Sun Potential


Biology Senior Seminar
David Ries
11-25-96



Topic outline 


As the world population soars, we as a global community are met with a need to fulfill the energy requirements of this increasing population. Probably no one is in complete agreement on how to accomplish this. The World Energy Conference has concluded that energy needs in 3 decades will be 75% higher than today. The popular concern over fuel consumption that was so prevalent following the 1970 oil crunches has gone by the wayside. This concern has recently been revived, but the action is still left to "other" people. One area of concern is the environmental impact of our consumption of fossil fuels. The use of these fuels are often blamed for global warming, however the reasons are still under much debate.

We are generally looking to achieve better fuel efficiency. But with lowering fuel costs, sometimes this is not a priority. Political and economic interests tend to maintain the status quo. The 1970 oil shocks increased our fuel efficiency tremendously, but we still have a ways to go relative "to European countries or Japan"(Chase). The current energy mix is also an area for debate. This has changed throughout the past couple centuries--are we in the process of another transition, is a change necessary? Currently oil is the principle energy supplier, followed by coal and natural gas. Natural gas would seem poised to become the fuel of the 21st century with advantages over coal and oil and being more abundant than previously thought (Chase). The view of the World Energy Council and other organizations is to maintain the current trend, but shift reliance somewhat toward other fossil fuels like lignate or shale. With this scenario large technological or policy changes will not have to occur (Flavin and Lenssen pg. 20). It is assumed that energy efficiencies will increase and that this may be enough to fulfill energy needs. What are neglected are the effects of a tremendously increased population and the effects of unsustainable energy trends both economically and environmentally.

Proponents of the status quo make an incorrect assumption that rapid technological improvements will not be made in the area of energy technologies. Actually vast improvements have been made over the past few years in the area of developing efficient energy technologies for example. There are items like light bulbs and refrigerators that are at least 75% more efficient than the current standard. The power plants of the early 90's are 50% more efficient than a decade ago (Flavin and Lenssen pg. 21).

With natural gas becoming so prominent, a trend toward cleaner, more versatile fuels seems evident. As natural gas is developed, it would allow fazing out of oil and coal and lead to the development of "more efficient and decentralized energy conversion and storage systems" (Flavin and Lenssen pg. 22). This last development makes the transition to renewable fuels more feasible.

The energies that we are primarily using now are not an unlimited resource, we will eventually need alternatives. Renewable or "alternative" energies have become economically viable in light of recent developments. The most abundant of these energies are solar and wind, but there are many other renewable resources. Costs are also declining, and these renewables should be fully competitive very soon.

We have about 100 years left of oil reserves at the current extraction rate. There is an attitude or assumption that we will stay dependent on oil until it is practically gone, and then move to coal because it is there. "If analysts had held a similarly blinkered view of other sectors, we would still be driving around in buggies and writing on typewriters. The world never ran out of either hay or paper. Rather, people discovered better means of accomplishing things more conveniently and economically. The energy sector is no exception. The age of oil was ushered in at the turn of the century less by the discovery of petroleum, which had been found much earlier, than by the development of a practical internal combustion engine that made oil useful" (Flavin and Lenssen pg. 23).

 
The Environment

Perhaps the main reason given to make the switch to fossil fuels is the idea that fossil fuels are the largest contributors to increased CO2 levels in the atmosphere and this may be causing global warming. Carbon dioxide emissions are increasing with CO2 levels 50% higher today than at the turn of the century and at the highest levels of the past 160,000 years. Temperatures have been rising globally, but the causes are still debated. The "modelers" of the systems predicting these changes say that they may be a decade away from complete confidence in their results. Carbon dioxide is not the only gas whose effects are being examined. Another gas that may actually have the largest effect is water vapor--the effects of the clouds, cooling during the day and warming at night. These interactions between the atmosphere, the land, and the oceans are extremely difficult to predict. Some scientists say that stabilizing the climate will require a reduction in global carbon dioxide emissions by 60-70%, the largest cuts of course coming from the wealthier, more industrialized nations. Since the world population is predicted to double in the middle of the next century, from 5 billion to 10 billion people, this means more fuel use and therefore more CO2 and other gas emissions. There are other issues like urban air pollution and acid rain. These need to be addressed on a more local level perhaps, and again, scientists are not in agreement as to the reasons. "Some scientists worry that not enough is yet known about the atmosphere and climate systems to justify spartan proposals of sacrifice and denial" and others will counter that "the world can't wait for proof of warming before trying to do something about it. We're engaged in a huge experiment, using our earth as the laboratory, and the experiment is irreversible. By the time we find that greenhouse warming has damaged the earth's ability to feed it's people, it will be too late to do much about it"(Stephen H. Schneider). "It is tempting to ask: If nature will correct what we do to the atmosphere, must we give up our profligate ways?"(National Geographic pg. 98).

