A central objective of the IlASA study was, as stated at the outset, to determine how the world might successfully negotiate the transition to a truly sustainable global energy system. This motivated the historical analysis of Section 2 (Where have we come from?), the long-term evaluation of supply possibilities in Section 3 (Where might we want to get to?), and the detailed analy- J sis of the more near-term future in Section 4 (In what direction
are we currently headed?). In the end, the results did not, by themselves, provide a definitive answer to the original question - but they did prove suggestive, and it is these suggestions that are
I the subject of this last section.
' I
There is an underlying unifying theme running throughout the work that, while not surprising in hindsight, was not obvious at the beginning. It has to do with the general pattern of the world's response to the increasing scarcity and expense of energy resources.
1 As we have become more aware of the problems of energy
/
resources throughout the 1970s, we have begun to adapt in waysI that make better use of the limited energy currently available.
,
Sometimes we label these adaptations conservation; sometimes we call them improvements in efficiency; sometimes they are I referred t o as productivity increases. Whatever we call them, theyrlLq
all involve reducing the energy needed to produce some service
I
- L L3
(be it a well heated sitting room or intercity jet travel) by replacing it with something else. In some cases this replacement is in the form of capital resources (e.g., investing in home insulation); in others it can be classified as labor (e.g., periodic tuneups of an automobile to increase i t s gas mileage); and in still others it may be labeled simply ingenuity or know-how (e.g., anything from more carefully planned shopping trips to largescale reconfigura- tions of industrial processes).
At a personal level, we are all familiar with such adaptations
- such substitutions of capital, labor, or know-how for energy in producing services. At more collective levels, ranging from small business enterprises to international alliances, we are becoming more familiar with them. And what will appear in the discussion to follow i s the conviction that what may now seem to us to be perhaps quite sophisticated, energy-conserving arrangements of our resources of capital, labor, know-how, and energy indicate only the direction in which we can travel. They in no sense even begin to suggest the limits of what can be done.
I
Of particular importance i s the notion of investing these resources to increase the stock available in each category. Again, these ideas are hardly unfamiliar - investments in education, in research and development, in capital equipment, in exploratory drilling have all contributed, and continue to contribute, to the resources that we can put to use. What i s less familiar i s what these same concepts lead us to when applied from a global perspective contemplating the next half century and beyond.Nuclear fwion, nuclear fusion, and hard solar power were described in Section 3 as possible bases for a sustainable energy sys- tem. However, that analysis ignored entirely the question of energy demand - in what forms energy will in fact be needed - and from this perspective it is clear that nuclear power and solar power are not without their disadvantages. As generally conceived, they pro- duce energy in the form of heat that is assumed to be used directly sometimes or, more often, converted t o electricity. And both heat and, t o a lesser extent, electricity have their drawbacks: they are difficult t o store and to transport. It is for these reasons that, in situations where favorable storage and transport characteristics are particularly important, we have tended t o rely on chemical energy carriers, principally in the form of the fossil fuels.
It is precisely these fossil energy carriers, however, that are getting scarcer. While electricity can replace them t o some degree, for the reasons listed above we might be better off developing an alternative that is itself a chemical, rather than an electrical, energy carrier.
A possible candidate is hydrogen. It is attractive, first, because the technology for converting electricity t o hydrogen via the elec- trolysis of water is well developed. Second, processes for converting nuclear o r solar heat directly t o hydrogen without the intermediate step of electricity production appear promising. Third, hydrogen is much more easily stored than electricity and might be particularly suited to large-scale storage in depleted natural gas reservoirs.
Fourth, the piping networks and the infrastructure associated with further Iargescale use of natural gas would be especially suited t o a gradual replacement of natural gas by hydrogen. And fifth, when hydrogen is burned (recombined with oxygen), it produces essen- tially only water vapor, thus making its use environmentally attrac- tive.
