Achieving a secure energy future: environmental and economic issues

ECOLOGICAL ECONOYIICS

ELSEVIER

Ecological

Economics

9 (1994) 201-219

Achieving a secure energy future: environmental and economic issues David Pimentel *, M. Herdendorf, S. Eisenfeld, L. Olarider, M. Carroquino, C. Corson, J. McDade, Y. Chung, W. Cannon, J. Roberts, L. Bluman, J. Gregg 6126 Comstock Hall, College of Agriculture and Life Sciences, Cornell UniLersity, Ithaca, NY 14853, USA (Accepted

15 February

1993)

.4bstract Energy, economics, and the environment are interdependent. Land, water, atmospheric, and biological resources #arebeing degraded by current high energy consumption. U.S. energy consumption is the highest in the world and the U.S. Department of Energy reports that the United States has only about 10 years of known and potentially 1,discoverable oil reserves. The U.S. should reduce its energy consumption by one half to help restore the quality of ithe environment while improving the American standard of living by strengthening the economy and increasing the Inumber of jobs. Because of the interdependence of energy, economics, and the environment, energy efficiency and 1:ransition to renewable energy sources are critical. An estimated 40% of current energy consumption could be produced employing solar energy technologies, but would require about 20% of total U.S. land area. Therefore, the Idevelopment of solar energy technologies to substitute for fossil energy is projected to compete for land required for ,lgriculture and forestry as well as have other environmental impacts. Key words: Economics;

Energy

consumption;

Environment;

1. Introduction From the beginning of time humans have sought control over nature and their environment. The consequences of this long fight against nature have reached a critical stage of profound and far-reaching environmental degradation commonplace throughout the world. Erosion of fer-” Corresponding

author.

0921-8009/94/$07.00 Q 1994 Elsevier !;SDI 0921-8009(93)E0022-9

Science

Renewable

energy

tile land and deforestation are more severe than ever; pollution of water, air and land by toxic chemicals, and ozone depletion are intensifying; and signs of global warming are increasing (WRI, 1991; Worldwatch, 1992). Excessive fossil energy use, over-population, and consumerism, all stress limited natural resources and have resulted in serious environmental and economic problems in the United States and other nations (WRI, 1991; Worldwatch, 1992). Because the strength and sustainability of the

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702

D. Pimentel et al. / Ecological Economics 9 (1994) 201-219

Table 1 Total fossil energy use by sector in the USA and world sectors

Transportation Industry Residential Food systems Commercial Military Total (Electricity

USA = 18.5 quads a Percentage ’

Table 2 Fossil and solar energy use in the USA and world

World = 319.2 quads b Percentage ’

26 25 20 17 10 2

33 25 15 1.5 10 3

100 34)

100

USA* Quads Fossil energy Solar energy Hydropower Biomass

78.5 6.6 3.0 3.6

Total energy

85.1

World b.c % 92.3 7.1 3.5 4.2 100

Quads 319.2 49.7 21.2 28.5 368.9

% 86.5 13.5 5.7 7.8 100

a DOE (199la); b DOE (199lb); ’ UNEP (1985).

a DOE (1991a); b UNEP (1985); ’ Estimated.

nation’s environmental and economic future are already intertwined, energy efficiency and development, the use of renewable energy sources, the development of alternate energy sources, and the maintenance of a quality environment have become essential. The goals of this paper are to assess: (i) the environmental and economic security problems that current U.S. and world energy policies have caused; (ii) current and projected energy use; (iii) the transition to renewable energy systems; and (iv) the development of a framework for a longterm energy policy that would enable nations to achieve both economic and environmental security for future generations. Included are strategies for more efficient energy use as well as resource conservation programs, increased environmental protection, and the rapid development of renewable energy technologies to replace nonrenewable fossil fuels.

2. Energy use The worldwide annual consumption of energy is presently 369 quads ’ (369 X lOi BTU or 390 x lOI joules) each year (Tables 1 and 2). Fossil fuels are the major source, supplying 319 quads or 87% of the total annual energy consumed (Tables 1 and 2).

’ 1 quad = 10” BTU or the equivalent barrels of oil per day for one year.

of nearly 500000

The United States, with only 4.7% of the global population, consumes about 25% of all the fossil fuel consumed in the world annually (DOE, 1991a). In other words, the average American uses more than 2700 gallons of oil equivalents of fossil fuel each year (1 gallon = 3.785 0, or 5 times the amount used by an average world citizen. The use of fossil fuels within the United States is divided into six different sectors (Table 1). These include the transportation and industry sectors, which account for more than half of the total annual fossil fuel consumption in the United States. Within transportation 15 quads, or 73%, is used in highway transportation (DOE, 1991a). This consumption is greater than the total transportation expenditures for all of Western Europe, Canada, Japan, Australia, and New Zealand combined (IEA, 1989)! In industry 25% of the total fossil fuel consumption is utilized in the production of fertilizers, pesticides, paints, and other toxic chemicals (IEA, 1989). Each year the residential sector of the United States consumes 20% of the total fossil fuel consumption (Table 1). Of this, more than half is for space heating (DOE, 1988, 1990X The two other major uses are appliances (25%) and water heating (18%). The entire food sector, commercial sector, and military sector account for an additional 17%, lo%, and 2%, respectively, of the total consumption of fossil fuel in the United States (Table 1). Consumption of fossil energy for agricultural production is extremely high due to some intensive agricultural techniques necessary to offset

D. Pimentel et al. / Ecological Economics 9 11994) 201-219

shortages and degradation of land, water, and biological resources. On U.S. farms about 3 kcal of fossil energy are needed to produce just 1 kcal of human food. This practice is similar for other industrialized nations. We wonder how long such intensive agriculture can be maintained in the industrialized nations and how long the rapidly growing use of fossil energy for agriculture can be sustained in developing nations. For example, since 1955 there has been a lOO-fold increase in the use of fossil energy in agriculture in China (Wen and Pimentel, 1984). As the world population escalates, how many lOO-fold increases in fossil energy use for food production and other needs are possible?