 
Renewables

Energy technologies are renewable when their source can be managed to sustain an average yearly energy output indefinitely (Kozloff pg. 7). A new study by U.S. government scientific laboratories suggests that renewables could supply 50-70% of current U.S. energy use by 2030. The six most frequently discussed technologies follow: Solar electric systems use photovoltaic cells to convert solar radiation directly into electricity. Solar thermal systems concentrate sunlight onto a fluid or engine to produce heat which can then be used as needed. Wind energy is produced by converting the kinetic energy of the wind into rotational energy that is used to run electricity-generating turbines. Biomass refers to wood, wood wastes and by-products, also agricultural and municipal solid waste. This is combusted to generate heat and electricity. This technology seems to hold increased promise for industrial use with the development of plasma incinerators. Burning fuelwood in the past has meant deforestation and loss of topsoil, but with new conservation techniques there can be fewer drawbacks. Geothermal energy is the heat that is trapped up to 3,000 feet below the earth's surface, in rock for example. There is tremendous potential here which, if care is not taken, can be easily mismanaged. Currently it is hydrothermal energy that is primarily used commercially to generate electricity and to heat buildings. This is steam, hot water, and hot brine that is generally within 900 feet of the earth's surface. At the moment, hydropower is perhaps the most important renewable energy technology generating 1/5 of the world's electricity. This comes primarily from dams and is then limited to the presence of the necessary bodies of water.

The Solar Option

Annually "the earth's surface receives about 10 times as much energy from sunlight as in contained in all the known reserves of coal, oil, natural gas, and uranium combined" (Hoagland pg. 170). Together the sun and wind energies "can provide the equivalent of nearly 1,000 trillion barrels of oil a year" (Flavin pg. 70). It isn't possible to collect all this energy, but this gives an idea of what is available. The resource that appears to hold the most potential to ease our dependence on fossil fuels is power from the sun. The sun provides wind power, biomass energy, and direct solar energy. Discussion will be concentrated on these three renewables.

Biomass is estimated to currently provide fuel to virtually 45% of the world's population. Biomass is a renewable resource, but much of it is being used in ways that are not renewable or sustainable (Flavin and Lenssen pg. 177). Firewood is becoming more scarce in many parts of the world as growing populations convert the forests to agricultural land and burn the remaining trees as fuel. The consequential fuel shortages have forced women and children to spend much of their time collecting wood or crop residues and animal dung, both valuable fertilizers, which are instead burned. The wood or charcoal is frequently burned inefficiently, often capturing less than 10% of the wood's energy--90% is wasted. It is estimated that simply "shifting food preparation from an open fire to a closed, more efficiently designed cook stove made of local materials could halve the use of firewood." (Brown and Shaw pg. 39). Many efficient cookstoves have been distributed enabling efficiency to be improved to 40% while also cutting down on emissions.

Methane produced by microbes digesting animal and human wastes or landfill garbage can be burned. This is a clean fuel source, producing neglegible carbon emissions.

Burning agricultural or industrial wastes can also generate steam for turbines. Wherever biomass is cheap, the electrical production by these types of facilities is already competitive with conventional electrical production. In Sweden, a power plant was recently completed that uses gasified wood to fuel a jet engine. This plant converts 80% of the wood energy into electricity and heat. This kind of technology makes the burning of biomass very clean. However, burning is not always the best solution. Some materials, like paper, save 2 to 4 times as much energy through recycling as can be produced by burning it.

It has also become economical to convert plant material into liquid or gaseous fuels. Energy crops, agricultural residues, and other wastes can be gasified and used to produce methanol. Ethanol is released from the fermenting of grains or wood. These alcohols are being blended with gasoline to improve fuel efficiency and reduce tail-pipe emissions--ethanol is also very effective when used alone. Growing energy crops could allow for better land management and higher profits. Much research is needed in these areas to produce consistently high crop yields in the various climates (Hoagland pg. 171).

