STUDENT HANDOUTSFOR

ALTERNATIVE ENERGY

7th Grade Science Class

Table of Contents

Graphic organizer for fact sheets page 1

Fact sheets for types of alternative energy page 2-24

Rubric for Expert Groups page 25

Alternative Energy Fact Sheet OrganizerType of alternate

EnergyHow it works Benefits Setbacks Application

How would I use it?

Solar Energy

The Earth receives an incredible supply of solar energy. The sun, an average star, is a fusion reactor that has been burning over 4 billion years. It provides enough energy in one minute to supply the world's energy needs for one year. In one day, it provides more energy than our current population would consume in 27 years. In fact, "The amount of solar radiation striking the earth over a three-day period is equivalent to the energy stored in all fossil energy sources." Solar energy is a free, inexhaustible resource, yet harnessing it is a relatively new idea. The ability to use solar power for heat was the first discovery. A Swiss scientist, Horace de Saussure, built the first thermal solar collector in 1767, which was later used to heat water and cook food. The first commercial patent for a solar water heater went to Clarence Kemp of the US in 1891. This system was bought by two California executives and installed in one-third of the homes in Pasadena by 1897.

Producing electricity from solar energy was the second discovery. In 1839 a French physicist named Edmund Becquerel realized that the sun's energy could produce a "photovoltaic effect" (photo = light, voltaic = electrical potential). In the 1880s, selenium photovoltaic (PV) cells were developed that could convert light into electricity with 1-2% efficiency ("the efficiency of a solar cell is the percentage of available sunlight converted by the photovoltaic cell into electricity"), but how the conversion happened was not understood. Photovoltaic power therefore "remained a curiosity for many years, since it was very inefficient at turning sunlight into electricity." It was not until Albert Einstein proposed an explanation for the "photoelectric effect" in the early 1900s, for which he won a Nobel Prize, that people began to understand the related photovoltaic effect.

Solar technology advanced to roughly its present design in 1908 when William J. Bailey of the Carnegie Steel Company invented a collector with an insulated box and copper coils." By the mid-1950s Bell Telephone Labs had achieved 4% efficiency, and later 11% efficiency, with silicon PV cells. From then on, interest in solar power intensified. During the late 1950s and 1960s, the space program took an active role in the development of photovoltaics. "The cells were perfect sources of electric power for satellites because they were rugged, lightweight and could meet the low power requirements reliably." Unfortunately, the cells were not practical for use on earth due to the high cost of making them efficient and lightweight, so further research was necessary.

Solar energy may have had great potential , but it was left on the backburner whenever fossil fuels were more affordable and available. "Only in the last few decades when growing energy demands, increasing environmental problems and declining fossil fuel resources made us look to alternative energy options have we focused our attention on truly exploiting this tremendous resource." For instance, the US Department of Energy funded the installation and testing of over 3,000 PV systems during the 1973-1974 oil embargo. By the late 1970s, energy companies and government agencies had invested in the PV industry, and "a tremendous acceleration in module development took place." Solar energy improvements were again sought during the Gulf War in the 1990s.

Considering that "the first practical solar cells were made less than 30 years ago," we have come a long way. The biggest jumps in efficiency came "with the advent of the transistor and accompanying semiconductor technology." The production cost has fallen to nearly 1/300 of what it was during the space program of the mid-century and the purchase cost has gone from $200 per watt in the 1950s to a mere $5 per watt today. The efficiency has increased dramatically to 18.8% the US Department of Energy's National Renewable Energy Lab's new world record as of February 1999.

We still use solar power in the same two forms today, thermal and photovoltaic. The first concentrates sunlight, converts it into heat, and applies it to a steam generator or engine to be converted into electricity in order "to warm buildings, heat water, generate electricity, dry crops or destroy dangerous waste." Electricity is generated when the heated fluid drives turbines or other machinery. The second form of solar power produces electricity directly without moving parts. Today's photovoltaic system is composed of cells made of silicon, the second most abundant element in the earth's crust. "Power is produced when sunlight strikes the semiconductor material and creates an electric current." The smallest unit of the system is a cell. Cells wired together form a module, and modules wired together form a panel. A group of panels is called an array, and several arrays form an array field.

There are several advantages of photovoltaic solar power that make it "one of the most promising renewable energy sources in the world." It is non-polluting, has no moving parts that could break down, requires little maintenance and no supervision, and has a life of 20-30 years with low running costs. It is especially unique because no large-scale installation is required. Remote areas can easily produce their own supply of electricity by constructing as small or as large of a system as needed. Solar power generators are simply distributed to homes, schools, or businesses, where their assembly requires no extra development or land area and their function is safe and quiet. As communities grow, more solar energy capacity can be added, "thereby allowing power generation to keep in step with growing needs without having to overbuild generation capacity as is often the case with conventional large scale power systems." Compare those characteristics to those of coal, oil, gas, or nuclear power, and the choice is easy. Solar energy technologies offer a clean, renewable and domestic energy source. Photovoltaic power even has advantages over wind power, hydropower, and solar thermal power. The latter three require turbines with moving parts that are noisy and require maintenance.

Solar energy is most sought today in developing countries, the fastest growing segment of the photovoltaics market. People go without electricity as the sun beats down on the land, making solar power the obvious energy choice. "Governments are finding its modular, decentralized character ideal for filling the electric needs of the thousands of remote villages in their countries." It is much more practical than the extension of expensive power lines into remote areas, where people do not have the money to pay for conventional electricity.

India is becoming one of the world's main producers of PV modules, with plans to power 100,000 villages and install solar-powered telephones in its 500,000 villages. By 2000, Mexico plans to have electrified 60,000 villages with solar power. Zaire 's Hospital Bulape serves 50,000 outpatients per year and is run completely on solar power, from air conditioning to x-ray equipment. And in Moroccan bazaars, carpets, tin ware, and solar panels lie side by side for sale. Probably the most outstanding example of a country's commitment to solar power is in Israel . In 1992, over half of all households (700,000) heated their water with solar energy systems. And there are 50,000 new installations every year.

Solar power is just as practical in populated areas connected to the local electrical power grid as it is in remote areas. "An average home has more than enough roof area to produce enough solar electricity to supply all of its power needs. With an inverter, which converts direct current (DC) power from the solar cells to alternating current (AC), which is what most home appliances run on, a solar home can look and operate very much like a home that is connected to a power line." Household energy supply is but one use of solar power. There are actually four broad categories that can be identified for solar energy use: industrial, rural habitation, grid-connected, and consumer/indoor. Industrial uses represent the largest applications of solar power in the past 30 years.

"Telecommunications, oil companies, and highway safety equipment all rely on solar power for dependable, constant power far from any power lines." Roadside call boxes and lighted highway signs rely on the sun's energy in order to provide reliable services without buried cable connections or diesel generators. Navigational systems such as marine buoys and other unmanned installations in harsh remote areas are also ideal applications for solar power because "the load demands are well known and the requirements for reliable power are the highest." Rural habitation includes "cabins, homes, villages, clinics, schools, farms, as well as individually powered lights and small appliances." Grid-connected systems pair solar power with an existing grid network in order to supply a commercial site with enough energy to meet a high demand, or to supplement a family's household supply. Consumer/indoor uses of PV cells include watches and calculators; PV modules power computers and radios.

The practicality and environmentally safe nature of solar power is influencing people worldwide, which is evident in equipment sales. According to Seimens Solar, production of PV cells and modules increased threefold from 40 MW in 1990 to about 120 MW in 1998. "Worldwide sales have been increasing at an average rate of about 15% every year during the last decade . We believe that there is a realistic possibility for the market to continue to grow at about a 15% rate into the next decade. At this rate, the world production capacity would be 1000 MW by 2010, and photovoltaics could be a $5 billion industry."

