Nonrenewable Energy What makes nonrenewable energy nonrenewable Energy

Non-renewable Energy What makes non-renewable energy “nonrenewable”?

Energy Usage � Energy is used for many products and activities in modern civilization. � Fuels – sources of chemical energy – have five primary uses to people: › › › Cooking Transportation Manufacturing Heating/cooling Electricity

Energy Usage �A large portion of our energy use is derived from fossil fuels – remnants of ancient organisms that can be combusted to produce energy. � Fossil fuels are very effective at providing energy, but pose two major problems: › They have a limited supply. › They produce various environmental problems.

Fossil Fuels � Fossil fuels are deposited unevenly around the world. � Coal forms from dead plants that lived in swamps or marshes millions of years ago. › For instance , most of the coal in the east U. S. was formed from the vast swampland found here 300 -320 million years ago. � Over time, heat and pressure transform the plant detritus into coal deposits.

Fossil Fuels � In contrast, oil and natural gas deposits form from the remains of tiny marine organisms. � These organisms were buried with ocean sediments, and heated until they were transformed into energy-rich molecules. � Oil and natural gas are can migrate through porous rock, creating concentrated deposits.

Coal � Most of the world’s fossil fuel reserves consist of coal. Asia and North America are the most coal-rich continents. � Coal is relatively inexpensive, and does not require extensive refining. � Almost half the electricity in the U. S. comes from burning coal.

Coal � Coal mining activities impact the environment in various ways. › Deep-shaft mining has a minimal impact on the surface environment. › In contrast, surface or “strip” mining is very destructive to the surface ecology. › Both types of mining can cause water and land pollution if waste materials from the mines is not contained.

Coal � Coal burning also affects the environment differently, depending on coal quality. › Higher quality coal, such as bituminous coal, produces more heat and less pollutants than poorer coals, like lignite. › Air pollution due to coal burning can lead to smog and acid precipitation. › Ash, a waste product of combustion, has to be sequestered properly to avoid contamination. › Carbon dioxide can act as a greenhouse gas.

Petroleum � Petroleum, or crude oil, is the technical name for oil pumped straight from the ground. › Petroleum products are those which are made from crude oil. This includes plastic, as well as refined fuels and chemicals. � Unlike coal, oil must be refined further into fuels and other byproducts.

Petroleum � Oil is commonly found in geological features around the world. Examples of these are salt domes, folds and faults. › Remember, oil can penetrate porous rock – these features are useful for trapping oil deposits. � Most of the world’s oil deposits are fond in the Middle East, though significant deposits also exist in the U. S. , Venezuela, Siberia, Nigeria and the North Sea.

Petroleum � Drilling for oil has the potential to cause ecological disasters. While many surface wells can be easily contained, both deep water and artic environments provide special challenges. › Leaks from deep water wells are very difficult to contain. › The severe cold in the artic both prohibits cleanup and damages rig equipment.

Petroleum � Petroleum combustion releases pollutants into the atmosphere, especially airborne pollutants. � Both legal and technological means are used to reduce emissions. › Emission regulations are used to prohibit highpollution engines and industrial processes. › Catalytic converters are commonly used to reduce combustion vapors.

Petroleum � Finally, note that petroleum leakage can pollute water sources. This leakage can come from industrial processes, or from household sources (cars, motor oil). › Remember, petroleum can penetrate porous rock!

Natural Gas � Natural gas (CH 4) was once considered a waste product in oil wells, but nowadays provides almost 20% of the world’s nonrenewable energy. � Natural gas burns more cleanly than other fossil fuels, so engines and technology that runs off of natural gas does not require as many regulations as other fossil fuels do.

Natural Gas � However, natural gas is a greenhouse gas, which means that it can trap excessive heat in the atmosphere in high quantities.

Fossil Fuels and the Future � The worldwide demand for energy is expected to increase as other countries develop. Some projections suggest this demand will increase by as much as 30% by 2040. � As demand for fuel increases, so will price. Also keep in mind that fossil fuels are nonrenewable, so dwindling supplies can also lead to rising fuel prices.

Fossil Fuels and the Future � Today, worldwide oil production is increasing, though not as rapidly as in years past. � The oil industry, by and large, does not expect to find new major reserves. However, it is beginning to tap into oil sources once considered too difficult or expensive to utilize, such as oil sands.

Fossil Fuels and the Future

Fossil Fuels and the Future � Geologists disagree widely as to when oil production will peak and stabilize. This is the point in time at which worldwide oil production will maximize. � Estimates for this event range from 2015 to 2030, and beyond. � Also, note that some geologists believe that oil production will plateau and stabilize, rather than peak and fall.

Fossil Fuels and the Future � Finally, note that future oil production is also largely dependent on supply and demand, as well as political considerations. › As such, all theoretical projections do need to be examined with this in mind.

