Pac. Ecologist: Global Energy – How much Remains?

PETER NORTH calculates how long the world’s energy supplies can continue to support the existing pattern of 2% pa increase in energy consumption. The figures suggest increasing energy consumption is unlikely to be sustainable for much longer. So, what next for energy? One option to tackle an emerging scenario of resource shortages is to increase development of renewable energy technologies. A concurrent approach is to conserve energy resources while we still have them. Either way we need to get more energy conscious than we are under the existing economic system that encourages endless GDP, population growth and associated environmental destruction.

Published in late summer 2005 issue of Pacific Ecologist - with cartoons and text highlights - available from PIRM. PO Box 12125, Wellington or pirmeditor@paradise.net.nz - Part of a 72-page issue covering energy, food security, water crisis & pathways to sustainable societies.

A popular Saudi Arabian proverb runs: “My grandfather rode a camel, my father drove a car, I fly a jet plane, my son will ride a camel.” According to this view from the oil capital of the world, the oil bonanza on which the world has been having a long free lunch has to end sometime. If the proverb holds true, after the hydrocarbon era has run its course, the future will look much like the past when much of the human race lived on the renewable energy of sunshine and firewood, the rich got around on domestic animals and the poor walked.

Energy optimists disagree with this view of the future, claiming plenty of oil lies underground somewhere waiting to be tapped. In any case, they point out, oil is but one energy source. In a world of boundless resources, when oil supplies run down, we merely switch to other forms of energy. As these are used up too, prices will rise and the market will deliver us further substitutes. And thus the present economy of endless growth that we have got to know and love can stretch indefinitely into the future. Which of these two visions of the energy future is likely to be more accurate?

How much energy is left?

If we look at the total energy picture and consider all currently known energy sources, and perhaps speculate about a few that are only thought about, we can ask: how much energy is left in the world? How long will it last? And once used, can it be replaced by something else?

Energy resources fall into two broad categories: renewable and non-renewable. Ultimately the planet’s energy comes from three sources: the sun, energy of radioactivity of Earth’s creation material, or momentum energy of objects in the solar system. In the very long term, none of this energy is unlimited. But for the purposes of human use, incident solar energy in its various forms such as biomass, hydro, photovoltaic cells, wave power and wind power can be considered sources of renewable energy, as can geothermal energy from hot radioactive creation material and tidal energy from the momentum of the Earth/Moon/Sun system. The major non-renewable energy sources are hydrocarbons – oil, natural gas and coal – which can be regarded as stored solar energy from photosynthesis of millions of years past, and nuclear materials such as uranium.

Currently most of the world’s energy comes from non-renewable sources. In 2001, the global energy split was as follows:

A common unit of Energy Accounting

To complicate the picture a little, the world uses all sorts of disparate units to report its energy consumption and production. Units tend to be traditional to particular industries. Oil is generally measured in barrels (equivalent to 42 US gallons). Natural gas is measured in cubic feet (at ambient temperature and one atmosphere).Coal is measured in tones. Uranium is measured in tonnes of natural uranium. Energy in global quantities is mostly reported in “Quads” – a rather odd unit defined as a quadrillion (10¹⁵) Btus (British Thermal Units).

For an exercise like this which seeks to contrast, compare and aggregate energy supply from its various sources, energy measured in its different ways needs to be reduced to a common unit. Since the world outside the US has adopted the metric system, I use the fundamental metric unit for energy – the Joule. For convenience the numbers are expressed in scientific notation throughout (ten to the power of something) because many of the numbers are so large.

Making an Estimate

For the purposes of making a first approximation of the total non-renewable energy endowment, let’s suppose, when one non-renewable energy resource is in decline another can be substituted. If this is assumed, we can convert the known reserves of energy resources into a single common energy unit and thereby approximate the total amount of useable energy on the planet. Depending on what we assume about future demand, we can then make a first order estimate on how likely ALL non-renewable resources are likely to last

To do this, we need to know two things: the energy content of non-renewable energy resources and the physical quantities of the remaining resources. Neither of these can be estimated with complete accuracy. But the first is certainly easier than the second!

Energy Content of Different Resources

The following table, drawn from various sources as noted, summarizes typical energy contents for various resources. These figures are used in later calculations of total energy available, and the time to go to energy exhaustion. The energy content of broad categories of resources varies, to some degree, with the quality of the deposit. For the purposes of a first approximation, these differences will be ignored for oil and gas, but included for coal, since the difference in energy content for different grades of coal is significant.