203

ture availability of vital natural resources is severely limited. At this time the United States has 256 million people, most of whom are consuming resources in an unsustainable manner. Land, groundwater, energy, and biological resources are all being depleted with no hope of renewal during the next century. Reports indicate that the average standard of living for children in the United States has declined during the last decade and is projected to continue to decline (Fuchs and Reklis, 1992). This is due to wasteful habits and ever increasing population growth. Based on current rates of growth, the U.S. population will double during the next 63 years (USCB, 1992). 3.2. Land resources

3. Energy use and environmental

degradation

Fossil energy has provided humans with the power to control nature and their environment. A rapidly growing world population of 5.5 billion is constantly increasing its consumption. This leads to increased energy use and consequently, unprecedented environmental degradation. The major environmental consequences are evidenced by signs of global warming, ozone depletion, severe soil erosion, deforestation, loss of biodiversity, plus an increase in solid and chemical waste production that pollutes the entire ecosystem.

3.1. Human populations The world population is presently at 5.5 billion and is expected to double in just 41 years (PRB, 1991). This is especially alarming because overpopulation greatly stresses the resources needed to support human survival. For example, about 1.6 billion people are malnourished (Kates et al., 1989) and from 1.2 to 2 billion are living in poverty, which includes the malnourished, people with heavy disease burdens, and those with shortened lives (Durning, 1989; V. Abernethy, Vanderbilt University, pers. commun., 1992). Critical shortages of land, water, and fossil energy resources are documented in many regions of the world (WRI, 1991; Worldwatch, 1992). The fu-

Rapid land degradation is a major threat to the sustainability of world food supply and affects most of the crop and pasture land throughout the world (La1 and Pierce, 1991; Pimentel, 1993). Estimates suggest that agricultural land degradation can be expected to depress food production between 15% and 30% over the next Z-year period, unless sound conservation practices are instituted now (Buringh, 1989). Soil erosion is the single most serious cause of this degradation, occurring at rates of 16 t/ha/ year in the U.S. and 40 t/ha/year in China (USDA, 1991; Wen, 1993). In Africa the rate of soil loss has increased 20-fold during the past 30 years (Tolba, 1989). The major cause is the employment of poor agricultural practices that leave the soil without vegetative cover to protect against water and wind erosion. Soil loss is particularly distressing because it takes approximately 500 years to reform 2.5 cm (1 inch) of topsoil under normal agricultural conditions (Troeh et al., 1980; OTA, 1982; Elwell, 1985). Unfortunately, throughout the world topsoil is being lost 16 to 40 times faster than it is being replaced. Each year because of land degradation primarily by erosion, about 15 million ha of new land must be found for agriculture (Pimentel et al., 1992). About 10 million ha is used to replace losses caused by land degradation. And an additional 5 million ha must be found to feed the 93

D. Pitnentel et al. /Ecological

204 Table 3 Land area (million (WRI. 1991)

ha) uses

Total area

Cropland

Region Africa N. America S. America Asia Europe Total

in major

regions

of the world

Pasture

Forest

Other 1301 813 240 1010 92

2 965 2 139 1753 2 679 473

184 274 140 450 140

792 368 468 678 84

688 684 905 541 1.57

10009 100%

1188 12%

2390 24%

2 975 30%

a Land that is either too dry, too steep, agriculture and forestry.

Economics 9 (1994) XII-21 9

a

3 456 34%

or too cold to use in

million humans added yearly to the world population. This added agricultural land tends to come from clearing of vast forest areas (Table 3). The spread of agriculture accounts for about 80% of the deforestation now occurring worldwide (Myers, 1990). In many cases the mining of fossil fuels threatens protected national parks. Dwindling oil and natural gas reserves have caused many countries

to permit fossil fuel mining in their nature preserves. For example, the possible opening of the Arctic National Wildlife Refuge (ANWR) for oil development is a highly controversial issue. ANWR covers about 18 million acres of Northeastern Alaska (1 acre = 0.405 ha) and includes the native lands of the Athabaskan Indians. Estimates are that about 3.2 billion barrels of oil, plus some natural gas, lay beneath this wilderness (Dentzer, 1991). This amount of fossil energy would provide the U.S. with only 200 days’ of fuel at current consumption rates. Yet the price of this fuel in environmental terms could represent a significant loss of habitat for native species and disruption of the Alaskan Indians’ way of life effects that will last far longer than a mere 200 days. 3.3. Water resources Water is an essential resource for energy and environmental quality. The greatest threat to fresh-water supplies is overdraft, or excessive

Solar Tec_hnologies

Mining Water

Biodiversity

bal Warmmg

Highways

8 Urbamzat!on

Fig. 1. Energy

system impacts

on the environment.

Loss

D. Pimentel et al. /Ecological Economics 9 (1994) 201-219

pumping of surface and groundwater resources, to meet the needs of a rapidly growing human population. The rate of U.S. groundwater pumping is 25% higher than that of replenishment (USWRC, 1979). Each individual requires nearly 3 1 of fresh water per day for drinking, but uses at least 90 I/day for cooking, washing, and other domestic energy-related needs (Brewster, 1987). Including industry and agriculture, each American uses a total of about 5200 l/day (USBC, 1990). Worldwide, about 87% of all the earth’s fresh water is consumed (non-recoverable) to support agriculture (S. Pastel, Worldwatch Institute, pers. commun., 1992). In the United States 85% is consumed by agriculture (NAS, 1989a) while the remaining 15% is consumed by the public and industry. Another major threat to water resources both in the United States and world is pollution (USBC, 1990). Pollution is a more serious problem in developing countries. Industries in some of these countries frequently dump their toxic chemicals into rivers and lakes without treatment (WRI, 1991). Likewise, the dumping of untreated sewage makes water unsafe for human drinking and agriculture. For example, in Latin America, where most urban sewage is dumped directly into rivers and lakes, the fecal-coliform bacterial counts in drinking water are frequently a million times higher than in the United States (WRI, 1991). 3.4. Biological resources The world is losing an estimated 150 species per day because of human activities such as deforestation, urbanization, and pollution of the environment, all of which are linked to energy use (Reid and Miller, 1989; Myers, 1992) (Fig. 1). Natural biota are vital to agriculture, forestry, and the integrity of the environment in general because they help to recycle manure and other organic wastes, to degrade chemical pollutants, and to purify water and soil (Pimentel et al., 1992). Furthermore, biodiversity provides a vital reservoir of genetic material for agricultural, forestry, and pharmaceutical products (Wilson,