There are only two primary disadvantages to using solar power: amount of sunlight and cost of equipment. The amount of sunlight a location receives "varies greatly depending on geographical location, time of day, season and clouds. The southwestern United States is one of the world's best areas for sunlight . Globally, other areas receiving very high solar intensities include developing nations in Asia, Africa and Latin America ." See also sustainable house designBut a person living in Siberia would not benefit much from this renewable resource. And while "solar energy technologies have made huge technological and cost improvements, [they]are still more expensive than traditional energy sources." However solar equipment will eventually pay for itself in 2 to 5 years depending on h ow much sun a particular location receives. Then the user will have a virtually free energy source until the end of the equipment's working life, according to a paper called "Energy Payback Time of Crystalline Silicon Solar Modules." Future improvements are projected to decrease the payback time to 1 to 3 years.

The best way of lowering the cost of solar energy is to improve the cell's efficiency, according to Larry Kazmerski, Director of the DOE's National Center for Photovoltaics. "As the scientists and researchers at the NCPV push the envelope of solar-cell efficiency, we can begin to visualize the day when energy from the sun will be generating a significant portion of the country's electric power demand." Any improvements and subsequent cost cuts will also be vital to space applications.Also try finding the right Electric company in order to save money. Power companies can help you benefit with decisions such as this.

As the price of solar power lowers and that of conventional fuels rises, photovoltaics "is entering a new era of international growth." So much so, that solar power "will remain an excellent energy option, long after the momentary fossil fuel model fades into smoke."

Wind Energy

Societies have taken advantage of wind power for thousands of years. The first known use was in 5000 BC when people used sails to navigate the Nile River . Persians had already been using windmills for 400 years by 900 AD in order to pump water and grind grain. Windmills may have even been developed in China before 1 AD, but the earliest written documentation comes from 1219. Cretans were using "literally hundreds of sail-rotor windmills [to] pump water for crops and livestock."

The Dutch were responsible for many refinements of the windmill, primarily for pumping excess water off land that was flooded. As early as 1390, they had connected the mill to "a multi-story tower, with separate floors devoted to grinding grain, removing chaff, storing grain, and (on the bottom) living quarters for the windsmith and his family." Its popularity spread to the point that there were 10,000 windmills in England . But perfecting the windmill's efficiency to the point that it "had all the major features recognized by modern designers as being crucial to the performance of modern wind turbine blades" took almost 500 years. By then, applications ranged from saw-milling timber to processing spices, tobacco, cocoa, paints, and dyes.

The windmill was further refined in the late 19 th century in the US ; some designs from that period are still in use today. Heavy, inefficient wooden blades were replaced by lighter, faster steel blades around 1870. Over the next century, more than six million small windmills were erected in the US in order to aid in watering livestock and supplying homes with water during the development of the West. The first large windmill to produce electricity was the "American multi-blade design," built in 1888. Its 12-kilowatt capabilities were later superceded by modern 70-100 kilowatt wind turbines.

Today, people are realizing that wind power "is one of the most promising new energy sources" that can serve as an alternative to fossil fuel-generated electricity. As of 1999, global wind energy capacity topped 10,000 megawatts, which is approximately 16 billion kilowatt-hours of electricity. That's enough to serve over 5 cities the size of Miami , according to the American Wind Energy Association. Five Miamis may not seem significant, but if we make the predicted strides in the near future, wind power could be one of our main sources of electricity. "With today's technology, wind energy could provide 20% of America 's electricity (or about the amount nuclear power provides) with turbines installed on less than 1% of its land area. And within that area, less than 5% of the land would be occupied by wind equipment the remaining 95% could continue to be used for farming or ranching." By the year 2010, 10 million average American homes may be supplied by wind power, preventing 100 million metric tons of CO 2 emissions every year.

Lessening our dependence on fossil fuels is critical to the health of all living things, and wind energy can do just that. "The 3 billion kWh of electricity produced by America's wind machines annually displace the energy equivalent of 6.4 million barrels of oil and avoid 1.67 million tons of carbon emissions, as well as sulfur and nitrogen oxide emissions that cause smog and acid rain." In other words, "more wind power means less smog, acid rain, and greenhouse gas emissions."

Hydroelectric Power

Moving water is a powerful entity responsible for lighting entire cities, even countries. Thousands of years ago the Greeks used water wheels, which picked up water in buckets around a wheel. The water's weight caused the wheel to turn, converting kinetic energy into mechanical energy for grinding grain and pumping water. In the 1800s the water wheel was often used to power machines such as timber-cutting saws in European and American factories. More importantly, people realized that the force of water falling from a height would turn a turbine connected to a generator to produce electricity. Niagara Falls , a natural waterfall, powered the first hydroelectric plant in 1879.

Man-made waterfalls dams were constructed throughout the 1900s in order to maximize this source of energy. Aside from a plant for electricity production, a hydropower facility consists of a water reservoir enclosed by a dam whose gates can open or close depending on how much water is needed to produce a particular amount of electricity. Once electricity is produced it is transported along huge transmission lines to an electric utility company.

"By the 1940s, the best sites for large dams had been developed." But like most other renewable sources of energy, hydropower could not compete with inexpensive fossil fuels at the time. "It wasn't until the price of oil skyrocketed in the 1970s that people became interested in hydropower again." Today one-fifth of global electricity is generated by falling water.

"Over the past 100 years, the United States has led the world in dam building. Secretary of the Interior Bruce Babbitt recently observed that, 'on average, we have constructed one dam every day since the signing of the Declaration of Independence.'"Of the 75,187 dams in the US , less than 3% are used to produce 10-12% of the nation's electricity. With over 2,000 facilities, the US is the second largest producer of hydropower worldwide, behind Canada . The dams that do not produce electricity are used for irrigation or flood control. Many people believe these pre-existing sites could contribute to the country's power supply in a cost-effective manner if hydroelectric facilities were constructed.

There are several favorable features of hydropower. Anywhere rain falls, there will be rivers. If a particular section of river has the right terrain to form a reservoir, it may be suitable for dam construction. No fossil fuels are required to produce the electricity, and the earth's hydrologic cycle naturally replenishes the "fuel" supply. Therefore no pollution is released into the atmosphere and no waste that requires special containment is produced. Since "water is a naturally recurring domestic product and is not subject to the whims of foreign suppliers," there is no worry of unstable prices, transportation issues, production strikes, or other national security issues.

Hydropower is very convenient because it can respond quickly to fluctuations in demand. A dam's gates can be opened or closed on command, depending on daily use or gradual economic growth in the community. The production of hydroelectricity is often slowed in the nighttime when people use less energy. When a facility is functioning, no water is wasted or released in an altered state; it simply returns unharmed to continue the hydrologic cycle. The reservoir of water resulting from dam construction, which is essentially stored energy, can support fisheries and preserves, and provide various forms of water-based recreation for locals and tourists. Land owned by the hydroelectric company is often open to the public for hiking, hunting, and skiing. Therefore, "hydropower reservoirs contribute to local economies. A study of one medium-sized hydropower project in Wisconsin showed that the recreational value to residents and visitors exceeded $6.5 million annually." Not to mention the

economic stimulation provided by employment.

Hydroelectric power is also very efficient and inexpensive. "Modern hydro turbines can convert as much as 90% of the available energy into electricity. The best fossil fuel plants are only about 50% efficient. In the US , hydropower is produced for an average of 0.7 cents per kilowatt-hour (kWh). This is about one-third the cost of using fossil fuel or nuclear and one-sixth the cost of using natural gas," as long as the costs for removing the dam and the silt it traps are not included. Efficiency could be further increased by refurbishing hydroelectric equipment. An improvement of only 1% would supply electricity to an additional 300,000 households.

Hydropower has become "the leading source of renewable energy. It provides more than 97% of all electricity generated by renewable sources worldwide. Other sources including solar, geothermal, wind, and biomass account for less than 3% of renewable electricity production." In the US , 81% of the electricity produced by renewable sources comes from hydropower. "Worldwide, about 20% of all electricity is generated by hydropower." Some regions depend on it more than others. For example, 75% of the electricity produced in New Zealand and over 99% of the electricity produced in Norway come from hydropower.

The use of hydropower "prevents the burning of 22 billion gallons of oil or 120 million tons of coal each year." In other words, "the carbon emissions avoided by the nation's hydroelectric industry are the equivalent of an additional 67 million passenger cars on the road 50 percent more than there are currently." The advantages of hydropower are therefore convincing, but there are some serious drawbacks that are causing people to reconsider its overall benefit.

