final exam modules 11, 12, 13, 14

Ground-Source Heat Pump

-a system which uses the constant temperature underground to exchange heat to operate a heat pump -These are initially expensive, but are very stable, efficient, and inexpensive to operate -efficient way to heat and cool air and water in a home or buildng

A geothermal-powered steam plant....

generates electricity by using heat originating in the earth, to boil water to produce steam, the force from it then turns a turbine, which then spins a generator, which produces electricity.

define fossil fuels

highly combustible substances formed underground over millions of years from the buried remains of ancient organisms -coal, oil, natural gas

Ocean Movements and Thermal Gradient

- There are a number of ways to capture the kinetic energy of the oceans (waves, tides, currents) and convert it into electricity. - The thermal gradient between the surface and ocean depths also may be used to run a turbine. (p. 378)

sustainability

'Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.'

electricity without combustion

- !! Remember !! that electricity typically is commercially generated when a force (i.e. steam) turns a turbine, then that turbine spins a generator shaft which spins the coils of wires in the magnetic field (a generator), which generates electricity. (p. 341; see ancillary materials in the Module 11) -The steam to turn that turbine typically is produced by burning a fuel to boil the water. Fossil fuels and nuclear are the most common ways to boil water to make steam. -there are other ways to produce electricity without burning fuel

Electricity may be generated from the ocean from...

-By capturing motion of the waves -Using the temperature differential between the surface water and deep water -Using current and tidal flows to turn a turbine

Generating electricity from concentrated solar energy...

-Could create thermal pollution -Uses steam -May store heat energy to use at night

more info on active heating

- Active solar heating techniques use solar collectors and pumps & fans to move heat throughout the building. (p. 371) - These techniques also allow for not just heating the building but also water heating. - Active solar systems in combination with photovoltaic (solar) panels may provide most of the energy needs for a typical home. - Although the costs are dropping, these are initially expensive, but pay for themselves quickly considering how much it costs per year just to create hot water.

geothermal energy production

- Geothermal systems use the heat from deep in the Earth to make steam to produce electricity. - There are three main methods. - One is to use steam directly from the Earth ('dry' steam) - Another uses hot geothermal water to heat another fluid to run the turbine (binary) - The other separates water from steam in an exchanger, and that steam then turns the turbine ('flash' steam). - Geothermal systems provide over 50% of Iceland's energy and almost 60% of the power along the Northern California coast. - Some drawbacks for geothermal power is that it has a limited area of use (only where there is hydrothermal activity), there may be bad odors from sulfur, the water reservoir may be depleted, and the hydrothermal area may shift over time.

hydroelectric power

- Like the wind, moving water has been used by people for millennia to turn a wheel to turn a shaft to perform various tasks (grind, saw, weave, pound, pump, etc.). - Current methods are to use falling (storage or pumped storage) or moving water (run-of-river) to turn a turbine to spin a generator to produce electricity. (pp. 379-380)

more info on passive heating

- Passive methods to heat buildings use positioning relative to the sun and prevailing winds and architecture to capture, store, and transport heat throughout the building. - These techniques have been used by people for millennia (e.g. native American cliff dwellers, Greeks). - Passive solar heating is constantly increasing in efficiency because new materials are always being developed (e.g. thermal glass, tiles, insulation, storage materials). - Simple changes in building design may make a big difference in the cost of heating and cooling a building. - Drawbacks are times with little or no sunlight and some locations are not suitable due to weather. - 'Backup' heating systems are usually necessary to take over when solar heating is insufficient.

wind power

- People have used the wind for millennia to power windmills and sailing ships. - We now have adapted the principle of the windmill to run wind turbines that turn generators which produce electricity. (pp. 374-376) - The demand for renewable energy sources has spawned 'wind farms' with hundreds of wind turbines providing more than 30% of our renewable energy needs. (p. 366) - This is one of the fastest growing renewable energy source.

drawbacks of wind as a source of energy

- Some of the drawbacks are noise, high initial costs, killing birds, and intermittent of wind. - Also, it has been shown that large wind farms may 'steal' energy and change local weather patterns.

