Chapter 12 Nonrenewable Energy

Power and Energy Power – Rate work is done (how fast energy is transferred) kW, J/S, watts At any given time Energy – The ability to do work kWh is the total amount of energy that has been delivered over a period of time kWh, cal, J, BTU… Similar to speed vs. average speed

Nonrenewable energy use Nonrenewable resources cannot be replaced Fossil fuels are derived from biological matter (coal, oil, and natural gas) Nuclear is derived from radioactive materials Amount of energy use depends on availability and affordability Patterns of use in US Wood until 1875, than coal followed by natural gas and oil. Nuclear around 1950 and renewable in the 1970s

Energy types and quality To determine best use of energy, we look at energy efficiency ((output/input) * 100) Gas used for transportation because a small volume goes a long way and it burns easily, but pollutes Most fossil fuels around 35% efficient Must know complete picture to choose best fuel and to calculate true efficiency How much energy does it take to obtain the fuel

Electricity generation Starts with sun, and the potential energy is converted into electricity Ultimate goal is to spin a turbine (fluid). Usually done with steam (burn coal to get steam) Spinning turbine spins a generator that creates electricity that gets sent through transmission lines Capacity is the maximum potential output Cogeneration is the use of fuel to generate electricity and heat Can be 90% efficient vs. 35% for just electricity

Coal Coal is mostly used for electricity Coal is solid fossil fuels made from plant remains Sediments piled up on plant remains and compressed them Chemical reactions break down chemicals except carbon Heat and pressure turned this into coal Stages: Begins as peat (compressed plant materials) Lignite (water gets forced out, and becomes 40% carbon) Bituminous coal (soft coal, 85% carbon) Anthracite coal (95% carbon) – most available energy Pros: plentiful, needs minimal refining, lots of energy, inexpensive Cons: nonrenewable, destroy landscape, runoff, pollution (SO2 and CO2), heavy metal release, acid rain

Environmental Impacts of Mining Coal Surface Mining Control and Reclamation Act (1977) Requires filling (reclaiming) of surface mines after mining Expensive! Reduces Acid Mine Drainage Requires permits and inspections of active coal mining sights Prohibits coal mining in sensitive areas

Petroleum Petroleum is liquid fossil fuel Oil and natural gas form from marine phytoplankton Found where porous rocks are capped by nonporous rocks Accumulate at bottom of ocean floor Buried and heated until they became complex carbon molecules Found in porous rocks covered by nonporous rocks Makes up fuels, plastics, lubricants, tar, etc Pros: lots of energy, helps economies, many uses, easy to transport (pipeline) Cons: pollution (CO2, sulfur, heave metals), oil spills, nonrenewable, plastics, foreign

OIL Refining crude oil: Based on boiling points, components are removed at various layers in a giant distillation column. The most volatile components with the lowest boiling points are removed at the top.

Natural gas Natural gas (CH4) is found with petroleum Pros: burns cleaner, transported through pipes, many uses, economical Cons: it is a greenhouse gas itself, leak easily, explosive, nonrenewable

Other Fossil Fuels Bitumen (tar, pitch, or oil sands)- 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. To mine for these is very energy intensive Less efficient Liquid coal Lots of coal available, but twice the pollution and more expensive

A small house uses two lamps A small house uses two lamps. Both lamps have a 60-watt light bulb which are used for 3 hours per day. The family watches 2 hours of television per day. The TV uses 200 watts. Finally, they run the ceiling fan in the living room while watching 2 hours of television. The fan uses 90 watts. The cost per kWh is 10.5 cents. Calculate the total cost of all the appliances for one year.

Fossil fuels are finite Less that 40 years of oil likely remain Slightly longer for natural gas At least 200 years of coal

US Energy Strategy Objective 1: Increase Energy Efficiency and Conservation Objective 2: Secure Future Fossil Fuel Energy Supplies Objective 3: Develop Alternative Energy Sources Objective 4: Meet the First Three Objectives Without Further Damage to the Environment

Nuclear energy Nuclear energy is energy from the nuclei of atoms Nuclear fission splits an atom, nuclear fusion sticks atoms together Forces that hold nucleus of an atom together are extremely powerful Uranium-235 is used for nuclear fission, the splitting of atoms If you bombard the nucleus of a uranium atom with neutrons, the atom will split and release more neutrons that will split more atoms (chain reaction (atomic bomb)) Heat turns water to steam and spins a turbine

How it works Split the atoms Fuel rods are cylindrical tubes that contain uranium pellets Metal control rods absorb excess neutrons to avoid an uncontrollable reaction Control rods are lowered between fuel rods to control the rate of fission (absorb excess neutrons) Water is between fuel and control rods to act as coolant Heat release generated electricity Breeder reactors use uranium-238 which produces plutonium in the end. Makes more fuel! Meltdown far more dangerous, and nuclear weapons easy

Advantages and disadvantages Pros Very concentrated (1” pellet = 1 ton of coal) Not much pollution Less radiation than fossil fuel plant Cons Expensive to maintain and build Need to store and move nuclear waste (10-100 thousands of years) Meltdowns Thermal pollution Nuclear weapons

Nuclear fusion Future is nuclear fusion, or the combing of nuclei This powers stars Unlimited source of energy Need temps of 180,000,000F Takes more energy to produce then return Cup of water could power a city for 100 years We’ve created it, but not contained