BASIC ELECTRICITY
WHAT IS ELECTRICITY?
A form of energy resulting from the existence of charged particles (such as electrons or protons), either statically
as an accumulation of charge or dynamically as a current.
Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property
of electric charge.
SOURCES OF ELECTRICITY
Wind
The kinetic energy of the wind can be harnessed with turbines that, although they are quieter,
sturdier, and more efficient, are not far from the age-old windmill. Once installed, turbines
produce no air or water pollution beyond a negligible amount produced during occasional
maintenance. Although wind energy can only be generated in windy areas, the potential for
wind energy in the United States is tremendous. It is estimated that the wind energy potential
in just two states, North and South Dakota, could meet 80 percent of the nation's electricity
needs. A potential drawback to wind power is that it relies on a naturally variable resource
that, though renewable, can not be turned on and off according to demand. But the fact that the wind is likely to be
blowing somewhere has underlied findings that up to half of overall system energy could be derived from wind power
before running into problems associated with variability. Wind power now contributes less than 1 percent of the
electricity used in the US, but it is also the least expensive and fastest growing renewable energy source.
Solar
The solar energy falling on the Earth each day equals nearly 500,000 times the electric power
capacity of the United States. This energy can be converted directly to electricity by
photovoltaic cells (PVs) which produce an electric current when struck by sunlight. Because
the solar energy supply is inexhaustible, its potential for electricity generation is limited only
by the efficiency at which we can capture it and the amount of surface area we can devote to
it. PVs are typically 99 percent silicon, an inert substance which is the second most abundant
element on Earth and a primary constituent of sand. PVs work without sound, air or water
emissions, moving parts, and require little maintenance and no water. Even when you consider the manufacture of
photovoltaics the environmental impacts are very low, and the PVs themselves are recyclable after their useful life
ends. Currently solar power contributes less than 1 percent of our electricity. Expansion has primarily been hampered
by its high cost, although this has fallen significantly in the last decade. Another drawback to PVs is that they only
generate electricity when the sun is shining. At a small scale, therefore, some sort of energy storage or back-up system
is required. At larger scales, however, studies and field experience have shown that integrating intermittent PVgenerated electricity into the electric grid provides few technical difficulties, even when considering much higher
levels of solar power usage.
Biomass
Biomass refers to wood, crops, harvest residues, urban refuse, or methane gas produced by landfills that are burned to
spin turbines and produce electricity. Biomas is an attractive energy source because it avoids two drawbacks
accompanying most other forms of renewable energy: high cost of collection and intermittency. The solar collectors
are the leaves of plants, requiring much less capital than wind turbines or PV cells and providing a convenient medium
for energy storage, allowing electricity to produced on-demand, and contributing no net carbon dioxide to the
atmosphere. However, if biomass were used for electricity production on a large scale, the impacts would be
significant. For example, commercial applications of biomass would require vast acreage of fertile land to be
committed to trees or crops grown specifically for energy production. Furthermore, biomass-fueled electricity
production would also be extremely water intensive. Put in perspective, to produce electricity for just one household
over the course of a year with biomass as a source would require over 25,000 gallons of water and almost three quarters
of an acre of land. It also produces 232 pounds of carbon monoxide per household each year -- more than thirty times
the level of any other source, as well as significant amounts of other air pollutants. Combustion of wood now
contributes about 1 percent of the nation=B9s electricity supply, and the electricity generated from waste about half
that amount. Waste is not considered a viable option for large-scale electricity production and is not a truly renewable
resource.
Hydroelectricity
The kinetic energy of flowing water can also be used to spin turbines. Hydroelectricity, which
currerntly generates about 9 percent of the nation's electricity, is renewable, can produce
electricity on-demand, and generates electricity with few emissions. On the other hand, a dam
can have devastating impacts on the ecological systems up and downstream. In the United
States alone there are more than 5,500 large dams impeding our rivers, leaving less than 2
percent of our country's 3.1 million miles of rivers and streams flowing free. An important
distinction to make, however, is between large and small hydroelectric projects. Large hydro
projects involve constructing a large dam on a river and flooding its river basin to create a reservoir. Small
hydroelectric plants generate less than 30 megawatts of electricity and have much smaller impacts than large hydro
projects, though they may not always be able to provide on-demand power because they are much more susceptible to
variations in river flow. Because the most promising large dam sites in the United States have either been developed
or protected, and because the general public has become outspoken about the negative impacts of large dams, dam
construction has been declining.
Natural Gas
Natural gas was formed millions of years ago when buried organic matter was subjected to very high temperatures and
pressures. Although the formation process continues, the rate is negligible compared to the rate of human extraction,
making natural gas a non-renewable resource. Natural gas may be found along with coal or oil, or it may be found
alone; off-shore drilling is becoming more prevalent, with about one-fifth of U.S. natural gas coming from off-shore
sites. Once extracted and refined, the gas is burned to create steam, which then turns turbines to produce electricity.