To introduce hydrogen on a scale comparable with that of electricity cannot be done overnight; but it can most certainly be started in a way that contributes from the beginning t o solving the critical, immediately pressing liquid fuels problem. Consider, first, hydrogen production. Among the many possible production pro- cesses there are some that begin by converting methane (the prin- cipal component of natural gas) into methanol, a liquid hydrocarbon fuel. Thus, even t o introduce just the first step of such processes would be t o introduce a capability to convert natural gas t o liquid fuel - t o convert a large resource that is often wasted (flared) be- cause of the world's currently undersized long-distance gas transpor- tation system into a form in which it can be much more easily transported, stored, and used.
Once hydrogen is available, moreover, it can be used t o exploit more efficiently the most extensive of the fossil fuels - coal. Spe- cifically it would allow the introduction of allothermal coal- liquefaction schemes, as discussed in Section 3. Thus, hydrogen produced by nuclear o r solar facilities, in conjunction with the heat generated by the same facilities, could be used to extend by a factor of three t o four the portion of our coal resources that must be devoted t o producing liquid fuels. In view of the results of Sec- tion 4, such an extension could be critical.
Still, t o produce and use synthetic liquid hydrocarbons from coal and other fossil resources is t o consume the store of carbon atoms that is available in these particularly convenient forms. If liq- uid hydrocarbons are therefore t o play any kind of role in a sustain- able energy system, the problem that must be solved is that of re- cycling carbon - of extracting carbon dioxide from the atmosphere and combining it, rather than fossil fuels, with hydrogen t o produce liquid hydrocarbons. The simplest way t o exploit the carbon reser- voir in the atmosphere is t o use the plants that are already extracting carbon dioxide continuously. Much technology for converting bio- mass into liquid fuels has been developed, and here again, external sources of hydrogen and heat can help conserve the carbon resource.
A more direct way t o conserve the carbon atoms incorporated in synthetic hydrocarbons is to capture immediately the combustion gases released when the fuel is burned and then recycle them.
These are only suggestions. They are motivated by the effort t o fill a crucial gap revealed by the analyses of the last three sections, the gap between the immediate but apparently persistent demand for liquid hydrocarbons and the supply of heat and electricity that could be produced by the only possible sustainable energy sources:
those based on nuclear and solar technologies. The central notion in filling this gap is the importance of using the world's store of carbon atoms prudently. The basic ideas are familiar - recycling and using coal as a bridge t o the future. Only the scale is different:
the continual recycling of the world's supply of carbon atoms for- ever - and the investment of our coal resources in building not only a bridge to the 2 1st century, but quite possibly a bridge extending all the way to the 22nd century.
Only the outlines of how the world's energy system might ultimately develop can be sketched here. How they might be filled in must be left for subsequent analysts, and whether the course suggested here will be pursued at all must be left for subsequent generations. It is clear, however, that building a sustainable energy system will require the continual expansion of the world's produc- tive capabilities - in all dimensions. This is why it is so important that the eight billion or so people living in 2030 be rich, not poor, and much richer than today. That they be rich does not mean that they must discover some new treasure of physical resources that has been completely overlooked in the study reported here;it means instead that they and their predecessors will have learned how to use
the limited resources available more efficiently, more ingeniously, more productively. The process is continuous, and it is cumulative.
Appendix
Forms of energy
This report distinguishes between primary, secondary, final, and useful energy.
Primary energy refers t o energy in the form of natural re- sources. Examples are oil, natural gas, freshly mined coal, water flowing over a dam, and natural uranium.
Secondary energy forms are those t o which primary energy is usually converted in order t o be transported t o consumers. Exam- ples are gasoline, electricity, charcoal, sorted and graded coal, and cut and split firewood. Note that a resource such as natural gas can be considered both as a form of primary energy and a form of sec- ondary energy. The form in which it appears in nature is also the form in which it is transported to consumers.
