Energy and The Environment: Scientific and Technological Principles PDF

INTRODUCTION

Modern societies are characterized by a substantial consumption of fossil and nuclear fuels needed to provide for the operation of the physical infrastructure upon which these societies depend: the production of food and water, clothing, shelter, transportation, communication, and other essential human services. The amount of this energy use and its concentration in the urban areas of industrialized nations have caused the environmental degradation of air-, water-, and land-dependent ecosystems on a local and regional scale, as well as adverse health effects in human populations. Recent scientific studies have forecast potentially adverse global climate changes that would result from the accumulation of gaseous emissions to the atmosphere, principally carbon dioxide from energy-related sources. This accumulation is aggravated by an expected expanding consumption of energy, both by industrialized nations and by developing nations seeking to improve the living standards of their growing populations. The nations of the world, individually and collectively, are attempting to limit the damage to human health and natural ecosystems that accompanies these problems and to forestall the development of even more severe issues in the future. But because the source of the problem, energy usage, is so intimately involved in nations' and the world's economies, it will be difficult to ameliorate this environmental degradation without some adverse effects on the social and economic circumstances of national populations.

To comprehend the magnitude of intensity of human use of energy in current nations, we might compare it with the minimum energy needed to sustain an individual human life, that of the caloric value of food needed for a healthy diet. In the United States, which ranks among the most intensive users of energy, the average daily fossil fuel use per capita amounts to 56 times the necessary daily food energy intake. On the other hand, in India, a developing nation, the energy used is only 3 times the daily food calorie intake. U.S. nationals expend 20 times the energy used by Indian nationals, and their per capita share of the national gross domestic product is 50 times greater. Evidently, the economic well-being of populations is closely tied to their energy consumption.

When agricultural technology began to displace that of the hunter–gatherer societies about 10,000 years ago, other activities than acquiring food became possible. Eventually other sources of mechanical energy, that of animals, wind, and water streams, were developed, augmenting human labor and further enhancing both agricultural and nonagricultural pursuits. As the world population increased, the amount of crop and pasture land increased in proportion, permanently replacing natural forest and grassland ecosystems by less diverse ones. Until the beginning of the industrial revolution several centuries ago, this was the major environmental impact of human activities. Today, we are approaching the limit of available land for agricultural purposes, and only more intensive use of it can provide food for future increases of the world population.

The industrial revolution drastically changed the conditions of human societies by making available large amounts of energy from coal (and later oil, gas, and nuclear fuel) far exceeding that available from the biofuel, wood. Some of this energy was directed to increasing the productivity of agriculture, freeing up a large segment of the population for other beneficial activities. Urban populations grew rapidly as energy-using activities, such as manufacturing and commerce, concentrated themselves in urban areas. Urban population and population density increased, while those of rural areas decreased.

By the middle of the 20th century, nearly all major cities of the industrialized world experienced health-threatening episodes of air pollution, and today this type of degradation has spread to the urban areas of developing countries as a consequence of the growing industrialization of their economies. Predominantly, urban air pollution is a consequence of the burning of fossil fuels within and beyond the urban region itself. This pollution can extend in significant concentrations to rural areas at some distance from the pollutant sources so that polluted regions of continental dimensions even include locations where there is an absence of local energy use.

Despite the severity of urban pollution, it is technically possible to reduce it to harmless levels by limiting the emission of those chemical species that cause the atmospheric degradation. The principal pollutants comprise only a very small fraction of the materials processed and can be made even smaller, albeit at some economic cost. In industrialized countries, the cost of abating urban air pollution is but a minor slice of a nation's economic pie.

While the industrialized nations grapple with urban and regional air pollution, with some success, and developing nations lose ground to the intensifying levels of harmful urban air contamination, the global atmosphere experiences an untempered increase in greenhouse gases, those pollutants that are thought to cause the average surface air temperature to rise and climate to be modified. Unlike the urban pollutants, most of which are precipitated from the atmosphere within a few days of their emission, greenhouse gases accumulate in the atmosphere for years, even centuries. The most common greenhouse gas is carbon dioxide, which is released when fossil fuels are burned. Because it is not possible to utilize the full energy of fossil fuels without forming carbon dioxide, it will be very difficult to reduce the global emissions of carbon dioxide while still providing enough energy to the world's nations for the improvement of their economies. While there is technology available or being developed that would make possible substantial reductions in global carbon dioxide emissions, the cost of implementation of such control programs will be much larger than that for curbing urban air pollution.