Fuel for Thought
By: Bibi Booth, Shelly Fischman, and Betsy Wooster are Bureau of Land Management (BLM) Environmental Education Specialists. Jennifer Kapus is a Bureau of Land Management Graphic Designer.
There has been an enormous rise in energy demand since the middle of the last century. That increase has resulted from not only rapid industrial development but also population growth. Between 1850 and 1970, world population multiplied by 3.2 times, and total energy use increased more than 12-fold.
Despite the importance of energy to every aspect of our lives, many Americans are not adequately armed with the basic energy knowledge to make informed decisions or determine what can be done to manage and conserve energy resources. In this article, we'll attempt to provide teachers with some basic energy information. We've done our best to highlight key points in an impartial manner. But with an issue this complex and dynamic, it's not possible to cover everything in an article of this length. Energy is indeed "fuel for thought" and will continue to be so for many years to come.
The poster back includes hands-on activities related to alternative energy resources and other activities that will help students develop their understanding of energy, its importance to and impact on our world, and the tough decisions that they—as our future scientists, policymakers, and voters— might have to face.
The Current Picture
More than 90 percent of the energy produced and consumed in the world today is from nonrenewable sources. Such resources as coal, oil, natural gas, and the uranium used for nuclear power cannot be replaced as they are used, or can only be replaced very slowly by natural processes. Each of these sources has both benefits and drawbacks in terms of the ways it can be used, the jobs it provides, and the effects it has on the environment. For example, today most fossil fuels are relatively plentiful and inexpensive. But combustion of fossil fuels generates numerous air pollutants as well as gases that may contribute to global climate change.
Now, let's take a quick look at each of the traditional energy resources.
Coal was formed from the remains of plants that lived in vast swamps some 350 million years ago. The decay of the plants in these swamps (similar to today's peat bogs) provided the carbon-rich materials that were subsequently buried under sediments. Over time, the sediments became rock and their weight generated heat and pressure on the material below, transforming the carbon of the decayed plants into coal.
The United States, with about 25 percent of the world's coal reserves, uses this plentiful and cheap fossil fuel primarily to generate electricity. However, coal is also used as a primary energy source on many industries, including steel, cement, and paper. Over its long history, coal mining has posed hazards not only to its workforce but also to the environment. thanks to stricter regulations, improvements have been made, but disturbances to soil, water, vegetation, and other resources during extraction can still be significant. The burning of coal at electric-generating plants also contributes to air particulates and acid rain. With modern technologies and tighter controls, it is possible to remove some noxious gases, but coal is still responsible for some 35 percent of world carbon dioxide emissions from fossil fuels.
Petroleum formed from the remains of tiny organisms that lived in seas and rivers millions of years ago. As in the coal-formation process, burial by sediments prevented the remains from rotting, and heat and pressure turned them into what we know as petroleum or crude oil. Oil is a versatile liquid that serves as the lifeblood of our transportation system: In the United States, more than half of it is refined into gasoline, jet fuel, and diesel fuel. Heating oil and propane are also derived from petroleum, as are a wide range of other products, from plastics and tires to synthetic fabrics and crayons. Petroleum, however, has a major drawback–it can spill. Tanker spills during ocean transport can significantly impact marine and coastal environments over a wide area. Even more oil is spilled each year during and after use, and via storm runoff.
Of concern to the United States in particular is the fact that only about two percent of the world's oil reserves lie within its borders. If demand continues to rise, the United States could be importing two-thirds of its oil by 2010. New technologies that allow for enhanced recovery from existing oil wells, along with drilling in new areas, may provide additional domestic supplies, but reliance on foreign supplies will almost certainly continue for the foreseeable future.
Natural gas was formed in much the
Nuclear energy is also considered "traditional"–at least since 1945. Nuclear energy comes from nuclear fission, the splitting of the atom. Only a few naturally occurring isotopes, such as uranium-235 and plutonium-239, are easily fissionable. Nuclear energy is used primarily to produce electricity. Just as in a fossil-fuel-powered plant, heat (from fission) boils water, which creates steam that turns a turbine-generator. Since there is no carbon and no burning takes place, nuclear power does not emit carbon dioxide into the atmosphere.
