Most of us enjoy reliable
electrical service, enough to satisfy our wants and needs. It is only when our service is interrupted are we reminded of the importance electricity plays in every facet of our daily lives.
In the Eastern part of
the country, most power plants use coal. The majority of the nation’s nuclear power generation is likewise located in the eastern half of the country. Most hydropower resources are in the Pacific Northwest, while most wind, solar, and geothermal resources are located in the West.
COAL Nearly half of the
electricity in the United States is produced by burning coal. Kingston Fossil Plant, Tennessee
Coal is first pulverized into
a fine powder and then moved to a furnace where it is burned in a boiler to create the steam that moves the turbine.
A ‘base load’ is the
minimum amount a power company must be generating to meet its customer’s minimum demands. Coal plants are most often ‘base load’ plants and are typically operated continuously, except for repairs or maintenance.Bull Run Fossil Plant, Tennessee
America’s coal reserves are vast;
it is estimated that the U.S. has at least 200 years left of available coal reserves, more than enough to use domestically and enough to export, too. Learn more about coal by clicking here.
Coal is most often shipped
to power plants by barge or by railroad. The cost of transporting coal is oftentimes more expensive than the mining process. Coal barge in the Louisville and Portland Canal, Ohio River
Coal trains delivering to power
plants can be over a mile long and carry 10,000 tons, enough to power a large plant for a day. During periods of seasonal high demand, a power plant may receive as many as 3 to 5 trains per day. Union Pacific coal train in Douglas, Wyoming
Photo by Nick Humphries Modern
day ‘scrubbers’ and other “clean coal” technologies have reduced these emissions, but coal- fired power plants still release significant emissions into the environment, accounting for 40% of the nation’s carbon dioxide emissions (2008).
Some by-products can be reused
in a variety of products, such as cement or concrete, while the remainder must be isolated and stored. Coal ash disposal is a serious environmental concern.
In December of 2008, 1
billion gallons of coal ash was spilled from the Tennessee Valley Authority’s Kingston Fossil Plant, covering 300 acres and destroying homes, poisoning rivers, and contaminating drinking water.
However, the combustion of coal
contributes to acid rain and air pollution, and emissions from burning coal have been connected with climate change. Proper disposal of the byproducts is a problem. Cumberland Power Plant, Tennessee
Nonetheless, the world’s demand for
electricity is expected to rise 60% by 2030, and the International Energy Agency estimates that 85% of this demand will be met by fossil fuels, much of that most likely to be coal.
THE PROS & CONS OF
COAL PRO: • America has abundant coal reserves. • It is inexpensive. • America’s existing infrastructure is set up for it. CON: • It is highly polluting. • Even with clean coal technologies, there are significant environmental impacts. • There are also significant impacts from the extraction of coal.
FOR MORE INFORMATION ON COAL:
Department of Energy, Clean Coal Technology & The Clean Coal Power Initiative: http://www.fossil.energy.gov/programs/powersystems/clean coal/ U.S. Department of Energy Information: Coal, Explained: http://www.eia.gov/energyexplained/index.cfm?page=coal_ home American Coal Association (pro-coal): http://www.teachcoal.org/aboutcoal/index.html America’s Power (pro-coal); http://www.americaspower.org/ Coal is Clean/Coal is Dirty (anti-coal): http://www.coalisclean.com/# Sierra Club: Beyond Coal (anti-coal): http://www.sierraclub.org/coal/
NATURAL GAS As an alternative
to using coal, some plants burn natural gas. Most new power plants being constructed use natural gas. New Pacific Corp. gas fired plant, Lindon, Utah Photo by arbyreed
Natural gas must be processed
before it can be transported and used. Gathering pipelines transport the gas from the wellhead to a processing plant, where impurities are removed to make pipeline- quality natural gas.
Some natural gas plants burn
the gas to run a steam turbine. Other plants use gas turbines and combustion engines instead. These turbines can be used to meet peak-load demands because they can be quickly powered on and off.
