Nonrenewable
Energy Sources
A
nonrenewable energy source is a natural energy source in limited supply. While
these energy sources may be plentiful, they cannot be produced at all or as
quickly as they are consumed. In addition to these resources being limited, not
only the burning but also the extraction of these energy sources has dire
consequences to our environment.
Petroleum
Petroleum,
also known as crude oil, is a naturally occurring toxic combustible liquid
primarily made up of hydrocarbons. Petroleum is the result of partial decay of
living organisms occurring in the rock strata of certain geological formations.
Coal
Coal is a
combustible black or brownish-black sedimentary rock formed from fossilized
plants. Coal consists of amorphous carbon with various organic and some
inorganic compounds and is normally occurring in rock strata in layers or veins
called coal beds.
Natural
Gas
Natural gas
is a combustible mixture of hydrocarbon gases that occurs with petroleum
deposits consisting primarily of methane. It is found with other fossil fuels
and in coal beds and is created by the decay of methanogenic organisms in
marshes, bogs, and landfills. Lower temperatures are likely to produce more
petroleum, and higher temperatures are likely to produce more natural gas.
Nuclear
Power
Nuclear
power is produced by controlled nuclear fission (splitting atoms). In most
cases nuclear power plants use nuclear fission reactions to heat water, using
the steam to produce electricity. Uranium, specifically, uranium -235, is one
of the few elements easily fissioned.
Renewable
Energy Sources
Renewable energy is energy that comes from
natural resources such as sunlight, wind, rain, tides, waves and geothermal
heat, which are renewable because they are naturally replenished at a constant
rate.
Geothermal
Geothermal
energy is power extracted from heat stored under the earth’s crust. This power
source is generally cost effective, usually reliable, mostly sustainable, and
generally environmentally friendly. Historically, geothermal energy extraction
has been limited to areas near tectonic plate boundaries. Recent advances in
technology have significantly widened the range of viable resources, especially
for applications such as home heating.
Wind
Wind power
is a renewable energy that is growing at a rate of 30% a year and is virtually
benign to the environment. There are three minor problems with wind energy:
wind is not available in sufficient quantity everywhere all the time, the
turbines can be loud, and birds sometimes fly into the propellers and get
killed. New technologies are helping to solve or reduce these issues.
Solar
Solar
energy has been used by humans since ancient times. There are three types of
solar energy: passive solar energy, active solar energy, and solar energy
created by converting solar radiation into electricity using photovoltaic
cells. Solar energy using photovoltaic cells is the fastest growing power
generating technology in the world at this time. And the technology is
advancing rapidly with exciting changes and much greater efficiency.
Hydropower
Dams
Hydropower
to produce electricity is power created from the force of moving water. Modern
large scale hydropower impacts the environment through habitat loss, changes to
the riverbed downstream, disrupting spawning, and the loss of fish and other
species.
Tidal
Hydropower
This is a form
of hydropower where the rising tide fills a damned reservoir, then as the tide
lowers, the water is released through a turbine that produces electricity.
There are no significant environmental threats known with this renewable
energy.
Wave
Hydropower
Wave power involves extracting energy from
the surface motion of waves or from the pressure fluctuations below the surface
caused by waves.
Radiant
Energy
This energy
is used for heating. An obvious example is using solar to heat the water for a
hot water heater or a swimming pool. Enertia homes use radiant heat from the
earth to heat themselves.
BioMass
Biomass is
biological material from recently living or currently living organisms such as
trees and landfill gasses and alcohol fuels. Burning grease or fuel ethanol
derived from corn to run a vehicle are two common examples of biomass energy
production.
Alternative
Energy Sources
Alternative energy is any energy source that is an
alternative to fossil fuel.
Hydroelectric
Energy
Hydropower,
the largest form of alternative energy, is derived by harnessing energy from
moving water. From the earliest use of a waterwheel to grind grain, forge
metals, or make paper to today’s massive hydroelectric plants that provide
electricity to entire cities, mankind has learned to harness the power of
moving water.
Hydroelectric
Power from Large Dams
Dams were
first used for hydropower around 1890. There were more than 45,000 large dams
in more than 140 countries by the end of the 20th century. But only a fraction
of these dams are used for hydropower. Most are used for irrigation, flood
control, and water supply. The percentage of dams constructed for hydropower
has been decreasing over the last 20 years. In the year 2000, the distribution
of large hydropower dams was as follows: Africa 6%; North America 11%, South
America 26%; Asia 7%; Australasia (Australia, New Zealand, New Guinea and
neighboring islands) 19%, and Europe 31%.
Hydropower
provides 96% of the renewable energy utilized in the United States, though it
provides only 10-11% of its electricity.
Hydropower
can be generated from the movement of any body of water. Rivers movement of any
body of water. Rivers, waterfalls, streams, ocean tides, and ocean waves are
all potential energy sources.
When we
think of hydropower, we usually imagine a massive dam. Behind the dam, water is
backed up to form a reservoir or an artificial lake. Gravity pulls water into
the intake area from the reservoir where it flows through a penstock (a chute,
sluice, tunnel, or pipe) downhill to pass through a turbine propeller, which
spins the turbine shaft. The hydraulic turbine converts mechanical energy into
electricity. [For an interesting in-depth explanation and great graphics, check
out the U.S. Geological Services website.]
