Annual Review of Environment and Resources - Volume 25, 2000

Civilization's advances during the twentieth century are closely bound with an unprecedented rise of energy consumption in general, and of hydrocarbons and electricity in particular. Substantial improvements of all key nineteenth-century energy techniques and introduction of new extraction and transportation means and new prime movers resulted in widespread diffusion of labor-saving and comfort-providing conversions and in substantially declining energy prices. Although modern societies could not exist without large and incessant flows of energy, there are no simple linear relationships between the inputs of fossil fuels and electricity and a nation's economic performance and social accomplishments. International comparisons show a variety of consumption patterns and a continuing large disparity between affluent and modernizing nations. The necessity of minimizing environmental impacts of energy use, particularly those with potentially worrisome global effects, is perhaps the greatest challenge resulting from the twentieth century's energy advances.

Phosphorus has a number of indispensable biochemical roles, but it does not have a rapid global cycle akin to the circulations of C or N. Natural mobilization of the element, a part of the grand geotectonic denudation-uplift cycle, is slow, and low solubility of phosphates and their rapid transformation to insoluble forms make the element commonly the growth-limiting nutrient, particularly in aquatic ecosystems. Human activities have intensified releases of P. By the year 2000 the global mobilization of the nutrient has roughly tripled compared to its natural flows: Increased soil erosion and runoff from fields, recycling of crop residues and manures, discharges of urban and industrial wastes, and above all, applications of inorganic fertilizers (15 million tonnes P/year) are the major causes of this increase. Global food production is now highly dependent on the continuing use of phosphates, which account for 50–60% of all P supply; although crops use the nutrient with relatively high efficiency, lost P that reaches water is commonly the main cause of eutrophication. This undesirable process affects fresh and ocean waters in many parts of the world. More efficient fertilization can lower nonpoint P losses. Although P in sewage can be effectively controlled, such measures are often not taken, and elevated P is common in treated wastewater whose N was lowered by denitrification. Long-term prospects of inorganic P supply and its environmental consequences remain a matter of concern.

Meeting the growing demand for personal mobility and transport of goods in a sustainable way presents a wide range of interrelated engineering and public policy challenges. This chapter reviews some of the technical options being developed for mitigating the local and global environmental impact of road vehicles, made possible using developments in the materials and combustion sciences, sensor technologies, catalysis, and information processing. Although the improved technical performance of these options can be quantified, the likelihood of commercial success is harder to predict. This review considers factors that may support the adoption of innovative vehicle technologies, recognizing that the ubiquity of existing solutions and infrastructures will make any change process complex.

Various applications using carbon dioxide (CO2) have developed within the last decade and, if current trends continue, the CO2 technology platform could emerge as the most commonly used solvent in the twenty-first century. An environmentally friendly platform that is wrapped in a successful business format with apparent implications for people and their communities is most likely to endure. Does the CO2 technology platform meet the criteria for becoming a sustainable enterprise? Utilizing CO2 as an alternative solvent in conventional processes has the potential to favorably impact the environment and our communities. There are, however, several barriers to adopting CO2-based applications. Several concepts as well as obstacles to adopting the carbon dioxide technology platform are highlighted in this chapter.

The 1990s saw a resurgence in the windpower industry, with installed grid-connected capacity expanding more than five-fold between 1990 and 2000. Most of this increase occurred in Europe, where governmental policies aimed at developing domestic energy supplies and reducing pollutant emissions provided a sheltered market for renewable energy generation. The 1990s were also marked by a return to large, megawatt-sized wind turbines, a reduction and consolidation of wind turbine manufacturers, and increased interest in offshore windpower. This article reviews recent trends in the windpower industry, including some of the fundamental engineering principles of wind turbine design. Technological impediments and advances are discussed in the context of changes in the global electricity markets and environmental performance.

An ultimate limit on the extent that biomass fuels can be used to displace fossil transportation fuels, and their associated emissions of CO2, will be the land area available to produce the fuels and the efficiencies by which solar radiation can be converted to useable fuels. Currently, the Brazil cane-ethanol system captures 33% of the primary energy content in harvested cane in the form of ethanol. The US corn-ethanol system captures 54% of the primary energy of harvested corn kernels in the form of ethanol. If ethanol is used to substitute for gasoline, avoided fossil fuel CO2 emissions would equal those of the substituted amount minus fossil emissions incurred in producing the cane- or corn-ethanol. In this case, avoided emissions are estimated to be 29% of harvested cane and 14% of harvested corn primary energy. Unless these efficiencies are substantially improved, the displacement of CO2 emissions from transportation fuels in the United States is unlikely to reach 10% using domestic biofuels. Candidate technologies for improving these efficiencies include fermentation of cellulosic biomass and conversion of biomass into electricity, hydrogen, or alcohols for use in electric drive-train vehicles.