Natural gas has many uses,
including as a heat source for cooking, hot water and home heating, and has potential as an alternative fuel for powering cars. Photo by Scott J. Lowe
Natural gas is the cleanest
burning of all fossil fuels, producing 45% less carbon dioxide than coal, less nitrogen oxides, negligible amounts of sulfur dioxide and mercury, and virtually no particulate matter. LS Energy, Morro Bay Photo by Mike Baird
Knowledge about America’s natural gas
reserves is imprecise, but a recent report estimated reserves at a 100 year supply, much less than coal. Haynes Steam Plant, Seal Beach, CA Photo by Mollivan Jon
A new process called ‘hydraulic
fracturing’ has the potential to utilize unconventional natural gas resources. Hydraulic fracturing (fracking) involves injecting fluid into the rock to fracture it, allowing the gas underneath to escape. Photo by Ari Moore.
As much as half of
the water can return to the surface, risking extensive contamination of drinking water sources and the environment. There is great concern for environmental impacts of this type of natural gas drilling.
More research is needed to
determine how much natural gas can be extracted, and the quality of unconventional natural gas resources is uncertain. In addition, research is needed to reduce the environmental impacts of some extraction methods.
THE PROS & CONS OF
NATURAL GAS PRO: • Natural gas is the cleanest burning of all the fossil fuels. • It is an abundant source of domestic energy. • New techniques have emerged that have increased America’s potential natural gas reserves. CON: • Natural gas does emit carbon and nitrogen oxides, but in much smaller amounts. • It is non-renewable. • Environmental impacts from some types of natural gas mining are significant. • It is more costly to process, transport and store.
FOR MORE INFORMATION ON NATURAL
GAS: U.S. Energy Information Administration: Natural Gas Explained: http://www.eia.gov/energyexplained/index.cfm?page=natural _gas_home U. S. Department of Energy website on natural gas: http://www.energy.gov/energysources/naturalgas.htm Natural Gas Supply Association website on natural gas: http://www.naturalgas.org/ Earthworks: Hydraulic Fracturing 101: http://www.earthworksaction.org/FracingDetails.cfm
Sequoyah Nuclear Generating Plant, Tennessee
Nuclear plants create electricity much the same way as coal or gas plants do, except a nuclear plant uses the fissioning of uranium atoms to create the heat instead of burning coal or gas.
America has the fourth largest
uranium reserves in the world, but the deposits are of lower grade and are uneconomical to mine when prices drop too low. In 2001, only 5% of the uranium used in power plants was mined in the United States.
Nuclear power produces very little
greenhouse gas emissions and the amount of radioactive waste produced is a fraction of the coal ash waste produced by coal-fired power plants. David Besse Nuclear Generating Station, Ohio
But the waste from the
spent nuclear fuel remains toxic for thousands of years, and disposal of waste is a problem. A national repository for nuclear waste planned at Yucca Mountain in Nevada has run into roadblocks and may never be completed.
THE PROS AND CONS OF
NUCLEAR POWER PRO: Emissions for nuclear power plants is very low. A single nuclear power plant can generate a substantial amount of energy. Nuclear power plants in the U.S. have good safety records. CON: Nuclear waste stays toxic for thousands of years, and storage is a problem. Accidents, though rare, are devastating. There is strong public opposition to nuclear power. Uranium is a non-renewable resource that will eventually be used up.
FOR MORE INFORMATION ON NUCLEAR
ENERGY U.S. Energy Information Agency: Nuclear Explained: http://www.eia.gov/energyexplained/index.cfm?page=nu clear_home Joseph Gonyeau’s Virtual Nuclear Tourist: Nuclear Plants Around the World: http://www.nucleartourist.com/ The Future of Nuclear Power: An interdisciplinary study by MIT: http://web.mit.edu/nuclearpower/ National Geographic Magazine: Nuclear Power: Risking a Comeback: http://ngm.nationalgeographic.com/2006/04/nuclear- power/petit-text.html Time for Change: The Pros and Cons of Nuclear Power (anti-nuclear): http://timeforchange.org/pros-and-cons-of- nuclear-power-and-sustainability
Wells are drilled deep into
the earth, bringing the hot water up to the surface where it is used to power the turbine directly without burning any fossil fuels. An injection well returns the water deep inside the earth to begin the process again.