Wind

- Temperature differentials on the Earth's surface create differences in air pressures (remember rising and falling air from earlier in the semester?) - Rising air creates areas of low pressure and falling air creates areas of high pressure. - These differences in pressure create airflows (= wind) that move from high to low pressures. - These winds may operate on a global scale (remember?), regional (weather fronts; storms), or local (offshore breezes; upwellings). *solar powered

hydroelectric power advantages

- The advantages are it is renewable, clean (in terms of pollution), and once built, low cost to consumers

Describe one way concentrated solar energy is used to produce electricity

- The basic process is to gather and concentrate the Sun's heat and transfer that heat to produce steam to turn a turbine to spin a generator to generate electricity. There often are heat storage facilities on site to store unused heat to be used at night. Molten salt is usually used to store that heat. - Different arrays of reflective surfaces gather and concentrate the heat, usually using large arrays of moveable mirrors or parabolic reflectors. (Please see module materials)

Thermal Gradient

- The difference between the warm surface water and cooler water underwater may be used to heat another fluid that turns a turbine which spins a generator to produce electricity. (p. 378) - The drawback is the corrosive actions of seawater and possible thermal pollution of the ocean's depths.

Wave, Tide, and Current Kinetics

- The up-and-down motion of waves may be used to move wire coils in a magnetic field to produce electricity or change air pressure in a closed space or power a pump to move air or water to turn a turbine. - The movements of tides and ocean currents also may turn a turbine (similar to a water wheel) to generate electricity. - There are some very creative and innovate ideas for capturing the renewable, clean, and 'free kinetic energy of the oceans. - Drawbacks for these techniques mostly stem from the very harsh environment of the sea. - The salt water is very corrosive and storms may damage the apparatus capturing the energy. - The places where this may operate are restricted to the coasts of continents. However, since most of the world's population lives near the coasts, that is not really a problem.

Concentrated Solar Power

- There are a number of techniques for capturing and concentrating the heat from the Sun. (pp.371-372). - That heat is then used to make steam, to turn a turbine, and spin a generator to make electricity. - There also are methods to store that heat (molten salt) for use at night. - Most of these CSP facilities are in deserts and other arid areas with clear, dry air and few cloudy days. - Drawbacks are cloudy days, environmental impacts from clearing large sometimes sensitive land areas, and the need for water in arid areas.

Photovoltaic Panels (Solar cells) more info

- These use semiconductors to capture the energy from light photons to create an electric current. (p. 372). - These were expensive when first developed, but widespread use across the world has reduced prices. - These require a substantial amount of surface area and a minimum amount of sunlight during the year to make then feasible. - However, some countries have significantly developed photovoltaic use (e.g. Germany now gets 5% of their total electricity from PV cells; pp. 365-366). - Also PV cell use is one of the most rapidly-increasing renewable electricity sources.

Describe two advantages of collecting energy from the wind

- Wind turbines operate at very low cost (after the initial investment) and tap an essentially inexhaustible source of energy. - Wind power is very clean.

Domestic Sewage and thermal pollution

-Domestic sewage is discharged into rivers, lakes, canals or streams with minimal treatment or without any treatment. -these wastes have a higher organic temperature and organic load. -this leads to decrease in dissolved oxygen content in the receiving waters resulting in the set-up of anaerobic conditions causing release of foul and offensive gases in water. -eventually, this leads to development of anoxic conditions resulting in rapid death of aquatic organisms.

Thermal pollution in streams by human activities...

-Industries and power plants use water to cool machinery and discharge the warm water into a stream -Stream temperature rises when trees and tall vegetation providing shade are cut. -Soil erosion caused due to construction also leads to thermal pollution -Removal of stream side vegetation -Poor farming Practices also lead to thermal pollution

Industrial effluents and thermal pollution

-Industries like textile, paper, pulp and sugar manufacturing release huge amounts of cooling water along with effluents into nearby natural water bodies. -the waters polluted by sudden and heavy organic loads result in severe drop in levels of dissolved oxygen leading to death of several aquatic organisms. Domestic Sewage: Domestic sewage is discharged into rivers, lakes, canals or streams

Passive solar heating of buildings...

-Is becoming more efficient than before -Uses structures to store heat -Is based on architecture

Active solar heating systems

-Require dedicated solar collectors. -Use pumps to move heat.

Problems with generation of electricity using photovoltaic cells could be...

-The inability to generate power at night -Efficient storage of electricity for periods of time -Initial expanse

Ocean thermal gradients...