205

1988). Honeybees and wild bees are natural biota that provide essential services such as pollination. Annually, these insects pollinate about S30 billion worth of crops and a multitude of natural plant species (Robinson et al., 1989). Humans have no technology to substitute for this process vital to fruit, vegetable, and other crop production. Odum (1971) suggested that if sufficient natural diversity is to be maintained in order to protect a quality environment, then about one-third of the terrestrial ecosystem should be kept in natural vegetation. Worldwide only 3.2% of the terrestrial environment is in protected parks (Reid and Miller, 1989) while humans occupy approximately 95% of the terrestrial ecosystem (Western and Pearl, 1989). We know that humans cannot survive with only their crops and livestock; however, world population growth and consumerism continue to cause losses in biodiversity. Therefore, there is an urgent need for the conservation of biological resources (Wilson, 1988; Reid and Miller, 1989; Paoletti et al., 1992: Pimentel et al., 1992). 3.5. Atmospheric resources Human-made emissions cause adverse changes in the atmosphere as well as in the terrestrial and aquatic ecosystems. Emissions of pollutants into our atmosphere are contributing to global warming, thinning of the ozone layer. and increased environmental and public health problems. The burning of forests and large quantities of fossil fuels increases the level of atmospheric carbon dioxide and other gases which contribute to the global warming problem (Schneider, 1989). Fossil fuel burning alone has added about hvothirds of the more than 175 billion tons of anthropogenic carbon dioxide expelled into the earth’s atmosphere (Woodwell et al., 1983). Of this total, approximately two-thirds has been released in the last 35 years, which attests to the seriousness of the problem (DOE, 1989). Deforestation accounts for the remaining third. Another serious group of pollutants are volatile compounds known as chlorofluorocarbons (CFCsI which reduce the upper atmospheric ozone layer. The upper atmospheric ozone layer protects all

206

D. Pimentel et al. /Ecological

life, including humans, from dangerous ultraviolet (UV) radiation (Kerr, 1992). Destruction of the ozone layer causes increased levels of UV radiation, especially in the Southern hemisphere, which can lead to skin cancer, cataracts, and reduced immunity to disease. Many other pollutants are emitted through energy consumption, especially coal and oil burning. An estimated 7 million tons of particulate matter, 20 million tons of SO,, 61 million tons of carbon monoxide, 20 million tons of nitrous oxides, and 20 tons of other pollutants are produced in the U.S. each year from the burning of fossil fuels (USBC, 1990). These pollutants may directly or indirectly result in mortality and morbidity in humans, kill vegetation, degrade ecosystems, and damage buildings and monuments (UCS, 1991).

4. Known fossil energy resources for the future Fossil energy - oil, natural gas, and coal - is a non-renewable resource that is being rapidly depleted worldwide. At current rates of consumption, oil and natural gas reserves are projected to last from 30 to 50 years and coal reserves about 100 years (Hubbert, 1972; Matare, 1989; BP, 1991;

Economics

9 (1994) 201-219

Davis, 1991; Gever et al., 1991; Worldwatch, 1992). The fossil energy supply problem is especially critical in the United States because the U.S. is such a heavy user of energy. Oil, the primary energy source, comprises 40% of the total annual energy consumption (DOE, 1991a). The nation has only 10 to 13 years of proven and potential supplies of oil (Matare, 1989; DOE, 1990). Based on constant 1967 dollars, the cost to discover a marginal barrel of U.S. oil has risen from $0.18 in 1967 to $8.81 in 1982 (K.E.F. Watt, University of California, Davis, pers. commun., 1992). This is nearly a 50-fold increase. In addition to the decline in oil reserves, our country also has a limited supply of natural gas and coal. The Department of Energy (DOE, 1991a) reported that at current usage rates, only 10 years remain until we are generally out of natural gas, and about 100 years until U.S. coal is gone. The rapid depletion of our oil reserve is expected to result in an increased dependence on coal (Gever et al., 1991). By the year 2010, coal is projected to constitute about 40% of our total energy use (DOE, 1991a). Given these projections and the absence of natural gas in 10 years, our coal supply could be used up in a much shorter period than 100 years.

Fig. 2. Historical fossil energy use (Davis, 1991) and projected fossil fuel use (see text). Historical solar or renewable energy use (Davis, 1991) and projected solar use (see text). Historical population growth (Coale, 1974) and current (PRB, 1991) and projected population growth (see text).

D. Pimentel et al. /Ecological

5. Projected

increase

in fossil fuel consumption

Despite the rapid decline in U.S. fossil fuel reserves, the rate of fossil fuel use is expected to increase by 27%, to 107 quads per year, by the turn of the century (DOE, 1991a). This increase is attributed both to the growing consumption per capita and the expanding U.S. population. Furthermore, studies by Hubbert (19721, Matare (19891, British Petroleum (BP, 1990, and Worldwatch Institute (1992) project that the availability of fossil energy is rapidly declining, not only in the United States, but worldwide. Significant per capita fossil energy increased use throughout the world is projected to start declining by 2050 and to continue to decrease for the next 100 years while the supply of fossil energy is depleted (Fig. 2). These projections bring to mind many questions concerning future energy use and availability. What will happen to fossil energy supplies as the world population continues to grow (Fig. 2)? The International Institute for Applied Systems Analysis (IIASA, 1981) predicts that if the world population doubles and developing countries increase their use of fossil energy, then fossil energy use worldwide will increase 2 to 3 times above the 1980 level by the year 2030. Starr et al. (1992) make a similar estimate when they project that global energy demand will increase about 4 times the present levels by the middle of the next century. Certainly, everyone agrees that developing countries should have a greater share of fossil energy resources in the future than they currently do. Assuming that these projections are accurate, the depletion of the world’s non-renewable fossil energy resources will occur much more rapidly than is projected in Fig. 2.