Final energy refers to the forms in which energy is consumed once it has reached the user - the energy in a motor, a stove, a computer, o r a lightbulb. Once again it is worth noting that natural gas can also be considered a form of final energy.
Useful energy is the energy ultimately stored in a product or used for a service - a well-lit room, a moving car, or a telephone conversation.
Energy units
There are two fundamental types of energy units: those that describe amounts of energy, and those that describe rates at which energy is supplied, converted, transported, o r used. In the first cat- egory are units such as barrels of oil equivalent (boe), tons of coal equivalent (tce), o r kilowatt-hours of electricity (kWhr(e)). In the second category are million barrels of oil per day (mbd), tons of
coal equivalent per year (tcelyr), and kilowatt-hours of electricity per year (kWhr(e)/yr).
The unit used most commonly in this report for amounts of energy is the terawatt-year (TWyr). One terawatt-year (1 TWyr) is equal t o 1,000,000,000,000 watt-years (which can also be written as 1012 Wyr). It is therefore also equal t o 1,000,000,000 kilowatt- years ( l o 9 kWyr) or 1,000,000 megawatt-years ( l o 6 MWyr) or 1000 gigawatt-years ( 1 O3 GWyr).
The unit most commonly used here for rates of energy supply, conversion, transportation, and use is the terawatt-year per year (TWyr/yr). The unit terawatt (TW), which is sometimes used in place of terawatt-year per year (TWyr/yr), is in this report reserved for the description of the capacities of various energy conversion facilities. Thus the capacity of an electricity generating station might be listed as 1000 MW(e) (= 0.001 TW(e)). Since energy con- version facilities seldom operate at their installed capacity all year long, their ratings in TW or GW or MW will differ from the actual rate at which they convert energy, as expressed in TWyr/yr, GWyr/yr, o r MWyr/yr.
Some particularly useful conversion factors are
1 TWyr = 3 0 quads (30 X 1015 British thermal units [BTU] ) 1 TWyr = 3 0 trillion cubic feet of gas
(30 X 1012 ft3 of gas)
1 TWyr = 1.1 billion metric tons of coal equivalent (1.1 X l o 9 tce)
1 TWyr = 5.2 billion barrels of oil equivalent (5.2 X l o 9 boe)
Elasticity
The final energy t o gross domestic product elasticity e is de- fined as follows: if E(t) is the amount of final energy consumed at time r and G(t) is the gross domestic product at time t, then, for
t ,
<
t,, the elasticity e is the exponent in this equation:SELECTED ENERGY-RELATED PUBLICATIONS BY IlASA
ENERGY IN A FINITE WORLD: PATHS TO A SUSTAINABLE FUTURE Report by the Energy Systems Program Group of IIASA, Wolf Hafele, Program Leader. 225 pp. $16.50.
Written by Jeanne Anderer with Alan McDonald and NebojXa NakiCenoviC
ENERGY IN A FINITE WORLD: A GLOBAL SYSTEMS ANALYSIS Report by the Energy Systems Program Group of IIASA, Wolf Hafele, Program Leader. 83 7 pp. $45.00.
Both of the above volumes are available from Ballinger Publishing Company, 17 Dunster Street, Cambridge, Massachusetts 02 138, USA.
The other publications listed here are divided into five subject areas:
1 Global, regional, and sectoral energy models - whether for energy demand, energy supply and conversion, or for economic, resource, or environmental impacts of energy technologies.
2 The analysis of different energy sources - i.e., fossil fuels, nuclear power, solar power and other renewables - and the conversion, storage, and transportation technologies associated with them.
3 The analysis of energy demand patterns.
4 Environmental and safety risks o f energy technologies.
5 The analysis of total energy systems and energy strategies including all the dimensions of the first four categories taken together.
Books i n the International Series on Applied Systems Analysis (Wiley) can be ordered from John Wiley & Sons Ltd., Baffins Lane, Chichester, Sussex PO19 2UD. United Kingdom.