Quantities of Remaining Resources

Estimating Earth’s store of energy resources has become a fraught subject in recent times, with a wide range of predictions from politicians, economists and geologists and the like. A key factor in assessing what might or might not be available as a future energy source is how much various low-grade energy assets, such as shale oil, future technology will render commercially viable. Similarly, the cut-off grade of non-renewable resources such as uranium may improve in future years.

Then there is the question whether any “new” non-renewable energy resources are likely to come along to help out the energy supply. Over 60-years-ago, uranium became the last major non-renewable energy resource to be exploited. But in recent times, a case has been made for using methane hydrates found on the ocean floor as an energy resource. Technology to extract methane from methane hydrate on the sea floor appears very difficult in theory, does not presently exist in practice and would carry the risk of releasing massive quantities of methane, a potent greenhouse gas to the atmosphere. In this article, no contribution to future energy has been allowed from methane hydrates. (see book review section, Methane Hydrates, the Clathrate Gun Hypothesis)

The number of estimates of future energy supplies that can be made is the same as the number of assumptions that can be made on the subject. Since room is restricted, this article considers two cases only. The first is based on an average of published data from reputable sources for known existing resources (Case 1). The second includes using lower grade resources, such as shale oil (Case 2). How long energy supplies hold out for these two cases is then calculated based on expectations of what might happen with consumption.
Oil

Estimates of the original global endowment of recoverable reserves of conventional oil (including yet to be discovered oilfields but excluding tar sands and shale oil) range between 2,000 Gigabarrels by people like Campbell and Deffeyes to 2,700 Gigabarrels by the US Department of Energy. Of this original endowment, so far we have used about 1,000 Gigabarrels. The World Oil Journal, estimates about 1,000 Gigabarrels (10¹² barrels) of oil remains to be used. According to the Oil and Gas Journal [2] it is 1,200 Gigabarrels. According to the US Department of Energy it is 1,700 Gigabarrels. In this article, Case 1 will use 1,000 Gb as the oil remaining. Case 2 will use 1,700Gb.

Natural Gas

The current estimate for global reserves of natural gas is around 5.5 x 10¹⁵ cubic feet. [3] This is the figure used for Case 1. While estimates of reserves include a figure for undiscovered resources, historically these have tended to err on the low side. Trainer8 cites figures of 10,000 x 10¹⁵ cubic feet. If we were to take a figure half way between these two, to include an allowance of 50% for gas fields yet to be discovered, the global reserves for natural gas would go to 8.25 x 10¹⁵ cubic feet. This is the figure used for Case 2.

Coal

Based on figures from the World Energy Council (that are broadly supported by a number of other authorities on the subject) reserves of coal for Case 1 are estimated at 1,080 billions of tonnes. [4] For convenience of calculation, coal is divided into two grade categories: bituminous coals and anthracite with a higher energy content and lignite and sub-bituminous coals with a lower energy content. Much higher reserve figures for coal are also cited by some writers. Trainer8 quotes figures of around double that of the World Energy Council. This estimate is taken as Case 2.

Tar Sands

The world has extensive near-surface deposits of tar-sand mixtures which can be used to produce oil. The total amount of tar sands is estimated around 300 Gb oil equivalent. Syncrude in Alberta, Canada is one company already in production on a tar-sands-to-oil project. However exploiting the resource does have some downside from an energy viewpoint. The process liberates tar from sand using steam, which requires considerable energy, estimated to be one third of the energy obtained from the oil the process produces. In addition tar must be hydrogenated to produce oil. Syncrude uses “stranded natural gas” for this purpose (ie natural gas distant from a pipeline). Exploiting tar sand deposits that don’t happen to have a stranded natural gas deposit handy will be a lot more questionable. Case 1 allows for 25% of the energy in tar sands being recovered. Case 2 allows 50%.