6. Transition

from fossil to renewable

energy

Worldwide, solar energy accounts for only 13.5% of total energy use (Tables 2 and 4). The remaining 86.5% of the world’s energy is based on fossil energy. Developing countries use about 62 quads of

Economics

207

9 (1994) 201-219

Table 4 Solar energy use by the US, world, (UNEP, 1985; IEA, 1991)

developing

World

USA Quads

and

%

Quads

Biomass Fuelwood Crop residues Dung Hydropower

3.6 3.53 0.07 0 3.0

55

45

28.5 17.4 8.6 2.5 21.2

Total

6.6

100

49.7

nations

Developing %

Quads

57

43

22.5 11.5 8.5 2.5 5

100

27.5

% 81.8

17.2 100

fossil energy and 27.5 quads of solar energy each year, or nearly one-third of their total consumption of energy (OTA, 1991a). Biomass comprises about 82% of this total solar energy and hydropower the remainder. Of the biomass, about 51% is fuelwood, 38% is crop residues and 11% is dung (Table 4). In 1850 the United States was 91% dependent on biomass wood (Pimentel and Pimentel, 1979). Gradually, fossil energy use increased until today the U.S. is 92% dependent on non-renewable fossil energy. The remaining 8% comes from biomass (4.2%) and hydropower (3.5%) (Tables 2 and 4). During the next decades a transition irom fossil energy to renewable energy sources will have to be made in the United States (Fig. 2). Clearly this should be done while fossil energy supplies are still available. There is an urgent need to give high priority to research focusing on more ways to convert solar energy into usable energy for society. Some renewable energy technologies are already available, including solar thermal receivers, photovoltaics, solar ponds, hydropower, as well as burning biomass. Also several technologies have been developed by which biomass is converted into liquid fuel such as methanol and ethanol (ERAB, 1981, 1982). While these solar energy systems have benefits, evidence also suggests that all solar energy technologies have serious environmental impacts (Holdren et al., 1980; Pimentel et al., 1984; Pimentel, 1992).

D. Pimentel et al. /Ecological

208 Table 5 Land resource requirements energy facilities that produce for a city of 100000 people Electrical

energy

a Modified (1991). 6.1.

after

Land (ha)

technology

Solar thermal central Photovoltaics Wind power Hydropower Forest biomass Solar ponds Nuclear Coal Geothermal

receiver

Pimentel

for construction and function of 1 billion kWh/year of electricity

1800 2700 2700 13000 330000 9000 68 90 40

a a a = a a = = b

et al. (1984). b Flavin and Lenssen

Biomass energy

Worldwide, some 2.5 billion metric tons of biomass, including forest resources, crop residues, and dung, are harvested each year for energy (FAO, 1983). As mentioned, biomass currently provides 4.2% of total energy needs in the United States (DOE, 1982, 1991a), compared to an average figure of 25% in developing countries (Table 4). Reliance on biomass as a direct source of energy is likely to increase in the future, but there are major limitations to expanded use, with land availability being the major limiting factor. For example, about 330000 ha of sustainable forest area are needed to supply the electrical needs of a city of 100000 people who consume 1 billion kWh of electricity per year (USBC, 1990) (Table 5). This is the largest amount of land area required for any solar energy technology. Approximately 0.1% of the total solar energy per hectare can be realized from biomass as energy (ERAB, 1981; Loftness, 1984). The total amount of solar energy captured by U.S. vegetation each year is about 58 quads (ERAB, 1981). The figure for agricultural crops and forest products harvested alone is 28 quads about half of the energy captured by all the U.S. vegetation. This suggests that the U.S. population is having a major impact on our environment. Three quarters of all U.S. land is already in production to provide food and forest resources such as fiber, pulp, and lumber (USDA, 1990).

Economics 9 (1994) 201-219

Another 10% of the land area is taken up by roadways and urbanization, leaving a relatively small percentage of land available for solar energy development. Most other regions (e.g., Europe and Asia) suffer more serious land shortages than the United States. As populations increase, the need for land to meet demands for increasing food and forest products must necessarily be given priority over land requirements for biomass energy production and other solar technologies. In addition, the removal of biomass for fuel also has severe negative side effects. Removal of vegetation threatens the environment by exposing the soil to erosion, rapid water runoff, and other ecological problems (ERAB, 1981; Darmstadter. 1992). 6.2. Solar thermal Solar thermal energy systems are capable of converting 22% of incoming sunshine into energy? an improved return when compared to the approximate 0.1% efficiency of green plants converting light to biomass. The land requirements for one type of solar thermal system, the central receiver, are about 1800 ha to produce 1 billion kWh/year (Table 5), assuming a 20% peak efficiency. Because this type of system relies on mirrored concentrators, it is only practical in areas where there is dependable, direct sunlight every day (Flavin and Lenssen, 1991). At night and on cloudy days this system requires a back-up system. Solar ponds are a type of solar thermal technology in which a salt gradient is employed to collect and store heat energy in a shallow body of water (Sargent, 1981). Approximately 9000 ha of solar ponds and associated evaporation ponds are needed to produce 1 billion kWh of electricity (Pimentel et al., 1984). Although the land area is relatively large (Table 51, solar ponds have the advantage of being able to store energy and do not require back-up systems. 6.3. Photocoltaic systems Photovoltaic (PV> cells are more dependable than solar thermal units in cloudy conditions, but

D. Pimentel et al. /Ecological

are not yet economically competitive. The efficiency and durability of the cells need to be improved, and production costs should be decreased about 5-fold to make them economically competitive. Predictions are that these goals can be reached with another lo-20 years of research (EBAB, 1982; Sheinkopf, 1991). Photovoltaics requires about 2700 ha to supply 1 billion kWh (Table 5). Some of these units can be placed on rooftops in order to reduce land area requirements by about 5% KJSBC, 1990). Serious, but not insurmountable, environmental problems exist in the disposal of defective cells and the toxic materials used in their production (Holdren et al., 1980; Darmstadter, 1992).

