[Solar-general] Fwd: [ox-en] keimform.de: The Earth’s the Limit (2): Peak Oil—Peak Energy?
Diego Saravia
dsa en unsa.edu.ar
Mie Mar 31 22:52:19 CEST 2010
seria bueno traducir esto
---------- Forwarded message ----------
From: Christian Siefkes <christian en siefkes.net>
Date: 2010/3/31
Subject: [ox-en] keimform.de: The Earth’s the Limit (2): Peak Oil—Peak
Energy?
To: ox-en <list-en en oekonux.org>
URL: http://www.keimform.de/2010/03/31/the-earths-the-limit-2/
[[1]First part]
During the last years, [2]humanity has consumed about 500 exajoules of
energy per year (an exajoule is a million million megajoules, or 10^18
joules). As usual, levels of energy consumption [3]vary strongly from
country to country. While the average consumption per person is about 70
GJ (gigajoules), the inhabitants of [4]Bangladesh, [5]Eritrea, and
[6]Senegal use less than 10 GJ on average.
At the other extreme, the inhabitants of the [7]United Arab Emirates and
[8]Iceland use 450–500 GJ per year, while per-capita usage in the small
emirate of [9]Qatar is a whopping 900 GJ. Germany uses about 180 GJ per
person—more than twice the global average. Other Middle European
countries are similar, while the United States and Canada use twice as
much (330–350 GJ).
Is it realistic that in the future, everybody will reach the consumption
level of Germany or the USA, or even more? There are reasons for doubt,
especially due to the source of the energy we use. More than 80 percent
of the consumed energy result from burning [10]fossil fuels: oil (~36%),
coal (~27%), and natural gas (~23%). This is problematic for two
reasons: (1) fossil fuels are non-renewable sources of energy that will
be exhausted sooner or later. (2) The burning of fossil fuels is the
main source of [11]global warming, the human-made climate change that
threatens humanity and other species with dramatic and often fatal
consequences.
Peak Oil, Peak Gas, Peak Coal
If consumptions of oil continues at the current level, we will [12]run
out of oil in approximately 43 years. Estimates for the remaining gas
and coal reserves are more varied. According to the estimates of the US
Department of Energy (cited in the same source), gas will last for 61
years and coal for 148 years. Other estimates are somewhat more
optimistic, but in any case it is clear that none of the fossil fuels
will last forever.
In reality, of course, future consumption levels won’t remain constant
until reserves suddenly “run out”. On the one hand, consumption is
likely to increase due to economic growth and due to the growth of human
population (if world population increases from 6.7 billion to 9 billion
in 2050, that alone would mean an 35% increase in the usage of fossil
fuels, even if the average usage per person remains constant). On the
other hand, easily accessible reserves are usually exploited first. At
some point worldwide extraction of petroleum will start to decline,
after accessible reserves have been exhausted and can only slowly be
replaced by reserves that are more expensive and energy-consumptive to
exploit. This point is known as [13]peak oil.
In the US, the [14]peak of oil extraction was reached in the the early
1970s; since then, oil extraction has gradually declined. It seems quite
certain that the global peak of oil extraction is not very far away.
[15]Most analysts seem to suppose that peak oil will occur sometime
before 2020; some believe that it already occurred in about 2007, before
the start of the current economic crisis (oil extraction declined since
then due to shrinking demand).
When the oil supply starts to decline while demand is still stable or
(more likely) growing, it will not only mean higher oil prices and
possibly violent struggles for the distribution of the remaining
resources. It will also mean that the resulting supply gap will be
partially filled by a faster exhaustion of gas and coal. Most estimates
therefore conclude that peak gas and peak coal will occur at most a few
decades after peak oil, probably between 2020–40 for [16]peak gas and
before 2050 for [17]peak coal. Since the energy gained from fossil fuels
will thus start to shrink in the near future, humanity will have to
learn to survive with less energy or to rely much more strongly on
[18]renewable energy—or more realistically, both. (Nuclear power is
sometimes advertised as another option, but it can’t fill the gap since
it’s not really renewable and [19]suffers its own peak; also nuclear
power would clearly be unsuitable for a decentralized peer economy for
various reasons.)
