseous deposits separate from petroleum. Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane.

Advantages and Disadvantages Natural Gas Contains fewer impurities and therefore emits almost no sulfur dioxide or particulates When unburned, methane escapes into the atmosphere Emits only 60% as much carbon dioxide as coal Exploration of natural gas has the potential of contaminating groundwater https://www.youtube.com/watch?v=timfvNgr_Q4

Other Fossil Fuels Oil sands- slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay. Bitumen (tar or pitch)- a degraded type of petroleum that forms when a petroleum migrates close to the surface, where bacteria metabolize some of the light hydrocarbons and others evaporate.

The Hubbert Curve Hubbert curve- a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil.

The Future of Fossil Fuel Use If current global use continues, we will run out of conventional oil in less than 40 years. Coal supplies will last for at least 200 years, and probably much longer.

Nuclear Energy Fission- a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts.

Nuclear Reactors

Nuclear Reactors Fuel rods- the cylindrical tubes that house the nuclear fuel used in a nuclear power plant. Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator. Control rods- cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction.

Advantages and Disadvantages of Nuclear Energy No air pollution is produced Possibility of accidents Countries can limit their need for imported oil Disposal of the radioactive waste

Radioactive Waste Radioactive waste- once the nuclear fuel can not produce enough heat to be used in a power plant but it continues to emit radioactivity. This waste must be stored in special, highly secure locations because of the danger to living organisms.

Radioactive Waste High-level radioactive waste- the form used in fuel rods. Low-level radioactive waste- the protective clothing, tools, rags, and other items used in routine plant maintenance.

Chernobyl, Ukraine 1986 http://www.youtube.com/watch?v=BfKm0XXfiis Explosion in a nuclear power plant Sent highly radioactive debris throughout northern Europe 32,000 deaths and 62,000 miles contaminated, over 500,000 people exposed to dangerous levels of radiation

Fusion Nuclear fusion- the reaction that powers the Sun and other stars. This occurs when lighter nuclei are forced together to produce heavier nuclei and heat is released. Fusion is a promising, unlimited source of energy in the future, but so far scientists have had difficulty cotaining the heat that is produced.

What is renewable energy? Renewable energy can be rapidly regenerated, and some can never be depleted, no matter how much of them we use.

How can we use less energy? Energy conservation- finding ways to use less energy. For example, lowering your thermostat during the winter or driving fewer miles. Energy efficiency- getting the same result from using a smaller amount of energy.

Benefits of Conservation and Efficiency Many energy companies have an extra backup source of energy available to meet the peak demand, the greatest quantity of energy used at any one time. Variable price structure- utility customers can pay less to use energy when demand is lowest and more during peak demand.

Sustainable Design Improving the efficiency of the buildings we live and work in.

Passive Solar Energy Using passive solar energy can lower your electricity bill without the need for pumps or other mechanical devices. Building the house with windows along a south-facing wall which allows the Sun’s rays to warm the house would be an example.

Biomass is energy from the Sun The Sun is the ultimate source of almost all types of energy

Modern Carbon vs. Fossil Carbon Many people are confused how burning biomass such as wood is better then burning coal. The carbon found in biomass was in the atmosphere as carbon dioxide, taken in by the tree, and by burning it we put it back into the atmosphere Burning coal is carbon that has been buried for millions of years and was out of circulation until we began to use it. This results in a rapid increase in the concentration of carbon dioxide in the atmosphere.

Biomass Wood, Charcoal and Manure- used to heat homes throughout the world. Ethanol and Biodiesel (biofuels)- used as substitutes for gasoline and diesel fuel.

The kinetic energy of water can generate electricity Hydroelectricity- electricity generated by the kinetic energy of moving water. This is the second most common form of renewable energy in the world.

Types of hydroelectric power systems Run-of-the-river systems- water is held behind a dam and runs through a channel before returning to the river. Water impoundment- water is stored behind a dam and the gates of the dam are opened and closed controlling the flow of water. Tidal systems- the movement of water is driven by the gravitational pull of the Moon.

The Sun’s energy can be captured directly Active solar energy- capturing the energy of sunlight with the use of a pump or photovoltaic cell and generating electricity.

Earth’s internal heat produces geothermal energy Geothermal energy- using the heat from natural radioactive decay of elements deep within Earth as well as heat coming from Earth.

Wind energy is the most rapidly growing source of electricity Wind energy- using a wind turbine to convert kinetic energy into electrical energy.

Hydrogen fuel cells have many potential applications Fuel cell- a device that operates like a common battery where electricity is generated by a reaction between two chemicals.

What is energy efficiency? Energy efficiency – Percentage of total energy input to a machine or equipment that is consumed in useful work and not wasted as useless heat. Life cycle cost - the initial cost plus lifetime operating costs The 3 least energy efficient using devices incandescent light bulbs vehicles w/ internal combustion engines nuclear power plants producing electricity for space heating

Why is it important to reduce energy waste? make nonrenewable fossil fuels last longer gives us time to phase in renewable energy resources decreases dependence on oil imports lessens need for military intervention in the oil-rich and politically unstable Middle East Reduces local and global environmental damage Is the cheapest and quickest way to slow projected global warming The reason there is not more emphasis on improving energy efficiency is low-cost underpriced fossil fuels! A second cause is huge government subsidies

Cogeneration Cogeneration- using a fuel to generate electricity and to produce heat. Example- If steam is used for industrial purposes or to heat buildings it is diverted to turn a turbine first. This improves the efficiency to as high as 90%.

How can we save energy in transportation? Increase the fuel efficiency of motor vehicles There is little interest in fuel-efficient vehicles when gasoline is so cheap Electric cars pollution to recharge batteries is produced elsewhere Electric cars are not very efficient Shift to more energy efficient ways to move people and freight

Vehicles Electric car- Hybrid car- (gasoline/electric) Almost no pollution Limited range between charges Hybrid car- (gasoline/electric) Increase mileage Reduce emissions Increase efficiency 5 important parts- engine-smaller in size reduces emissions and increase efficiency Fuel tank- energy storage device Advanced electronics- electric motor acts as a generator, draw energy from batteries to accelerate Generator- similar to electric motor and produces electrical power Batteries- energy storage device for the electric motor

How can we save energy in buildings? Use the most energy-efficient ways to heat houses: passive solar heating and high-efficiency natural gas furnaces electric resistance heating is the most wasteful Heat pumps work in warm climates For existing homes add insulation, plug leaks and install energy saving windows Use the most energy-efficient ways to heat water (using electricity is the least efficient) Use the most energy-efficient appliances and lights Rebates or tax credits for building energy-efficient buildings Direct use of solar energy for heat and electricity

Sustainable Energy Strategy Improve energy efficiency Use natural gas as we make transition to decentralized, local renewable sources What can the government do? increase fuel efficiency standards for motor vehicles establish energy-efficiency standards for buildings and appliances increase government sponsored R&D to improve energy efficiency