Geothermal Heating System Greenhouse heated
by geothermal energy Geothermal fluids can also be directly used for heating buildings and greenhouses, to melt snow on the sidewalks in winter time, and even to grow fish on fish farms.
The United States leads the
world in geothermal energy production. The largest group of geothermal plants is located at the Geysers geothermal field in Northern California.
Geothermal plants produce very little
emissions - only about one-sixth of the carbon dioxide that a natural gas plant would produce, and very little if any other gases. The white smoke coming from the plants is actually steam from the cooling process. The Leathers geothermal plant , Salton Sea
Most geothermal plants in operation
today are either a flash system or a dry steam system. Both of these types of geothermal power production require reservoirs of high temperatures. A dry steam plant at the Geysers geothermal field
Binary cycle plants are a
newer technology that has been developed to utilize more moderate geothermal temperatures, allowing expansion of geothermal energy to more areas of the country. Most geothermal plants of the future will likely be binary. Ormat facility in Steamboat Springs, Nevada Click here to learn more about geothermal energy production.
Geothermal fluids can contain salts
and dissolved minerals which can be corrosive to equipment and require maintenance. Geothermal fluids along with the minerals are usually reinjected back into the earth, recycling the water and replenishing the reservoir. Geothermal plant, Heber, CA
This doesn’t affect the operational
costs because a geothermal plant does not burn any fuel. However, it does affect the return on capital for building the plant, the costs of which are substantial and involve significant risk. Geothermal plant, El Centro, CA
Geothermal energy is a clean
domestic source of renewable energy, one that doesn’t require storage, transportation or combustion of fuels. Geothermal plant, Imperial Valley, CA
However, building a geothermal plant
is very expensive and involves significant risks. At this time, geothermal energy is not always cost- competitive with other sources of electricity. Geothermal plant, Imperial Valley, CA
THE PROS AND CONS OF
GEOTHERMAL POWER PRO: • Geothermal energy is nearly completely non- polluting. • Plants are inexpensive to operate, once built. • A renewable source of domestic energy. • Geothermal plants do not require extraction, transportation or storage of fuels. CON: • Geothermal power is only available in certain areas of the country. • Initial drilling and construction is complex and expensive • Geothermal reservoirs must be carefully managed and maintained. • Lifespan of plants is unknown; Movement of the earth or other factors can cause the resource to dry up.
FOR MORE INFORMATION ON GEOTHERMAL
POWER: U.S. Energy Information Administration, Geothermal Explained: http://www.eia.gov/energyexplained/index.cfm?page=geothe rmal_home National Renewable Energy Library, Geothermal Energy Basics: http://www.nrel.gov/learning/re_geothermal.html How Geothermal Energy Works, by How Stuff Works: http://science.howstuffworks.com/environmental/energy/geot hermal-energy.htm Geothermal Energy Slideshow: http://geothermal.marin.org/geopresentation/sld001.htm Take a virtual tour of a geothermal plant: http://www.calenergy.com/aboutus4.aspx
The amount of electrical output
produced depends on the volume of water flowing through the turbine, and the height between source and the outflow of the water, called the hydraulic head.
Hydropower dams are most often
located on a river with a large drop in elevation. The reservoir acts as stored energy which can be regulated and controlled to follow fluctuating consumer power demands.
But not all hydropower dams
have reservoirs behind them. A ‘run of the river’ hydropower plant utilizes the natural flow and elevation drop of the river. All or a portion of the flow is diverted through the turbines at the power plant.
Lower Granite Dam on the
Snake River, Washington Since there is no reservoir behind it, a run-of-the-river plant has little or no capacity for storage, and cannot coordinate electrical output with consumer demand.
