GLOBAL ENERGY PROBLEMS AND PROSPECTS
DAVID BODANSKY
Department of Physics, University of Washington, Seattle, WA 98195, USA
OVERVIEW OF ENERGY-RELATED PROBLEMS
The availability and utilization of energy technologies has had a profound effect in determining the development of human societies. When the resources appeared to be stable––in the slowly changing era of wood, wind, water, and animals––there was relatively little attention paid to energy. Its role was accepted uncritically and even the concept of energy was not formulated.
All this has changed in the past two centuries, as energy from coal, oil, natural gas, uranium, and large-scale hydroelectric sources has transformed the way we live and work. Energy is now a matter of major interest, and concern has grown during the past several decades that the world is too dependent on energy sources that may not prove sufficient for the future and whose use may harm the environment.
This concern is related to a number of fundamental energy problems. The impact of these problems has still not been felt with much direct force, but their collective effect could become critical as this century progresses. They include:
• The rising demand for energy. Rising world population and the low present use of energy in developing countries creates the need for additional energy sources.
•The depletion of fossil fuels. Fossil fuels now provide about 85% of world primary energy and these resources are limited.
•Possible global climate change. The use of fossil fuels, and especially of coal, threatens substantial climate change with possibly serious adverse effects.
•Difficulties in finding replacements for fossil fuels. No replacements exist that are accepted, beyond any serious dissent or doubt, as being abundant, practical, and clean.
•Possible social disruption or war. If competition for energy sources and for water supplies becomes sufficiently severe, the result could be social disruption or war.
This listing makes clear the central role of fossil fuels. We are highly dependent on them, but their use creates environmental problems and their loss may create severe social and economic problems.
PATTERNS OF ENERGY USE
Distribution of Energy Among Countries
The overall energy problems are exacerbated by the very uneven distribution of energy consumption among the countries of the world, reflecting the wide disparities in economic and technological development. The United States and Western Europe, with 13% of the world's population, accounted in 1998 for 43% of the world's primary energy consumption and 47% of the world's electricity generation1.
Illustrative data on per capita electricity and energy consumption are presented in Table 1. It is seen, for example, that Japan consumes about nine times as much electricity per capita and six times as much primary energy as China. In a wider extreme, the per capita consumption of electricity and primary energy in the United States is more than 100 times that in Bangladesh.
Table 1. Per capita consumption of electric power (average kilowatts) and total primary energy (gigajoules) in selected countries, 1998).
Country / Electricity(average kWe) / Primary Energy
(GJ)
United States / 1.42 / 370
Japan / 0.84 / 178
Western Europe / 0.62 / 155
Eastern Europe & FSU / 0.40 / 132
World / 0.24 / 67
China / 0.09 / 29
India / 0.05 / 14
Bangladesh / 0.01 / 3
Given the finite nature of the world's energy resources and the environmental impacts of energy use, it is important for all countries to produce and use energy efficiently and particularly for the largest per capita users to moderate their use rates. But the key difficulty is not so much that the industrialized countries are using more than "their share," but that the developing countries are using too little energy. This reflects the fact that they have not yet reached a desirable level of industrialization, where "desirable" is defined not only in terms of the standards of the industrialized countries but also by the goals of the developing ones.
Although there are still very great disparities, it should be noted that some of the developing countries have been closing the gap at a substantial rate. Thus, total electrical generation in China was only 13% of the U.S. total in 1980 but has risen to 30% in 1998. But for China and the rest of the developing world there is still a long way to go.
Sources of Energy in the World Today
World consumption of primary energy in 1998 was about 400 exajoules (EJ)2,3. The breakdown by individual energy sources is given in Table 2. About 85% of this energy comes from fossil fuels. Petroleum products head the list, because they are crucial in transportation and are used also for heating, electricity generation, and as a chemical feedstock. Renewable energy provides 8% of the reported primary energy with the overwhelming share coming from hydroelectric power. Nuclear energy provides the remaining 7% of primary energy.
Electricity generation totaled 13,600 billion kWh in 1998 or, in alternative units, 1550 gigawatt-years (GWyr). Of this 63% was generated using fossil fuels (mostly coal), 20% with renewable sources, and 17% with nuclear reactors. The 1550 GWyr corresponds to a primary energy of about 150 EJ, roughly 38% of all primary energy4.
One of the major trends in energy use is the increase in the relative importance of electricity, as the world's energy economy is gradually becoming electrified. The average annual growth in world electricity consumption from 1980 to 1998 (3.1%) was roughly twice the growth rate for primary energy consumption (1.5%)5. In the United States, electricity generation in 1998 was roughly 10 times that of 1950, although total energy consumption did not even triple6.
Table 2. Scenarios for energy consumption and CO2 emissions in 2050, compared to actual in 1998.
Scenarios for 2050Actual / IIASA-WEC Scenarios / Sailor
1998 / A3 / B / C2 / et al.
