United States energy demand

Figure 4.1 (a) United States energy demand by consuming sector (b) United States energy supply by source. 

Due to the relative sparsity of timber inventory data it is difficult to accurately determine the total amount of wood residue available in the United States. However, estimates indicate that approximately three percent of the total United States energy demand could possibly be supplied by wood residues (2). There are several sources of wood residues suitable for fuel. A primary criteria is that the material be of a non-commercial nature and have a longterm and reliable supply. The primary sources of wood residue are forest and mill residue. The U.S. Forest Service publishes statistics which can provide the basis for estimating the potential amounts of available wood residues. Other state and regional organizations also publish data which are useful in estimating the quantity of available material(3). 

In most of the rest of the world the olefins industry was originally based on naphtha feedstocks. Naphtha is the dominant olefins feedstock in Europe and Asia. In the middle 1980s several large olefins complexes were budt outside of the United States based on gas Hquids feedstocks, most notable in western Canada, Saudi Arabia, and Scotiand. In each case the driving force was the production of natural gas, perhaps associated with cmde oil production, which was in excess of energy demands. 

Olefin Feedstock Selection. The selection of feedstock and severity of the cracking process are economic choices, given that the specific plant has flexibiUty to accommodate alternative feedstocks. The feedstock prices are driven primarily by energy markets and secondarily by supply and demand conditions ia the olefins feedstock markets. The prices of iadividual feedstocks vary widely from time to time as shown ia Figure 2, which presents quarterly prices of the various feedstocks ia the United States from 1978 through 1991 ia dollars per metric ton (1000 kg) (4). 

The market penetration of synthetic fuels from biomass and wastes in the United States depends on several basic factors, eg, demand, price, performance, competitive feedstock uses, government incentives, whether estabUshed fuel is replaced by a chemically identical fuel or a different product, and cost and availabiUty of other fuels such as oil and natural gas. Detailed analyses have been performed to predict the market penetration of biomass energy well into the twenty-first century. A range of from 3 to about 21 EJ seems to characterize the results of most of these studies. 

Hydrocarbons from petroleum (qv) are still the principal energy source for the United States as shown in Table 1. About 60% of the world s energy is supphed by gas and oil and about 27% from coal (6—8). The annual energy demand for oil in different world areas is given in Table 2. 

It is a mature industry and the capacity in the United States is not expected to increase rapidly. The annual capacity of 5.3 x 10 t already substantially exceeds the domestic demand. Approximately 20% of U.S. production is exported. The U.S. styrene producers benefit from the huge ethylene capacity and the relatively low energy cost present in the Gulf Coast. 

Clinker production requires large quantities of fuel. In the United States, coal (qv) and natural gas are the most widely used kiln fuels but fuels derived from waste materials, eg, tires, solvents, etc, are increasing in importance (53) (see Fuels fromwaste Gas,natural). In addition to the kiln fuel, electrical energy is required to power the equipment. This energy, however, amounts to only about one-ninth that of the kiln fuel. The cement industry carefully considers all measures that can reduce fuel demand. 

The demand for energy is continually increasing and the highest energy consumption in the world occurs in the United States. In 1989 consumption totaled 8.6 x 10 MJ (81.3 x 10 Btu) or 11.7 metric tons of coal-equivalent per capita (85). World recoverable reserves were about 120 times the annual coal production in 1988 and about 10 times that for the additional reserves beheved to be in place (1). Estimated coal consumption reduces the known recoverable reserves at about 1%/yr. Whereas the use of bituminous coal is expected to continue to increase in terms of tonnage, the percentage of coal used in the United States has stabilized as shown in Table 11. 

There has been not only gi owth m the total number of electric motors (more standard appliances in use), but also a proliferation in their use for new, novel applications. Both trends will continue to increase demand for the electricity to run electric motors. In the United States, electric motors arc responsible for consuming more than half of all electricity, and for the industrial sector alone, close to two-thirds. Since the cost of the electricity to power these motors is enormous (estimated at more than 90 billion a year), research is focused on finding ways to increase the energy efficiency of motors and motor systems. 

The United States became the world s first producer of deep crude oil from an oil well when in 1859 Colonel Edwin Drake successfully used a pipe drilled into the ground to obtain oil. From then until about 1970, the United States was virtually energy-independent with only some oil and gas imports from Mexico and Canada. Wliile U.S. reserves of coal, natural gas and uranium continue to be large enough to supply internal demand with enough left over to export, the supply of oil took a sharp turn downward. After 1970, even while U.S. demand continued to increase at a steep 6.5 percent per year, the supply of U.S. oil began to decline, necessitating sharp increases in U.S. oil imports. 

Another U.S. policy to attain energy independence was to force all Alaskan North Slope crude oil to he consumed inside the United States and not be allowed to he exported. The problem was that North Slope crude oil is relatively heavy and not suitable for west coast fuel needs. The mismatch of supply and demand caused California refineries to sell heavy distillate fuels abroad and import lighter fuel additives. Furthermore, the forced selling of Alaska crude oil on a very saturated west coast market caused Alaska crude prices to he 1 to 5 per barrel less than the international price, resulting in less oil exploration and development in Alaska. The upshot of all this was lower tax revenue, a loss of jobs in the oil fields, and less oil exploration and development on the North Slope. The United States actually exported heavy bunker fuel oil at a loss, as opposed to the profit that could have been attained by simply exporting crude oil directly. 

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