Geoengineering is the intentional large-scale manipulation of the environment, particularly manipulation that is intended to reduce undesired anthropogenic climate change. The post-war rise of climate and weather modification and the history of U.S. assessments of the CO2-climate problem is reviewed. Proposals to engineer the climate are shown to be an integral element of this history. Climate engineering is reviewed with an emphasis on recent developments, including low-mass space-based scattering systems for altering the planetary albedo, simulation of the climate's response to albedo modification, and new findings on iron fertilization in oceanic ecosystems. There is a continuum of human responses to the climate problem that vary in resemblance to hard geoengineering schemes such as space-based mirrors. The distinction between geoengineering and mitigation is therefore fuzzy. A definition is advanced that clarifies the distinction between geoengineering and industrial carbon management. Assessment of geoengineering is reviewed under various framings including economics, risk, politics, and environmental ethics. Finally, arguments are presented for the importance of explicit debate about the implications of countervailing measures such as geoengineering.

The first phase of promoting renewable energy in Europe is coming to an end. The timetable of the European Commission's Single Electricity Market (SEM) Directive has been the key recent driver of change within European energy and electricity markets. As mainland European countries have been forced to restructure their electricity industries and reappraise their renewable energy policies, they have been impressed by the results of the England and Wales Renewable Non-Fossil Fuel Obligation (NFFO). The NFFO is a mechanism for promoting renewable energy that has a competitive basis. However, the United Kingdom is in the process of creating a new policy. As new renewable energy policies have been discussed or put in place in mainland European countries, so these have influenced those of the United Kingdom. Renewable energy policies throughout Europe are converging. This paper analyzes the history behind these changes and underlines the lessons to be learned.

Industrial symbiosis, as part of the emerging field of industrial ecology, demands resolute attention to the flow of materials and energy through local and regional economies. Industrial symbiosis engages traditionally separate industries in a collective approach to competitive advantage involving physical exchange of materials, energy, water, and/or by-products. The keys to industrial symbiosis are collaboration and the synergistic possibilities offered by geographic proximity.

This paper reviews the small industrial symbiosis literature and some antecedents, as well as early efforts to develop eco-industrial parks as concrete realizations of the industrial symbiosis concept. Review of the projects is organized around a taxonomy of five different material exchange types. Input-output matching, stakeholder processes, and materials budgeting appear to be useful tools in advancing eco-industrial park development. Evolutionary approaches to industrial symbosis are found to be important in creating the level of cooperation needed for multi-party exchanges.

Fossil fuels account for about 80% of energy consumption in Asia. Because of its abundance and easy recoverability, especially in India and China, coal will remain the fuel of choice in the foreseeable future. If current trends continue, sulfur dioxide emissions from Asia may soon equal the emissions from North America and Europe combined. These trends portend a variety of local, regional, and global environmental impacts. Acid rain damages human health, ecosystems, and built surfaces. Many ecosystems will be unable to absorb these increased acidic depositions, leading to irreversible ecosystem damage with far-reaching implications for health, forestry, agriculture, fisheries, and tourism. RAINS-ASIA is a scenario-generating tool used to estimate the extent of damages caused by acid rain and to review the costs and impacts of alternatives to provide a look into the future. Its use extends from national-, regional-, and city-scale evaluation and inputs for cost-effective options analyses, to international negotiations on transboundary pollution.

The notion of capacity development (CD) has been receiving increasing attention as a way to assist the South in its environmental management. Consequently, there has been an exploration of various facets of the capacity issue in the literature and an incorporation of CD in environmental programs of donor agencies. Yet, many of these discussions have remained rather broad, and efforts to develop environmental capacity have shown only limited success. Based on an examination of the capacity needs for environmental management in agriculture and industry, and for dealing with climate change, this review suggests that strengthening domestic capabilities for policy research and innovation as well as for managing technological change may be particularly critical to allow for adaptation of policies and technologies for local conditions and needs. Examination of innovative local experiments on environmental management in developing countries can also provide useful lessons on how to develop and utilize capacity that works under the constrained conditions often found in developing countries. Furthermore, it is important to stress that improving the environment in developing countries also requires capacity in the North to examine and reorient Northern policies that impact the environment, as well as capacity for the environment, in the poorer parts of the world. Ultimately, though, the development of sustainable and appropriate capacity for the environment will require not merely donor-driven programs but a systematic effort driven by Southern governments and organizations.

Water vapor is the dominant greenhouse gas, the most important gaseous source of infrared opacity in the atmosphere. As the concentrations of other greenhouse gases, particularly carbon dioxide, increase because of human activity, it is centrally important to predict how the water vapor distribution will be affected. To the extent that water vapor concentrations increase in a warmer world, the climatic effects of the other greenhouse gases will be amplified. Models of the Earth's climate indicate that this is an important positive feedback that increases the sensitivity of surface temperatures to carbon dioxide by nearly a factor of two when considered in isolation from other feedbacks, and possibly by as much as a factor of three or more when interactions with other feedbacks are considered. Critics of this consensus have attempted to provide reasons why modeling results are overestimating the strength of this feedback.