Since the most feasible sites for dams are in hilly or mountainous areas, the faults that often created the topography pose a great danger to the dams and therefore the land below them for thousands of years after they have become useless for generating power. In fact, dam failures do occur regularly due to these terrain conditions, and the effects are devastating.

When a new dam's reservoir floods the countryside, people who live in the area have to move and relinquish their former lifestyles in order to make way for the project. This is very stressful and often controversial, especially if a community has maintained a particular way of life on the same land for generations. Such is the case in Chile, where the indigenous Pehuenche "are currently fighting construction of the 570MW, US $500,000,000 Ralco Dam on the Biobo River Eight families continue to refuse to negotiate land exchanges with Endesa [the utility company], and wish to remain on their lands." If the project succeeds, a 13-square-mile reservoir would flood the land and force 600 people out of their homes, 400 of whom are Pehuenche "whose ancestral home is the upper Biobo." A total of five dams have been planned, which "would force the relocation of 1,000 Pehuenches, 20% of the survivors of this ancient culture."

The construction of a dam not only affects the people nearby, it can severely alter a river's natural functions. According to American Rivers, a conservation organization, "by diverting water for power, dams remove water needed for healthy in-stream ecosystems. Stretches below dams are often completely de-watered." This may not seem like a significant problem until animal species are studied. Birds that have migrated to a specific riparian environment for generations no longer have enough insects on which to prey when the water level drops. If they have few migration alternatives, that could mean the endangerment of species that once flourished. Fish species such as salmon "depend on steady flows to flush them down river early in their life and guide them upstream years later to spawn. Stagnant reservoir pools disorient migrating fish and significantly increase the duration of their

migration." Native populations of fish may decrease or disappear altogether due to temperature changes caused by dams. Slower water flow means warmer temperatures, and bottom-release of cold water means cooler temperatures. Several of hydropower's disadvantages focus on fish. It is easy to forget how important fish and other aquatic life are, some of which reside at the bottom of the food chain. The environmental changes caused by hydroelectric projects may be obvious to the local biologist, but elude the average person. Most people will more readily notice a smoggy haze developing in an area where a coal plant is operating than a smaller population of a particular bird species where a hydropower facility functions. Such oversights lead people to believe that nothing is wrong.

Hydroelectric companies and organizations often emphasize their "clean" manufacture of electricity and neglect to mention the long-term environmental hazards. "Dams hold back silt, debris, and nutrients." Silt collects behind the dam on the river bottom, accumulating heavy metals and other pollutants. Eventually this renders the dam inoperable, leaving the mess for future generations, who will either have to remove the collected debris or live with a potentially catastrophic mudflow poised to inundate the area below the dam.

There is also a debate between preserving rivers for their aesthetic value versus meeting the energy needs of thousands of people. The latter has prevailed. Today "there are 600,000 river miles impounded behind dams. In contrast, only 10,000 river miles (not even half of 1%) are permanently protected under the National Wild and Scenic Rivers System." The only undammed river in the US that is longer than 600 miles is the Yellowstone .

Hydropower may be better on the environment than fossil-fuel sources, but its future is so uncertain that we may need to focus on other alternatives. According to the National Hydropower Association, "an increasing array of statutes, regulations, agency policies and court decisions have made the hydroelectric licensing process costly, arbitrary and time-consuming. A typical hydropower project takes 8 to 10 years to find its way through the licensing process. By comparison, a natural gas fired plant, which emits significant carbon dioxide (CO 2 ) gases, can typically be sited and licensed in 18 months. Given this uncertain climate, few investors are willing to risk their capital on new hydropower development. Furthermore, some project owners and operators contemplate abandonment of their projects rather than proceeding with relicensing."

Relicensing is a complex process in which private dams are re-evaluated every 30 to 50 years. The Federal Energy Regulatory Committee "considers anew whether it is appropriate to commit the public's river resources for private power generation FERC is now required, when deciding whether to issue a license, to consider not only the power generation potential of a river, but also to give equal consideration to energy conservation, protection of fish and wildlife, protection of recreational opportunities, and preservation of other aspects of environmental quality." Relicensing was infrequent until 1993, when hundreds of licenses began to expire. "The Hydropower Reform Coalition formed in 1992 to take advantage of this once-in-a-lifetime opportunity to restore river ecosystems through the relicensing process." To the Coalition's dismay, a new bill is being considered called the Hydroelectric Licensing Process Improvement Act, which if passed, "would limit the abilities of federal agencies to protect natural resources," making relicensing easier for dam operators.

Some people favor dam removal so that healthy rivers and riverside communities can be restored, but American Rivers reports that most of the larger dams in the US "are not likely candidates for removal." In that case it may be wasteful not to use them to their full potential as long as they are still sturdy. A hydropower assessment conducted by the US Department of Energy found that 4,087 sites could be

developed without constructing a new dam. "The assessment consider[ed] such values as wild/scenic protection, threatened or endangered species, cultural values and other non-power issues. If all of this potential were to be developed 22.7 million metric tons of carbon could be avoided." But this savings in carbon emissions pales when compared to the tonnage of silt and other material that must be handled if the river is to be restored to a freely-flowing state. All rivers will eventually silt up the dam. At this point future generations will have the choice to either keep the useless dam or remove it. Keeping the poorly consolidated silt and mud behind the dam is potentially dangerous. Removal costs will often exceed the value of power produced over the dam's lifetime.

Unlike other renewables such as wind and solar power that receive more praise than criticism, hydropower is a highly controversial issue. While it does have many merits, it too is like so many other sources of energy if we ignore the critics' warnings, we may not realize its full impact on our natural resources until it is too late.

BIOMASS

The term "biomass" refers to organic matter that has stored energy through the process of photosynthesis. It exists in one form as plants and may be transferred through the food chain to animals' bodies and their wastes, all of which can be converted for everyday human use through processes such as combustion, which releases the carbon dioxide stored in the plant material. Many of the biomass fuels used today come in the form of wood products, dried vegetation, crop residues, and aquatic plants. Biomass has become one of the most commonly used renewable sources of energy in the last two decades, second only to hydropower in the generation of electricity. It is such a widely utilized source of energy, probably due to its low cost and indigenous nature, that it accounts for almost 15% of the world's total energy supply and as much as 35% in developing countries, mostly for cooking and heating. Biomass is one of the most plentiful and well-utilised sources of renewable energy in the world. Broadly speaking, it is organic material produced by the photosynthesis of light. The chemical material (organic compounds of carbons) are stored and can then be used to generate energy. The most common biomass used for energy is wood from trees. Wood has been used by humans for producing energy for heating and cooking for a very long time. Biomass has been converted by partial-pyrolisis to charcoal for thousands of years. Charcoal, in turn has been used for forging metals and for light industry for millenia. Both wood and charcoal formed part of the backbone of the early Industrial Revolution (much northern England, Scotland and Ireland were deforested to produce charcoal) prior to the discovery of coal for energy. Wood is still used extensively for energy in both household situations, and in industry, particularly in the timber, paper and pulp and other forestry-related industries. Woody biomass accounts for over 10% of the primary energy consumed in Austria, and it accounts for much more of the primary energy consumed in most of the developing world, primarily for cooking and space heating.It is used to raise steam, which, in turn, is used as a by-product to generate electricity. Considerable research and development work is currently underway to develop smaller gasifiers that would produce electricity on a small-scale. For the moment, however, biomass is used for off-grid electricity generation, but almost exclusively on a large-, industrial-scale.

Biomass, Defining green or environmentally sustainable biomass-generated electricity has proved difficult and contentious. Biomass can be so broadly defined to include unsustainably harvested forest timber, contaminated waste wood, municipal solid waste, and tires. Some definitions include landfill gas, while some do not. Environmental groups are pushing for a more narrow definition of biomass green power which excludes burning garbage and limits biomass to sources such as forest-related harvesting residue, landscaping and right-of-way trimmings, and agricultural crops and crop by-products. Additionally, biomass must be burned cleanly to be green, and this is not a given. Burning landfill gas is viewed by environmentalists as an environmentally sound practice, but many object to characterizing it as biomass energy.

