Formal Launch Scheduled for May, 2005. 
Feedback Welcomed
Main Menu
Scale Project Home
Energy2022-Aug-15  9:14:21 PM

1. The history of civilization is also the history of the human use of energy. Both progressed from human muscle power to wood for fire in pre-historic times; to animal muscle power made possible by agricultural surpluses; to water, wind and steam in the pre-industrial era; and to coal, oil, gas and electricity in the industrial period. Up to the fossil fuel era, human energy use involved exploiting natural energy flows, in photosynthesis, water flows and food chains.

2. Prior to the Industrial Revolution, at least 70% of all work was done by human muscle power; most of the rest was done by domesticated animals.

3. More energy was used by humans in the 20th century than in all of previous human history. This was largely due to the development of various technologies that allowed for the widespread exploitation of fossil fuels –coal, oil and natural gas.

4. Fossil fuels represent a unique energy resource – one which was created by natural processes over hundreds of millions of years; which are highly concentrated; and easily transportable. Human use will deplete these unique resources significantly over a short time span of approximately three centuries (1850 to 2150).

5. On a global scale, the main energy sources are approximately: oil 35%; coal 23 %; natural gas 21%; biomass and waste 10%; nuclear 6%; hydro 2%; with wind, solar, and geothermal together making up only 2%. Of these sources, over 80% are non-renewable and in decline. By the end of this century it is unlikely these sources will be able to provide even 20% of global energy needs.

6. Peak oil production refers to the year in which global oil production will reach its peak, and then begin to decline. This will likely occur when about half the world''s oil is used, after which its increasing scarcity will lead to dramatically increased prices for oil. Global peak oil production is thought most likely to occur sometime in the next decade, although it should be noted that forecasts of energy use are notoriously unreliable.

7. All of the non-renewable energy sources upon which our civilization currently relies, may reach their peak production capacity sometime in the present century, with the possible exception of coal. It is questionable whether renewable technologies will be capable of completely making up for the decline in fossil fuels, let alone provide additional growth.

8. The number of new mega oil projects (those with reserves of at least 500 million barrels, and capable of producing at least 100,000 barrels a day) expected to come onstream over the next few years is declining:

  • In 2005 18 mega projects expected
  • In 2006 11 expected
  • In 2007 3 expected
  • In 2008 3 expected
9. Future oil production capacity is not expected to meet the increase in demand. Most new projects are from technically more difficult and therefore more costly (in both energy and financial terms) “unconventional” sources (tar sands, offshore in deep oceans, oil shale, in arctic areas).

10. Since the “oil crisis” of the late 1970’s extensive exploration of potential oil fields has occurred, much of it using sophisticated new technologies. These meager results are confirmation that there are unlikely to be more than a very few large fields left to discover.

11. It takes energy to make energy. For every unit of energy used to find, extract, refine and deliver energy to end users, fewer and fewer units of energy will be produced. This energy return on investment (or EROI) is declining as we move from conventional to nonconventional sources of oil and gas, and will decline even further as we move to renewables.

12. Global demand for energy is expected to rise over the coming decades by 1.5% per year. At this rate global energy demands would double between 2000 and 2035, and treble by 2055. The greater the increase in demand, the sooner peak production for all non-renewable energy sources will occur. Declining demand for non-renewable energy sources would prolong their availability.

13. Use of energy in the 20th century has been concentrated in a few nations, representing a small portion of the earth’s population. The seven largest economies at the end of the 20th century (with 10% of the global population) used about 45% of the total primary energy supply. Approximately 2 billion people worldwide do not have access to electricity.

14. Per capita energy consumption is approximately 1300% higher in North America than in Southeast Asia. The average North American’s annual energy consumption is equivalent to having 75 human slaves.

15. Energy for transportation is the biggest user of petroleum, and the sector where demand is increasing most rapidly. Air transportation is particularly dependent on oil and therefore particularly vulnerable. Whenever the anticipated oil peak occurs, it will have an especially dramatic impact on this and related sectors.