Population (billion) / 5.9 / 10.1 / 10.1 / 10.1 / 9.0
Primary Energy (EJ) / 396 / 1033 / 830 / 597 / 900
petroleum / 158 / 181 / 169 / 110
coal / 92 / 94 / 173 / 62
natural gas / 89 / 331 / 188 / 140
total fossil fuel / 339 / 606 / 531 / 311 / 300
renewables / 31 / 308 / 185 / 211 / 300
nuclear / 26 / 118 / 115 / 74 / 300
CO2 emissions (GtC) / 6.1 / 9.3 / 9.6 / 5.1 / 5.5
Data from International Energy Annual1, Nakicenovic et al.,7 and Sailor et al.8 In the latter scenario, the CO2 production rate is for the same relative mix of fossil fuels as in 1997.
ENERGY SCENARIOS FOR THE FUTURE
Anticipated Growth in Energy Consumption
One can expect world energy consumption to rise substantially, partly due to rising population and partly due to an increase in the per capita consumption in the developing countries. If the entire world now used energy at the per capita rate of Western Europe, world primary energy consumption would be over 900 EJ, not the actual 400 EJ. At one-half the U.S. rate, it would be about 1100 EJ.
A joint study of the International Institute for Applied System Analyses (IIASA) and the World Energy Council (WEC) developed a number of scenarios that describe possible future energy patterns. These are reported in Global Energy Perspectives, written by a number of the study participants7.Three of the IIASA-WEC scenarios for 2050 are summarized in Table 2: Scenario A3, a high growth, "technology driven," scenario in which heavy use is made of renewable energy (largely biomass) and nuclear energy; Scenario B, which is a "middle course" case; and Scenario C2, an "ecologically driven" scenario. Also listed is a scenario from Sailor et al. for a case where extensive use is made of nuclear energy8. The latter two scenarios are designed to hold down CO2 production, but they differ greatly in the postulated use of nuclear energy and therefore in the total available primary energy.
Given the past failures of long-term energy predictions, there is no reason to expect that any scenario developed today will accurately depict the actual course of events. Aside from this generalized skepticism, specific difficulties can be seen in the scenarios of Table 2. Scenario A3 assumes the consumption of more oil and gas than may prove to be available. Scenario C2 couples a decrease in the world's per capita energy production with a large increase in the gross world product, requiring an increase in the efficiency of energy use that may not be achievable. The Sailor et al. scenario allows per capita energy consumption to rise through the large-scale use of nuclear energy, but the public support necessary for such a large expansion may be lacking. Scenario B may be closest to a "realistic" picture, but in this scenario carbon dioxide (CO2) emissions rise substantially.
The value of such scenarios is that they suggest some of the possible directions in which an energy policy can try to move. Some of the constraints and opportunities are discussed in succeeding sections.
FOSSIL FUEL RESOURCES
Oil resources
Warnings of imminent oil shortages have been frequent over the past thirty years, but to date the shortages have not materialized. During this period additional countries have become important producers and estimates of world oil resources have risen. At the same time, oil consumption has not grown at the anticipated rate. Thus, although there have been abrupt increases in oil prices in response to policy-driven cutbacks in oil production, these have not been fundamentally due to global resource limitations.
It is not clear if the predicted world oil crisis is a realistic threat during the next several decades. Recent estimates from the IIASA/WEC study and from a United States Geological Survey assessment9 reach similar totals for the remaining resource of conventional crude oil. The average of their results is about 2200 billion barrels (bbo). This corresponds to an energy resource of approximately 13,000 EJ.
At the 1999 rate of world oil production –– 24 bbo per year10 –– this oil would suffice for about 90 years. But it is highly unlikely that oil production will be flat. Instead it is expected to rise. The profile of oil production is commonly taken to be that of the "Hubbert curve." The Hubbert curve is roughly bell-shaped and its hypothesized future evolution is extrapolated from the production history to date11. The date of concern is the year when production peaks, when one-half of the original resource – commonly termed the "estimated ultimate resource" (EUR) – has been extracted. This date is quite insensitive to the amount of the original resource because resource consumption rises to a higher peak if the EUR is greater12,13,14. Thus, for an EUR of 2000 bbo the calculated peak is reached in 2004 while for an EUR of 4000 bbo the peak is reached in 203014. For a remaining resource of 2200 bbo, discussed above, the EUR is about 3000 bbo, the peak is reached in 2019, and by 2090 production would be only about one-fifth of the 1999 rate.
It should be noted that an EUR of 3000 bbo is considerably higher than the values estimated in most other studies made over the past two decades. These ranged, as reported in a 1996 summary, from about 1700 bbo to 2600 bbo, with a median near 2000 bbo12. In a 1998 estimate by two experienced oil analysts the remaining resource is given as only about 1000 bbo, implying an EUR of under 2000 bbo13. The differences between the low and high estimates are obviously more important in a model where consumption remains relatively flat than in the Hubbert model.
