Nonrenewable Energy Resources Chapter 12 Nonrenewable Energy Resources

Nonrenewable Energy Sources cannot be replenished Fossil fuels Biological basis Nuclear fuels Radioactive basis

Commercial and Subsistence Energy Commercial energy Produced, bought and sold on a large scale Coal, oil, natural gas, wood, charcoal, peat, animal waste, wind, hydroelectric Subsistence energy Gathered or created by individuals for personal use wood, charcoal, peat, animal waste, wind, hydro

World Energy Use Reported in exajoules In US can be reported as quads = 1 x 109 gigajoules 1 gigajoule = 1 x 109 joules In US can be reported as quads 1 x 1015 BTU In US per capita energy use = 355 GJ

US Energy Use Has shifted from wood to fossil fuels over the past 150 years Hydroelectric and nuclear power have been developed in the past 75 years Use changes regionally and seasonally

Energy Sources Primary Sources Secondary Sources Produce usable energy through combustion or other reactions Sunlight, fire, fossil fuels Secondary Sources Obtained from the conversion of a primary source to energy Electricity

Energy Types Depend on what it’s used for Compact, portable sources are best for transportation Other types can be good for heat, cooking, or generating electricity

Energy Quality The energy provided by a resource must be compared to the energy required to obtain and use the resource High quality energy sources require little energy to produce compared to the energy they generate The inputs required to extract and use an energy resource are called embodied energy

Energy Efficiency Can be a good measure of energy quality Can be measured as EROEI (energy return on energy investment) Energy produced from a source for the unit of energy expended on its production

Transportation Mostly accomplished by vehicles fueled with petroleum or electricity Accounts for 30% of the energy use in the US and a large portion of air pollution Vehicles that use less fuel or carry a large number of passengers are generally more efficient

Electricity Is an energy carrier Movable, can deliver energy to users 40% of energy use in the US is for electricity generation Only 13% of the energy converted into electricity is available for end users

Electricity Generation Fuel is burned to generate heat Heat is used to generate steam Steam turns turbines Turbines turn generators Generators generate electricity Electricity is sent out on wires through an electrical grid

Combined Cycle Plants Natural gas is burned A turbine is turned to generate electricity Waste heat is used to generate steam Steam turns a turbine which generates electricity

Cogeneration Also called combined heat and power Steam can be used to heat buildings and turn turbines to generate power Best used in industries that use steam or generate their own power

Electrical Capacity Is the maximum electrical output Is 500 megawatts (MW) for the average thermal power plant Must take into account the capacity factor The amount of time a power plant actually operates Thermal power plants can be as high as 0.9 Other forms of energy generation can be as low as 0.25

Electricity Efficiency Thermal power plants (coal, nuclear) are about 35% efficient Combined cycle plants are about 60% efficient Cogeneration plants are about 90% efficient

Fossil Fuels Include coal, oil, and natural gas Most commonly used primary energy source in the world Form when organic matter is exposed to high heat and pressure over long periods of time (kerogen) Form most often in swamps, river deltas, and the ocean floor

Coal Forms from compressed plants Lignite Youngest coal; least amount of energy content Sub-bituminous and Bituminous Middle-aged coal; most common type Also called soft coal Anthracite Oldest coal; has the highest energy content Also called hard coal

Coal Is used in 50% of the power plants in the US Is one of the cheapest fuels Easier to extract than others Cheaper to build and operate coal power plants than other types

Problems with Coal Storage of ash from burning If above ground, can be washed or blown away If buried, can leach pollutants into soil and groundwater Releases high levels of CO2 and other pollutants when burned Sulfur Metals Mercury Lead Arsenic

Petroleum Forms from compressed algae in the spaces of sedimentary rocks Capped by non-porous rocks This cap must be drilled through to extract the oil Called crude oil Pumped out Flows out artesian-style

Petroleum Refining* Extracts various petroleum products from crude oil Involves heating crude oil and allowing components to condense out

Petroleum Use Major use is for fuel Gasoline accounts for 50% of petroleum use in the US Also used to make products from plastics to pharmaceuticals

Problems with Petroleum Releases pollutants Fewer than coal Extraction and transport are expensive and can be damaging Oil spills

Natural Gas Also called methane, CH4 Forms as a byproduct from petroleum, or by itself from organic decomposition Used for electricity, industrial processes, and transportation Releases less CO2 and fewer pollutants than coal or petroleum

Problems with Natural Gas Methane is a very potent greenhouse gas Leaks can be worse than CO2 Extraction is harmful to the environment “Thumper” trucks Fracking

Fracking Short for hydraulic fracturing Is an extreme form of natural gas extraction Uses drilling and large quantities of water to create cracks in rock that allow gas to flow out Can use other chemicals that may harm the environment Can contaminate groundwater

Oil/Tar Sands Form when oil deposits are not capped with non-porous rock Bitumen, or tar, is mixed with sand Makes an oil-filled ooze that is difficult and expensive to extract and refine Generates 2-3 L of waste water for each L of oil extracted

Liquified Coal (CTL, Syngas) Creates a liquid similar to oil from coal Burns cleaner than solid coal Expensive to process Generates toxic waste

The Hubbert Curve and Peak Oil M. King Hubbert generated a bell curve predicting global maximum oil production This maximum is called peak oil Some predictions show we have already reached peak oil Find new oil sources Find new oil extraction technologies Find completely new fuel options

Nuclear Energy Uses radioactive fuel Is powered by fission A neutron hits a large atomic nucleus Causes the nucleus to split Releases more neutrons which cause nearby atoms to split This type of energy does not produce air pollution

Nuclear Power Plants Radioactive fuel rods emit heat, which is absorbed by water The heated water flows through pipes next to another set of pipes also filled with water Heat is transferred from one set of pipes to the other Heat transfer creates steam Steam turns a turbine Turbine generates electricity

Problems with Nuclear Energy Processing uranium to make fuel rods generates large amounts of waste 900 kg uranium ore to make 3 kg fuel Radioactive fuel is a health hazard Exposure can cause radiation sickness and cancer Storing radioactive waste safely is difficult and expensive Controlling nuclear reactions requires constant vigilance

Radioactive Waste Must be stored securely and for a LONG time Still emits radioactivity after it stops producing heat U-235 has a half-life of 704 million years High-level waste Used (“spent”) fuel rods Low-level waste Contaminated items, including clothing and tools

Controlling Nuclear Reactions Control rods are used to prevent nuclear reactors from overheating Made from compounds that absorb radiation Are inserted in between fuel rods Too much heat can cause a meltdown of the nuclear fuel

Fusion Reactions Power the Sun and other stars Occur when lighter atoms fuse with heavier atoms Fusing hydrogen atoms to make helium is the focus of most research Requires reactors that can withstand heat 10x greater than the sun Requires only hydrogen for fuel Generates no radioactive waste