 About 0.25% of the total energy of the sun that reaches into the lower atmosphere is transformed into wind energy. One study suggests that 100% of the electricity consumed in the United States could be provided by the wind energy available in North and South Dakota and Texas, excluding environmentally sensitive areas. Or using 0.6% of the land area of the "48-states"--primarily the Great Plains--could provide 20% of current national electrical needs. Large wind projects have been set up worldwide. In the U.S., wind already supplies 1% of California's electricity. Newer and lighter windmill designs allow wind-generated electricity to be sold for 4-5 cents per kilowatt-hour. Already this is cost-competitive with conventional electrical generation and costs are dropping.

There are a few problems with wind-generated electricity. One is that it has the potential to generate some land use conflicts. However while wind farms do occupy large areas, most of this would be where few people or wildlife are. Furthermore this occupation is primarily in the visual sense as the use of the land around the turbines can be the same as before--grazing animals or raising crops. The turbines can also supply supplementary income to farmers and perhaps increase land values by functioning as a windbreak thereby reducing erosion. Another problem is that wind energy is, in a sense, self-limiting. Wind is intermittent, and if wind comprises 25-45 % of the power supply, a shortfall would be costly. Better storage of energy is necessary to anticipate these occurrences. The wind farms could also be outfitted with a gas turbine or perhaps a hydropower project that can be run when the wind is not.

 Another means to generate electricity is through a solar thermal system. This system uses the sun's radiant energy to drive an engine. There are usually 4 components: a system to collect the sunlight, a receiver to absorb it, a storage device to store the thermal energy, and a converter to change the heat to electricity. The collectors are of three basic types: a parabolic dish to focus light to a point, a parabolic trough to focus light to a line, perhaps onto a tube of oil or water, or an arrangement of flat mirrors over a large area to focus light to a central tower. The troughs and parabolic dishes are mounted on devices to track the sun and keep it focused.

These systems are between 10 and 30% efficient at converting direct sunlight to electricity. Tests concentrating on solar troughs show "that improved collector surfaces, polar-axis tracking, and a better trough design can increase sunlight collection by nearly one-fourth" (Flavin pg. 73). If vacuum insulation is added to the heat carrying pipes, annual efficiency is pushed to 20% and peak efficiency is near 30%. This new design can run for eight hours without sunlight by storing heat in a bed of rocks. Power can be provided for around 6 cents per kilowatt-hour.

The parabolic dish tends to be more thermally efficient than troughs. They can reach temperatures 3-4 times that of trough systems thus producing more steam and electricity. They can also be added incrementally as needed since they are built in separate units. Solar thermal systems have primary usefulness in the commercial market.

Solar electric systems using photovoltaic cells show the most potential for use privately and for transportation. High potential is recognized for use in rural areas separated from a main power grid or in "developing" countries where fossil fuel is difficult to afford and wood, for example, is becoming increasingly difficult to find. Rooftop solar panels and ideas like solar box cookers have been promoted in these countries. Solar electric systems generally use a silicon photovoltaic device. Sunlight is captured directly generating a voltage. "Advanced solar technologies have the potential to use less land than does biomass cultivation"(Hoagland pg. 170). This is because typically photosynthesis captures between 1 and 3% of available sunlight; new solar technology can achieve efficiencies between 20 and 30%.

The cost is the primary factor preventing widespread use of these systems. There are two approaches to cost reduction: cheaper materials are being developed for the flat-plate systems (these flat-plate systems are what are commonly called solar panels), and lenses or reflectors are being used to concentrate the sunlight onto smaller areas of the solar cell (Hoagland pg. 172). It is important for the concentrating systems to track the sun but these tracker systems add to the cost. Concentrating systems do not use cloud-covered sunlight as efficiently as do the traditional flat-plate systems. However, since the flat-plate systems generally do not track the sun, they also do not capture as much light early and late in the day. Costs for both of these systems are expected to decrease considerably as more modern manufacturing techniques have only recently been implemented. Photovoltaic generated electricity should become competitive with conventionally generated electricity early in the next century.