-Use the temperature difference between the surface and deeper water to generate electricity -Ultimately gets its energy from the Sun

Geothermal energy...

-Uses steam to generate electricity. -Is restricted to certain areas on Earth

ground source heat pump process

-a network of pipes filled with water and antifreeze extends underground -soil is cooler than air in the summer, and warmer than air in the winter -by running fluid between the house and the ground, these systems adjust temperatures inside

What environmental problems come from hydraulic fracturing, or 'fracking' ?

-a very large amount of water is required for each well, impacting the water availability to organisms. -leaky well casings often contaminate aquifers, destroying water supplies for those living there. -the waste water and chemicals are toxic, and disposal often is incomplete. -there is a release of natural gas, which is a very potent greenhouse gas, contributing to atmospheric warming. -the infrastructure necessary to support the drilling and extraction creates habitat destruction, noise, and air pollution. -earthquakes from fracking occur.

Outline the process hydraulic fracturing

-a well is drilled miles deep into shale where gas and oil is trapped between the layers of rock. -a lateral porous pipe is then run through the rock layer and a mixture of water, sand, and other chemicals is forced into the rock layers at very high pressure -this separates the rock layers, releasing the gas and oil, which is pumped back to the surface, where it is separated from the water and chemicals

Environmental problems from coal extraction and use could be...

-acid mine drainage -environmental damage from surface mining -release of carbon dioxide into the atmosphere during its combustion

coal powered power plants and thermal pollution

-coal fired power plants constitute a major source of thermal pollution. The condenser coils in such plants are cooled with water from nearby lakes or rivers. -the resulting heated water is discharged into streams thereby raising the water temperature by 15C. -heated effluent decreases the dissolved content of water resulting in death of fish and other aquatic organisms. -the sudden fluctuation of temperature also leads to "thermal shock" killing aquatic life that have become acclimatized to living in a steady temperature

Outline the process of commercial electricity production from a typical coal 'steam plant'...

-coal is burned to heat water to create steam. -the high pressure of the steam spins a turbine, which is connected to a generator. -the generator spins many coils of wire through a magnetic field, creating an electrical current

Control measures for thermal pollution...

-cooling towers -cooling ponds -spray ponds -artificial lakes

The Sun is the ultimate source of power for...

-electricity generated by fossil fuel combustion -hydroelectric power -electricity generated from photovoltaic cells -wind-generated power

Explain why most forms of energy humans use could be traced ultimately to the Sun

-fossil Fuels were originally plants, which captured energy from the Sun. Burning them releases that energy. -hydroelectric uses falling water which was initially evaporated by heat from the Sun, which then precipitates and follows gravity to be stored and fall. -wind temperature differentials across the Earth's surface create the wind. -ocean waves, tides, and temperature differentials all may be traced back to influences from the Sun. -photovoltaic cells use photons from the Sun to create an electrical current. -animal power requires food, which ultimately comes from plants and so the Sun

Hydro-electric power and thermal pollution

-generation of hydroelectric power sometimes leads to negative thermal loading in water systems. -apart from electric power industries, various factories with cooling requirement contribute to thermal loading.

Geothermal energy

-heat energy that comes from the Earth to make steam to drive a turbine that spins a generator to commercially produce electricity. (pp. 376-378) !! It is incorrect to use the use of the term 'geothermal' to describe Ground-Source Heat Pumps (ground exchange systems) that are used to heat & cool buildings. - The term 'geothermal' often is used to describe these ground-exchange heat pumps. (Wrong!!) *not solar powered

hydroelectric power more info

-kinetic energy of flowing river water to turn turbines and generate electricity

disadvantages of solar energy

-not all regions are equally sunny -solar energy is an intermittent resource.... night and day -up front cost of equipment for solar techonolgy

what are sources of thermal pollution?