16. A variety of technical and financial challenges will need to be overcome if renewable energy resources are to provide anything like the anticipated demands based on current patterns of consumption:

  • 10,000 more of the largest nuclear reactors would be needed to replace current levels of fossil fuel use (safety and disposal concerns may eliminate this option altogether)
  • use of all remaining coal and other fossil fuels will likely trigger severe climate change
  • direct solar is limited by the rate of energy emitted by the sun, its low concentration on earth, and its relatively low energy return on investment
  • wind is limited in terms of location
  • use of biomass will be competing for agricultural land with growing global food requirements
  • hydrogen is not a fuel but a carrier, and itself requires energy to produce. Clean and safe production will be a significant challenge.
  • hydro, wave/tidal and geothermal are too limited geographically.
17. Conservation and increased energy efficiencies offer important opportunities for meeting global energy needs. Currently, energy efficiency on a global scale (the amount of energy actually used to do work as a portion of the amount consumed) is approximately 37%. A variety of technical and social strategies will be required to reduce overall energy demand.

18. A successful transition from non-renewable to renewable fuel sources by the end of this century may require a dramatic reduction in global energy use. However, it may be possible to maintain a desirable quality of life for the world''s population with the per capita supply then available, provided we learn to reduce our expectations.


Exceeding Maximum Sustainable Scale Maximum sustainable scale regarding energy use has to do with how much energy is being used in the global economy relative to how much is available and being renewed, and the impact of its use on ecosystem integrity. In considering maximum sustainable scale for global energy use, it is helpful to distinguish between renewable and non-renewable energy sources.

Non-renewable Resources. Maximum sustainable scale for non-renewable energy sources is zero because there is virtually a zero rate of replenishment of these unique resources. [Note: this does not mean we shouldn’t use any nonrenewable resources, but that we should be investing in substitutes. This issues s b addressed in the section on policy implications of energy use ]

Over 80% our civilization’s global industrial energy consumption is currently dependent on unique non-renewable fuels. Oil and natural gas production may reach their peak levels sometime early in the present century; some estimates anticipate peak oil production as early as 2007. In addition, use of these remaining fossil fuels may be foreshortened by the potentially severe impact their continued emissions would have on global climate stability, especially if we rely on the vast amounts of coal still available (see Climate Change).

Non-renewable fuel sources for nuclear fission reactors (the current technologies) appear to be abundant, but only if the nuclear industry does not expand significantly. Safety concerns alos make this an uncertain substitute for fossil fuels. Sources for nuclear fusion reactions are said to be “inexhaustible,” but nuclear fusion is many decades away from commercial reality, at best, and the remaining technical challenges are considerable. Nuclear technologies without radioactive waste are a possible, but distant, option.

The present level of demand for energy is expected to increase by at least 1.5 to 2% annually for the next several decades. At these levels of increasing demand, the most desirable non-renewable sources of energy upon which our modern civilization is based (gas and oil) are unlikely to be available. What gas or oil remain in the ground may be either unrecoverable or uneconomic before the end of this century, if not considerably sooner.

Renewable Resources. Maximum sustainable scale for renewable energy resources is currently unknown. At present, less than 20 % of global energy consumption uses renewable energy sources – hydro electric, biomass, solar, wind and geothermal. Considerable technical, financial and environmental challenges must be overcome before any of these renewable sources could replace the energy output of fossil fuels, and none would be as flexible as petroleum. In addition, most renewable energy sources appear to have a low energy return on investment.

Solar energy is the primary renewable resource. How much of what reaches the earth is usable will depend on whether passive or active solar technologies are used; the efficiencies achieved by further research; and the infrastructure built to support it. The total amount of solar energy reaching the earth''s surface is immense, but it is also dilute. Concentrating it for human use requires energy. And the amount of land that can be allocated for collecting solar energy will be competing with other land uses.

An immense supply of solar energy is available for the next few billion years, but it is a dilute energy source, and one which is not evenly distributed across the globe. Increased efficiencies for active solar technologies may be possible, although current research seems have reached a plateau. Engineering studies have concluded that sufficient surface areas (eg on roof tops) are available in most industrialized countries to generate up to half of current electricity needs.

Wind power is perhaps the promising source of renewable energy, and is one of the fastest growing alternatives. Efficiencies are improving, making wind energy a major future resource. Use of wind turbines is in many cases compatible with agricultural land uses, and is also feasible offshore. Aesthetic concerns have been an obstacle in some areas, but wind''s intermittency has been the most serious drawback.