Economics

9 (1994) 201-219

209

cated that, on average, 13 000 ha of reservoir area are required per 1 billion kWh produced (Table 5). Some major environmental problems associated with hydropower include the resettlement of humans and wildlife, and the loss of productive agricultural land when they are inundated by reservoir water. For instance, a project under consideration for the Yangtze river in China would involve the relocation of about 1 million people (OTA, 1991b). Some small hydropower plants, of about 100 kW capacity, do not require large reservoirs; therefore their environmental impact is less than that imposed by the large hydropower plants (IAEA, 1991). 6.6. Ethanol production

6.4. Wind power The amount of energy available in the wind is dependent on its speed, timing, and location. Because wind energy is not constant, back-up energy is essential to wind-powered systems. Wind turbines require approximately 2700 ha of land to supply 1 billion kWh/ year, even though the wind machines would occupy only about 1% of that area (Table 5). This is an advantage because the remaining land could be devoted to some types of low-growth forestry and/or agriculture, if managed in an innovative manner. Offshore deployment of wind turbines, though still a largely undeveloped technology, would further alleviate the need for land (IAEA, 1991). The American Wind Energy Association (AWEA, 1991) predicts that wind energy could provide a substantial portion of U.S. electric capacity.

The conversion of corn and some other food crops into ethanol by fermentation is a well-known and established technology. Although it is often cited as energetically and environmentally sound, about 72% more energy is required to produce a gallon of ethanol than is in a gallon of ethanol (Pimentel, 1991). Another major environmental constraint, when considering the advisability of producing ethanol for automobiles, is the amount of cropland needed for the corn raw material that is required to fuel one automobile. Based on available data, nearly 9 times more cropland is required to fuel one car than is needed to feed one American (Pimentel, 1991). When considering the food supply requirements of the expanding world population, using land for fuel rather than for food presents many ethical problems. 6.7. Geothemal

energy

6.5. Hydropower At present, hydropower produces about 19% of the world’s total electricity (IAEA, 1991). This technology exploits a highly efficient power source, but its costs vary widely depending on many factors, including the associated environmental problems. Most hydroelectric plants require land for the water-storage reservoirs they use. An analysis of 190 hydroelectric sites in the United States indi-

Geothermal technology is promising, but at this time is generally not considered economically competitive. Extraction of heat energy from hot dry rock is one technique to produce geothermal energy. Only the high grade portion (10%) of the heat energy extracted is considered economically competitive in the present market (Tester et al., 1991). The land area required for a geothermal plant to generate 1 billion kWh is estimated to be 40 ha (Table 5). The major problems with

710

D. Pimentei et al. /Ecological Economics 9 (1994) 201-219

geothermal energy are the high costs involved in drilling into the reserves and the highly corrosive nature of the steam and wastes that are produced. Future research might well find ways to reduce some of these problems and, therefore, make the geothermal technology a part of the answer to our energy problem. 6.8. Nuclear fission and fusion energy At present, nuclear fission provides 18% of U.S. electric needs (USBC, 1990). Nuclear fission energy production of electricity has many advantages: it requires less land than coal-fired plants and causes lo- to lOO-fold fewer human deaths than underground coal mining and coal transport, respectively (Whipple, 1990). Also, nuclear fission does not contribute to either acid rain or global warming (Holdren, 1991; Meeks and Drummond, 1991). The problem is the pollutants of nuclear fission technology - the radioactive wastes and the enormous amounts of waste heat produced and released into the environment (Moore and Jaluria, 1971; Bartlett, 1989). For example, if the number of nuclear power plants were increased from the current 108 to 1500, it is estimated that the temperature of aquatic ecosystems in the United States would increase an estimated 10°C (H.W. Kendall, MIT, pers. commun., 1992). This great temperature rise would cause a major loss in the biological diversity of aquatic systems and would also influence climatic patterns in adjacent areas. However, if the heat were dissipated into the atmosphere, the heating problem would be greatly reduced (D. Hammer, Cornell University, pers. commun., 1992). Any prolonged reliance on nuclear fission energy is seriously limited by uranium resources which are estimated to last only about 100 years worldwide, assuming current use rates for fission plants (Hafele, 1991). Fission technology also has major risks .associated with the disposal of radioactive wastes (OTA, 1987; Kendall, 1991). Nuclear fusion technology, which will require a great many years of research for development, will have similar environmental limitations to fission technology (Matare, 1989).

6.9. Renewable energy for the future

Optimistically, an assumption can be made that the current level of 6.6 quads of solar energy used in the United States could be increased more than 5-fold without adversely affecting agriculture, forestry, or the environment. Then about 35 quads of solar energy could be produced (Pimentel et al., 1984; Ogden and Williams, 1989). This increase, however, is only about 40% of the current total energy consumption (86 quads), including solar energy, in the United States (DOE, 1990). To produce 35 quads from solar energy would commit about 180 million ha or nearly 20% of the U.S. land area to solar energy systems. Based on available data, biomass, hydropower, wind power, and photovoltaic systems, if fully developed, will provide most of the 35 quads while the remaining could come from the other solar energy systems. Because the United States is fortunate to have some of the most productive land in the world, the increase to 35 quads seems well within the possibility. However, the terrestrial ecosystem in the rest of the world is not as favorable as in the United States. Worldwide, if about 1 billion ha were to be devoted to solar energy production, a total of 200 quads of energy might be secured by various solar energy systems (Table 3) (Fig. 2). This is about two-thirds of the total current world use of energy (369 quads). Again, it should be emphasized that this is an optimistic estimate and does not take into consideration that, if the world population doubles or triples in the next 100 years, the competition for land and water for food and forest production will become intense (Fig. 1).