-nuclear power plants -coal fired plants -industrial effluents -domestic sewage -hydroelectric power

nuclear power plants and thermal pollution

-nuclear power plants including drainage from hospitals, research institutions, nuclear experiments and explosions, discharge a lot of heat that is not utilized along with traces of toxic radio nuclides into nearby water streams. -emissions from nuclear reactors and processing installations are also responsible for increasing the temperatures of water bodies. -the operations of power reactors and nuclear fuel processing units constitutes the major contributor of heat in the aquatic environment. -heated effluents from power plants are discharged at 10 C higher than the receiving waters that affects the aquatic flora and fauna

nuclear fission

-occurs in large atoms (like uranium & plutonium) are split, creating two smaller atoms and releasing energy (heat) and neutrons. -these neutrons then may split another atom, creating a chain reaction which releases ever-increasing amounts of energy (an explosion = atomic bomb) unless it is controlled. -this is the form of nuclear energy used for power generation and transportation because it may be controlled by absorbing neutrons and slowing the chain reaction.

Generating electricity from nuclear energy...

-produces radioactive wastes that last a long time -creates thermal pollution -uses steam

major uses for the fossil fuel petroleum...

-production of chemicals -transportation

Effects of Thermal pollution...

-reduction in dissolved oxygen -increase in toxicity -interference in biological activity -interference in reproduction -direct mortality -food storage for fish

disadvantages of geothermal power

-restricted to regions where we can tap energy from naturally heated groundwater

why is the extraction of coal harmful?

-strip mining of coal, especially contour mining causes extensive habitat and aquatic ecosystem destruction when the overburden is dumped down the mountainside into the valleys. -acid mine runoff also results from strip mining, destroying stream ecosystems. -deep mining is very dangerous and creates large piles of mine tailings which may leach toxic chemicals into the water systems

solar energy

-the sun releases astounding amounts of energy by converting hydrogen to helium through nuclear fusion -the tiny proportion of this energy that reaches Earth is enough to drive most processes in the biosphere, helping to make life possible on our planet -each day, earth receives enough solar energy, or energy from the sun, to power human consumption for a quarter of a century

the process of hydraulic fracturing...

-uses massive amounts of water -threatens groundwater supplies -has created thousands of jobs -has dramatically increased production of oil and natural gas

Explain why it is dangerous to base modern food production on the use of fossil fuels

-we have exchanged fossil fuels for food because the mechanization, irrigation, and fertilizers required to grow the amounts of food necessary to support the current (and future) all require the manufacturing and transportation systems based on the use of fossil fuels. Without the energy from fossil fuels we could not grow enough food. Since fossil fuels are non-renewable this system is not sustainable. However, a system based on solar power (as it was before industrialization) would be sustainable. When the supply of fossil fuels dwindle and eventually are exhausted we will not be able to grow enough food to support the human population. -thus, basing our food production on the energy from fossil fuels is dangerous because unless we change our current system, mass starvations will occur when fossil fuels are gone. (We're all gonna die!)

why is the burning of coal harmful?

-when coal is burned fly ash, sulfur dioxide, and oxides of nitrogen are released. Fly ash may trap toxins or carcinogens and then carry them deep into lungs where they lodge for extended periods. -the oxides of sulfur and nitrogen are the primary pollutant which then is converted to acid dissolved in the atmosphere causing acid precipitation. -the remnants of coal burning (ash) often may have significant environmental impacts if not disposed of properly. -thermal pollution from power plants also may occur when local water systems are used to condense steam back to water.

nuclear fusion

-when two or more atoms merge to form a new atom. -when this happens there is a difference in the atomic masses. -this becomes a release of large amounts of energy. -fusion usually occurs in smaller, lighter atoms. ----> meaning... -hydrogen is the 'most fusible', and also releases the most amount of energy when two hydrogens fuse to form helium. -this is what is happening in stars (like our Sun) and thermonuclear detonations (i.e. hydrogen bomb). -there is so much energy released that it is very difficult to contain and maintain, currently making it unavailable for power generation.

The Sun is the ultimate source of power for

-wind-generated power -hydroelectric power -Electricity generated by fossil fuel combustion.