Shale Oil

The world also has extensive deposits of shale oil – estimated at 400Gb oil equivalent. The phrase “shale oil” is to a degree a misnomer suggesting this stuff might be more useful than it’s ever likely to be. Shale oil isn’t oil at all. It’s kerogen, which in the normal course of events only becomes oil and gas after residing for a hundred million years or so in the hot underground rocks of Earth’s pressure cooker. No process has yet proved successful in turning shale oil into crude oil, though many companies have tried. Case 1 considers shale oil will never be an energy source. Case 2 allows for 25% of the intrinsic energy of shale oil being someday recoverable.
Uranium

The energy content of the world’s reserves of uranium is an order of magnitude less predictable than energy from fossil fuels. Unlike hydrocarbon deposits, where the oil, gas and coal is extracted with little associated waste matter, the grade of uranium ores varies from high grade ores downward. The “cut-off” grade where mining uranium becomes uneconomic in terms of money depends on the current ore price. The “cut-off” grade in terms of energy depends on the energy needed to extract uranium from low grade ores, compared to the energy produced from the nuclear power plant.

Another complicating factor is that natural uranium exists as two isotopes. Most of the energy from nuclear power stations of current design comes from U-235 which only occurs in uranium ore at a concentration of seven parts per thousand. For most nuclear power station designs, the reactor fuel is “enriched” to around 3-4% U-235. After enrichment, the balance of the non U-235 rich, “depleted” uranium is a radioactive nuisance (though depleted uranium does make excellent bullets.)

Furthermore, it is possible to convert some U-238 into fissionable fuel in “fast breeder” reactors. However fast breeding has proved disappointing technology. Currently the world’s entire stock of fast breeder reactors located in the US, UK, France, Japan and Russia, have been de-commissioned. Not widely realised is that once we have used up the U-235 existing in the world’s supplies of uranium-generating conventional nuclear power, the options for technology like fast breeders will no longer be available since fast breeders need U-235 or plutonium as start-up fuel. If we are to adopt breeder reactions as a solution to a likely future energy crisis, we need to be doing something now. We aren’t. So it probably isn’t going to happen.

Yet further possibilities are using thorium (which like U-235 is fissionable [5] ) and extracting uranium from seawater where it exists in such dilute quantities that the process is most unlikely to be net energy positive (ie we are unlikely to get more energy out of the uranium we succeed in extracting than we put into processing the sea water). Such possibilities outside the present range of power plants of current design are long shots. While the uranium deposits of the world are being mined for energy production, it would be unwise to assume the source of the world’s nuclear power will be fuelled by anything but U-235 energy from uranium ores of a reasonable grade and fissioned in conventional nuclear power plants.

Taking these factors into account, the most commonly reported estimate of global deposits of uranium from ore at present grades that are economical to extract, contain around 3 million tonnes of natural uranium (ie containing nature’s mix of U-235 and U-238 isotopes), [6] with perhaps about the same energy content later available if lower grade ores or thorium reactors prove net energy efficient. Three million tonnes of natural uranium equivalent is assumed for Case 1 and 6 million tonnes for Case 2.

Any allowance for fusion power is excluded. After 50 years of unsuccessful attempts to harness nuclear power through fusing light elements such as hydrogen, helium and lithium, the technology looks unlikely to arrive in time to save us.
Total Non-Renewable Energy

Total global supplies of non-renewable primary energy calculated for both cases are summarised in the tables below:

The Quality of Energy

A final note to the calculation should be added. In this simplified analysis, we have assumed one source of energy can be substituted for another. This is a reasonable first level approximation, but not totally accurate.

Oil, the resource most likely to be in short supply first, is the energy industry’s most versatile product. Of the three phases of matter, liquids are the most convenient to transport and distribute. One of oil’s priceless advantages is that it is a liquid under normal ambient conditions. Next best of the hydrocarbons is natural gas, chemically part of the same series as oil. Broadly speaking, gas will do the same job as oil, but not as easily. Coal, being a solid, is not quite as adaptable as the other hydrocarbons and has lower energy content per unit weight. Coal is most usable in power stations and least usable in airplanes. Uranium energy is less adaptable again. Nuclear power plants for ships and submarines can be built, but don’t expect a nuclear-powered car any time soon.

In addition, the way energy is measured is occasionally a source of confusion. Most measures are expressed as “primary” energy, as the energy released as heat, that can be recovered from the fuel. But under the laws of thermodynamics, only a fraction of this heat can be converted into useful work. Though high-efficiency fuel cells are theoretically practicable, after at least 50 years research, none are yet in large-scale commercial production. Presently most energy sources, if converted to electricity, go through a heat engine of some sort which is likely to be about 35% efficient. At best it takes about 3 kW of primary energy to produce one kW of electricity. Since some fuels produce more usable energy per unit of intrinsic energy than others, energy content isn’t strictly interchangeable between one fuel and the next. And since, in our market-driven consumption-based economy, we are cherry-picking the highest quality fuels first - in particular oil - the first approximate analysis outlined in this article is likely to err on the optimistic side.

