recycling, conservation policies, etc. Industrial processes are much more effective nowadays, because of improved equipment and new technologies. Many of them were developed during and after the oil shock of the 70's. Another important impact on efficiency concerning the raw materials is recycling. For example, just 5% as much energy is needed to recycle aluminum as to produce it from bauxite, the original raw material. Therefore recycling materials can lower the total energy consumption. Other studies show that the energy efficiency of buildings could double by 2010 by using new technologies such as advanced technology windows, compact fluorescent lights , shade trees and light colored buildings. [Bevington, Rosenfeld, 1990] Also we should keep in mind an early technology transfer to the FEB and LDC countries to avoid the same mistakes which were made in the western world in the past decades. Extracted Trends This section describes a trend analysis for world energy use in the sectors of residential, public, industry and transportation. Residential and public buildings data were available for USA only. Residential and Public / Commercial Buildings Buildings use 36% of total USA energy supply and commercial buildings alone had an annual energy bill of $200 billion. During the time of oil crisis in the 70's, the energy use in homes and buildings fell some 30%. Although building improvements continue, energy use in the building sector is growing at the rate of 3.3% per year in the USA. [ Bevington, Rosenfeld, 1990] Industry and Manufacturing Industries consume 2/5 of the developed world's energy. Output has risen but total energy consumption has gone down, due to making industrial processes more productive by investing in conservation. The amount of fuel consumed by USA industry overall per unit of output has declined by 50 percent during the past 30 years. This decline is due to improved efficiencies of equipment, recycling of scrap material, continuous process improvements, and new technological breakthroughs. The most energy intensive step of manufacturing is the initial conversion of raw materials. More than half of energy consumption is converting ores and feed stocks to basic commodities such as metals, glass, plastics, and paper. The remaining energy use is agriculture, mining, construction, and manufacturing of intermediate and finished products such as food cans, newspapers, magazines and vehicles. Currently, companies recycle most scrapped materials, but once items are passed to consumers, recycling will significantly drop. For example, about 40 percent of inputs to steel making consist of recyclable materials from outside the mill. [Ross, Steinberger, 1990] Transportation One half of the world's oil is consumed by 500 million road vehicles. Currently, the number of vehicles is growing faster than the human population. The growth of vehicle use is 4.7% per year for cars and 5.1% per year for buses and trucks. By 2030, studies project that there may be 1 billion vehicles on the world's roads. The growth of vehicle use is 4.7% per year for cars and 5.1% per year for buses and trucks. [Bleviss, Walzer, 1990] 2.1.2 Future Energy Consumption More than 12 billions humans in the next century could populate this planet without having severe physical constraints on raw material, food and environment. [Gaudin, 1991] Regarding energy, some constraints appear: consumption of fossil fuels will be limited for environmental reasons, use of atomic energy will be restricted to those countries which accept its risk and can acquire technology, and hydroelectric power is limited by geographical reasons. The energy needs per year are now about 12 TWy/year (note that 1 TWy/year = 8760 TWh/year) computed for a world population of 5.4 billion inhabitants. Depending on the model assumptions the projected energy needs for 2020 are in a range of 11-28 TWy/year for a population of about 7.4-7.8 billion people and, for 2100 the energy needs will be in a range of 17-50 TWy/year for a world population of 10-14 billion. [Deschamps, 1992] In this section the model assumptions will be examined. Predictions What can be predicted from today's energy consumption behavior related to the different economic blocks: OECD, LDC and FEB. A first scenario for future demand could be that energy usage per
RkJQdWJsaXNoZXIy MTU5NjU0Mg==