Explain why petroleum is such a valuable resource relative to daily life in developed countries by giving at least three reasons

1) Most petroleum is used for transportation (planes, trains, and automobiles) using gasoline, diesel oil, and jet fuel (kerosene) 2) The other big use for a fossil fuel is coal used for electricity generation. This is the most plentiful and least expensive fossil fuel and will continue to be used for many years 3) Petroleum also is invaluable as the raw material for the plastics that have become a central part of our everyday lives. The use of plastics has exploded since after WW II, and it is now difficult to see modern life without plastics

geo-thermal power plant process

1) magma heats groundwater 2)where natural fissures or cracks appear, heated water or steam surfaces in geysers or hot springs 3)wells tap underground heated water or steam to turn turbines and generate power 4)steam is cooled and condensed, and water is injected back into the aquifer to maintain pressure

Describe the process of a power plant (coal-powered steam plant)

A coal-powered 'steam plant' generates electricity by burning coal to boil water to produce steam, the force of which is used to move the blades of a turbine, which then spins a generator which produces electricity

artificial lakes

Artificial lakes are man made water bodies that offer once-through cooling. The heated effluents can be discharged into the lake at one end and water for cooling purposes may be withdrawn from the other end. The heat is eventually dissipated through evaporation

cooling ponds

Cooling ponds are the best way to cool thermal discharges. Heated effluents on the surface of the water in cooling ponds maximise dissipation of heat to the atmosphere and minimise the water area and volume. The warm water wedhe acts like a cooling pond.

hydroelectric power disadvantages

Most of the problems arise from changes of the aquatic ecosystems and surrounding environment from creating impoundments (reservoirs) and maintenance. - Building dams and the water it impounds behind it have severe impacts on the river ecosystem: - It changes what used to be a flowing water system to a lake ecosystem, both behind and below the dam. Periodically releasing water from the reservoir often disturbs the riverbed below the dam. - The water released from the bottom of the reservoir is much colder than normal, with severe impacts on life below the dam. (a type of thermal pollution) - Dams block fish migrations (e.g. salmon) and the turbines kill aquatic life. - There is a significant loss of land and soil, often that land is prime agriculture land. - Creating the large surface area of water increase water losses from evaporation. - Sediment always collects behind the dam and must be periodically removed (at great cost). - There is a potential for disaster from the dam bursting with catastrophic water release.

spray ponds

The water coming out from condensers is allowed to pass into the ponds through sprayers. Here water is sprayed through nozzles as fine droplets. Heat from the fine droplets gets dissipated to the atmosphere

Describe two problems from collecting energy from the wind

Some of the drawbacks are noise, high initial costs, killing birds, and intermittent of wind. - Large wind turbines may generate a lot of noise, disturbing wildlife and people in the area. - Wind turbines often are placed in areas where winds are constant and concentrated. The problem is that these areas also often are the favored migration routes for birds or hunting areas for large raptors (hawks, eagles). - The wind does not always blow, and there are areas that could not support wind farms. - Many people feel that wind turbines are an eyesore and disturb the natural aesthetics

Explain how the energy we capture from wind could be traced ultimately to the Sun

Temperature differentials on the Earth's surface create differences in air pressures (remember rising and falling air from earlier in the semester?) - Rising air creates areas of low pressure and falling air creates areas of high pressure. - These differences in pressure create airflows (= wind) that move from high to low pressures.

problems with impoundments/reservoirs for hydroelectric power

There are many problems associated with impounding water. - It changes what used to be a flowing water ecosystem to a lake ecosystem, both behind and below the dam. Periodically releasing water from the reservoir often disturbs the riverbed below the dam. - The water released from the bottom of the reservoir is much colder than normal, with severe impacts on life below the dam. (this is a type of thermal pollution) - Dams block fish migrations (e.g. salmon) and the turbines kill aquatic life. - There is a significant loss of land and soil, often that land is prime agriculture land or sacred land for indigenous people. - The new reservoir displaces all the terrestrial life that used to live there. - Creating a new area of standing water provides habitat to a group of parasites and diseases that rely on large bodies of water (Schistosomyasis, mosquitoes, guinea worms). - Creating the large surface area of water increase water losses from evaporation. - Sediment always collects behind the dam and must be periodically removed (at great cost). - There is a potential for disaster from the dam bursting with catastrophic water release.

cooling towers

Use of water from water systems for cooling systems for cooling purposes, with subsequent return to the water way after passage through a condenser, is called cooling process. Cooling towers transfer heat from hot water to the atmosphere by evaporation. Cooling towers are of two types: -Wet cooling tower: Hot water coming out from the condenser (reactor) is allowed to spray over baffles. Cool air, with high velocity, is passed from sides, which takes away the heat and cools the water. -Dry cooling tower: Here, hot water is allowed to flow in long spiral pipes. Cool air with the help of a fan is passed over these hot pipes, which cools down hot water. This cool water can be recycled.