With hydropower, there is no
expense for fuel; it is a domestic source of cheap, renewable, clean energy. Hydropower plants have a long life and low operating costs.
Reservoirs behind dams can provide
recreational benefits, as well as water storage for drier months and flood protection for communities downstream. Lake Oroville, California Lake Oroville, California
Although hydropower provides clean and
inexpensive electricity, dams are not without their environmental impacts. Creation of a reservoir behind a dam submerges valuable land and riparian environments.
Dams disrupt a river’s ecosystem
by preventing sediment from flowing downstream, which can cause loss of riverbanks and scouring of river beds, even beach erosion. Hoover Dam, Colorado River, Arizona-Nevada
Expansion of hydropower in the
United States is limited by available rivers and the competing uses for those rivers, such as tourism, industry, and existing cities. The best sites have already been developed. Anderson Ranch Dam, Boise River, Idaho
THE PROS AND CONS OF
HYDROPOWER PRO: • A completely clean, renewable source of domestic energy • Once built, inexpensive to operate and maintain • Dams can be built to provide flood control, and to store water for municipal use, recreation, and irrigation. CON: • Dams and reservoirs disrupt natural ecosystems and habitat. • Only certain sites are suitable for hydropower; most of these have already been developed.
FOR MORE INFORMATION ON HYDROPOWER:
U.S. Energy Information Administration, Hydropower Explained: http://www.eia.gov/energyexplained/index.cfm?page=hydrop ower_home U.S Bureau of Reclamation, Hydropower pamphlet: http://www.usbr.gov/power/edu/pamphlet.pdf U.S. Department of Energy, Energy Efficiency & Renewable Energy, page on hydropower: http://www1.eere.energy.gov/windandhydro/hydro_how.html Hydro Research Foundation: http://www.hydrofoundation.org/
SOLAR POWER Solar power uses
the energy of the sun to create electricity, either directly by using photovoltaic cells, or indirectly by using a concentrated solar power system.
The economic viability of a
solar project depends on a number of factors, such as the number of cloudless days, the latitude of the installation, and the cost of collectors.
In a power tower design,
thousands of mirrors tracking the sun focus sunlight onto a receiver which is sitting on top of a tower. Sierra Sun Tower, Lancaster, CA
Inside the receiver, the sunlight
heats the molten salt to over 1000 degrees; the hot salt then flows to a storage tank and eventually is used to run a steam generator.
In a dish system, a
large parabolic dish focuses the energy onto a receiver above the dish which powers a small engine to create the electricity.
There are many other different
types of solar energy systems being developed and used throughout the world. The solar furnace at Odeillo in the French Pyrenees-Orientales Fresnel solar plant in southern Spain
THE PROS AND CONS OF
SOLAR POWER PRO: • A non-polluting, inexhaustible source of domestic energy • Can supply electricity to places not served by the grid • Inexpensive, once installed • More reliable than wind power CON: • Initial costs are high • Power is only generated when the sun is shining • Weather and pollution affect output
FOR MORE INFORMATION ON SOLAR
POWER: From the U. S. Department of Energy, Energy Efficiency and Renewable Energy office: http://www.eere.energy.gov/basics/renewable_energy/sola r.html The American Solar Energy Society: http://www.ases.org/
WIND POWER Wind power is
actually a form of solar energy, caused by the sun’s uneven heating of the atmosphere, irregularities of the earth’s surface, and the rotation of the earth. Wind power is the fastest growing energy technology.
And since wind power must
compete with conventional power sources on a cost basis, profitability is dependent on the local wind conditions.
Currently, wind power accounts for
about 1% of our power generation. While no doubt wind power will play a greater role in electrical production in the future, it cannot be expected to fulfill all of our nation’s electrical demand.