Landfill Gas, Landfills produce methane gas which is a powerful greenhouse gas if vented un-burnt to the atmosphere. While burning landfill methane gas is not pollution-free, it is much better to burn it than vent it. Burning landfill gas to produce electricity also reduces fossil fuel use, another plus.

There are two issues that affect the evaluation of biomass as a viable solution to our energy problem: the effects of the farming and production of biomass and the effects of the factory conversion of biomass into usable energy or electricity. There are as many environmental and economic benefits as

there are detriments to each issue, which presents a difficult challenge in evaluating the potential success of biomass as an alternative fuel. For instance, the replacement of coal by biomass could result in "a considerable reduction in net carbon dioxide emissions that contribute to the greenhouse effect." On the other hand, the use of wood and other plant material for fuel may mean deforestation. We are all aware of the problems associated with denuding forests, and widespread clear cutting can lead to groundwater contamination and irreversible erosion patterns that could literally change the structure of the world ecology.

Biomass has to be considered in the search for an alternative source of energy that is abundant in a wide-scale yet non-disruptive manner, since it is capable of being implemented at all levels of society. Although tree plantations have "considerable promise" in supplying an energy source, "actual commercial use of plantation-grown fuels for power generation is limited to a few isolated experiences." Supplying the United States ' current energy needs would require an area of one million square miles. That's roughly one-third of the area of the 48 contiguous states. There is no way that plantations could be implemented at this scale, not to mention that soil exhaustion would eventually occur. Biomass cannot replace our current dependence on coal, oil, and natural gas, but it can complement other renewables such as solar and wind energy.

According to Flavin and Lenssen of the Worldwatch Institute , "If the contribution of biomass to the world energy economy is to grow, technological innovations will be needed, so that biomass can be converted to usable energy in ways that are more efficient, less polluting, and at least as economical as today's practices." When we have enough government support and have allotted enough land for the continuous growth of energy crops for biomass-based energy, we may have a successful form of alternative energy. But "as long as worldwide prices of coal, oil and gas are relatively low, the establishment of plantations dedicated to supplying electric power or other higher forms of energy will occur only where financial subsidies or incentives exist or where other sources of energy are not available." Although it is currently utilized across the globe, biomass energy is clearly not capable of sustaining the world's energy needs on its own.

Hydrogen and Fuel CellsIntroduction Fossil and nuclear fuel reserves are becoming increasingly limited, and the world's energy future will have to include several renewable alternatives to these failing resources. A promising possibility is to exploit the energy potential of the most plentiful element in the known universe hydrogen.

We will look at how hydrogen was initially discovered and how it has been used in the past. Next we will examine methods of production, distribution, and transport of hydrogen, as well as how hydrogen can be used safely. Then we will look how hydrogen can be used safely. Lastly, we will examine the present state of the art in terms of energy applications available now, such as fuel cells and hydrogen as a combustible fuel, and we will also consider the developing ideas and technologies that will be used in our energy future. History The quest for understanding the natural world around us is as old as human consciousness. This quest continues in the present day, as scientists and researchers delve with increasing intensity into the mysteries of physics, chemistry, and biology to unlock the secrets inherent in the physical universe.

Hydrogen H Atomic Number: 1 Atomic Weight: 1.00794 Electronic Configuration: 1 Hydrogen is a gaseous element that was first discovered by Henry Cavendish in 1766. It is the first element on the Periodic Table. Hydrogen is:

• Colorless • Tasteless • Odorless • Slightly soluble in water • Highly explosive

Hydrogen is the most abundant element in the universe, and serves as the fuel for the fusion reactions in stars. Normal hydrogen is diatomic (two hydrogen atoms chemically paired). Atmospheric hydrogen has three isotopes: protium (one proton in nucleus), deuterium (one proton and one neutron in nucleus), and tritium (one proton and two neutrons). ( 1 )

Paracelsus (1493-1541), a Swiss physician, naturalist and alchemist, was a contemporary of Leonardo da Vinci and Copernicus. In the course of investigating what would become chemistry and medicine, Paracelsus wrote of combining sulfuric acid and iron, noting that this combination produced a gas or "air" as he conceived it at the time, and that when this air was produced it was released under considerable pressure.

Later a French chemist, Nicholas Lemery , showed that the gas produced in the sulfuric acid/iron reaction was flammable, but it was Henry Cavendish (1731-1810), a British physicist, who was credited with the discovery of hydrogen in 1766. Another French chemist, Antoine-Laurent Lavoisier (1743-1793), considered the founder of modern chemistry, described one of the component elements of water as hydrogen , from the Greek words hudor (water) and gennan (generate). It was also Lavoisier who noted that the only byproduct of burning hydrogen was water itself.

In 1802 a British chemist named Sir Humphry Davy (1778-1829) was studying the chemical effects of electricity when he found that by passing an electric current through water, he was able to cause the

water to chemically decompose into its component elements of hydrogen and oxygen. This process, which later became known as electrolysis, led Davy to theorize that chemical compounds are bound together by electric energy.

Working with the concept of chemical decomposition through applied electricity, a Welsh lawyer and non-scientist who was also a knighted judge, Sir William R. Grove, expanded on the work done by Sir Humphry Davy. Grove demonstrated that the process of chemical decomposition could be reversed, and that hydrogen and oxygen could be compelled to bind together forming water. At the same time the process produced an electric current that "could be felt by five persons joining hands, and which when taken by a single person was painful." Grove's discoveries came to fruition in the form of the first hydrogen fuel cell, which he invented in 1839. While it would be over one hundred years before interest was rekindled in Grove's work, it would prove to be extremely important in fuel cell technology, which today is the main source of electric power for space vehicles.

During the latter part of the Nineteenth Century , before the advent of what we now know as natural gas, a hydrogen-rich gas was produced from coal to be used in the gas lamps and heaters of European and American homes. Known in the U.S. as "town gas," and consisting of 50% hydrogen and 50% carbon monoxide, this fuel helped lay the foundation for the safe use of hydrogen, which due to its highly volatile nature, must be handled and transported with the utmost care.

For most of us, the most infamous use of hydrogen was in the lighter-than-air zeppelin. While balloons and flying air ships had been using hydrogen for almost fifty years, it was the development in 1900, by Count Ferdinand von Zeppelin of Germany, of the rigid framed air ship that allowed for greater speed and durability in flight than had previously been possible. With its aluminum skeleton framing a solid outer shell, von Zeppelin's first ship, the LZ 1, was designed with military applications in mind, opening up the possibility of long range battlefield reconnaissance from the air, as well as opportunities for tactical options like dropping bombs.

With Germany's entrance into World War I, zeppelins were equipped with bombs and machine guns, making them dangerous targets for the fledgling efforts of early British air forces using the limited biplane technology of the time. Bombs were carried from German held bases in France , and dropped with impunity over London . While the accuracy of these attacks was very poor, they served a devastating psychological role in demoralizing Britains . By the end of the war however, improvements in airplane design and capability, as well as the innovation of the phosphorus coated incendiary tracer bullets spelled the end of the hydrogen-filled dirigible.

Following World War I , Germany and the United States both continued with the development of rigid framed air ships, enhancing their air speed and reliability. Especially in Germany , these huge dirigibles, often over four hundred feet in length, became commonplace, and were used extensively for luxurious passenger travel. In 1928, the Graf Zeppelin, designated LZ127, was launched, and would go on to fly farther than any zeppelin before or since.

Test flown initially in March of 1936, the zeppelin Hindenburg would fly into history as perhaps the most memorable air disaster of the Twentieth Century. Having made the transatlantic crossing from Germany to Lakehurst , New Jersey ten times in the year previous to May of 1937, the 804-foot air ship represented the state of the art in zeppelin design, and such trips were fairly routine.