But other health and environmental hazards are associated with nuclear power. From mining of uranium through fuel processing to waste disposal, the use of nuclear energy involves radioactive material. Exposure to radiation can cause genetic mutations, serious illness, and even death. The threat of accidents and the possibility that nuclear materials could get into the wrong hands contribute substantially to public fears about this resource. Even the normal operation of a nuclear power plant creates low-level radioactive waste in the form of ordinary trash, tools, clothing, and other contaminated items that must be carefully isolated from other materials.
No long-term solution to the disposal of highly irradiated spent fuel assemblies has yet been widely accepted. Currently, all spent fuel in the United States is stored at the power plant at which it was used. However, in February 2002, the President recommended to Congress that a geologic repository at Yucca Mountain in Nevada be developed as a disposal site for spent fuel and other high-level nuclear waste.
Hydropower is a traditional energy source that provides a notable amount of electricity and other power worldwide. Since it is a form of renewable energy, however, it is covered in the section that follows.
For the foreseeable future, fossil fuels will continue to power our planet. There is little doubt that demand for energy will continue to grow. But as traditional resources become depleted and as concerns grow about their impact on the environment, the quest for alternative energy sources becomes more compelling.
Powering the Next Generation
Almost all renewable energy resources originate in the sun. Non-hydropower renewable energy currently accounts for only four percent of U.S. energy and two percent of the electricity supply. Hydropower provides an additional 10 percent of production and seven percent of electricity. In the last decade, the growth in U.S. renewable energy production outpaced all sources except for nuclear energy.
Barriers to renewable energy development include high up-front costs and higher power costs. For example, electricity produced from natural gas currently costs three cents per kilowatt-hour, compared to about six cents for solar energy. But the generating costs for renewable energy are shrinking, and surveys show that Americans are increasingly supportive of non-polluting power.
Ancient peoples used the energy in flowing water to operate machinery. Today, U.S. hydropower is used primarily to produce electricity, especially in the western states.
Hydropower is produced by channeling the flow of rivers or by storing water in reservoirs behind dams and directing it through turbines. There is no pollution of the types associated with the burning of fossil fuels. Hydropower is clean, renewable, and domestically produced, yet it supplies less than 20 percent of the world's electricity. Advocates of hydropower cite the recreational benefits derived from reservoirs and the provision of water for irrigation.
On the other hand, dams disrupt river ecosystems, causing upstream flooding and downstream flow depletion. Water redistribution adversely affects many habitats and can make it impossible for anadromous fish such as salmon to travel upstream to spawn. Though fish ladders have helped mitigate this problem, there is still growing public opposition to dams.
This most basic source of energy is produced in the sun's core by nuclear fusion. The slight mass lost in this process is emitted as radiant energy; though less than one percent of it reaches the Earth, in 30 minutes it can provide a year's worth of human energy needs. The amount of solar energy a specific place receives depends on such factors as the season and proximity to the equator.
Humans have long used sunlight to cook food and heat water and homes. Today, solar energy is still used for those purposes and to provide hot water for industries such as laundries.
Photovoltaic cells, made of semiconducting materials, are used to collect solar energy and generate electricity. Solar electrical plants are not suited to locations with scarce or unreliable sunlight. Large solar plants can also involve clearing of land for infrastructural components.
Wind is moving air produced by uneven solar heating of the Earth's surface. Wind power has long been used for grinding grain and pumping groundwater.
Windmills' modern equivalent, tall wind turbines, use wind energy to generate electricity. Turbines catch the wind with blades mounted around a shaft to form a rotor. On the downwind side of the blade, blowing wind forms a low-pressure pocket, which pulls the blade, turning the rotor to spin an electrical generator.
Wind power is now the fastest-growing energy source worldwide. However, land clearing for vast "wind farms" may produce environmental concerns. Many predict that wind energy will provide more U.S. electrical production as new turbine designs enhance economic and environmental viability.
Geothermal energy comes from intense heat within the Earth, which also produces hot springs, geysers, and volcanoes.