New hydro electric dams are being built, often at great environmental and social costs. Several major untapped river systems have the potential for generating additional power. At the same time some older dams are being dismantled, largely for environmental reasons. Many of those that are still operating will eventually become nonfunctional due to siltation. The unprecedented task of refurbishing such large dams would require enormous financial, technical, material and energy resources. Opportunities for small scale hydro electric projects still exist. Large increases from this renewable source are unlikely.

Biomass is currently the most widely used renewable energy source. Wood, waste (sometimes converted to methane), and grains (converted to ethanol) are the main sources of biofuels. Care must be exercised in any expansion plans for biofuels. Dedicating forests or crop lands to biofuel production may compete with the increasingly important role in carbon sequestration, and the need for agricultural land to feed a growing global population. The latter will be especially important as soil fertility continues to decline, and as petroleum is less available as a source for chemical fertilizers. Furthermore, the net gain in energy from biofuels can be small(often with an EROI of less than 2:1), depending on source and local environmental conditions. On the other hand, tree plantations may generate an energy return on investment as high as 40:1.

Geothermal power is abundant at the core of the earth, but is near enough to the surface to be useable in only a few locations around the globe, such as Iceland. While some expansion of geothermal power can be expected, it is unlikely to be a major substitute for fossil fuels.

Tidal and wave sources of energy are in early stages of development and it is unclear at this point what future roles they might play in replacing fossil fuels.

Given the strengths and limitations of these various renewable energy sources, many knowledgeable analysts suggest that multiple sources will be the way of the future. However, each of these separate sources will require its own expensive infrastructure. The dismantling of current infrastructures, and in particular the development of new infrastructures, will themselves consume considerable amounts of materials and energy. Furthermore, such infrastructure will take many years to design, develop and put in place.

It is impossible to identify the total amount of energy resources that might be available from renewable resources in 50 or 100 years. Research and development is in its early stages for several of these renewable energy technologies. And it is at least theoretically possible that new technologies could be discovered which radically increase efficiency. But even renewable energy sources are finite, and some analysts have suggested that the growing global demand may not be met by these renewable sources once fossil fuels are exhausted. [quote by Odum re renewables only being able to meet 2/3 of today’s energy needs] [ WWI report draws opposite conclusion????]

In summary, a clear conclusion from these considerations is that civilization’s use of fossil fuels is not sustainable from either a source or sink perspective. The more desirable non-renewable energy resources will be exhausted by the middle or end of the 21st century, depending upon demand and transition to renewable substitutes. More importantly, the peak production periods for gas and oil, the more desirable fossil fuels, may begin very soon, leading to significant price increases. The renewable energy infrastructures required to replace them are not yet a priority for governments around the world. In addition, continued use of fossil fuels will threaten global climate stability.

A more tentative conclusion of this brief review is that the global demand for energy may well exceed the amount that it is feasible to extract from renewable resources, in a timely or cost-effective fashion. While technological innovations may continue increasing the efficiencies of renewable energy sources, the total amounts of energy these sources can produce will be constrained by both biophysical and financial limits. These limitations have to do with both resource and sink limitations. Nonetheless, the impact of various energy uses on ecosystems will be an ongoing concern (eg. climate stability, ozone depletion, biodiversity loss, etc). Whether or not renewable energy sources are sustainable will depend on the level of demand made upon these resources, and the specific technologies used to exploit them.

Maximum Scale Maximum scale for energy use is defined as the level of material throughput in the global economy that would trigger the collapse of the biophysical systems that maintain the production of energy sources. It is unlikely we will approach this extreme limit for all energy sources, but it is nonetheless useful to consider this limit to ensure we avoid it. Maximum scale for global energy may also be considered in terms of renewable and non-renewable energy resources.

Non-renewable Resources Whether maximum scale is reached for non-renewable resources will depend on how future demands are managed, and how quickly renewable technologies come into play. There is little doubt that at current and anticipated rates of consumption, the more desirable non-renewable fuels in use today will be exhausted well before the end of the next century – maximum scale for these resources will be exceeded when this occurs. While the depletion of these resources will have a dramatic effect on energy use, equally dramatic impacts will occur for agriculture (which rely on petroleum based fertilizers and herbicides), and a host of other petroleum based products – including pharmaceuticals. All will become more expensive. Climate stability will also be dramatically affected.