American manufactured air ships had by this time switched to the less volatile and nonflammable lighter-than-air helium gas. However, the German ship still used hydrogen as its lift medium, a fact

which still generates controversy sixty years after the events that would indelibly link the Hindenburg tragedy with the dangers of hydrogen gas.

On May 6, 1937, as the Hindenburg approached its mooring tower at the Lakehurst Naval Air Station, it burst into flames. While the fire consumed only the zeppelin's cover material at first, it quickly ignited the explosive hydrogen within the massive ship. Thirty-five of the ninety-seven people aboard the Hindenburg lost their lives that day, as well as one American Navy crewman on the ground. The continuing controversy over the cause of the Hindenburg crash is central to the issues here, as modern historians and investigators differ in their opinions as to the chain of events leading up to the disaster. Unsubstantiated rumors of sabotage not withstanding, opinions differ as to whether the fire was started by leaking hydrogen ignited by a static electricity spark, or by static electricity starting a fire in the zeppelin's cover material. Thunderstorms were passing through the Lakehurst area that day, providing ample conditions for a static discharge, but whether it was the cover material or leaking hydrogen that provided the fire with its starting place will probably never be known.

The Hindenburg experience has actually helped ensure the safe handling of hydrogen in what are primarily industrial applications in the present. Safer storage mediums have also been developed, which will be described later, replacing earlier dangerous storage. The perception that handling hydrogen is inherently dangerous has done much to hamper the public acceptance of hydrogen research and applications. However, properly handled, hydrogen is no more dangerous than gasoline or propane. Curiously, it was reported that no fatality from the Hindenburg accident was directly attributable to hydrogen burns, as the millions of cubic feet of hydrogen burned off in less than one minute. It was the diesel fuel, which powered the air ship's drive engines, that burned many of the dead and injured that day, as well as feeding the ground fire which took several hours to extinguish.

It was in the United States that Francis Bacon, a descendant of the famous English scientist and philosopher, developed the first modern successful hydrogen fuel cell in 1932, which was refined until a 5 kilowatt fuel cell system was demonstrated in 1952. As the United States began its push for space flight in the late 1950's, fuel cell technology appealed to many scientists and engineers. It was much less dangerous than any known nuclear application, much more compact and lighter than any type of battery, as well as being simpler to deal with mechanically than any solar photo-voltaic technology available at that time. Today hydrogen fuel cells provide much of the electric power for the Space Shuttle, as well as power for electric automobiles and varied other emerging applications. With a little imagination we can see the direct line from Paracelsus five hundred years ago to the possibilities that lay in front of us in the near future.

Energy from the Earth What could be more natural or plentiful? The source of geothermal power is the heat contained inside the Earth; heat so intense that it creates molten magma. There are a few different types of geothermal energy that can be tapped. "Some geothermal systems are formed when hot magma near the surface (1,500 to 10,000 meters deep) directly heats groundwater." The heat generated from these hot spots flows outward toward the surface, manifesting as volcanoes, geysers, and hot springs . Naturally-occurring hot water and steam can be tapped by energy conversion technology to generate electricity or to produce hot water for direct use. "Other geothermal systems are formed even when no magma is nearby as magma heats rocks which in turn heat deeply-circulating groundwater." In order to maximize the energy gleaned from these so-called "hot dry rocks," geothermal facilities will often fracture the hot rocks and pump water into and from them in order to use the heated water to generate electricity.

The concentration of geothermal energy at any given location must be quite high in order to make heat extraction feasible, and not all geothermal sites are created equally. Regions that have well-developed geothermal systems are located in geologically active areas. These regions have continuous, concentrated heat flow to the surface. The western United States has the best geothermal regions in the country, while Iceland , New Zealand , the Philippines , and South America , are some of the more prominent global "hot spots." In Iceland , geothermal energy, caused by the constant movement of geologic plates coupled with the volcanic nature of the island, is used to heat 95% of all homes.

Unfortunately even good geothermal areas are a non-renewable renewable. "The Geysers," the world's largest geothermal facility, is a working model on how not to approach a so-called "renewable" geothermal resource. Built in the 1950s on a steam field in Northern California , the facility was established on the apparent assumption that geothermal resources were infinite at that locatio. However, by the late 1980s, steam decline became noticeable and sustained. Depletion occurred because steam was being extracted faster than it could be naturally replaced. According to a report by Pacific Gas and Electric, "because of declining geothermal steam supplies, the Company's geothermal units at The Geysers Power Plant are forecast to operate at reduced capacities." In response, "plant operators and steam suppliers continually seek new operating strategies to maximize future power generation coupled with daily injection of millions of gallons of reclaimed municipal wastewater." Even though improvements in efficiency and conservation are being implemented and in 1996 The Geysers was still producing enough electricity to supply the power demand of a city like San Francisco , it is projected that the steam field will be defunct in 50 years or so. To prevent this sort of thing from happening elsewhere, geothermal facilities can use a closed-loop system at all times, or the re-injection of water back into the system for constant steam generation, as PG&E is now implementing at The Geysers.

Despite the fact that geothermal energy is abundant renewable, and able to reduce our dependence on imported fuels, the fact remains that fields of sufficient quality to produce economic electricity are rare. In addition, many of those that are known are located in protected wilderness areas that environmentalists want to preserve. Unless research and technology join forces to "harvest" geothermal power through non-traditional means, such as deep-crustal drilling or the acquisition of heat from magma, the tapping of geothermal energy is limited to a handful of locations.

Environmental concerns also taint the issue of geothermal energy. Although no combustion occurs, some applications produce carbon dioxide and hydrogen sulfide emissions, require the cooling of as much as 100,000 gallons of water per megawatt per day, and dispose of toxic waste and dissolved solids.

Another type of geothermal energy being used commercially is Earth energy, extracted through heat pumps. Heat contained in shallow ground is used to directly heat or cool houses since the temperature inside the ground tends to stay at the yearly average. Therefore, in the winter the ground is warmer than the air and can be used to heat a building, and in the summer the ground is cooler than the air and can act as an air conditioner. Researchers know that "no active technology for home cooling is more efficient than the geothermal heat pump." This technique reduces the reliance on other resources and can be utilized anywhere, resulting in significant environmental benefits and reduced energy costs.

Hydrothermal Reserves: Geothermal energy is found in many places on the earth. Its use contributes to the development of important third-world countries including the Philippines, Indonesia, Mexico, countries of Central and South America, and countries in eastern Africa and in eastern Europe. Italy, Iceland, New Zealand, Japan and France, along with the United States, are developed countries using geothermal energy.There is a very large geothermal resource base in the U.S. and in the world, much of which can not yet be economically used. In fact, the resource base for the renewable energies- geothermal, solar, biomass and wind -- is much larger than the total resource base in coal, oil, gas, and uranium (nuclear power).

There are also other problems that prevent us from taking full advantage of this form of energy. Even though there are geothermal resources throughout the world, our current technology is not sufficient or economical enough to warrant its widespread use. Funding for energy extraction that involves the penetration of magma is not available because we do not yet know how to prevent a high-temperature, high-pressure blowout. When heat pumps are considered, which tap local sources of heat and can help to reduce a family's electricity bill by about $1 per day, the system is not economically viable. It "may have a payback period in excess of 5 years," which will increase with decreased electricity rates "unless equipment and installation costs drop dramatically." In addition, Earth energy is not "intense" enough to produce power for the electrical distribution grid; it is only sufficient to reduce the draw from the grid.

There are definite obstacles to be overcome before geothermal energy can be easily and economically harnessed for everyday, worldwide use. Case in point: "Construction of new domestic electricity-producing geothermal facilities in the Western United States during 1996 was limited to one site, due to the availability of cheap, plentiful natural-gas-fired electricity in the West."

Other Forms of Renewable Energy

Other forms of conventional renewable energy include tidal, ocean thermal, wave, and hot fusion. Tidal energy utilizes the gravitational energy of the attraction of the Sun, Earth and Moon. Wave power converts the energy released in crashing waves, which originated in the wind, which is driven by sunlight. Ocean thermal energy exploits the greatest collector of solar energy on Earth the sea. Hot fusion is not strictly renewable since it consumes hydrogen, but hydrogen is so abundant that it can be considered limitless for human purposes. Each of these energy forms has its own advantages and disadvantages, but none of them is the answer to the looming energy crunch. We will address each of them in turn.