7. Energy efficiency

and conserving

environmen-

tal resources

Each person in the United Kingdom consumes less than one half the amount of energy that each person in the United States consumes (Davis, 1991). Yet people in the United Kingdom have a fairly similar standard of living to that enjoyed in the United States. This suggests that opportuni-

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ties e.xist to improve the efficient use of energy without affecting the U.S. quality of life. Increasing energy efficiency in the U.S., other developed nations, and developing nations would improve both the economy and environment, including increasing the number of jobs (Rennet-, 1991; OTA, 1992a). Some alternatives to conserve energy and improve efficiency in an effort to help restore the quality of the environment and economy are suggested below. 7.1. Transportation Current U.S. subsidies of $44 billion/year to the energy industry obscure the true cost of energy, encourage energy consumption, and discourage energy conservation (Heede et al., 1985). The elimination of these subsidies and the transfer of the true costs of energy to the consumer would emphasize the need to reduce consumption and could help pay the enormous debt facing the nation, mostly caused by oil imports. With the elimination of the energy-industry subsidies, the average household would gain $523 in reduced taxes (Heede et al., 1985). Since transportation is the largest consumer of fossil energy in the U.S. (26%), major changes are needed in this sector to reduce fuel use (UCS, 1991). The Union of Concerned Scientists (UCS, 1991) suggests that energy use for transport could be reduced by more than 60%. A major incentive would be pricing gasoline at $4SO/gallon, which represents the real cost of gasoline use in motor vehicles - including air pollution, highway construction, traffic regulation, police, and other service costs related to transportation (Worldwatch, 1989). A high gasoline and diesel fuel price would also reflect the true cost of driving. Currently, “the market and external costs of motor vehicle use that are not reflected in user charges amount to almost $300 billion per year” (MacKenzie et al., 1992, p. 23). Any program for raising fuel prices should take place over a period of time. The widespread use of small, energy-efficient cars would cut present energy use. Europeans have already taken this step and are effectively able to carry out their business and pleasure needs with small cars. Currently, U.S. autos aver-

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age only 19 mpg (USBC, 1990); however, present technology could increase this to 45 mpg (OTA, 1991b; Schipper, 1991). Volvo reports that they have a LCCP 2000 model that averages 63 mpg in the city and 81 mpg on the highway (Bleviss and Walzer, 1991). In addition, clean, safe, reliable mass transit is a necessity as it provides efficient, economic transport. At present, only 6% of public transport in cities is by mass transit (Bleviss and Walzer, 1991). In contrast, Europeans utilize mass transit 6 times more than Americans (Newman and Kenworthy, 1989). According to the UCS (1991) a major opportunity exists to increase the use of mass transit to conserve fuel and reduce air pollution. A single metro rail can carry 17000 passengers per hour compared with a single auto lane, which has a transport rate of only 3000 passengers per hour (Marston, 1975). In addition, change to electric rail travel is estimated to reduce hydrocarbon emissions by 90% and nitrous oxides by 50%. At present, trains account for 37% of inter-city transport of goods in the United States while trucks account for 25% (UCS, 1991). Not only do trucks use 6.4 times more fuel per ton of goods transported than trains, but they are heavily subsidized by state and federal taxes (UCS, 1991). Thus, significant savings could be achieved by greater use of trains instead of trucks. Fewer trucks would make highways safer for automobile drivers. Where feasible, more goods should be transported by ship; ship transport is nearly 10 times more energy efficient than truck transport (Pimentel, 1980). 7.2. Industry Between 1970 and 1983, U.S. industry made an effort to reduce its energy use in production by 30% (IEA, 1989). Despite this, however, U.S. industry remains only 60% as energy efficient as Japanese industries (IEA, 1989). A 5-fold increase in the cost of energy over current lowpriced, subsidized rates would immediately encourage the efficient use of energy as it has in Japan, Germany, and other nations. Using more

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energy-efficient technologies as well as solar energy systems, U.S. industries could improve their energy efficiency by at least 50%, employing a wide variety of known technologies (Reddy and Goldemberg, 1991). The entire food production system is the fourth largest consumer of energy in the United States (Table 1). Agricultural production, including cultivation, planting, fertilizer and pesticide use, and harvesting, accounts for 33% of the total energy expended by the U.S. food system (Pimentel, 1992). Because much of the fruits and vegetables produced in California and Florida have to be transported long distances to the marketplace, large amounts of energy are expended (Pimentel et al., 1975). The return of some fruit and vegetable production close to major markets would reduce the transport and irrigation energy costs. The composition of the human diet affects energy use in a given food production system. Specifically production of animal protein is more energy intensive than production of plant protein. For example, to produce 1 kcal of beef protein requires about 35 kcal of fossil energy, whereas 1 kcal of soybean protein requires only 1.3 kcal of fossil energy (Pimentel, 1980; Pimentel et al., 1980). Thus, the production of animal protein, which is consumed in excess, accounts for not only a significant portion of our energy resources but also is associated with land and water degradation (Durning and Brough, 1991). Americans consume about 105 grams/day of protein per person, of which 71 grams come from animal protein (Putnam and Allshouse, 1991). The recommended daily allowance is 53 grams of total protein per day (NAS, 1989b). U.S. consumption of meat is 4 times greater than the world average (Stephenson, 1981>, although other highly industrialized nations also consume diets high in animal protein. Modification of diets to include more plant proteins and less animal proteins would diminish the energy used in the food system and also benefit the environment. To produce the amount of meat, milk, and eggs consumed by Americans, about 70% of U.S. grain is fed to livestock and about one-half of U.S. land is used to produce grain and pasture needed to support that production system (USDA, 1990).