Books published by Pergamon Press can be ordered from Pergamon Press Ltd., Heading- ton Hill Hall,OxfordOX3 OBW, United Kingdom, or Pergamon Press, Inc., Fairview Park, Elmsford, N.Y. 10523. USA.
All other publications can be ordered from the Publications Department, IIASA, A-2361 Laxenburg, Austria.
1. Energy Models
RR-80-31. The IlASA Set of Energy Models: Its Design and Application. P.S. Basile.
December 1980.65 pp. $7.00
RR-78-17. MEDEE-2: A Model for Long-Term Energy Demand Evaluation. B. Lapillonne.
November 1978.45 pp. $6.00
RR-798. The Economic IMPACT Model. Yu.D. Kononov, A. Por. October 1979.72 pp.
$8.50
The Energy Supply Model MESSAGE. L. Schrattenholzer. 1981. (Forthcoming Research Report.)
A Long-Term Macroeconomic Equilibrium Model for the European Community. H.H.
Rogner. 1981. (Forthcoming Research Report.)
Modeling of Large-Scale Energy Systems. Proceedings of the IIASA-IFAC Symposium on Modeling of Large-Scale Energy Systems. W. Hafele, Editor, L.K. Kirchmayer, Asso- ciate Editor. 1981.462 pp. (Available from Pergamon Press.) $72.00
CP-74-3. Proceedingsof IlASAWorking Seminar on Energy Modeling, May 28-29, 1974.
May 1974.342 pp. $13.00
Beaujean, J.-P. Charpentier, Editors. December 1976.33 pp. $4.00
RR-78-12. A Review of Energy Models: No. 4 - July 1978. J.-M. Beaujean, J.-P. Char- pentier, Editors. July 1978.48 pp. $6.00
CP-77-2. Methodsof Systems Analysis for Long-Term Energy Development. Yu.D. Kono- nov, Editor. March 1977.38 pp. $5.00
RR-76-11. Modeling of the Influence of Energy Development on Different Branches o f the National Economy. Yu.D. Kononov. October 1976. 15 pp. (Microfiche only.) $4.00
RR-79-13. The Dynamics of Energy Systemsand the Logistic Substitution Model. C. Mar- chetti, N. NakikenoviC. December 1979.73 pp. $8.50
RR-79-12. Software Package for the Logistic Substitution Model. N. NakikenoviC. Decem- ber 1979.69 pp. $7.00
RR-77-22. Macrodynamics of Technological Change: Market Penetration by New Tech- nologies. V. Peterka. November 1977. 128 pp. (Microfiche only.)
RR-80-28. Market Substitution Models and Economic Parameters. 0.1. Spinrad. July 1980.26 pp. $4.00
Economic Evolutions and Their Resilience: A Model. M. Breitenecker, H.R. Griimm.
1981. (Forthcoming Research Report.)
Dynamic Linear Programming Models o f Energy, Resources, and Economy Development Systems. A Propoi, I. Zimin. 1981. (Forthcoming Research Report.)
2. Energy Sources
North Sea Oil. Resource Requirements for Development of the U.K. Sector. J.K. Klitz.
1980. 260 pp. (Available from Pergamon Press.) $36.00
Future Supply of Nature-Made Petroleum and Gas. R. Meyer, Editor. IIASA, UNITAR.
1977. 1046 pp. (Available from Pergamon Press.) Hard cover $60.00, soft cover $40.00 Conventional and Unconventional World Gas Resources. M. Grenon, C. Delahaye, Editors.
1981. (Forthcoming from Pergamon Press.)
Future Coal Supply for the World Energy Balance. M. Grenon, Editor. 1979. 720 pp.
(Available from Pergamon Press.) $90.00
RR-80-20. Energy and Entropy Fluxes in Coal Gasification and Liquefaction Processes.