Although
hydro-electrical power is green energy that is clean, renewable, and
sustainable, it has negative environmental and societal impacts.
Damming a
river creates a reservoir which floods a large area, burying whatever was there
before, whether it was a town or a wilderness area. Rotting vegetation releases
methane gas. Habitats are destroyed. Natural fish migration is disrupted. Water
released through the dam carries less silt and it scours and erodes the banks
and the riverbed downstream.
The World
Commission on Dams report (Nov. 2000) estimates 40-80 million people have been
displaced through forced resettlement due to dam construction, with whole
societies losing their cultural heritage, their homes, and their livelihoods.
Many did not receive any form of compensation or resettlement assistance.
Downstream
communities are at great risk if a dam fails. The Association of State Dam
Safety Officials has concluded that the U.S. safety expenditures for dams are
insufficient. They rate 9,326 of the 80,000 large and small dams in the U.S. as
high hazard and 1,600 of these dams lie within one mile upstream of a city.
Less than 40% of high hazard dams have an emergency action plan for nearby
residents to follow.
Smaller
Dams and Run-of-the-River Systems
Smaller
dams and run-of-the-river systems exert less environmental and societal impact.
A smaller dam may be built with storage and pumping capacity, reusing water it
pumps back into its reservoirs. Run-of-the-river systems either place turbines
within the river or divert water through pipes which run through a turbine and
flow back into the river downstream.
If we are
to increase our use of inland hydropower as an alternative power source with
low impact on the environment, we must do a better job of assessing and
mitigating its short-term and long-term consequences.
Energy
from the Ocean Tides
Tidal
energy plants build a low dam or barrage across an inlet. Water passes through
gates or sluices into the inlet. When the tide goes out, it turns turbines to produce
energy. There is no pollution, the fuel is free, the plants are easy to
maintain, and they should last for a hundred years. Unfortunately, there are
few locations in which to build them. Construction costs are expensive.
Fortunately the environmental impact appears to be minimal. The French tidal
plant, La Rance, has been producing electricity since 1968.
Energy
from Ocean Waves
There are
several ways to capture energy from ocean waves. Wave motion can push air
through a pipe; the air spins a turbine. Or water can be focused into a narrow
channel to increase its power and is used to spin turbines or can be channeled
into a catch basin. Currently this potential energy source is being explored
for use in Japan, but there are no large commercial energy wave plants at this
time. One demonstration tower built in Norway proves the potential of this
technology with one drawback, noise pollution. The whine of the turbines can be
heard for miles.
Ocean
Thermal Energy Conversion
In tropical
areas where the difference between the surface temperature of the water and the
deep water temperature is 38 degrees or more, this difference in temperature
can be used to create energy. Hawaii has experimented with ocean thermal energy
conversion since the 1970s, but it is estimated to be 15-20 years before this
technology, which is limited to tropical climates, will be available.
Wind
Energy
Windmills
have been used to harness energy for thousands of years, first for
transportation (sailing ships), later for grinding grain and pumping water.
Today, single wind towers are providing green energy to isolated homes or
farms, while large-scale wind farms are being built both on land and off shore
to provide energy for national electrical grids and pre-planned
communities.
Wind energy is gaining in popularity across
the world. Britain is investing in offshore wind farms with a goal of
generating enough green power to light every home in Britain by wind energy.
European countries, Canada, the U.S., Brazil, China, India, and Mexico are all
pursuing wind as a viable source of energy.
This
renewed interest has resulted in vast improvements in wind tower design and
efficiency. It has also sparked creative and innovative ideas such as wind
kites; deep water (floating rather than fixed), off-shore wind farms; and
overhead turbines placed on freeways that are powered by wind created by
passing cars.
While wind
power is sustainable and pollution free, the power generated is intermittent.
Noise has been cited as a factor. A cute video comparing the noise of a single
tower to everyday urban and rural noise suggests traffic noise is much more
disruptive. Many argue the huge towers are an eyesore, whether onshore or
offshore. Bird and bat mortality is also a consideration, but this issue is
being researched and addressed by the industry.
Solar
Energy
By far the
most utilized alternative power source throughout mankind’s history, solar
power seems to have been the least exploited in recent years. Solar energy,
both active and passive, is a well known source of power. But for years we have
heard large scale use is cost prohibitive, takes up too much space, is too
affected by the weather, and produces too little output. Due to the rising
costs of fossil fuel, new research, new technology, and new application will
hopefully give rise to an increase in the use of solar power.
Whether
active or passive, or photovoltaic, solar lends itself to onsite green energy
applications. Active solar energy can be used to heat hot water, an obvious
need, but heated water can also be used to heat a home or pool and solar energy
can be used to heat air. Solar panels can also be used to create electricity,
while passive solar design utilizes the sun’s rays for both heat and light.
Solar
energy plants (also called thermal plants) collect the suns energy and convert
it to electricity through various means. Solar cells are the most widely known,
but solar energy can also be used to make steam which is used like wind or
water to turn turbines.