THE PROS AND CONS OF
WIND POWER PRO: • Wind power is a clean, renewable source of domestic energy production. • Wind power is generally compatible with grazing and agricultural land uses CON: • Wind power produces power only when the wind is blowing, which can be unpredictable • The amount produced depends on how fast the wind is blowing • Installations must be sited properly; often the best places are remote and require costly transmission lines
FOR MORE INFORMATION ON WIND
POWER: U.S. Energy Information Administration, Wind Power Explained: http://www.eia.gov/energyexplained/index.cfm?page=wind_ home National Renewable Energy Laboratory page on wind power: http://www.nrel.gov/learning/re_wind.html Wind Energy Resource Atlas of the United States: http://rredc.nrel.gov/wind/pubs/atlas/
It is estimated that 39%
of all freshwater withdrawals in the U.S. each day are for electrical power production, the majority of that needed for plants using fossil fuels. ELECTRICAL PRODUCTION AND WATER USE
Electrical power production is the
second only to agriculture as the largest user of water in the U.S.. Most power plants using thermal processes require water for cooling equipment, which is why power plants are usually located near the ocean, a river, or some other body of water.
Once-through cooling systems draw water
from a waterbody, run it through the plant to cool the equipment, and then return it to the waterbody,only now much warmer. This warmer water is not good for fish, and a lot of aquatic species are killed by these intake systems.
Even though the power plant’s
water usage is not consumptive, during times of drought, lower flows can impact power production by making less freshwater available for cooling.
In 2010, Lake Mead dropped
to it’s lowest level since the 1950s, and there was real concern that if the level were to continue to drop, the turbines at Hoover Dam would no longer be able to produce power.
While the U.S. population is
expected to rise, freshwater availability will not. This increase in population will need both electricity and food, putting the two largest users in competition for increasingly scarce water resources.
FOR MORE INFORMATION ON WATER
& ENERGY ISSUES: Energy-Water Nexus Overview & Report, by Sandia Labs: http://www.sandia.gov/energy-water/nexus_overview.htm Choke Point U.S., from the Circle of Blue Water News: http://www.circleofblue.org/waternews/featured-water- stories/choke-point-u-s/ Special Report: Water vs. Energy, by IEEE Spectrum: http://spectrum.ieee.org/static/special-report-water-vs-energy
The rest of the demand
is met by peaking plants – smaller, faster and usually more expensive plants that can start up quickly to meet demand. Typically these are combined-cycle natural gas or pumped hydroelectric operations. Photo by Mollivan Jon (flickr). Photo by Braden Kowitz (flickr). Photo by the CA DWR.
The United States power grid
consists of approximately 200,000 miles of transmission lines that are operated by about 500 different companies.
In the 1960s, North America
was physically and administratively divided into four major grids: These interconnections were established as a way for power companies to share electrical generation resources and increase their reliability.
The electrical grid is designed
and managed to operate 99.9% of the time with less than 2% variation in voltage, regardless of how much demand is placed on the system. Photo by Duke Energy.
The electrical grid works because
hundreds of components combined have a large amount of output capability that are operated together to form one very large and reliable system.
However, in a widely connected
grid, electricity generation and consumption must remain balanced, as electricity is consumed almost as soon as it is produced, and the potential for cascading failures and widespread power outages exists.
That’s just what happened on
November 9, 1965, when the largest blackout in history occurred in the Northeastern U.S., leaving 30 million people without power, some for as long as 13 hours.
This led to the electric
utility industry to establish the North American Electric Reliability Council (NERC), a self- regulatory agency who works to develop and promote rules and protocols for the reliable operation of North American power grid. Photo by Tripp (flickr)
Under NERC, the four interconnecting
systems are further subdivided into eight regional reliability councils, whose members come from all segments of the electric industry, from utilities and power producers of all sizes to power marketers and end-use customers.
NERC does not run the
day to day operations of the grid; instead, it is an oversight agency whose main duties are to develop and enforce industry standards, identify trends and potential reliability issues regarding the power grid, and to provide providing educational and training resources for power system operators.
In areas of the country
where power supplies are tight, Regional Transmission Organizations exist to administer the transmission grid for their respective regions. RTOs, sometimes called Independent Systems Operators, are overseen by the Federal Energy Regulatory Commission.