Our uncertainty concerning climate sensitivity is disturbing. The range most often quoted for the equilibrium global mean surface temperature response to a doubling of CO2 concentrations in the atmosphere is 1.5°C to 4.5°C. If the Earth lies near the upper bound of this sensitivity range, climate changes in the twenty-first century will be profound. The range in sensitivity is primarily due to differing assumptions about how the Earth's cloud distribution is maintained; all the models on which these estimates are based possess strong water vapor feedback. If this feedback is, in fact, substantially weaker than predicted in current models, sensitivities in the upper half of this range would be much less likely, a conclusion that would clearly have important policy implications. In this review, we describe the background behind the prevailing view on water vapor feedback and some of the arguments raised by its critics, and attempt to explain why these arguments have not modified the consensus within the climate research community.

Over the past 25 years more than 20 major studies have examined the technological potential to improve the fuel economy of passenger cars and light trucks in the United States. The majority have used technology/cost analysis, a combination of analytical methods from the disciplines of economics and automotive engineering. In this review we describe the key elements of this methodology, discuss critical issues responsible for the often widely divergent estimates produced by different studies, review the history of this methodology's use, and present results from six recent assessments. Whereas early studies tended to confine their scope to the potential of proven technology over a 10-year time period, more recent studies have focused on advanced technologies, raising questions about how best to include the likelihood of technological change. The review concludes with recommendations for further research.

Theoretical considerations and empirical data suggest that existing technologies and procedures can improve indoor environments in a manner that significantly increases productivity and health. The existing literature contains moderate to strong evidence that characteristics of buildings and indoor environments significantly influence rates of communicable respiratory illness, allergy and asthma symptoms, sick building symptoms, and worker performance. Whereas there is considerable uncertainty in the estimates of the magnitudes of productivity gains that may be obtained by providing better indoor environments, the projected gains are very large. For the United States, the estimated potential annual savings and productivity gains are $6 to $14 billion from reduced respiratory disease, $1 to $4 billion from reduced allergies and asthma, $10 to $30 billion from reduced sick building syndrome symptoms, and $20 to $160 billion from direct improvements in worker performance that are unrelated to health. Productivity gains that are quantified and demonstrated could serve as a strong stimulus for energy efficiency measures that simultaneously improve the indoor environment.

Current guidelines for green buildings are cursory and inadequate for specifying materials and designing ventilation systems to ensure a healthful indoor environment, i.e. a “healthy building,” by design. Public perception, cultural preferences, litigation trends, current codes and regulations, and rapid introduction of new building materials and commercial products, as well as the prevailing design-build practices, pose challenges to systems integration in the design, construction and operation phases of modern buildings. We are on the verge of a paradigm shift in ventilation design thinking. In the past, thermal properties of air within a zone determined heating, ventilating, and air-conditioning specifications. In the future, occupant-specific and highly responsive systems will become the norm. Natural ventilation, displacement ventilation, and microzoning with subfloor plenums, along with the use of point-of-source heat control and point-of-use sensors, will evolve to create a “smart,” responsive ventilation-building dynamic system. Advanced ventilation design tools such as the modeling of computational fluid dynamics (CFD) will be used routinely. CFD will be integrated into air quality and risk assessment models.

Low environmental damage is one of the main justifications for continued efforts to reduce energy consumption and to shift to cleaner sources such as solar energy, especially now that supply security has slipped from public consciousness. In recent years there has been much progress in the analysis of environmental damages, in particular thanks to the ExternE (External Costs of Energy) Project of the European Commission. This paper presents a summary of the methodology and key results for the external costs of the major energy technologies. Even though the uncertainties are large, the results provide substantial evidence that the classic air pollutants (particles, NOx and SOx) from fossil fuels impose significant public health costs, comparable to the cost of global warming from CO2 emissions.

Indian megacities are among the most polluted in the world. Air concentrations of a number of air pollutants are much higher than levels recommended by the World Health Organization. In this paper, we focus on Mumbai and Delhi to characterize salient issues in health risks from particulate air (PM10) pollution in Indian cities. We perform a synthesis of the literature for all elements of the causal chain of health risks—sources, exposure, and health effects—and provide estimates of source strengths, exposure levels, and health risks from air pollution in Indian cities. We also analyze the factors that lead to uncertainty in these quantities and provide an overall assessment of the state of scientific knowledge on air pollution in urban India.

This paper reviews the available data and models on energy and material flows through the world's 25 largest cities. Throughput is categorized as stored, transformed, or passive for the major flow modes. The aggregate, fuel, food, water, and air cycles are all examined. Emphasis is placed on atmospheric pathways because the data are abundant. Relevant models of urban energy and material flows, demography, and atmospheric chemistry are discussed. Earth system–level loops from cities to neighboring ecosystems are identified. Megacities are somewhat independent of their immediate environment for food, fuel, and aggregate inputs, but all are constrained by their regional environment for supplying water and absorbing wastes. We elaborate on analogies with biological metabolism and ecosystem succession as useful conceptual frameworks for addressing urban ecological problems. We conclude that whereas data are numerous for some individual cities, cross-cutting compilations are lacking in biogeochemical analysis and modeling. Synthesis of the existing information will be a crucial first step. Cross-cutting field research and integrated, multidisciplinary simulations will be necessary.