cogeneration

a way we can improve the efficiency of power plants... excess heat produced during electricity generation is captured and used to hear nearby workplaces and homes and to produce other kinds of power

In terms of the environment, the 'dirtiest' fossil fuel to use is...

coal

Which fossil fuel has the most impact from its use and why?

coal, especially the 'softer' coal (bituminous or sub-bituminous) the extraction and burning of coal creates environmental and health problems.

major use for the fossil fuel coal...

electricity generation

Coal produces electricity because when coal is burned, electrical radiation may be collected from the burning coal and used as energy. TRUE OR FALSE

false

Fossil fuels are considered to be 'renewable' because they are constantly being formed deep within the Earth. TRUE OR FALSE

false

One danger from using nuclear power to produce electricity is the possibility of a nuclear explosion. TRUE OR FALSE

false

passive

is where architecture and materials are used to collect or prevent solar heating. There also are mechanisms to store heat. Convective (natural) air movements inside & outside the building distribute the heat. No outside assistance (pumps etc.) are used to move heat

active

is where solar collectors actively gather solar energy and then pumps or fans distribute the heat to exchangers in the building -flat plate solar collectors

In terms of the environment, the 'cleanest' fossil fuel is considered to be

natural gas

Explain what is meant by 'non-renewable' sources of energy and the consequences of being non-renewable

non-renewable indicates that once that resource is consumed it is lost 'forever'. The resource is not currently being replenished (like solar, tidal, biomass, wind). -fossil fuels are non-renewable because it take millions of years to 'produce' fossil fuels from organic matter. This essentially is 'out of reach' for our civilization. -nuclear resources (radioactive ores) are formed on a geologic time scale and so 'new' sources also essentially are out of reach for us.

What two forms of energy humans use cannot be traced ultimately to the Sun?

nuclear and geothermal sources of energy are not ultimately derived from the Sun

photovoltaic systems

photovoltaic cells convert sunlight to electrical energy when light strikes one of a plates made primarily of silicon, a semiconductor that conducts electricity. The light causes one plate to release electrons, which are attracted by electrostatic forces to the opposing plate. Connecting the two plates with wires enables the electrons to flow back to the original place, creating an electrical current, which can be converted into alternating current (AC) and used for residential and commercial electrical power

hydropower main process

storage technique: as reservoir water passes through a dam, it turns the blades of a turbine, which cause a generator to generate electricity. Electricity generated in the powerhouse is transmitted to the grid by transmission lines, while the water flows into the riverbed below the dam and continues downriver. By storing water in reservoirs, dam operators can ensure a steady and predictable supply of electricity, even during periods of naturally low river flow

how do solar collectors provide heating?

systems for heating water vary in design, but typically sunlight is gathered on a flat plate solar collector, until a controller switches on a pump to circulate fluid through pipes to the collector. The sunlit collector heats the fluid, which flows through pipes to a water tank. The hot fluid in the pipes transfers hear to the water in the tank, and this heated water is available for the taps of the home or business. Generally an external boiler kicks in to hear water when solar energy is not available

energy efficiency

the ability to obtain a given amount of output while using less energy input

what is thermal pollution?

the addition of excess of undesirable heat to water thereby making it harmful to man, animal or aquatic life. -thermal pollution may also cause significant departures from nor activities of aquatic communities

how do we collect solar energy?

the easiest way to harness solar energy is through the use of passive solar energy collection

nuclear energy

the energy that holds together protons and neutrons in the nucleus of the atom

energy conservation

the practice of reducing wasteful or unnecessary energy use

Explain how the energy we capture from hydroelectric could be traced ultimately to the Sun.

uses falling water which was initially evaporated by heat from the Sun, which then precipitated 'upstream' and follows gravity to be stored and then fall to turn a turbine to spin a generator to generate electricity.

concentrated solar power plants

we can harness energy from sunlight to produce electricity at CSP plants, which generate electricity at large centralized facilities and transmit power to homes and businesses via the electric grid

nuclear reactors

we harness nuclear energy by converting it to thermal energy inside nuclear reactors, facilities contained within nuclear power plants... this thermal energy is then used to generate electricity by turning turbines with steam