Chapter 12 Nonrenewable Energy Resources

 Nonrenewable energy resource use- fossil fuels (coal, oil, natural gas) and nuclear fuels. Worldwide Energy Patterns

 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. Energy Use

 Renewable energy 7%, fossil fuels (coal, oil, natural gas) 84%, and nuclear 9%. U.S. Energy Patterns

Energy Types and Quality  Calculate the energy efficiency of a fuel type by looking at the efficiency of obtaining the fuel and the efficiency of the process that converts it to work.  35% of the coal burned becomes electricity. It is much less when you consider the embodied energy costs – All the energy inputs needed to extract and use an energy source (energy used to build coal extraction machinery, construct power plant, and remove and dispose of waste the efficiency is even lower. (2 nd law of thermodynamics)

Process of Energy Use – Embodied Energy Costs

Energy Return on Energy Investment (EROEI)  EROEI = Energy obtained from the fuel Energy invested to obtain the fuel  In order to obtain 100 J of coal from a surface coal mine, 5 J of energy is expended  EROEI = 100J= 20J 5J  The higher the number suggests a more efficient and desirable process.

Right Energy Source for the Job Electric Hot Water HeaterNatural Gas Hot Water Heater 99% Efficient at converting electrical energy into hot water 80% efficient at converting natural gas to hot water – due to venting some heat and combustion waste However, if you are using coal to make the electricity it is only 35% efficient. However it is lower due to the energy needed to extract, process, and deliver the gas to your home Therefore: even though the electrical water heater has higher efficiency as a system it is less than 35% efficient. Therefore: even though the gas heater is less efficient as a system it is only a little less than 80% efficient.  Point- from an environmental perspective it is important to look at the overall system efficiency when considering the pros and cons of an energy source.

Overall Fuel Efficiency of U.S. Transportation

 Electricity is a secondary source that comes from the conversion of a primary source of energy.  Electricity is a great energy carrier which can move and deliver energy in a convenient usable form to the end user.  40 percent of the energy used in the US is used to generate electricity.  Due to conversion losses only 13% of the 40 makes it to the end user.  This is less efficient than heating your house directly with wood or oil. Electricity Generation

Coal Burning Power Plant

Power Plants  Capacity – A maximum electrical output. If a plants capacity is 500 MW, this means that when the plant is operating, it generates 500 MW of electricity over 24 hours or 1 day.  500 MW x 24 hours = 12,000 MW hours (MWh)  Most energy is measured in kilowatt hours (kWh). The power plant above would be 12,000,000 kWh/day  Capacity Factor – is the amount of time a plant actually runs. Most thermal plants are 0.9

 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%. Cogeneration

 Coal- a solid fuel formed primarily from the remains of trees, ferns, and other plant materials that were preserved 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. Fossil Fuel-Coal

AdvantagesDisadvantages Energy-dense – 33 MJ/kg Carbon is released into the atmosphere which contributes to climate change Plentiful ≈200 years worth Releases impurities into air when burned.-particulates 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 SO x and NO x and other air pollutants into the atmosphere. Economic costs are low Ash is left behind Easy to handle and transport Needs little refining Advantages and Disadvantages of Coal

 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 million years ago.  Countries with the most petroleum are Saudi Arabia, Russia, the United States, Iran, China, Canada, and Mexico. Fossil Fuel-Petroleum

AdvantagesDisadvantages 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 Found in very sensitive and hard to get places (ANWR or a mile underwater) Advantages and Disadvantages of Petroleum

Oil Spills - Petroleum  BP Oil Spill was the largest spill in US history after Exxon Valdez in 1989 (>206 million gallons)  Most oil is non point source pollution from land – accidentally or intentionally

Oil Pollution Prevention Act 1990  Followed the Exxon Valdez Oil Spill  Made the company that is responsible for the spill, liable for the cleanup costs and damages  Created the Oil Spill Liability Trust Fund  National Oil Spill and Hazardous Sub. Pollution Contingency Plan – makes a gov./industry blueprint for responding to an incident.  Increased penalties for noncompliance.

 Oil sands- slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay. (Tar Sands of Canada – Keystone XL pipeline)  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. Other Fossil Fuels

 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 Hubbert Curve

 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. The Future of Fossil Fuel Use

 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. Natural Gas - Fracking

AdvantagesDisadvantages 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 Creates Billions of Gallons of waste water with toxic chemicals Releases cancer causing air pollutants like benzene, toluene, xylene Advantages and Disadvantages Natural Gas – Fracking

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

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. Nuclear Reactors

AdvantagesDisadvantages No air pollution is producedPossibility of accidents Countries can limit their need for imported oil Disposal of the radioactive waste Nuclear materials can be used as weapons Advantages & Disadvantages of Nuclear Energy

 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. Radioactive Waste

 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 containing the heat that is produced. Fusion

Nuclear Waste Recovery Act 1982  Looks at deep geological repositories for safe nuclear storage and disposal.  Sets up a procedure for evaluation of a site.  A procedure for state and federal interactions  Sets timetables and milestones for carrying out the program.  Yucca Mountain was part of this – defunded by the state and federal government.