Solar
energy is clean, renewable, free and worldwide, but of course can be collected
only during daylight hours. Pollution and cloud cover adversely affect solar
power collection, but newer technology is addressing these factors.
Like wind
technology, investment in solar research and design is booming. It will be
exciting to see what the next few years hold in store for utilization of this
age old resource.
Biomass
and Biofuel
Biomass is
used as a fuel or is converted to biofuel. Biomass is organic matter, vegetable
or animal, including crops, wood, refuse from industry such as paper mills, or
matter from landfills. It can be burned to create electricity; gases from
decomposition can be collected and used, or crops can be grown to make fuel,
such as corn grown to make ethanol.
Proponents
argue that burning biomass, which releases CO2 into the atmosphere, is green
power because it is part of the carbon cycle. They claim, on the other hand,
that burning fossil fuels disrupts the carbon cycle. If the Earth is viewed as
a closed system, this logic seems suspect and a weak argument for cutting down
forests for biofuel.
It is interesting, however, to remember that Henry
Ford built a car out of biomass that was stronger than steel. And the fuel he
chose was made from the oil of seeds. Today we are manufacturing new
bio-degradable plastics from biomass and raising crops for ethanol. But it is
essential we consider the entire impact of turning to biofuels to replace
fossil fuels, including the stewardship of croplands and food sources.
Geothermal
Energy
Geothermal
energy can refer to the use of the Earth to provide heating and/or cooling on a
small scale through the design of a home or through the utilization of a heat
pump. Or it can refer to the use of the Earth’s heat to run power plants.
Geothermal
Design and Heat Pumps
If you dig
below the frost line, the temperature of the ground remains constant—about 50
degrees. This median temperature can be used as an aid to cool a building in
the summer and heat it in the winter. Combined passive solar and geothermal
designs circulate air around and under a building, venting heat in the summer,
trapping it in the winter.
Heat pumps
pipe water or coolant underground to heat or cool it to 50 degrees, cutting
down on the amount of electricity needed to reach the desired temperature.
Geothermal
Plants
The depth
of the Earth’s crust varies on average from 5-25 miles deep. But there are
places on the Earth where magma oozes or explodes to the surface, mud flats
boil and bubble, and steam shoots into the sky. And there are places where the
Earth’s crust is thin and drilling below the surface can easily tap into heat
sources below.
Geothermal
power plants use water, steam, and/or heat from below the Earth’s crust to make
electricity or to provide a direct source of heat. Underground bodies of water
heated by hot rocks or magma can be pumped through buildings, under streets,
and under sidewalks. In Iceland, this method is used to heat most of the homes
and commercial buildings in the nation.
Geothermal
electric power plants use steam to turn turbines and make electricity in one of
three ways: a direct source of steam is tapped, hot water sources are tapped
and turned into steam, or above ground water sources are diverted into deep
wells where water is heated by hot rocks or magma and turned into steam. One
process utilizes chemicals in addition to hot water to make steam.
Proponents of geothermal energy tell us it is safe,
sustainable, and non-polluting. These sweeping statements are not entirely
true. Destruction from drilling, landslides, earthquakes, and pollution from
released gases and toxic elements impact the environment.
A
geothermal plant in California, believing their source of steam to be an
inexhaustive supply, vented the steam rather than capturing it and returning it
to the source. The underground water source, which had produced geysers for
thousands of years, was depleted.
Open system
plants vent steam along with gases such as hydrogen sulfide, carbon dioxide,
ammonia, and methane and toxic elements such as mercury and arsenic, though
some systems capture gases and other pollutants and either return them to the
source or utilize them. But accidents can happen as well. A blow-out in a
Hawaiian geothermal plant caused toxic gases to spew into the sky for thirty
hours.
Enhanced
Geothermal Systems (EGS) drill down to dry, hot, non-porous rock and pump in
water under high pressure into the well to create steam which rises through a
second bore hole. The water, once cooled, is again injected into the well in a
closed loop system. One plant in Switzerland was forced to close within days of
starting operation due to seismic activity generated by this process. But EGS
technology is in its infancy. New research is underway using carbon dioxide
instead of water for EGS systems.
Alternative
Energy—The Future
As we move
forward with research and application of green power, it makes sense to look at
a wide array of alternative energy resources, rather than search for the one
solution that will replace fossil fuels.
Of course
we should conserve energy, not waste it. But will we continue to build houses
that consume energy like a hummer guzzles gas? Or will we plan whole
communities off the grid?
Can you
image a community where every home and businesses is built with a passive solar
heat and geothermal design? Where every house has solar panels that generate
electricity as well as solar panels that heat water? A neighborhood wind farm? A run-of-the-river type generator if it’s
located near moving water?
At the very
least, our homes should incorporate every possible alternative energy source to
minimize the need for energy from the grid.
We can
capture the energy of the sun. We can harness the energy of the wind. We can
build run-of-the-river systems and tap into natural steam with a closed system
that returns the water to its source.
As we build
new power plants and develop new technology, we should fully embrace the idea
of working with Mother Nature instead of against her.
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