Although the Hubbert picture is widely cited, and at some level appears inescapable, predictions made on the basis of it should be taken as suggestive but not necessarily precise in quantitative detail. The Hubbert model achieved a notable triumph in anticipating the peak in U.S. oil production (excluding Alaska) that occurred in about 1970. However, world production has been rising more slowly in recent years than would be expected from this model. It was only 5% higher in 1999 than in 1979, and was actually less in 1999 than in 199710.
Beyond conventional oil, resources of unconventional oil (including tar sands, and heavy crude oil, and shale oil) are estimated in the WEC-IIASA studies to somewhat exceed the original conventional oil resource. If these can be economically extracted, the onset of oil shortages would be postponed. [The term "economically extracted" is a highly flexible one. For example, if the efficiency of automobiles (in kilometers per liter of oil) were doubled, then oil that is twice as expensive would remain "affordable."]
This may suggest that there is no reason to be concerned about future oil supplies. However, complacency is not justified. While an oil crisis may not be imminent, oil remains a limited resource and it would be unfortunate if it is further squandered. Our children may or may not pay the penalty but our grandchildren are likely to. Oil demand has been restrained in recent years by a combination of improved efficiencies in use, switching to other fuels, and economic difficulties in some parts of the world. Assuming that the world economy grows, the demand for oil will also grow unless its use is limited to applications where it is uniquely valuable (in particular, transportation).
Finally, it should be noted that oil resources are to a large extent concentrated in limited geographical areas. Oil, and especially oil that is extractable at low cost, is disproportionately found in the Middle East. This gives countries such as Saudi Arabia great power in influencing the global economy and gives countries like the United States a strong incentive to intervene politically or militarily. The greater the world's dependence on oil, the greater the risks of crises.
Natural gas resources
Estimated resources of conventional gas, expressed in energy terms, are somewhat greater than those of oil, and the consumption rate is less. The average of the IIASA/WEC and USGS estimates (which differ by about 20%) is in the neighborhood of 15,000 trillion cubic feet (Tcf), corresponding to roughly 16,000 EJ. Again, in the IIASA/WEC estimate, unconventional resources somewhat exceed conventional ones.
World production of natural gas in 1998 amounted to 83 Tcf1. Were the use rate to remain constant, conventional natural gas resources would therefore suffice for almost 200 years. However, there is an incentive to switch to natural gas as the preferred fossil fuel because less CO2 is produced with natural gas than with coal, for the same energy output. If all the electricity generated in 1998 using fossil fuels were generated entirely by gas-fired plants at a 50% thermal efficiency, about 56 Tcf of gas would be required. If world electricity use doubles in the next two or three decades, as appears quite likely, that alone would mean a very large increase in natural gas use for an expansion based largely on gas. At the same time, gas is also a potential replacement for oil in the heating of buildings and perhaps even in transportation, further hastening the day when supply shortages might occur.
A very large additional natural gas resource may exist in the form of methane hydrates. It is not established that this methane can be extracted from the oceans in an economical and environmentally benign manner. If that can be done, the estimated resource is enormous. In the IIASA/WEC summary, it is the equivalent of about 800,000 EJ. However, this possibility must be viewed as speculative because there has been no significant exploitation of the methane hydrates to date, and it is not known whether this will prove to be a practical resource.
Coal resources
Coal resources are so ample that relatively little effort has gone into determining their actual magnitude. The IIASA/WEC study places these resources at an equivalent of about 140,000 EJ –– roughly ten times the resources of conventional oil or natural gas. Were there no concern about the emission of CO2 and other pollutants, this would suffice for well over a century even at greatly expanded levels of energy use. But the prospect of global climate change, as well as other pollutants from coal, makes the use of this coal –– at least by present methods –– an unattractive option.
FOSSIL FUELS AND GLOBAL CLIMATE CHANGE
A counterpart to the problems of limited supplies of fossil fuels is the problem of the environmental effects of the use of fossil fuels. In particular their combustion leads to the production of CO2 with the consequent prospect of substantial climate changes. The expected effects are being studied by scientists in many countries, and some of this work is captured in continual studies by the Intergovernmental Panel on Climate Change (IPCC). The IPCC Second Assessment was published in 199515 and the Third Assessment is now in the final review stage.
While the details of the potential climate changes are not firmly established, the results of the analyses by the IPCC and by most atmospheric scientists point to a rise in global temperature, increasing sea level, changing rainfall patterns, and a possible increase in the frequency and severity of violent climate events, such as hurricanes.
The response of the world community to the perceived dangers is reflected in the 1997 Kyoto Protocol. The industrialized countries (a defined group of so-called Annex I countries) are responsible for a disproportionate share of the current emissions, and the protocol calls upon the original Annex I countries to reduce, on average, their greenhouse gas emissions to 95% of their 1990 totals by about 2010. This refers to all greenhouse gases collectively, but carbon dioxide is the dominant component. It was responsible, for example, for 83% of the 1996 greenhouse gas emissions by OECD countries (converted to CO2 equivalents)16. As of early 2000, there were 84 signatories to the Protocol but only 22 of these had ratified it. Of the Annex I countries, all had signed the Protocol but none had ratified it17.