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Packaging requires about 15% of the total energy used in the U.S. food system (Pimentel and Pimentel, 19791. The evidence suggests that packaging could be reduced by one-half without any effect on the quality or shelf life of foods. Outright waste of food is responsible for energy waste. For example, studies have shown that about 15% of U.S. food is wasted in homes and restaurants, thus representing a value of about $50 billion/year (Harrison et al., 1975; Alive, 1988). Reducing this waste would save energy while protecting land and water resources, as well as reducing the garbage transported to landfills. As much as two-thirds of the metal, glass, and paper now discarded could be reused in various ways (Neal and Schubel, 1987). Much of this material comes from packaging foods, beverages, and other goods. If industry used recycled materials, it could reduce energy use substantially. This, of course, would require that the public participate in recycling. Consider that in the United States each day 230 and 103 million pounds of steel and aluminum, respectively, are discarded. When aluminum is recycled, about 90% of the energy required to produce the same product from virgin materials is saved (OTA, 1989). 7.3. Residential and industrial buildings Considerable energy efficiency can be achieved in the home by switching to more efficient appliances and increasing insulation (OTA, 1992b). Lowe (1991) estimates that the use of energy in residential establishments can be reduced overall from 50% to 75% through improved appliances, lighting, and heating. For the country as a whole, the cost of conserving energy is 2 to 10 times less than the cost of the development of new energy supplies (Kahn, 1986). In industrialized countries, space heating accounts for 54% of energy use in residential buildings (DOE, 1990). In the average American home 20% to 25% more energy is used for heating than in European homes @chipper, 1990, but U.S. homes are larger and more are individual structures than in Europe. The most efficient new electric heat pumps and gas furnaces now marketed use one-third less

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energy than older units (Goldemberg et al., 1988). Also, lighting energy could be reduced by as much as 90% without any effect on the home and commercial environment and work efficiency (Fickett et al., 1991). Designing or retrofitting buildings to take advantage of passive heating and cooling helps reduce fossil energy use in buildings (Brewer, 1990). As mentioned, commercial establishments and homes need to be retrofitted with improved insulation and efficient storm windows. 8. Energy and environmental

security

Until the 1960s the U.S. generally held the belief that energy and other natural resources were in unlimited supply, and that pollution and other environmental problems were of minimal concern. In fact, the impact of human activities, including fossil energy use, were not even considered in energy use policies until the 1960s (Spurt-, 1982). Then in the late 1970s governmental policy makers recognized the seriousness of the growing energy shortage. Intense research and development of alternative energy sources followed. During the remainder of the decade great strides in conservation and improved efficiency occurred and resulted in savings of $100 billion to the economy (N. Myers, Oxford, pers. commun., 1991). However, during the 1980s the successful conservation policies of the 1970s were almost abandoned under the assumption that individual initiative would take over where government regulation left off. As a result, during the 1980s energy conservation appropriations decreased by over 96% and funds for the development of renewable energy resources fell by 91% (USC, 1991). Accurate market prices of energy products have the potential to catalyze conservation efforts and may even spur research and development of alternative energy sources. However, current prices do not include environmental effects and costs. If the market price of petroleum products in transportation, and fossil fuel in general for electrical generation were a true reflection of the environmental and social costs associated with oil

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use, then the cost would be $4 to Sj/gallon (Worldwatch, 1989). At present, with gasoline at the unrealistically low price of about Sl.OO/ gallon, efficiency of energy use is not encouraged (UCS, 1991). Indeed, the opposite is true. Instead of supporting policies that encourage energy efficiency, the White House policy has been to open natural park preserves for oil and gas development (NES, 1991). The White House appeared to have little concern for the environment as exemplified by the section of the National Energy Strategy (NES, 1991) dealing with “Enhancing the Environment”, in which one major recommendation is to “increase flexibility in meeting environmental requirements.” In other words, this means reducing current environmental standards. Or to put it bluntly, this is directly opposite of enhancing the environment! 9. Security U.S. oil production has declined between 400000 and 500000 barrels per year for the past two decades (USC, 1990). Currently the United States imports 54% of its oil (Gibbons and Blair. 1991) and this rate is projected to rise from 60% to 70% by the turn of the century. With U.S. oil reserves of only 10 to 13 years, the United States will enter the 21st century captive to a growing oil import bill. Both the decline in our own fossil energy supplies and our escalating reliance on importing oil place the United States - its energy and economic security, food security, environmental integrity and, indeed, its overall security - in jeopardy (Pendleton, 1991). Most policy analysts agree that a strong economy and military insure a strong and secure nation. But domestic oil is a finite resource and will be scarce in the very near future. With an increasingly volatile oil market due to instability in the Persian Gulf and the former Soviet Union, combined with increasing oil consumption in developing countries by 170% by 2010, U.S. oil dependency becomes an ever-worsening policy issue (Murkowski, 1991). Excessive oil dependency is an equally inept policy from an economic perspective. The United