How Long might supplies hold out?

Given the present culture of global economic management, it’s almost impossible to make sensible predictions on how long supplies of non-renewable energy will last even if we can get confident about how much energy we have. Two reputable institutions forecasting aspects of mankind’s future for the next century or so are MIT, which published “Limits to Growth, The 30-year update” in 2004, [7] and the “Intergovernmental Panel for Climate Change” (IPCC) which publishes annual updates on its projections for future climate. “Limits for Growth” considered ten “scenarios” for the future. IPCC considered 40 (which it termed “storylines”). [8] Both these bodies produced such a wide range of answers depending on the assumptions they barely qualify as predictions – just possibilities for the future. Both found the most important factor in determining the prospects for aspects of the natural world, in particular climate and resources, was not so much what nature provided but how mankind manages its future in the coming decades.

Currently, society is incredibly wasteful of energy. Using “growth” as the principal measure of progress in the consumer economy is the single most important factor driving mankind into fast exhaustion of its energy resources. Reporting economic performance as increases in GDP - a unit that measures waste as “progress” – merely proves an adage well known to management consultants - poor reporting standards yield poor decision-making. Comments of most economists on the oil price spike in 2004 were typical. In expressing concern about the tightening oil market, most economists worried not how the global growth rate (of 5% or so) might reduce the oil supply, but how the oil shortage might reduce the growth rate!

The most obvious conservation measures could stretch energy supplies considerably. Existing technology such as energy-saving light globes and hybrid cars, save money and greatly improve energy efficiency with no loss of amenity. But passion for growth reigns supreme among policy makers and two percent annual growth of energy consumption continues, to the delight of coal-mining companies, bulk-shipping companies and primary- producing countries - to mention a few of the short-term beneficiaries of mankind’s profligacy. It would be unwise to expect a rational strategy for dealing with energy shortages will emerge any time soon.

Since a culture of energy conservation is proving so difficult to implement, a first measure approximation of long-term energy supply and demand is to examine the consequences if present patterns of energy use remain as they are. World total energy consumption in 2001 was 404 Quads (=4.22 x 10²⁰ Joules). Assuming non-renewables continue to supply 92% of total energy, and the rate of consumption continues to rise at 2% pa, simple arithmetic shows the non-renewable energy endowment calculated for Case 1 would last until 2054, and for Case 2 until 2076.

Neither of these two calculations, it must be emphasised, is a prediction. What the calculation shows is that the growth model of increasing energy consumption at 2% per year – is impossible under the stated assumptions about energy resources. Only if an abundant new energy source is found can the world keep raising its energy consumption at an exponential rate over a long period. Plenty of depletion curves for natural resources have been observed historically. Depletion of a stressed resource follows a curve, the general shape of which, if not the precise detail, is well established. As its consumption rises, the supply of a resource reaches a peak then declines over a number or years, or even centuries. After peak production, one way and another, societies whether animal or human, are forced to adjust to diminishing resources - which is almost always an arduous experience.
Renewable Energy

By definition, non-renewable resources are not sustainable in the long-term. Unless sufficient renewable resources are found in time to make up for the shortfall in non-renewable energy, energy consumption will commence a decline and thereby alter the way we live. So a key question about the energy future is, what are the prospects for renewable energy? One of the assumptions of the foregoing section was that non-renewable energy resources would continue to play a minor role (currently shown in Table 1 as 8%) in energy production. Can this assumption be relaxed? Can the contribution of renewable energy to total energy supplies be increased?

This subject is too big to tackle here. However two general points can be made about renewable energy, the first being that it takes energy to bring it on-stream. So it would be smart, while we still have it, to invest the remaining hydrocarbon energy in renewable energy projects instead of burning it up on budget holidays in Bali and driving cars around in aimless circles. Secondly, renewable energy projects on a large scale are likely to need a long lead time to develop. So it would be smart to start getting serious about renewable energy sooner rather than later.