Tidal Energy works on the same fundamental principal as the water wheel. In the case of tidal energy, however, the difference in water elevation is caused by the difference between high and low tides. The technology involves building a dam, or barrage, across an estuary to block the incoming tide, the outgoing tide, or both. When the water level on one side of the dam is higher than the level on the other side due to a tidal change, the pressure of the higher water builds. The water is channeled through a turbine in the dam in order to get to the other side, which produces electricity by turning an electric generator.

Tidal energy is being harnessed in several countries around the world, from facilities in Russia to France with 400 kW to 240 MW capacities. Some proposed sites, however, exhibit extraordinary potential. Britain 's Severn Estuary and Canada 's Bay of Fundy have potential capacities of as much as 8,000 and 30,000 MW, respectively. The Severn Estuary averages an 8.8-meter (26-foot) tidal range and the Bay of Fundy averages a 10.8-meter (32-foot) tidal range, ideal for substantial electricity generation. But the rarity of these exceptionally high tides is the main limitation of this energy source. Considering that "a tidal range of at least 7 meters is required for economical operation and for a sufficient head of water for the turbines," few places in the world can make a facility's establishment worthwhile. Since tidal power's "estimated capacity is 50 times smaller than the world's hydroelectric power capacity," it cannot compare to other renewables.

Another constraint to the tidal system is the sheer amount of time that passes in which little electricity can be generated between the rising and falling tides. During these times, the turbines may be used to pump extra water into the basin to prepare for periods of high electricity demand, but not much else can be done in the interim to generate more electricity. By its very nature, a tidal-based energy facility can only generate a maximum of ten hours of electricity per 24-hour day. That means it cannot be expected to supply power at a steady rate or during peak times.

Although the operation and maintenance of a tidal power plant is low, the cost of the initial construction of the facility is prohibitive, so the overall cost of the electricity generated would be quite high. For example, it is estimated that the Severn tidal project with a proposed capacity of 8,640 MW will cost $1,600 per kW, or over $13.8 billion. This cost exceeds that of coal and oil facilities by a considerable amount.

In contrast to the combustion of fossil fuels , the use of tidal energy makes no contribution to global warming. But tidal energy facilities do not come without an environmental price tag. The alteration of the natural cycle of the tides may affect shoreline as well as aquatic ecosystems. Pollution that enters a river upstream from the plant may be trapped in the basin, while the natural erosion and sedimentation pattern of the estuary may be altered. Local tides could decrease by more than a foot in some areas, and

the "enhanced mixing of water" could stimulate the growth of organisms, better known for their red tide effect, which paralyze shellfish. So little is known about the potential harm of a tidal energy facility that some people believe "one of the only methods of increasing our knowledge about how tidal barrages affect ecosystems may be the study of the effects after such facilities have been built." With such uncertainty, tidal power appears to be an unproven alternative energy candidate.

Assuming that the high costs and the environmental issues were circumvented, the problem of distributing the energy generated by tidal facilities would still exist. Since the collection sites are limited and fixed at unalterable locations, the power they generate must still be distributed throughout the inland areas serviced by the plant via a transmission grid system. The distribution of the energy across vast inland spaces presents formidable problems. This would make it extremely difficult to replace the existing energy infrastructure, and our entire electricity needs could never be met by tidal power alone.

"Worldwide, approximately 3000 gigawatts (1 gigawatt = 1 GW = 1 billion watts) of energy is continuously available from the action of tides. Due to the constraints outlined above, it has been estimated that only 2% or 60 GW can potentially be recovered for electricity generation." Despite tidal power's inability to replace conventional energy sources, it will not be dismissed in the near future. Britain , India , and North Korea have planned to supplement their grid with this renewable energy source. Meanwhile, "a university study in January [1998] said New Zealand could become the first country in the world to run solely on fossil fuel-free power if it exploited the tides on its long coastlines as well as its plentiful wind and sunshine. But while the wind may not constantly blow and the sun may not shine 24 hours a day, the advantage of the tides is that they never cease."

Wave Energy, like tidal power, will always be available, but there are current constraints that limit its contribution to the electrical grid. Areas with the strongest winds will produce the highest concentrations of wave power a low-frequency energy that can be converted to a 60-Hertz frequency. The best areas are on the eastern sides of the oceans (western side of the continents) between the 40 and 60 latitudes in both the northern and southern hemispheres. The waters off California and the UK are regarded as the best potential sites. " California 's coastal waters are sufficient to produce between seven and 17 MW per mile of coastline."

There are several drawbacks of wave energy . While the "wave power at deep ocean sites is three to eight times the wave power at adjacent coastal sites," constructing and mooring the site and transmitting the electricity to shore would be prohibitively costly. Especially considering that "a wave power unit will probably not have much more than three times the output of a single wind turbine." Once in place, the device could be a dangerous obstacle to navigational craft that cannot see or detect it on radar, while fishermen may have trouble with the underwater mooring lines. Conversely, an onshore wave energy system or offshore platform would have a significant visual impact. Scenic views would be replaced by industrial activity.

Wave energy has received little attention in comparison to other renewable sources of energy. Though 12 broad types of wave energy systems have been developed combinations of fixed or moveable, floating or submerged, onshore or offshore scientists have not fully investigated this technology. "Many research and development goals remain to be accomplished, including cost reduction, efficiency and reliability improvements, identification of suitable sites in California, interconnection with the utility grid, better understanding of the impacts of the technology on marine life and the shoreline. Also essential is a demonstration of the ability of the equipment to survive the salinity and pressure environments of the ocean as well as weather effects over the life of the facility."

Even a successfully built and operated wave power facility could not provide extra power for peak demand, nor would it be a reliable source of energy.

There is a handful of wave energy demonstration plants operating worldwide, but none produces a significant amount of electricity. Projects have been discussed for various sites in California San Francisco, Half Moon Bay , Fort Bragg , and Avila Beach but no firm plans have been made. While government agencies in Europe and Scandinavia are sponsoring research and development, "wave energy conversion is not commercially available in the United States . The technology is in the early stages of development and is not expected to be available within the near future due to limited research and lack of federal funding."

Ocean Thermal Energy Conversion (OTEC) seems to be a promising source of renewable, non-polluting energy for the future. The oceans comprise over two-thirds of the earth's surface, meaning they collect and store an enormous amount of solar energy. The raw numbers show that if even 0.1% of this stored energy could be tapped, the output would be 20 times the current daily energy demands of the United States .

Ocean thermal energy conversion exploits the temperature gradient between the varying depths of the ocean, requiring at least a 36F difference from top to bottom, as is found in tropical regions. This difference in temperature is the "heat engine" for a thermodynamic cycle. There are three types of OTEC designs: open cycle, closed cycle, and hybrid cycle. In an open cycle, seawater is the working fluid. Warm seawater is evaporated in a partial vacuum, expanding through a turbine connected to an electrical generator. The steam then passes through a condenser that uses cold seawater from the depths of the ocean, and the result is desalinated water that can be used for other purposes. New seawater is used in the next cycle. In a closed cycle, a low boiling point liquid such as ammonia or refrigerant is used as the working fluid, vaporized by warm seawater. After expanding through a turbine connected to an electrical generator, cold seawater is used to condense the vapor back into a liquid to start the process again. A hybrid cycle combines the two processes, in which flash-evaporated seawater creates steam, which in turn vaporizes a working fluid in a closed cycle. The vapor from the working fluid powers the turbine while the steam is condensed for desalinated water, as in an open system. The hybrid system continues to process seawater and produce electricity.

OTEC taps energy in a consistent fashion, producing what "is probably the most environmentally friendly energy available on the planet today." Unfortunately, the realization of this promising potential is largely experimental in nature for the time being. In fact, the only ocean thermal energy conversion plant in the U.S. was an experimental facility the Natural Energy Laboratory of Hawaii (NELHA), which was closed at the end of a successful test in 1998.