Storage is one challenge to wind energy and solar radiation energy. As both of these systems are intermittent, storage systems are necessary. "...the more promising long-term solar systems are designed to produce only electricity" (Hoagland pg. 173). Therefore a system to transport energy is needed. Much research has gone into the production of a better battery, especially related to transportation. A lithium/sulfide battery has been recently developed that promises 5 times the energy and 10 times the life of the current "high-tech" batteries.

One device that holds considerable promise is a flywheel. This is a sort of "mechanical battery that stores energy in the form of a spinning disk rather than in chemical form" (Flavin and Lenssen pg. 212). These have the potential to store and release energy at efficiencies of more than 90%. Flywheels are also able to produce large bursts of energy, making them ideal for hybrid cars that combine solar technology with some form of fossil fuel. These flywheels will also probably outlast most cars.

Storage is also possible in the form of hydrogen. Sunlight, falling on an electrode produces a current to split water into hydrogen and oxygen--a process called photoelectrolysis. The hydrogen that is produced can be burned as a fuel or used to produce electricity in a fuel cell, the only by-product being water. "Photobiology" is the term used to describe a class of biological systems that produce hydrogen. Further research may produce photocatalysts that could allow sunlight to split water directly, thus lowering cost. Fuel-cell-powered cars are being developed with current efficiencies of 35-65%. The disadvantage to hydrogen as a fuel is that it is bulky to store and expensive; liquid form decreases the bulk. It is attractive if it is efficient. Hydrogen provides one solution to the solar energy storage problem. The energy can be contained in the form of hydrogen indefinitely. And when transported over 1,000 kilometers it is cheaper than transmitting electricity.

Other concerns about solar energy collection have to do with the relatively large surface areas required by the current collectors--this is changing with the development of the condensing systems. Questions are raised as to what kind of effect these large solar farms will have on the desert ecology--the effect is judged to be minimal (Federal Energy Administration pg. III-18).

Outlook

It is not reasonable to assume that one solar technology will be the answer or that wind power or photovoltaics will provide all of the world's energy needs. The global variations in economics and geography, the availability of sunlight will determine what the best approach will be. A broad range of renewables used together seems more likely. Presently "developed" nations consume 10 times the energy per person than is used in "developing" countries. "In the past, energy transitions have occurred on a country-by -country basis. But the next transition is one that the world as a whole must achieve, because the economic and ecological problems driving it are global in nature. By the year 2030, today's developing countries will have upward of 80% of the world's population. These nations have little hope of achieving their basic developmental goals if they follow the energy path blazed 100 years ago by the West. But they could "leapfrog" industrial countries and follow a sustainable energy strategy from the start, avoiding billions of dollars of misdirected investments" (Flavin and Lenssen--Beyond pg. 49). "Solar technologies could enable the developing world to skip a generation of infrastructure and move directly to a" (Hoagland pg. 173)...better source of energy.

 
Policy Changes

In order to bring about this reform in energy consumption, global and national policy changes are needed. "When the decision to change is made will depend on the importance that is placed on the environment, energy security, or other considerations" (Hoagland pg. 173). Needed are a reordering of energy priorities. Some of this is occurring brought about by goal setting like those to reduce gases thought to be responsible for global warming. The rules of the present energy economy tend to be biased against renewable energies.

Flavin and Lenssen site four priorities: subsidies must be reduced for fossil fuels and taxes raised on them to reflect security and environmental costs. Governments continually provide subsidies to the traditional energy sources which keep the prices artificially low and encourage waste. The cost of protecting the oil reserves in the Persian Gulf is not added to the cost of oil. The American Lung Association Estimates that air pollution from automobiles adds $40 billion to medical bills annually. These costs also need to be incorporated into the price of energy.

Research and development of efficiency and renewable energy technologies needs to be increased. Incentives need to be offered for investments in efficiency.

Reform needs to take place in the electric utility industry, and state and local energy policies need to be strengthened. Encouragement of independent power development at the lowest possible cost needs to occur. To create this it is necessary to establish a bidding system in order to allow power companies to compete for production rights. On a local level cities can develop policies to reduce the reliance on automobiles and encourage a switch to public transportation, biking, or walking. They can also develop policies to control urban sprawl through careful land-use planning by using tax incentives and/or zoning regulations. Cities can also easily promote the use of renewable energy resources (Flavin and Lenssen--Beyond pgs. 27-38).