About 15 percent of US electricity comes from natural gas combustion. Like coal, natural gas is relatively cheap, the
technology involved is simple and widespread, and electricity can be produced on-demand. It produces much lower
levels of air pollutants such as particulates, sulfur dioxide and nitrogen oxides than coal, but significantly more than
other source apart from biomass. For instance, a household supplied only by natural gas for a year would generate 24
pounds of air-borne particulate matter which has been implicated in respiratory infection and asthma. Maybe most
significant, however, is the amount of the greenhouse gas carbon dioxide emitted during natural gas combustion: over
10,000 pounds per household per year if natural gas were the sole source. Touted as the cleaner alternative to coal, this
claim may be true, but it doesn't make natural gas sustainable.
Coal
Coal production has been increasing since the 1950s, and today the United States extracts huge quantities of coal (over
1 billion short tons in 1998). Currently, coal contributes over half of the nation=B9s electricity, and over 90 percent of
the coal produced is used for electricity generation. Besides being cheap and abundant, the only thing that coal has to
recommend it is that is can provide power on-demand. Coal mining has major impacts on terrestrial and aquatic
ecosystems. In many cases, whole mountaintops are removed for coal extraction, and valleys are filled in with the
waste rock (tailings). Whether it is mountain-top removal, open-pit, or underground mining, however, a major
problems stems from rain filtering through the coal mine and tailings. Some of the sulfur in the coal dissolves into the
water, turning it acidic; this "acid mine drainage" has impacted thousands of stream miles across the country. The
combustion of coal also produces many gaseous wastes, some of which are "scrubbed" out of the emission stream in
smokestacks, but many are not, including carbon dioxide. A single household being supplied solely from coalproduced electricity would generate over 61 pounds of sulfur dioxide, 60 pounds of nitrogen oxide, 30 pounds of
particulates, 6 pounds of carbon monoxide, 2 pounds of volatile organics, and 17,000 pounds of carbon dioxide, and
require over 7,000 gallons of water.
Nuclear
While every other source of electricity is basically solar energy in one form or another, nuclear
power harnesses the power contained within the nuclei of atoms. Consequently, risks and
impacts involved are unique. With its low emissions and low land use, nuclear seems falsely
attractive at first glance, but when you begin to look at its entire lifecycle, the potentially
devastating human health and safety concerns are clear. The nuclear fuel cycle begins with
the mining of uranium ore (a non-renewable resource), releasing radon (radioactive gas) and
creating large amounts of radioactive waste rock (tailings). The uranium is then processed in
a highly energy-intensive process and fabricated into fuel rods. Nuclear power plants produce energy through either
fission reactions (when an atom of a radioactive element such as uranium or plutonium collides with a neutron, splitting
the element apart) or fusion reactions (where two elements collide at high speed, forming one or more heavier
elements). In both cases, a large amount of heat is released which is used to create steam to turn turbines and generate
electrical energy.
Along with heat, a significant amount of radiation is produced. Radiation is extremely dangerous to people and
biological systems, causing acute illness or death at high doses, or cancer or genetic mutations at lower doses. Although
most of this radiation is not released into the atmosphere, it does not disappear. It is contained instead in large amounts
of radioactive waste, which remains hazardous for many thousands of years. No permanent facility for the storage of
high-level waste exists, and even if one is built, it may adequately contain the waste for only 1,000 years. Routine
plant operation produces upwards of 3.64 tons of low-level waste per GWh of electricity, and about 30 to 40 tons of
high-level waste over the course of a power plant year. The largest volumes of nuclear waste, however, stem from the
decommissioning of plants at the end of their life spans. Current decommissioning practices of reactors consist of
processing some of the waste, but "mothballing" the reactor core and much of the rest of the reactor in the hopes that
better methods of dealing with its might be found in the future.
One of the most frightening propositions in the modern world is the event of an accident involving a nuclear power
plant or radioactive waste. The U.S. Nuclear Regulatory Commission (NRC) has estimated that there is a 45 percent
chance of a severe accident occurring in the next twenty years at one of the 109 U.S. reactors. The possibility of an
accident and the unavoidable reality of the nuclear waste highlights a moral issue: what are we leaving for our children
and all future generations? The risks that stem from the air pollution emitted during fossil fuel combustion are
significant, but they have short-term impacts only. The same people (or at least generation of people) that are suffering
the costs are also receiving the benefits of that electricity. In contrast, the legacy of the nuclear electricity being
produced and consumed today will continue to pose a threat for many generations to come.
Nuclear power plants multiplied rapidly during the late sixties and early seventies, but interest declined for various
reasons including high operating costs, and public disfavor over the risk of serious accidents after the Three Mile
Island incident in 1979. Currently, nuclear provides the United State with a little less than 20 percent of its electricity.
More than half of the current reactors are scheduled to retired in the next 20 years and no new ones are scheduled to
be built. Consumers can send a loud message to the electricity industry by refusing to buy power that includes nuclear
in the mix.
Table 1. Pros and Cons of Electricity Sources
Source
Advantages
Disadvantages
Wind
 Renewable energy source
 Very low greenhouse gas
emissions
 Very low air pollution
emissions
 Very low water requirements
 Very safe for workers and
public