The technology is still far from being developed to an extent to make this type of innovation viable as a widespread alternative energy source. The facility in Hawaii , for instance, produced the highest amount of electricity to date with a 210 kW open-cycle OTEC experimental facility that operated from 1992 to 1998. When considering the capacity of conventional combustion turbines, ranging from a typical output of 25 MW to a maximum 220 MW, this technology is not even in the running. It is most applicable on small islands that depend on imported fuels. This system would render an island more self-sufficient while improving the sanitation and nutrition standards, with an abundance of desalinated water that could be used to grow aquaculture products. It will be some time before OTEC technology is in a position to partially phase out the use of fossil fuels. The location limitations stall any worldwide progress, and the ability of the technology to

produce the quantity of energy needed to supply the world energy demands is still largely theoretical.

Nuclear fusion has been called "the Holy Grail of the energy field." It is the diametrically opposite process of nuclear fission, in which an atom of the heavy isotope Uranium-238 is split in a collision with an accelerated neutron, releasing some of the energy from inside the atom. Fusion involves combining light atoms, which releases an enormous amount of energy. The waste product of this reaction is helium and it is precisely this process which fires most stars, in particular our sun. "Fusion is attractive as an energy source because of the virtually inexhaustible supply of fuel, the promise of minimal adverse environmental impact, and its inherent safety."

The atoms fused together in a reaction are not ordinary hydrogen atoms that contain only one proton in the nucleus. They are the heavy isotopes of deuterium or tritium that contain one or two neutrons along with the protons in their nucleus. These isotopes are somewhat rare in nature "about one part [deuterium] in 6000 is found in ordinary water" but the technology exists to isolate them in great abundance.

The fundamental problem with traditional nuclear fusion is that the fuel, the heavy hydrogen, must be raised to over one hundred million degrees. At such a tremendous temperature, the electrons are stripped away from the heavy hydrogen atoms leaving a fully ionized state called "plasma." This plasma must then be held together in order to produce useful amounts of electricity. There are no known construction materials that can withstand such temperatures, so the plasma must be contained by magnetic or inertial confinement. "Magnetic confinement utilizes strong magnetic fields, typically 100,000 times the earth's magnetic field, arranged in a configuration to prevent the charged particles from leaking out (essentially a 'magnetic bottle'). Inertial confinement uses powerful lasers or high energy particle beams to compress the fusion fuel."

Another fundamental problem with hot fusion revolves around "whether a fusion system producing sufficient net energy gain to be attractive as a commercial power source can be sustained and controlled." While fusion power production has increased from less than one watt to over 10 million watts over the years, we still have yet to witness a net energy gain. Even if this were to be achieved in the near future, the metallurgical requirements that must be met by the surrounding structural materials are extremely demanding and cost prohibitive. Accomplishing a net energy gain in hot fusion will involve the construction of a $1 billion device for experimenting with burning plasma. Add to this the estimate of $300 million per year that the fusion community in the US will require for "significant enhancements of the program" up from the current $230 million. The US is not alone in its fusion expenditure. Concerned about reliance on imported energy, Japan and Europe, respectively, have allotted 1.5 and 3 times the budget that the US currently spends for hot fusion.

The incredible complexity and cost of this process is the precise reason why the announcement of a "cold fusion breakthrough" at the University of Utah a few years ago met with such enthusiasm. If the process could be brought about at room temperatures, the complexity that now prevents the generation of power based on nuclear fusion would disappear.

While billions of dollars and decades of research have been devoted to hot fusion, we are far from mastering this type of energy generation. " Optimistic projections do not suggest that fusion energy will contribute significantly to energy supply until well into the next century." Nevertheless, the US Department of Energy's August 1999 Final Report of the Task Force on Fusion Energy concluded "that we should pursue fusion energy aggressively." .

NUCLEAR REACTORS

Nuclear energy is the largest producer of electric power without emitting any significant pollution or greenhouse gases into the air. It gives us approximately 20 percent of our electricity each year. By comparison, the second-largest non-emitting producer is hydroelectric power (about 7 percent), followed by wind and solar power (each about 2 percent).

Since nothing is burned in the generation of nuclear energy, no harmful emissions are vented into the atmosphere. This is why nuclear power plants do not have the smokestacks common to fossil fuel generation facilities. Some nuclear power plants use large cooling towers to remove excess heat from cooling water before it is returned to the waterways. The discharge from these towers is water vapor, not smoke or radioactive matter.

So how is nuclear power produced, especially without creating air pollution?A nuclear power plant produces electricity in much the same way as other electric power plants: Water is heated to produce steam, and the steam turns turbines that turn a generator shaft to make magnetism, which is what electricity is. The difference in a nuclear power plant is how the water is heated. Most power plants today use coal or natural gas to heat the water to become steam. Nuclear power comes from a reactor where atoms are split to release their energy, which produces great amounts of heat.The design of a nuclear reactor is complex, but basically, each reactor has six main elements: (1) Fuel, (2) Control rods, (3) Coolant, (4) Moderator (5) Shield, (6) Reflector, and (7) Nuclear Vessel. Let's look at each part.

Fuel Fuel is needed in all energy-producing processes, and fuel is at the heart of the reactor. For fuel to produce energy, it must be altered, which happens inside the reactor core. In most U.S. reactors, the fuel consists of pellets of enriched uranium dioxide. The pellets are held inside 12-foot-long metal tubes called “fuel rods.” These fuel rods are put together, or “bundled,” to form the fuel assembly. The process of preparing the fuel, burning the fuel, and disposing of the fuel is called the “fuel cycle.” A closed fuel cycle recycles the fuel from the last stage for reuse in the reactor. An open fuel cycle does not recycle the fuel.

Control rods The control rods are lowered or raised next to the fuel assembly to speed up or slow down the rate of the chain reaction by absorbing some of the neutrons released in fission. To speed up the chain reaction, the rods are pulled up away from the fuel assembly. To slow the reaction down, the rods are lowered next to the fuel assembly. Most control rods use the element boron to absorb neutrons.Coolant The cooling process in a nuclear reactor is similar to the way a car radiator works to cool the engine. Because the fuel assembly gets very hot during a chain reaction, a coolant, usually water, is pumped through the reactor to carry the heat away. As with most power plants, two-thirds of the energy produced by a nuclear power plant goes into waste heat, and that heat is carried away from the plant in the coolant water (which remains uncontaminated by radioactivity).

In large reactors, as much as 330,000 gallons of water coolant flow through the reactor core every minute. The water that leaves the reactor is sent to either cooling towers or discharged into large bodies of water such as cooling ponds, lakes, rivers, or an ocean.

Coolants have very specific requirements: non-absorbent for neutrons, excellent resistance to high temperatures and high levels of radiation, non-corrosive, high boiling point for liquids to prevent evaporation from the high heat inside the reactor, low melting point for solids, and be easily circulated

by a pump.

Moderator: When a neutron causes fission, fast neutrons are released. These fast neutrons need to be slowed down to lower energy levels. Neutrons have a better chance of causing an atom to fission if they move considerably slower than their initial speed after being emitted from a fissioning nucleus. The material used to slow down the fast neutrons is called the “moderator.” Fast moving neutrons strike the moderator material, which is not efficient at absorbing them, and slows them down.

Moderators are made of various materials. Water is an excellent moderator because the water can also serve as a coolant. Normal water, known as “light water,” is used in most reactors simply because it is cheap and abundant. The only downside to using light water is that reactor fuel must be enriched when water is the moderator. Another moderator material is deuterium, also known as “heavy water” because it has an extra hydrogen atom. Deuterium is costly to manufacture, but it does not require fuel to be enriched. Other moderator materials are graphite and beryllium, which are used in different types of reactors.

Shield Nuclear fission results in the release of neutrons and several other by-products such as alpha rays, beta rays, gamma rays, and fast moving neutrons. Radiation shielding is required to prevent this harmful radiation from leaving the reactor and affecting people and materials outside the reactor.Typical reactor cores require an inner lining of steel that is almost half a meter thick. Even at that thickness, the steel is not enough protection, so it is reinforced with a few meters of concrete to make it safer. Concrete and steel are very good at absorbing radiation, and they are strong.