Geothermal resources are found where the Earth's crust is relatively thin. The only widely used type of geothermal energy is hydrothermal, produced when subsurface water contacts hot rock and turns to steam, which is piped to the surface. In some cases, water or steam is used directly to heat homes or provide process heat for businesses. In a typical geothermal electric plant, steam is piped to a turbine to power an electrical generator.
Geothermal development has disadvantages, particularly the hydrogen sulfide gas emitted during extraction. Many of the same environmental concerns surrounding exploitation of oil and gas may also impact the development of geothermal resources, which must be similarly drilled and piped to the point of use. The advantage to geothermal energy, however, is that it does not produce pollution when used.
Biomass and Biofuels
Biomass is any modern organic matter used as an energy source. The most common examples are wood, bioenergy crops, and organic wastes such as agricultural residues. Unlike other renewable energy sources, biomass can be burned or converted directly into liquid biofuels.
All biomass is solar energy transformed through photosynthesis. Biomass energy is usually released by burning, and less often by bacterial decay and fermentation. If vegetation is regrown as biomass is used, the net release of carbon dioxide due to the burning of biomass is zero.
Today, wood stoves are used world-wide for heating and cooking, making biomass one of the most common energy resources. Biopower is the burning of biomass to generate electricity. Waste-to- energy biopower plants use organic garbage as a feedstock, which reduces the amount of waste entering landfills.
Toxic substances may enter the atmosphere when municipal waste is incinerated, so contaminants should be removed for treatment before waste incineration. As landfill sites become harder to find, waste-to-energy plants may be an increasingly attractive option.
Alternative fuels offer another application for biomass technology. Crops can be fermented to produce liquid biofuels, the most common of which are ethanol and methanol. Today these alcohols are relatively high-cost, and oil prices would have to double to make them a cost-effective alternative. But gasohol, a mixture of just 10 percent ethanol and 90 percent gasoline, is highly cost-competitive and can be used in a traditional gasoline engine. It also has higher octane than gasoline and is far cleaner-burning. The air pollution savings from the increased use of ethanol and/or gasohol could be significant.
Scientists debate the consequences and benefits of genetically modified crops and forests that are managed for biomass resources.
Biogas is methane produced from animal waste and by the decay of organic garbage. Because of current natural gas prices, biogas is usually flared as waste. More productive uses include onsite burning of biogas for heating of livestock barns and greenhouses.
Most experts agree that with some additional guidelines and new technologies, biomass can be part of a "greener" U.S. power portfolio.
Hydrogen (Fuel Cells)
Fuel cells chemically convert pure hydrogen or hydrogen-rich fuel into electricity, a process so efficient that 80 percent of the fuel's energy is used. Currently, the most economical hydrogen sources for fuel cells are hydrocarbons. When pure hydrogen is used, a fuel cell produces only electricity and water.
First used in the U.S. space program, fuel cells resemble batteries. Electricity is produced by a chemical reaction between a hydrogen-based fuel and an oxidant inside the fuel cell. Fuel cells can produce electricity as long as they are supplied with fuel.
Fuel cells can be used in applications ranging from electric vehicles to large power plants. Fuel cell power plants tend to have fewer emissions than traditional power plants, even when fossil fuels are used as a hydrogen source, so are well suited to congested urban areas.
Overall cost reductions must be achieved before fuel cells are competitive with internal combustion engines, and the size and weight of fuel cell systems must be decreased to accommodate consumer vehicles. Significant research and development have already been completed, and the automobile industry is aggressively exploring fuel cells.
Using Less, Doing More
Balanced community energy plans incorporate conservation and efficiency initiatives. The challenge is usually not one of inadequate technology but of public misperception and persistent behaviors. The key is finding the right blend of education, incentives, and regulation to encourage communities to use approaches that have already proven effective.
Practicing "The Three 'Rs'"—Reduce usage and potential waste; Reuse (rather than discard) materials; and Recycle materials—helps households and businesses to save energy. Along with lessening landfill waste and conserving natural resources, following the Three Rs decreases pollution by reducing the need to manufacture, distribute, and use materials from raw resources.