H. Voigt. April 1980. 25 pp. $4.00
CP-77-5. Medium-Term Aspects of a Coal Revival: Two Case Studies. Report of the IlASA Coal Task Force. W. Sassin, F. Hoffmann, M. Sadnicki, Editors. August 1977.90 pp. $8.50 Methods and Models for Assessing Energy Resources. M. Grenon. Editor. 1979.605 pp.
(Available from Pergamon Press.) $75.00
RM-78-35. On Fossil Fuel Reserves and Resources. M. Grenon. June 1978.37 pp. $5.00 RR-75-2. Studies on Energy Resources i n the IIASA Energy Project. M. Grenon. January 1975.42 pp. (Microfiche only.) $4.00
RR-75-38. Transport and Storage of Energy. C. Marchetti. November 1975. 33 pp. $5.00
R R - 7 7 8 . Fusion and Fast Breeder Reactors. W. Hafele, J.P. Holdren, G. Kessler, G.L.
Kulcinksi. July 1977. 506 pp. $24.00
RR-75-36. Considerations on the Large-Scale Development of Nuclear Fuel Cycles. R.
Avenhaus, W. Hafele, P.E. McGrath. October 1975. 98 pp. $8.50
RR-75-40. Application of Nuclear Power Other Than for Electricity Generation. W. Hafele, W. Sassin. November 1975. 120 pp. (Microfiche only .) $6.00
RR-73-14. Hypotheticality and the New Challenges: The Pathfinder Role of Nuclear Energy. W. Hifele. December 1973.20 pp. $4.00
RR-73-5. The Fast Breeder as a Cornerstone for Future Large Supplies of Energy. W.
Hafele. September 1973.60 pp. $7.00
The Possible Share of Soft, Decentralized Renewables in Meeting the Future Energy Demands of Developing Regions. A.M. Khan. 1981. [Forthcoming Research Report.) RM-77-26. Mobilization and Impacts of Bio-Gas Technologies. J.K. Parikh, K.S. Parikh.
November 1977.19 pp. $3.00
RR-81-5. The Helios Strategy: A Heretical View of the Potential Role of Solar Energy in the Future of a Small Planet. J.M. Weingart. Reprinted from Technological Forecasting and Social Change, Volume 12 (4), pp. 273-315 (1978)
RR-77-20. Power from Glaciers: The Hydropower Potential of Greenland's Glacial Waters.
R. Partl. November 1977. 52 pp. $7.00
RR-76-7. On Hydrogen and Energy Systems. C. Marchetti. March 1976. 10 pp. (Micro- fiche only.) $4.00
RM-78-62. Genetic Engineering and the Energy System: How to Make Ends Meet. C.
Marchetti. December 1978. 11 pp. $4.00
3. Energy Demand
Evolution of Future Energy Demand Till 2030 in Different World Regions: An Assess- ment Made for the Two IIASA Scenarios. A.M. Khan, A. Holzl. 1981. (Forthcoming Research Report.)
RR-79-15. Simulation of Macroeconomic Scenarios to Assess the Energy Demand for India (SIMA). J.K. Parikh, K.S. Parikh. December 1979. 59 pp. $7.00
The growth of Energy Consumption and Prices in the USA, FRG, France and the UK, 1950-1979. C.P. Doblin. 1981. (Forthcoming Research Report.)
RM-78-46. Energy Demand by US Manufacturing Industries. C.P. Doblin. September 1978.43 pp. $6.00
RM-76-43. German Democratic Republic: Energy Demand Data. C.P. Doblin. June 1976.
29 pp. (Microfiche only.) $4.00
.CP-76-1. Proceedings of the Workshop on Energy Demand. W.D. Nordhaus, Editor. Jan- uary 1976.880 pp. (Microfiche only .) $16.00
RM-76-18. Data Provided for W.D. Nordhaus Study: The Demand for Energy: An Inter- national Perspective. C.P. Doblin. March 1976. 72 pp. $8.50
4. Environmental and Safety Risks
Climate and Energy Systems. J. Jiger. 1981. (Forthcoming.)