Bell Ringer 1. 2. A. B. C. D. E. State the five purposes of fuels. Identify the fossil fuel(s) that each statement is describing: Capable of penetrating porous rock Does not require much refining Created from the remains of swamp/marsh plant life Mainly used for transportation and manufacturing Mainly used for electricity

Nuclear Energy � Nuclear energy is derived from the energy found in the nucleus of the atom. Due to the dangers of radioactivity, nuclear energy is suitable only for electricity. Uranium isotopes are used as the fuel. � We can access that energy through nuclear fission or fusion. Since all real-world nuclear energy uses fission, we will discuss that first.

Nuclear Energy � Nuclear fission is the act of splitting the nucleus of a large atom. In nuclear reactors, uranium-235 is used. � Fission begins when uranium-235 is bombarded with neutrons, which renders the nucleus unstable. As a result, the nucleus breaks up, releasing smaller atoms, energy, and critically, more neutrons.

Nuclear Energy � The newly released neutrons bombard other atoms of uranium-235, repeating the process. Each time, the number of atoms struck increases; this results in a chain reaction, or an escalating series of reactions. � It is absolutely vital that the reaction be strictly controlled at all times. › Atomic bombs are a good example of an uncontrolled reaction!

Nuclear Energy �A nuclear reactor has to be protected with a thick pressure vessel filled with coolant. The vessel is designed to contain fission by products as best as possible. � Concrete walls are also used, to block fallout and radiation.

Nuclear Energy �A nuclear reactor uses the energy from the chain reaction to heat up water, creating steam. This steam is used to crank a turbine for an electric generator. › Thus, chemical energy is converted to thermal, kinetic and electrical energy! � However, due to the dangers of a runaway chain reaction, a nuclear plant uses three different circuits of water to accomplish this.

Nuclear Energy

Nuclear Energy � First, the fuel rods (which contain uranium-235) are bombarded with neutrons, which produces energy. This energy heats up the water in the first circuit. › Note the control rods; these are designed to absorb neutrons. The deeper they go, the more neutrons they absorb, and the slower the chain reaction proceeds.

Nuclear Energy Next, the heated water from the first circuit is used to boil water in the second circuit, creating steam. This steam activates a turbine – a wheel that captures a liquid’s or gases’ kinetic energy. � The kinetic energy is converted into electrical energy through a generator. �

Nuclear Energy Note that we do NOT want the water in the first circuit to evaporate; it must remain water to work as an effective heat sink for the nuclear reactions. � As such, the first circuit is kept under high pressure, to prevent evaporation. �

Nuclear Energy � The steam from the second circuit is cooled down by the cold water from the third circuit (or cooling circuit). This condenses the steam back into water, so it can absorb more heat from the first circuit. › Excess heat is transferred to the third circuit, and is released from the cooling tower.

Nuclear Energy Because of the need for strict control, we have to use a fairly complex system to harness the energy of nuclear fission. � Compare this to a coal reactor, which also uses thermal energy to create steam for a generator, but also only uses one circuit! �

Coal Reactor Diagram

Nuclear Energy � Nuclear fuel is highly concentrated; the pellets of uranium are small enough to fit in the palm of your hand, and yet each pellet generates as much energy as around 1800 pounds of coal!

Nuclear Energy � Nuclear power plants do NOT produce any greenhouse gases; steam will be the only gaseous product released during operation. � Nuclear energy is a useful energy source for countries with very limited fossil fuel resources, such as France. › About 75% of France’s energy comes from nuclear power. Contrast with the U. S. , from which about 75% of its energy comes from fossil fuels.

Nuclear Energy � However, nuclear reactors are expensive to build and to maintain, compared with other sources of energy. › Contrast nuclear energy with wind energy – the last 20 reactors built in the U. S. cost over $3000/k. W, while wind generators can be installed at $1000/k. W.

Nuclear Energy � Also, nuclear reactors do release a lot of solid nuclear waste – the byproducts of nuclear fission. � These waste products are radioactive, and have to be contained to prevent them from being a health hazard. › Dangerous radiation is capable of causing cell death and mutations.

Nuclear Energy � Once decommissioned, nuclear reactors and the liquids inside are also considered hazardous, and must also be isolated. � All nuclear waste has be stored in regions that prevent future leakage. As such, these areas MUST be geographically stable. › Designating storage areas can be controversial: See the Yucca mountain site for an example.

Nuclear Energy � Once decommissioned, nuclear reactors and the liquids inside are also considered hazardous, and must also be isolated. � All nuclear waste has be stored in regions that prevent future leakage. As such, these areas MUST be geographically stable. › Designating storage areas can be controversial: See the Yucca mountain site for an example.

Nuclear Energy � Finally, nuclear reactors can be very dangerous if poorly designed or managed. › The reactor on Three Mile Island had to be temporarily shut down, due to a minor leak. It was caused by faulty equipment and human error. › The Chernobyl reactor melted down and released hazardous fallout, due to poor design quality and human error.

Nuclear Energy � Nuclear fusion is the reverse of fission; instead of splitting a large molecule, we are creating a large molecule from smaller particles. � Fusion is responsible for energy emission from all stars, including our sun.

Nuclear Energy � Fusion produces significantly less hazardous waste products, making it potentially safer and easier to manage. � However, fusion also requires very expensive and complex infrastructure to work on Earth, and as such, remains impractical today.