18.4.Recycling and Domestic Waste 383 TABLE 18.6.Average annual yield of certain materials produced on 1 hectare(104 m2 or 2.47 acres)of land 30 kg of woola 105 kg of juteb 500 kg of natural rubber 700 kg of linen (flax)fiber 1,000 kg of cotton 7,000 kg of wheat 10,000 kg of rice 70,000 kg of sugar beets aSheep may eventually end up as meat. Of which maximal 7.5%is fiber. disadvantage of biodiesel is,however,that it is uneconomic.At present,the price of RME before taxes is about twice that of conventional diesel.Expressed differently,the energy price given in dollars per gigajoule is 10.2 for rapeseed oil,13.8 for RME, and 5.2 for diesel oil.2 However,one should not forget in this context that crops for energy production may eventually compete for prime land on which food is grown for a steadily increasing world population. Mankind may eventually have to make a choice and decide how much of the available farm land is utilized for food and clothing, and how much is used for renewable energy,including solar en- ergy.It is therefore instructive to know the quantity of various goods that can be harvested from a given piece of land.Table 18.6 provides this information.It is,of course,realized that not all land is equally suited for each of the listed raw materials,and that the availability of water is also a major factor for some crops,par- ticularly for rice. 18.4.Recycling and Domestic Waste As already discussed,Table 18.2 contains the projected number of years at the end of which the currently known world reserves may be exhausted.These data strongly suggest the necessity for recycling if we want to preserve essential resources for future generations.This is particularly true for copper (pipes,wires), lead (batteries),zinc (galvanized steel,brass plumbing fixtures), 2 Source: Bundesministerium fur Umwelt,Naturschutz und Reaktor- sicherheit,Berlin,Germany,(2000)
disadvantage of biodiesel is, however, that it is uneconomic. At present, the price of RME before taxes is about twice that of conventional diesel. Expressed differently, the energy price given in dollars per gigajoule is 10.2 for rapeseed oil, 13.8 for RME, and 5.2 for diesel oil.2 However, one should not forget in this context that crops for energy production may eventually compete for prime land on which food is grown for a steadily increasing world population. Mankind may eventually have to make a choice and decide how much of the available farm land is utilized for food and clothing, and how much is used for renewable energy, including solar energy. It is therefore instructive to know the quantity of various goods that can be harvested from a given piece of land. Table 18.6 provides this information. It is, of course, realized that not all land is equally suited for each of the listed raw materials, and that the availability of water is also a major factor for some crops, particularly for rice. As already discussed, Table 18.2 contains the projected number of years at the end of which the currently known world reserves may be exhausted. These data strongly suggest the necessity for recycling if we want to preserve essential resources for future generations. This is particularly true for copper (pipes, wires), lead (batteries), zinc (galvanized steel, brass plumbing fixtures), 18.4 • Recycling and Domestic Waste 383 2 Source: Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit, Berlin, Germany, (2000). TABLE 18.6. Average annual yield of certain materials produced on 1 hectare (104 m2 or 2.47 acres) of land 30 kg of woola 105 kg of juteb 500 kg of natural rubber 700 kg of linen (flax) fiber 1,000 kg of cotton 7,000 kg of wheat 10,000 kg of rice 70,000 kg of sugar beets aSheep may eventually end up as meat. bOf which maximal 7.5% is fiber. 18.4 • Recycling and Domestic Waste
384 18.Economic and Environmental Considerations and tin (cans,alloys).Some technocrats see this,however,in a different light.They claim that there will always be enough re- sources available through price-driven explorations.Moreover, optimists believe that human ingenuity will eventually provide new avenues which have not yet been imagined that may satisfy our needs.However,recycling is also an obligation for protect- ing the environment,by reducing landfills(which emit methane, a powerful greenhouse gas)and removing toxic and other dele- terious elements (mercury,lead,selenium,heavy metals)from soil and water.Additionally,recycling can have economic bene- fits by saving the energy and other costs for extracting valuable materials from minerals and agricultural sources. Table 18.7 displays the amount of secondary materials which were recovered in the United States from scrap during 1990.It TABLE 18.7.Recycling of metals in the United States in 1990 Value of Percent Percent secondary of value Secondary of total metal of total metal secondary (million secondary Metal (metric tons) metal dollars) metal Iron (incl.steel) 55,500,000 91 25,000 68 Aluminum 2,400,000 4 3,900 11 Copper 1,300.,000 3,600 10 Lead 920,000 2 930 2 Zinc 340.000 1 560 2 Manganese 60,000 3 Magnesium 54,000 170 Nickel 25,000 220 Antimony 20,400 Titanium 15,000 Tin 7,800 Molybdenum 3.,000 Tungsten 2,200 Silver 5950 1,700 Cobalt 1.600 Cadmium 700 05 Selenium 100 Vanadium 100 12 Chromium 90 580 1 Mercury 90 <1 Platinum Group 71 660 2 Tantalum 50 18 Gold 49 600 2 Totals (rounded) 60,600,000 100 36,800 100 Source:U.S.Department of the Interior,Bureau of Mines
and tin (cans, alloys). Some technocrats see this, however, in a different light. They claim that there will always be enough resources available through price-driven explorations. Moreover, optimists believe that human ingenuity will eventually provide new avenues which have not yet been imagined that may satisfy our needs. However, recycling is also an obligation for protecting the environment, by reducing landfills (which emit methane, a powerful greenhouse gas) and removing toxic and other deleterious elements (mercury, lead, selenium, heavy metals) from soil and water. Additionally, recycling can have economic benefits by saving the energy and other costs for extracting valuable materials from minerals and agricultural sources. Table 18.7 displays the amount of secondary materials which were recovered in the United States from scrap during 1990. It 384 18 • Economic and Environmental Considerations TABLE 18.7. Recycling of metals in the United States in 1990 Value of Percent Percent secondary of value Secondary of total metal of total metal secondary (million secondary Metal (metric tons) metal dollars) metal Iron (incl. steel) 55,500,000 91 25,000 68 Aluminum 2,400,000 4 3,900 11 Copper 1,300,000 2 3,600 10 Lead 920,000 2 930 2 Zinc 340,000 1 560 2 Manganese 60,000 — 3 — Magnesium 54,000 — 170 — Nickel 25,000 — 220 — Antimony 20,400 — 35 — Titanium 15,000 — 140 — Tin 7,800 — 65 — Molybdenum 3,000 — 17 — Tungsten 2,200 — 9 — Silver 1,700 — 260 1 Cobalt 1,600 — 30 — Cadmium 700 — 5 — Selenium 100 — 1 — Vanadium 100 — 2 — Chromium 90 — 580 1 Mercury 90 — 1 — Platinum Group 71 — 660 2 Tantalum 50 — 18 — Gold 49 — 600 2 Totals (rounded) 60,600,000 100 36,800 100 Source: U.S. Department of the Interior, Bureau of Mines