Intermittent energy source
Limited to windy areas
Potentially high hazard to birds
Moderate land requirements
Solar
 Renewable energy source
 Very low greenhouse gas
emissions
 Very low air pollution
emissions
 Very low water requirements
 Modular, low-profile, lowmaintenance
 Very safe for workers and
public




Intermittent energy source
High land requirements
Expensive
Manufacture involves some toxics
Biomass
 Renewable energy source
 Very low greenhouse gas
emissions
 Can produce energy ondemand
 Energy is easily stored




Low energy return on investment
High air pollution emissions
Very high water and land requirements
High occupational hazards
Small
Hydro
 Renewable (if silt removed in
reservoir)
 Rery low greenhouse gas
emissions
 Very low air pollution
emissions
 Inexpensive to build and
operate
 Safe for workers and public
 Dependent on stream flow
 Large numbers of small dams can have significant
effects on terrestrial and aquatic habitats, possibly as
great as a large dam producing the same amount of
electricity
Large
Hydro
 Very high return on energy
investment
 Very low greenhouse gas
emissions
 Very low air pollution
emissions
 Inexpensive once dam is built
 Can produce energy ondemand
 Provide water storage and
flood-control





Non-renewable (silt removal unfeasible)
Very high land requirements
Extremely high impacts to land and water habitat
Best sites are already developed or off-limits
Disastrous impacts in case of dam failure
Natural
Gas
 Inexpensive
 Low land requirements
 Can produce energy ondemand
 Relatively safe for workers
and public




Non-renewable energy source
High greenhouse gas emissions
Relatively moderate air pollution emissions
Danger of explosion if handled improperly
Coal
 Inexpensive
 Abundant
 Low land requirements
 Non-renewable energy source
 Very high greenhouse gas emissions
 Very high air pollution emissions
Nuclear
 Can produce energy ondemand
 High land/water impacts from acid rain, mine drainage
 Highly hazardous occupation
 Low greenhouse gas
emissions
 Low air pollution emissions
 Low land requirements for
power plants (though not for
waste storage)
 Can produce energy ondemand





Non-renewable energy source
High water requirements
Relatively expensive
Waste remains dangerous for thousands of years
Serious accident would be disastrous
There are two types of Electricity, Static Electricity and Current Electricity. Static Electricity is made by rubbing
together two or more objects and making friction while Current electricity is the flow of electric charge across an
electrical field.
Static Electricity
Static electricity is when electrical charges build up on the surface of a material. It is usually caused by rubbing
materials together. The result of a build-up of static electricity is that objects may be attracted to each other or
may even cause a spark to jump from one to the other. For Example rub a baloon on a wool and hold it up to the
wall.
Before rubbing, like all materials, the balloons and the wool sweater have a neutral charge. This is because they
each have an equal number of positively charged subatomic particles (protons) and negatively charged
subatomic particles (electrons). When you rub the balloon with the wool sweater, electrons are transferred from
the wool to the rubber because of differences in the attraction of the two materials for electrons. The balloon
becomes negatively charged because it gains electrons from the wool, and the wool becomes positively charged
because it loses electrons.
Current Electricity
Current is the rate of flow of electrons. It is produced by moving electrons and it is measured in amperes. Unlike
static electricity, current electricity must flow through a conductor, usually copper wire. Current with electricity is
just like current when you think of a river. The river flows from one spot to another, and the speed it moves is the
speed of the current. With electricity, current is a measure of the amount of energy transferred over a period of
time. That energy is called a flow of electrons. One of the results of current is the heating of the conductor. When
an electric stove heats up, it's because of the flow of current.
There are different sources of current electricity including the chemical reactions taking place in a battery. The
most common source is the generator. A simple generator produces electricity when a coil of copper turns inside
a magnetic field. In a power plant, electromagnets spinning inside many coils of copper wire generate vast
quantities of current electricity.
There are two main kinds of electric current. Direct (DC) and Alternating (AC). It's easy to remember. Direct
current is like the energy you get from a battery. Alternating current is like the plugs in the wall. The big difference
between the two is that DC is a flow of energy while AC can turn on and off. AC reverses the direction of the
electrons.