This will be quite a challenge, since only about 1.6% of the current
energy comes from the renewable energy sources that have a large
untapped potential—mainly [20]solar energy (1.3%) and [21]wind power
(0.3%). There are other sources of renewable energy that currently play
a more important rule, namely [22]biomass and biofuels (13.5%) and
[23]water power (3.3%), but these have already reached a high share of
their maximum capacity—they lack the theoretical potential to yield
enough energy to replace today’s non-renewable energy sources. Solar
power currently mainly comes in the form of [24]solar thermal energy
used for heating; the contributions of solar [25]photovoltaics are
negligible. (These and the following figures are from the [26]Renewables
2007 Global Status Report, p. 9, 12, 38, unless another source is
specified.)
If humanity wants to continue (or even increase) its current levels of
energy consumption, it will have to increase the energy produced from
solar and wind power by factor 50 or more before fossil fuels run out.
Limited Renewable Sources
There are some other renewable sources of energy, but their potential is
limited. About 3.3% of the current energy mix comes from [27]hydropower,
but the International Hydropower Association [28]estimates (PDF) that
one third of the realistic global potential of water power has already
been developed. If this estimate is true, it means that water power will
never be able to contribute more than about 10% to the global energy
mix.
[29]Biomass plays an important role as energy source, mainly in the form
of so-called traditional biomass: wood, charcoal (made from wood), and
agricultural waste used for heating and cooking, especially in Africa
and Asia. These “traditional” uses comprise about 13% of the global
energy mix, while nontraditional uses ([30]biofuels and electricity made
from biomass) comprise about 0.5%.
But the Earth’s surface area that could be used for biomass production
is limited. [31]According to the FAO (UN Food and Agriculture
Organization), energy gained from wood accounts for 7–9% of the energy
consumed worldwide (up to 80% in some developing countries), but wood
fuels already account for 60% of the global consumption of forest
products. [32]Forests cover about four billion hectares—30% of total
land area of the Earth. 34% of these forests are primarily used for the
production of wood and other forestry products; more than half of all
forests are used for productive purposes either primarily or in
combination with other functions such as recreation or biodiversity
conservation. A large part of the rest (36% of all forest area) are
primary forests largely untouched by human activity—which should better
remain so, since wilderness areas are important for biodiversity and for
keeping Earth a planet that is not totally subjected to utility concerns
([33]Global Forest Resources Assessment 2005, p. 4, 6).
So the area available for biomass production is already largely used for
this purpose, since the 70% of land surface that aren’t covered by
forests are usually needed for human habitation or agriculture (except
where they are deserts or natural reserves). Even if the energy
extracted from biomass was doubled, it wouldn’t account for more than
one quarter of humanity’s current energy needs, and it is hard to see
how more than that could be achieved. Modern biofuels don’t seem to do
better than traditional fuel wood regarding their space
requirements—ethanol and other biofuels already consume 17% of the
world’s grain harvest (Richard Heinberg, [34]Searching for a Miracle, p.
48), but contribute only 0.3% of the energy produced. And biofuels have
rightly [35]come under criticism for absorbing grain that could
otherwise be used for human consumption and contributing to raising food
prices during the last years.
[36]Geothermal power is another source of energy that is marginal as of
today but might play a more important role in the future. It utilizes
heat stored below the surface of the Earth for heating or for generating
electricity. Geothermal energy comes in two flavors: there are
[37]geothermal heat pumps, which can be an efficient and decentralized
approach to heating (or cooling) buildings. And there are [38]geothermal
plants that generate electricity. This latter flavor is a large-scale
technology that interferes much more heavily with the Earth;
construction of geothermal plants has [39]triggered earthquakes (e.g. in
Basel, Switzerland) and caused slow deformation of the land surrounding
the plant (e.g. in the German Black Forest).