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States currently spends about $65 billion a year on oil imports (Gibbons and Blair, 19911, plus an additional $50 billion to protect U.S. interests in the Gulf oil supply (Rader, 1989). These expenditures further increase the U.S. trade deficit and are a drain on our entire economy. According to Pate (1990, for every $1 increase per barrel in the price of imported oil, American consumers must spend $3 billion more per year on energy and goods (Pate, 1991). Further, he noted that “Oil price volatility and increased import reliance have combined to reduce America’s productivity and purchasing power.” In these ways our great dependency on foreign oil serves not only to threaten our national security, but it also balloons our trade deficit and weakens the economic foundation of the nation. The only sure way to remedy these problems is to drastically cut oil use and develop and use renewable and stable energy sources. 10. Environment

and population

As human populations have increased throughout the world, the need for resources of land, water, energy, biota, and food has escalated; more serious problems of environmental degradation and energy shortages have developed due to high levels of energy consumption in developed nations and rapid population growth worldwide. Despite the fact that there are from 1.2 to 2 billion humans living in poverty worldwide (Durning, 1989; V. Abernethy, Vanderbilt University, pers. commun., 1992) and 32 million Americans living in poverty WSBC, 19901, U.S. policies tend to encourage population growth in developing countries as well as in the United States (Fornos, 1987). Both Presidents Reagan and Bush withdrew support for the International Planned Parenthood (IPP) fund and the United Nations Fund for Population Activities WNFPA). In fiscal year 1985, U.S. aid to UNFPA was reduced by $10 million, and in 1986 and 1987 it was totally eliminated (Fomos, 1987). These moves contributed to an increased rate of population growth in the United States during the past few years and a continuation of rapid population growth throughout the world (PRB, 1991).

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Many leading scientists and public organizations, including the U.S. National Academy of Sciences, Royal Society of London, and the United Nations, have suggested that the U.S. population and the world population are significantly above the optimum for a sustainable environment (CEQ, 1980; Keyfitz, 1984; Demeny, 1986; Hardin, 1986; UNFPA, 1991; Holdren, 1992; Meadows et al., 1992). During the last two years the rate of U.S. population growth increased (USCB, 19921, the doubling time for the U.S. population is now only 63 years. At the end of this short period of time the U.S. population will be more than a half billion people! This is about half the population of China. Is this the population Americans want? The world population situation is far more serious for it will double in 41 years to about 11 billion. This population density is 5 to 10 times the optimum for the tiorld’s environmental and natural resources (Giampietro et al., 1992; Pimentel et al., 1993). The optimum for a prosperous population in the United States is estimated to be 200 million, and for the world, 1 to 2 billion, based on the availability of limited land, water, energy, and biological resources (Pimentel et al., 1993). If Americans and other members of the world do not reduce their population, the numbers of people living in absolute poverty will increase (Gever et al., 1991; Meadows et al., 1992). Clearly, ethical choices have to be made concerning which freedom people prefer - freedom from poverty and hunger, or freedom to reproduce without constraint. Unfortunately, society cannot enjoy both. The carrying capacity of the earth with its finite supply of land, water, energy, and biological resources eventually will make the decision for us. Thus, if humans do not controi their numbers, eventually nature will. 11. Conclusion

Among the major problems facing the United States today are, rapid population growth, excessive consumption of energy and other natural resources, economic decline, and serious environmental degradation. Throughout the world the

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problems are similar to those in the U.S. except that the rate of population growth is much higher and at present energy consumption per capita is lower. The United States, with only 4.7% of the worId population, consumes 25% of the total fossil energy annually. Heavy energy consumption is one of the major reasons why U.S. oil reserves are estimated to last only 10 to 13 years. Despite this critical situation, current government tax and subsidy policies encourage energy consumption. Worldwide, the energy situation is also critical and per capita fossil energy use is projected to start declining because most oil and gas resources will be depleted by 2050, and to continue to decrease for the next lOO-plus years (Fig. 2). The environmental degradation of land, water, atmosphere, and biological resources now occurring in the United States is attributed to heavy energy consumption. The problems of global warming, diminishing supplies of groundwater, soil erosion, and loss of biodiversity attest to the seriousness of the present situation. In addition, the American population is too large to support a sustainable society and environment. For instance, the more than 256 million people in the United States are burning 40% more fossil energy than the total amount of solar energy captured by all the U.S. plant biomass (ERAB, 1981). Clearly, U.S. consumption and numbers of people are out of balance with their natural resources and environment. This is particularly true if Americans seek a sustainable environment and energy source for a prosperous society of future generations. The heavy use of energy among the transportation, industry, residential, commercial, and food sectors could be reduced. Estimates are that the United States could reduce its per capita energy use by at least 50% overall through alternatives and improved efficiency (UCS, 1991). This would help restore the quality of the environment while improving the American standard of living by strengthening the economy and increasing the number of jobs. Not only do Americans want to improve their standard of living, but an estimated 4 billion people living in developing countries would pre-

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fer a better standard of living. What are our ethical responsibilities toward the less fortunate people? What are our individual and national responsibilities for conserving energy and other resources to protect the integrity of the environment for future generations? Thus far, the U.S. and world society appear unable to deal with the global problems of energy and resource shortages, overpopulation, and environmental degradation. Our study, however, substantiated that the overconsumption of energy, limited land and water resources, together with overpopulation are causing the environmental and economic bind now faced by all nations. Because of the interdependence of energy, economics, and the environment, energy efficiency and transition to renewable energy sources are critical. Clearly, the United States must move toward the development of renewable energy sources and sustainable land, water, and biological resource policy.

12. Acknowledgements This paper was significantly strengthened by the constructive suggestions given by the following scientists: R. Brener, Environmental Protection Agency, Washington, DC; J.M. de Miguel, Universidad Complutance, Spain; M.T. El-Ashry, World Bank, Washington, DC; J.F. Galdo, Dept. of Energy, Washington, DC; M. Giampietro, Istituto Nazionale della Nutrizione, Rome, Italy; S. Harris, Oak Harbor, WA; C.R. Imbrecht, California Energy Commission; H.F. Matare, Physicist Consultant, Los Angeles, CA; M. Munasinghe, World Bank, Washington, DC; F.D. Pineda, Universidad Complutance, Spain; G. Tyner, Norman, OK; F.W. Vallentino, New York State Energy Research and Development Authority; F. Vancini, Yale University; K.E.F. Watt, University of California, Davis; and at Cornell University: J.W. Gillett, D. Hammer, and M. Pimentel.

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