The few books that have been written specifically on renewable energy options are generally not optimistic. Ted Trainer, [9] who has worked for a number of years quantifying various renewable energy options, concludes that no future society running on renewable energy can supply energy on the scale it has been consumed during the hydrocarbon era. However, Ted points out that living on an energy-frugal budget and living a full life are not incompatible. Heinberg’s follow up book “Power Down” also examines the prospect for an energy-depleted world. The bleakest view of the energy and resource deficient future is summed up by gloomy prophets such as Jay Hanson in the self-explanatory term, “die off.” [10]

The foregoing is the view of the pessimists. But what of the optimists? The major argument advanced by most economists, is that market forces will inspire inventors to introduce clever new energy-producing technologies when energy prices rise sufficiently to prompt them to do so. These unknown technologies, which of course cannot be revealed at this stage (since they haven’t been invented yet), will enable the growth economy to endure indefinitely. On this assumption economics bases its energy plans for the near and distant future.

How realistic are these expectations? Considering that no new major energy-producing technologies have been developed for a long time, the economic argument sounds suspiciously like the cargo cult economics after the Second World War when some Melanesians thought if they stared at the empty sky long enough, food-bearing planes would arrive as they had in the past. Despite a sustained program of sky-gazing, the planes failed to materialize. Pessimists my well ask if the market-inspired future energy model would fare any better?

In Conclusion

Given its vital importance, interest in the planet’s longer-term energy future has been muted. Most energy discussions so far have been about the oil price, and the likely timing of peak-oil production. (Like the peak of the stock market, no one will recognize the oil peak until it’s already history).

No known technology is yet capable of transforming the global economy from one which relies on 92% of non- renewable resources into being 100% self-sufficient with renewable energy. But eventually, the choice is to develop some renewable energy resources or suffer the consequences of increasing energy shortages. Since the lead times on new technology and construction of infrastructure are likely to be considerable, the sooner we get serious about developing and building a sustainable economy the more likely it is to happen. Every day we fritter away denying the problem exists is a day the window of opportunity to implement sustainable alternatives closes a little further.

The 2004 oil price spike may have been a wake-up call to some. But with the global economy ripping along at 5% growth, and with China and India trying to turn themselves into energy-consuming economies, it seems unlikely this call will be heeded. We still live in the era of the unplanned market economy in which central planning is anathema, resources are considered infinite and the future is left to unfold according to its own pattern. Do we need to throw-out the growth economic paradigm before it’s too late and develop new economic theories to deal with the emerging scenario of resource shortages, environmental destruction and over-population?

FOOTNOTES:

1. Energy Depletion\ConocoPhillips — Global Energy.htm
2. See US Department of Energy compilation of statistics from various sources at http://www.eia.doe.gov/pub/international/iea2002/table81.xls
3. See US Department of Energy http://www.eia.doe.gov/emeu/international/reserves.html. and http://www.eia.doe.gov/pub/international/iea2002/table81.xls
4. World Energy Council, Table 8.2, “World Estimated Recoverable Coal”
5. For a summary of the possibilities of thorium reactors, see World Nuclear Association’s “Nuclear Electricity” on http://www.world-nuclear.org/education/ne/ne3.htm
6. See “Uranium Ore Deposits” http://www.antenna.nl/wise/uranium/uod.html and Energy Conversions: Typical Heat Values of Various Fuels http://patzek.berkeley.edu/E11/energyconversionfactors.htm
7. Meadows D, Randers J, Meadows D “Limits to Growth – The 30-Year Update”, Chelsea Green Publishing Company, White River Junction, Vermont, 2004.
8. IPCC Climate Change Report: http://www.grida.no/climate/ipcc_tar/wg1/index.htm
9. Ted Trainer “Renewable Energy; What are the Limits?” http://www.arts.unsw.edu.au/tsw/D74.RENEWABLE-ENERGY.html
10. Jay Hanson, who some years ago abandoned hope that the energy problem can be solved, is known by some as the Paul Revere of hydrocarbon depletion. See Jay Hanson’s website at http://groups.yahoo.com/group/dieoff/message/10. For reading only by those of robust mental disposition.

Peter North, is an engineer, with qualifications in economics and accountancy. He has worked in the mining industry and later in the manufacturing industry. In recent years he has combined teaching finance and accounting with writing books, articles and papers combining technological, economic, environmental and political themes. Eight of Peter’s books have been published, with an additional book, “Culture Shock! Cambodia” to be published in 2005. This article is copyright of the author and Pacific Ecologist. Reproduction of articles in Pacific Ecologist, may be allowed on request to the author and Pacific Ecologist, provided credit is given to Pacific Ecologist as publisher’s of the original article.

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