On an international level it is necessary to assist developing countries in promoting and improving energy efficiency. They also need assistance to develop renewable energy resources. Some of the problems here are a shortage of capital and misallocation of funds.

Some argue that reduced energy consumption will produce massive layoffs in energy-producing industries. Flavin and Lenssen argue to the contrary saying that a sustainable energy economy is more likely to produce more jobs since improving energy efficiency creates more employment than supplying energy.

It is difficult to begin large-scale renewable energy projects since these are capital intensive technologies. High initial investments are necessary, but savings are soon realized due to very low operating costs. As renewable resources continue to prove themselves, investors will become more comfortable in giving their support. With increased production comes reduced costs. Initially states could use "safe-harbor rules" to encourage utilities to invest in renewables. These would provide full cost recovery in case of failure (Kozloff pg. 28).

 
Stewardship and Action

The simplest thing that we can do at the moment as a global community to develop towards a sustainable society is to take care of what we have. Brown and Shaw offer some steps to take to achieve the sustainable society. One thing that must happen is a stabilization of the world population. Without this, we cannot hope to protect our cropland, attempt reforestation, or conserve our energy use. These things must occur as well. The economic role of the forests is well known, their ecological role may be more difficult to define. What we do know leads to words of caution and alarm at the rate of deforestation--every year shrinking by an area the size of Hungary (Brown and Shaw pg. 28). There is a throwaway mentality that must be abandoned before we can bring in an age of renewable resources. We can no longer afford this attitude as there are so many people competing for fewer and fewer resources. "...how long will it be before we learn that we must reduce waste before we try to reform production?"(Potts and Scanlon pg. 4). We in the United States have a tremendous potential for conserving energy. This is in part because the amount of waste we generate is so large, and also because we have the technology and engineering ability to increase our economy's energy efficiency. We need to continue to develop our renewables. We must have a well-established energy structure in place when the fossil fuels that we rely on now are depleted.

To accomplish these steps a large amount of funding will be necessary. To gain this capital, it may very well be necessary to shift funds from the military sector and work together as that global community. Governments might not become interested in an action like this until they realize that not doing so will result in declining living standards. Investment priorities will need to be realigned in order to match new environmental and economic realities. This is vitally important. Values are the key to the evolution of a sustainable society. They influence behavior and determine a society's priorities. Our society has become extremely materialistic. This has progressed to where the acquisition of material goods is beyond human need. The development of a new society is a large undertaking, but large also are the consequences of failure.

 

Works Cited

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Bahm, Raymond J. and Associates. (1996). Solar Energy -- An Introduction, [Online] http://www.rt66.com/rbahm/seintro.htm [11-13-96].

 

Brown, Lester R. and Pamela Shaw. Six Steps to a Sustainable Society. Washington, D.C.: Worldwatch Institute, 1990.

 

Chase, Kevin. (1996). Focus on Energy Issues, [Online]. http://www.physics.rutgers.edu/~chase/energy.html [11-13-96].

 

Energy Information Administration, U.S. Department of Energy. (1996), Energy INFOcard United States (1995), [Online]. http://www.eia.doe.gov/neic/infocard.html [11-13-96].

 

Flavin, Christopher. USA Today: Harnessing the Sun and Wind. Nov. 1995.

 

Flavin, Christopher and Nicholas Lenssen. Beyond the Petroleum Age: Designing a Solar Economy. Washington, D.C.: Worldwatch Institute, 1990.

 

Flavin, Christopher and Niccholas Lenssen. Power Surge: Guide to the Coming Energy

Revolution. New York: W. W. Norton and Company, 1994.

 

Hoagland, William. Scientific American: Solar Energy. Sept. 1995.

 

Kazloff, Keith Lee. Environment: Renewable Energy Technology: an urgent need, hard sell. November 1994.

 

Matthews, W. Samuel. National Geographic: Is Our World Warming? Oct. 1990.

 

Potts, M. The Mother Earth News: The Future of Solar is Now. Aug./Sept. 1995.

 

United States Interagency Task Force on Solar Energy. Project Independence . Washington, D.C.: U.S. Government Printing, 1995.