ISO/RTOs oversee the operation of
the grid 24 hours a day, coordinating electricity generation and demand, scheduling and managing flows over the transmission lines, and coordinating the operation of network equipment.
Managing the grid has become
much more complex over the past twenty years as electrical consumption has grown and more generation capacity from various sources has come online. Since ISO/RTOs oversee the operation of the grid on a regional basis, they are better positioned to detect and respond to developing problems, and to make recommendations for system improvements.
Find your state’s energy profile
here: http://www.eia.doe.gov/state/ California leads the nation in generating electricity from renewable sources, such as solar, wind, geothermal and hydroelectric power. California imports the most electricity from other states. Texas both produces and consumes more electricity than any other state. Wyoming is the nation’s top producer of coal, producing more than West Virginia, Kentucky, Pennsylvania and Montana combined. Washington produces the most hydropower of all the states; New York produces the most of any state east of the Rockies. SOME FACTS ABOUT STATES AND ELECTRICITY
FOR MORE INFORMATION ON THE
ELECTRICAL GRID & REGULATING AGENCIES: How Power Grids Work, from How Stuff Works: http://science.howstuffworks.com/environmental/energy/power. htm Electrical System Overview: http://www.globalsecurity.org/security/intro/power.htm National Electrical Reliability Corporation (NERC) website: http://www.nerc.com/ Federal Energy Regulatory Commission: http://www.ferc.gov/ ISO/RTO Council: http://www.isorto.org/site/c.jhKQIZPBImE/b.2603295/k.BEAD/ Home.htm
Electricity sent over transmission lines
is in the form of alternating current (AC), because it is easier to generate AC rather than direct current, and transformers can be used to change voltage to a higher voltage which is needed for transmission over long distances.
Newer models of large flat
screen TVs use significant amounts of power, due to their larger screen size and that users tend to spend more time watching them. Some models can draw more power than a refrigerator.
SOMETHING TO THINK ABOUT …
Electrical demand is increasing in the United States, even as we make efficiency gains. Nonetheless, the U. S. Energy Information Administration predicts electrical demand will grow by 41% by 2030. Where will this additional electricity come from? Photo by Deacon MacMillan (flickr)
Given that electrical power generation
accounts for more carbon dioxide emissions than transportation, and that nearly half of America’s electrical production comes from coal, how ‘green’ is a plug-in electric car?
MORE WEB RESOURCES Electricity:- A
comprehensive article on electricity generation & distribution from AAEnvironment.com: http://aaenvironment.com/Electricity.htm Energy Explained: Your Guide to Understanding Electricity, from the U. S. Energy Information Administration: http://www.eia.doe.gov/energyexplained/index.cfm Topics in Energy, from the Energy Library: http://theenergylibrary.com/taxonomy/term/2329 Photo gallery of the world’s 100 largest power plants: http://www.industcards.com/top-100-pt-1.htm Energy Consumers Edge: A comprehensive website on all things energy: http://www.energy-consumers-edge.com/energy-resources.html Frequently Asked Questions about Electricity, from the U. S. Energy Information Administration: http://www.eia.doe.gov/ask/electricity_faqs.asp#power_plants
Pictures in this presentation were
sourced from Wikimedia Commons, Flickr photographers under the Creative Commons License, the California Department of Resources, Bureau of Reclamation, the NREL’s Photographic Information Exchange, and Dreamstime.com. Locations are given when known.
Also available online Follow the
path California’s first water project, learn a bit of it’s history and find out how the Los Angeles Aqueduct works by clicking here. Follow the path of water as it flows from the Colorado River, through the fertile fields of the Imperial Valley and on to the Salton Sea by clicking here. In the world of California water, we’re always arguing about the Delta. What is the Delta and why is it important? Find out by clicking here. Hottest, driest, lowest. Death Valley is all of these. Check out the wonders of Death Valley by clicking here.