Reflector Fast moving neutrons are controlled with a moderator and reflectors to keep them inside the reactor core so that a sustained and controlled chain reaction takes place. In the fission process, a bullet neutron is absorbed by the target nucleus, which causes the nucleus to divide into two nuclei and emit heat and two or three more neutrons. If all the neutrons keep hitting other nuclei, a chain reaction results. But some neutrons miss other nuclei and bump into the reactor core, which serves no useful purpose. To reduce neutron loss, the inner surface of the reactor core is surrounded by a material to reflect these escaping neutrons back to the reactor core. This lining is known as “reflecting materials.”

Various materials are used as reflecting material. Some, such as light water, heavy water, and carbon, can even serve the dual purpose of reflector and moderator. All reflecting materials must have low absorbtion of neutrons, be stable to withstand high levels of radiation, and resist oxidation.The reflector helps make the reactor core more efficient because it reduces the consumption of the fissile material and therefore, the reactor core can be reduced to attain the amount of energy needed. Pressure Vessel The housing that contains all the components in the core is called the “vessel.” The vessel holds the coolant, provides a space for the rods, and acts as a buffer between the core and the environment outside the vessel. The material used to construct the vessel must be very strong and resilient so that it can withstand great pressures; steel is commonly used for vessel construction. The structure around the pressure vessel is called the “containment.” It protects the reactor from outside intrusion and the people working inside the building from the effects of radiation in case of malfunction. The containment typically is a meter-thick concrete and steel structure.

Types Of Nuclear ReactorsMost nuclear electricity in the United States is generated in two types of reactors, pressurized water reactors (PWR) and boiling water reactors (BWR). Both types are “first generation reactors,” developed in the 1950s, that have maintained the design but with improvements. New reactor designs are coming forward, and some are in operation. The newer designs will be used to replace the first generation reactors as they come to the end of their operating lives.

What is the difference in PWR and BWR reactors?Pressurized water reactor The most common of the reactor types, PWR reactors, originated as a submarine power plant. In PWRs, the water is kept under pressure so that it heats but does not boil. Coolant water from the reactor flows in a cooling circuit through the core of the reactor under very high pressure. A secondary circuit produces steam to drive the turbine. The water that is turned into steam travels in separate pipes and never mixes with the coolant water. PWRs use ordinary water as both coolant and moderator.

A PWR has fuel assemblies of 200 to 300 rods each that are arranged vertically in the core. Large reactors have about 150 to 250 fuel assemblies.Boiling water reactor BWR reactors have many similarities to PWRs, except the water flows in only a single circuit under a lower pressure. The water that is heated by fission actually boils, and 12 to 15 percent of the water in the top part of the core is steam; therefore, the water has a lower moderating effect. A secondary control system involves restricting water flow through the core so that steam in the top part reduces its moderation effect.

The steam passes through drier plates (steam separators) above the core and then directly through a closed-loop circuit to the turbines. Because the water around the core of a reactor is always contaminated with traces of radionuclides, it means that the turbine must be shielded and radiological protection provided during maintenance. The cost of this protection balances with the savings gained from the simpler BWR design. Most of the radioactivity in the water is very short-lived, so the turbine hall can be entered soon after the reactor is shut down.

A BWR has fuel assemblies of 90 to 100 fuel rods each, and a reactor core has up to 750 assemblies.

Building a Nuclear Power PlantStatistics show that U.S. commercial power plants have operated safely for more than a half-century. The success of nuclear power plants comes from continuing to apply technology advances to improve plant safety and health. It also results from the strict licensing, building standards, and regulations governing plant operations.

A nuclear power plant can only be built in the United States once the Nuclear Regulatory Commission (NRC) reviews both construction and operating plans. Before issuing a building permit and operating license for a nuclear plant, the NRC carefully reviews technical aspects of the proposed plan to verify that: Constructing and operating the plant will not present undue risk to public health and safety; Licensing the plant will not be harmful to national defense and security; The utility is technically qualified to design, construct, and operate the proposed facility; and The project complies with the National Environmental Policy Act.

The complete licensing and construction of a nuclear power plant requires a lengthy series of licenses and permits from Federal, State, and local government agencies. These permits and licenses determine

where the plant can be located, whether the power is actually needed, and how excavation and construction will be carried out. They also ensure the protection of land, air, water, and local plant and animal life from pollution.

Nuclear power plants are designed and built to operate for at least 40 years; permits may be renewed for 20 years, following stringent reviews. After the plant begins operating, more than 200 workers handle its everyday operation and maintenance. These workers include operators and supervisors, mechanical maintenance crews, instrument technicians, electricians, laborers, experts in radiation protection called “health physicists,” and a security guard force.

Handling FuelAll operations involving radioactive materials-including nuclear power plants, hospitals, research centers, and industrial processes-create radioactive wastes that must be handled and disposed of safely. Because these wastes vary from slightly to intensely radioactive, they are handled in different ways depending on their level of radioactivity, their form, and other factors.

Industrial users that manufacture radiopharmaceuticals, smoke alarms, emergency exit signs, luminous watch dials, and other consumer goods produce low-level waste, consisting of machinery parts, plastics, and organic solvents. Most of this waste requires little or no shielding and no cooling, and may be handled by direct contact. About half of the total low-level waste generated today comes from nuclear power plants. This includes used resins from chemical ion-exchange processes, filters and filter sludges, lubricating oils and greases, and detergent wastes from laundry operations and from decontaminating personnel and equipment. Most of this waste is processed and packaged for disposal at a specially designed waste facility.

A 1-million kilowatt nuclear power plant typically contains about 100 tons of uranium fuel. Each year, about one-third of the fuel, or roughly 66 of its fuel bundles, are removed and replaced.As the used fuel rods leave the plant, they are physically similar to the new fuel rods that were originally installed. The main difference is that the uranium fuel that released its energy in the reactor created radioactive fission products and other long-lived radioisotopes. Although they represent only a very small percentage, they continue to generate head and release radiation long after the fuel is removed from the reactor.

Most used fuel from nuclear power plants is stored in forty feet deep pools of water at the reactor site. The water cools the fuel rods to keep them from overheating, and it serves as an effect shield to protect workers from the radiation. The level of radiation begins to decline immediately, and within 10 years it has decayed by some 90 percent. Nevertheless, some fission products remain radioactive for many years. Recognizing that a permanent waste repository was necessary, Congress passed the Nuclear Waste Policy Act of 1982 to establish a national policy for the safe storage and disposal of high-level radioactive waste. The waste is shipped by truck or railroads to places specially designed to safely store the material. The NRC is responsible for licensing and regulating all commercial users and handlers of radioactive materials, including waste shippers and carriers.

ALTERNATIVE ENERGY EXPERT GROUP RUBRIC

CATEGORY 100-90% 89-80% 79-70% 69-60% Content Shows a full

understanding of the topic.

Shows a good understanding of the topic.

Shows a good understanding of parts of the topic.

Does not seem to understand the topic very well.

Comprehension Student is able to accurately answer almost all questions posed by classmates about the topic.

Student is able to accurately answer most questions posed by classmates about the topic.

Student is able to accurately answer a few questions posed by classmates about the topic.

Student is unable to accurately answer questions posed by classmates about the topic.

Vocabulary Uses vocabulary appropriate for the audience. Extends audience vocabulary by defining words that might be new to most of the audience.

Uses vocabulary appropriate for the audience. Includes 1-2 words that might be new to most of the audience, but does not define them.

Uses vocabulary appropriate for the audience. Does not include any vocabulary that might be new to the audience.

Uses several (5 or more) words or phrases that are not understood by the audience.

Enthusiasm Facial expressions and body language generate a strong interest and enthusiasm about the topic in others.

Facial expressions and body language sometimes generate a strong interest and enthusiasm about the topic in others.

Facial expressions and body language are used to try to generate enthusiasm, but seem somewhat faked.

Very little use of facial expressions or body language. Did not generate much interest in topic being presented.