In 1999, for example, U.S. recycling activities prevented about 64 million tons of materials from ending up as waste. Curbside recycling programs served roughly half the U.S. population. Some communities even have "pay-as-you-throw" programs, with waste collection fees based on the amount discarded—a direct economic incentive to generate less waste.
Today, the United States recycles 28 percent of its waste, almost double the level of 15 years ago. Recycling of specific materials, such as aluminum, has grown even more. Purchasing recycled materials closes the recycling loop and makes recycling programs successful.
Energy efficiency increases when energy conversion devices, such as appliances or car engines, undergo technical changes that allow them to provide the same service while using less energy.
Residential and commercial buildings account for more than a third of U.S. energy demand. The energy efficiency of buildings can be enhanced through the use of insulation, appropriate landscaping, and design improvements.
For example, super-insulated houses in bitterly cold climates stay comfortable using only their occupants' body heat. More than 100,000 such houses now exist worldwide.
Efficient lighting saves on air conditioning and electricity. Compact fluorescent light bulbs (CFLs) are cooler-burning, and use only one-fourth the energy of standard bulbs. While initially expensive, CFLs soon pay for themselves via reduced energy bills, and they last 10 times as long as standard bulbs. Most commercial building owners still are not taking full advantage of such efficient technologies unless local utilities provide financial incentives.
Air conditioners and other appliances need not squander energy either. Today's most efficient new appliances typically use half the energy of the most wasteful appliances. The average U.S. household could reduce its energy bills if it maximized use of efficient appliances, which would also result in notable savings in greenhouse gas emissions. Homeowners can evaluate their homes' energy efficiency via the U.S. Department of Energy's website at www.homeenergysaver.lbl.gov.
Excellent opportunities also exist to lessen vehicles' use of fossil fuels, including raising federal Corporate Average Fuel Economy (CAFE) standards for gasoline-powered cars and light trucks. New hybrid cars can achieve an impressive 112 km per gallon using a combination of gas and electric drive trains and ultra-light bodies.
Even high fuel prices haven't changed Americans' car-buying or driving habits. Car sales are on a record pace, and customers are still buying mostly trucks and sport utility vehicles (classified as light trucks for purposes of CAFE). According to The New York Times, 1996 was the first year in which the cars entering junk-yards actually got better mileage than those rolling off dealer lots.
People also tend to drive alone: Half of the savings due to automobile fuel efficiency increases from 1972 to 1992 were canceled out by decreases in vehicle occupancy. Greater dissemination of car-pool and public transportation information to commuters, as well as employer-provided incentives, would help to lower the number of single-occupancy cars on the road.
For most industries, energy is a small part of operating costs, so there is little incentive to conserve. But cogeneration is an area where industry could save both energy and money. Process steam from boilers can do double duty, first for the industrial process and then to run a turbine for electricity. This allows up to 90 percent of the energy in fuel to be used productively.
Providing electricity, light, heat, or mechanical energy near their point of use lessens the need for transmission lines and pipelines. Such "distributed" energy may use renewable resources, or it may incorporate alternative uses of traditional energy, such as natural gas micro-turbines for small businesses.
The issue of how best to meet the world's energy demands is complicated. Energy education and literacy are key to the process: Only an informed public can make useful contributions to discussions of energy issues.
Economic, environmental, and behavioral factors must be considered simultaneously, so we often face tough choices beyond a simple "either/or." And the choices we make will have an enormous effect on the kind of world we leave to future generations.
Fortunately, we are also presented with vast opportunities to make a difference today. Studying and working with energy sources can help us develop a new sensitivity to the flow of energy in the world around us, and a deeper appreciation for energy's interconnected elements and impacts.
There are almost limitless possibilities for scientific exploration and innovation in the fields of energy technology, energy efficiency, and conservation, especially as applied to renewable and alternative energy resources.
Energy use and conservation are areas where individuals of almost any age can have an immediate, positive impact on our world. In fact, in many cases, concerned students are actually leading their parents, teachers, and other adults to a greater awareness of the environmental, economic, and other impacts and benefits that can result from personal behaviors. In this regard, energy can provide an arena in which young people can show the way. More