Climatic Constraints and Human Activities. Task Force on the Nature of Climate and Society Research, February 4-6,1980. J. H.Ausube1,A.K. Biswas, Editors. 1980. 214 pp.
(Available from Pergamon Press.) $30.00
CP-77-9. Climate and Solar Energy Conversion: Proceedings of a I IASAWorkshop, Decern- ber 8-10,1976. J. Williams, G. Kromer, J.M. Weingart, Editors. December 1977.
Carbon Dioxide, Climate and Society. J. Williams, Editor. 1978. 332 pp. (Available from Pergamon Press.) $30.00
RM-76-17. On Geoengineering and the CO, Problem. C. Marchetti. March 1976. 13 pp.
$4.00
RR-75-45. The Carbon Cycle of the Earth - A Material Balance Approach. R. Avenhaus, G. Hartmann. December 1975. 27 pp. $4.00
RR-80-30. Possible Climatic Consequences of a Man-Made Global Warming. H. Flohn.
December 1980.92 pp. $8.50
RRIO-21. The Impact of Waste Heat Release on Climate: Experiments with a General Circulation Model. J. Williams, G. Kromer, A. Gilchrist. Reprinted from Journal of Applied Meteorology, Volume 18, pp. 1501-1 511 (1979)
RRIO-15. A Comparative Study,of Public Belief? About Five Energy Systems. K. Thomas, D. Mauer, M. Fishbein, H.J. Otway, R. Hinkle, D. Simpson. April 1980.32 pp. $5.00 RRIO-25. The Value of Human Life: A Review of the Models. J. Linnerooth. Reprinted from Economic Enquiry, Volume 17, pp. 52-74 (1979)
RM-78-69. What Are We Talking About When We Talk About "Risk"? A Critical Survey of Risk and Risk Preference Theories. R.E. Schaefer. December 1978. 54 pp. $7.00
RR-7514. Avo~dance Response to the Risk Environment: A Cross-Cultural Comparison.
H.J. Otway, R. Maderthaner, G. Guttmann. June 1975. 29 pp. (M~crofiche only.) $4.00
RR-80-18. Nuclear Energy: The Accuracy of Policy Makers' Perceptions of Public Beliefs.
K. Thomas, E. Swaton, M. Fishbein, H.J. Otway. April 1980. 37 pp. $5.00
Material Accountability: Theory, Verification, and Applications. R. Avenhaus. 1977.
188 pp. (Available from John Wiley and Sons Ltd.) $32.85
RR-76-19. The WELMM Approach to Energy Strategies and Options. M. Grenon, B.
Lapillone. December 1976.41 pp. $6.00
RR-76-13. Environmental Impacts of Electrical Generation: A Systemwide Approach.
W.K. Foell, W.A. Buehring. April 1976. 32 pp. (Microfiche only.) $4.00
5. Energy Systems and Energy Strategies
RM-78-18. Energy Systems - The Broader Context. C. Marchetti. April 1978. 14 pp.
RR-73-1. Energy Systems. W. Hafele. July 1973.45 pp. (Microfiche only.) $4.00
RR-78-7. On 10": ACheck on Earth Carrying Capacity for Man. C. Marchetti. May 1978.
I I pp. $4.00
RR-76-5. Definitions of Resilience. H.R. Grumm March 1976. 20 pp. (M~crofiche only.)
$4.00
Management of EnergyIEnvironment Systems: Methods and Case Studies. W.K. Foell, Editor. 1979.488 pp. (Available from John Wiley and Sons Ltd.) $39.50
RR-79-10. On Energy and Agriculture: From Hunting-Gathering to Landless Farming.
C. Marchetti. December 1979. 13 pp. $4.00
RR-74-20. Future Energy Resources. W. Hafele. November 1974. 28 pp. (Microfiche
RR-74-20. Future Energy Resources. W. Hafele. November 1974. 28 pp. (Microfiche