Renewable Resources Maximum scale for renewable energy would be exceeded only if the level of material throughput required for renewable energy use caused the collapse of the ecosystems which provide either the resource input, the materials for the necessary infrastructure, or the sink capacities involved. The potential for approaching maximum scale for renewable energy use will differ for each of the renewable sources of energy.

Maximum scale for solar energy cannot be exceeded because of the nature of these renewable sources. No amount of solar energy use will affect the energy output of the sun. However, the technologies used to manufacture photovoltaic cells, and the uses to which the energy might be put, could create environmental challenges. In addition, the return per unit area is low, and any appropriation of solar energy for human use will no longer be available for natural systems. These are issues we have hardly begun to understand.

Use of wood as a biofuel would exceed maximum scale if forestry practices destroyed the forest’s capacity to regenerate. In the absence of fossil fuels and adequate substitutes, short term economic interests could lead to destruction of forests’ regenerative capacities. Properly managed, wood as a source of biofuel, with an EROI of 30 or 40:1, could be a significant contributor to a sustainable energy regime. However, large increases from this source are unlikely because of competing needs for agricultural and other ecosystem services from the land available.

The fact that some credible analysts suggest the global demand for energy will in fact exceed what is available from renewable resources is cause for reflection about our global energy efficiency, the uses to which we put energy, and the distribution of energy among the nations and people of the planet. Even if renewable sources could meet growing energy demands, large supplies of cheap renewable energies would only encourage more material throughput. Such continued increases in throughput would have significant negative impacts on ecosystem functioning regardless of the source of energy used. We are reaching the point where material throughput must be managed at levels which sustain critical ecosystems functions.

Optimal Scale Optimal scale for energy use is that level which is less than or equal to the amount which is maximally sustainable, and where the social and environmental costs are less than the benefits. If the analysts who suggest that renewable resources are not likely to meet global energy demands are correct, then the issue of optimal scale will involve determining what levels of consumption are physically possible without degrading or endangering critical ecosystem services, and how to distribute energy fairly. If significant increases in amounts of renewable energy are possible, we will still be faced with the impact on overall levels of material throughput.

A significant advantage of renewable energy sources is that they have the potential to be available for a very long time. Solar energy will continue to be emitted regardless of how much is used on earth. However, it is possible for the use of renewable energy sources to create significant environmental and social problems, depending on the materials used in the creation of renewable energy technologies and infrastructures, and the fairness of distribution. It is also possible that excessive use of some renewable sources (eg biofuels) could exceed maximum scale. The process of determining optimal scale for energy use will ideally address these issues of ecological sustainability and social justice for both current and future generations.

A Key Role for Conservation. Our technologies and practices are very wasteful of energy. Considerable reductions in energy consumption are possible while meeting human needs. Conservation comes from either reduction in demand or increased efficiencies. While increased efficiencies are important, they often lead to an overall increase in energy use (because it is cheaper, more people use the technology that is more efficient, and/or because those that use the technology use it more often). Overall energy use is highly correlated with material throughput, and therefore with impacts on ecosystems. In addition to encouraging increased efficiencies in our technologies, we also need to achieve overall reduction in energy demand to achieve sustainable scale, while meeting the needs of a growing global population.

A Hopeful Note? Energy use is higly connected to quality of life, but the relationship is not perfect. Quality of life and energy use are highly correlated up to a certain point (approximately 50-70 GJ/capita). Nations with this much energy use enjoy fairly high levels of life expectancy, food availability, educational opportunities, health standards, and political freedoms. Further, but diminishing, returns in these well-being indicators occur up to approximately 100 GJ/capita. Energy consumption beyond this level is simply wasteful, adding little or nothing to human well-being. Currently, many affluent nations consume energy in excess of 300 GJ/capita.

From a scale perspective the issue is not per capita energy consumption, but the absolute quantity (and quality)of energy consumed. A major social challenge in the current century will be whether the inevitable transition to renewable sources can also provide sufficient energy for the well-being of every person on the planet.

About Us
More Info
© 2003 Santa-Barbara Family Foundation