This makes geothermal plants problematic, especially for a peer
production–based society that favors decentralized and unobtrusive
technologies. In any case, the electricity generation potential of
geothermics is limited—[40]estimates vary wildly, ranging from 35 to
2000 GW. Even the highest estimate—2000 GW—, which is almost certainly
strongly exaggerated, would correspond to only 13% of the current
worldwide energy demand; space heating (which could partially be
satisfied though geothermal heat pumps) makes up another [41]less than
16% of the total energy demand. Thus the contributions of geothermal
energy are necessarily limited as well.
So, while water power, biomass, and geothermal heat will be able to
contribute to a global renewable energy mix, they hardly will be able to
make up for the energy currently extracted from fossil fuels. The
biggest part will have to come from solar and wind energy.
[To be continued…]
References
1. http://www.keimform.de/2010/02/09/the-earths-the-limit-1/
2. http://en.wikipedia.org/wiki/World_energy_resources_and_consumption
3.
http://en.wikipedia.org/wiki/List_of_countries_by_energy_consumption_per_capita
4. http://en.wikipedia.org/wiki/Bangladesh
5. http://en.wikipedia.org/wiki/Eritrea
6. http://en.wikipedia.org/wiki/Senegal
7. http://en.wikipedia.org/wiki/United_Arab_Emirates
8. http://en.wikipedia.org/wiki/Iceland
9. http://en.wikipedia.org/wiki/Qatar
10. http://en.wikipedia.org/wiki/Fossil_fuel
11. http://en.wikipedia.org/wiki/Global_warming
12. http://en.wikipedia.org/wiki/Fossil_fuel#Levels_and_flows
13. http://en.wikipedia.org/wiki/Peak_oil
14. http://en.wikipedia.org/wiki/Hubbert_peak_theory
15. http://en.wikipedia.org/wiki/Peak_oil#Timing_of_peak_oil
16. http://en.wikipedia.org/wiki/Peak_gas#World_peak_gas
17. http://en.wikipedia.org/wiki/Peak_coal
18. http://en.wikipedia.org/wiki/Renewable_energy
19. http://en.wikipedia.org/wiki/Peak_uranium
20. http://en.wikipedia.org/wiki/Solar_power
21. http://en.wikipedia.org/wiki/Wind_power
22. http://en.wikipedia.org/wiki/Biomass
23. http://en.wikipedia.org/wiki/Hydropower
24. http://en.wikipedia.org/wiki/Solar_thermal_energy
25. http://en.wikipedia.org/wiki/Photovoltaics
26. http://www.ren21.net/pdf/RE2007_Global_Status_Report.pdf
27. http://en.wikipedia.org/wiki/Hydropower
28.
http://hydropower.org/downloads/F8%20Hydropower%20and%20Sustainability.pdf
29. http://en.wikipedia.org/wiki/Biomass
30. http://en.wikipedia.org/wiki/Biofuel
31. http://www.fao.org/forestry/28816/en/
32. http://www.fao.org/forestry/28808/en/
33.
http://www.fao.org/forestry/foris/data/fra2005/kf/common/GlobalForestA4-ENsmall.pdf
34. http://www.postcarbon.org/report/44377-searching-for-a-miracle
35. http://en.wikipedia.org/wiki/Food_vs._fuel
36. http://en.wikipedia.org/wiki/Geothermal_power
37. http://en.wikipedia.org/wiki/Geothermal_heat_pump
38. http://en.wikipedia.org/wiki/Geothermal_electricity
39. http://en.wikipedia.org/wiki/Geothermal_power#Environmental_impact
40. http://en.wikipedia.org/wiki/Geothermal_power#Resources
41.
http://en.wikipedia.org/wiki/World_energy_resources_and_consumption#By_sector
--
|------- Dr. Christian Siefkes ------- christian en siefkes.net -------
| Homepage: http://www.siefkes.net/ | Blog: http://www.keimform.de/
| Peer Production Everywhere: http://peerconomy.org/wiki/
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When the great lord passes the wise peasant bows deeply and silently farts.
-- Ethiopian proverb
--
Diego Saravia
Diego.Saravia en gmail.com
NO FUNCIONA->dsa en unsa.edu.ar
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