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Energy
yesterday - today - tomorrow
A rapid increase in the world population and in effect in the number of the
energy consuming devices -in industry, transport household etc., rises dramatically
energy demand. An open question is how to deal with this problem.
Today roughly 80% of energy is supplied by combustion of coal, oil and gas.
Additionally, a few percents are gained by combustion of the bio-mass i.e. of
wood, peat, straw and of the especially cultivated fast growing plants. Nuclear
reactions supply less than ten percent of the world energy production (15 - 20%
when solely electric energy is considered). The share of the other methods,
mentioned later, is less significant.
Everything indicates that the methods of energy “production” dominating
today, founding on combustion or nuclear reactions, will parallel exist for a long
time. It is to decide which one should be developed in a privileged way. Both have
some serious advantages but also some disadvantages which should be taken in
consideration. The lasting for long time discussion is boring. Permanently the same
arguments, expressed in different ways, are presented. Each of the debaters
perceives exclusively advantages of the method promoted by himself and
diminishes, or even passes in silence, its weaknesses. Exactly opposite way of
argumentation is applied when speaking on the method presented by his
protagonist. The presented text tries to discuss that problem impartially.
Combustion processes
The main advantage of the combustion processes is that they can be easily
carried out (sometimes even, in defiance to our intentions, too easily). Therefore,
since the beginning of the humanity human race, they were used for heating,
preparation of food and also in the “embryonic” forms of the industry – metals
gaining (from ores), metal forming, pottery etc.
In XIXth century the people learned how to transform the heat, obtained in
combustion processes, in other forms of energy. It was the beginning of the
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contemporary technical civilization. Steam obtained in the high pressure boilers
drives engines or turbines supplying mechanical energy which may be also
converted, using generators, into the electric energy. On each step of these
transformations (combustion
production of steam
mechanical energy
electric
energy) a part of the energy is dissipated i.e. is practically lost from the point of
view of a consumer.
Using liquid or gas fuels it possible to convert the combustion energy directly
into its mechanical form (internal combustion engines).
Some disadvantages of the energy “production”based on combustion
processes should be also mentioned. – World resources of coal, oil and gas are large
and in spite that the energy consumption rises steeply it is not likely that, in the
next few decades, they will be totally exploited. However sooner or later it must
happen.
Emission of CO2 is perceived as a main negative effect of the combustion of
all types of fuels.
Increase of the carbon dioxide content in the atmosphere is usually
perceived as the cause of the, recently observed, changes of the climate It may
lead to the melting of glaciers followed by rise of the sea levels and to the floods.
The experimental data indicating on the existence of the “global warming effect:”
caused by the increasing CO2 emission (so called “green house effect”) are scarce.
They are limited to the relatively short period of no more than past two centuries
when the systematic temperature measurements started. Initially they were
performed in not numerous places (mainly in Europe and later also in America). In
spite of that the hypothesis of the global warming , basing on these deficient data,
has been accepted as an axiom. Also as an axiom is perceived that this effect is
caused by the increase of the CO2 emission. – Of course, carbon dioxide emission
may to some extend influence the climate. However in the bygone period, of over
hundred thousands of years, glaciers were moving towards the equator several
times and afterwards withdrawing. It is rather doubtful that these effects could be
attributed to a greater or smaller number of fires ignited by the Neanderthals or
some other of our early ancestors. Therefore the question to what extend the
present time emission of the carbon dioxide is responsible for the climate changes
remains open. According to the geologists* – who developed recently several
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methods to determine the temperatures in the past millennia (analysis of the deep
drilling samples of the arctic ice and also of some mineral deposits) – the “global
warming effect”, much higher than actually observed, happened several times in
the past.
No sooner then in the last two centuries the number and accuracy of the
temperature measurements , performed all over the world, began to supply
sufficient data to formulate hypothesis on the eventual climate change, but solely
in that period of time
The problem of the climate changes, in the past hundreds thousands of
years, has been recently analyzed* on the basis of the information supplied by the
deep drillings (in glaciers and in the sedimentary rocks).
When pit- or brown – coal, also to some extend oil, are used as fuels , some
contaminants may be as well present in the combustion gases (CO, sulfur and
nitrogen oxides, dust, soot) Removal of these polutants is already to a large extend
executed. Removal of CO2 could be done as well, several methods are known, but it
would be very expensive. Among other disadvantages of the “combustion energy”
should be mentioned the following facts:
-
the main coal, oil and gas deposits are present in a few countries. Limiting
production of these fuels, or imposing embargo on their export, these
countries may extend some serious economic and political pressure on the rest
of the world;.
-
production of milliards of tons of coal, oil, of milliard of cubic meters of the
gas, and their subsequent transport to the consumers create serious technical
and organizational problems. They rise also significantly the price of these
fuels and consequently the costs of the energy production
-
it is obvious as well that the coal, oil and gas resources, in spite of their size ,
one day will be exhausted.
“Producers and consumers” of CO2
Balance of the CO2 emission - absorbtion
Often is assumed that the fact of the „global warming” is unquestionable
and that it is effect of the rising presence of the CO 2 in the atmosphere ( increasing
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combustion of all kinds of fuels and of the decreasing area, of the cut down forests
– the natural absorbent of that gas.).
However the problem is more complicated. Long times ago, when the
humans were still absent the lasting, hundreds thousands of years, periods of
cooling or warming of the climate happened several times*.
The presented in the literature data on the concentration of the CO 2 in the
atmosphere are not reliable. They depend on several factors – the region where the
samples have been collected (industrial area or countryside, over seas or over
continents, season of the year, part of the world etc.etc.) Therefore it is not
possible to calculate on their basis the reliable balance of the CO 2 content in the
atmosphere of our globe. The more it is not possible to estimate how this content
had been changing in the past and how it will be changing in the future.
The CO2 content in the atmosphere is resultant of several, running in the
reverse direction, reactions:
organic substances (fuels, food) + O2
CO2 + H2 O + energy
Reactions running to the right emit (E) the carbon dioxide in the , supplying energy
for the industry and for heating (E 1 - combustion of fuels) and also energy for the,
consuming organic food, living organisms (E2 ; E21 by humans and E22 by “the other
animals” – from protozeans to mammals).. It should be also taken in consideration
that E2 = E21 + E22 , will rise in effect of the increase of the human population (in
the past century almost three times to ca. 6 milliards today) and of the number of
the breaded animals (cattle, pigs, poultry, fish etc).
According to geologists* significant masses of CO2 (E3 ) are emitted by
volcanoes, mineral sources etc.
I have not met any reliable attempts to estimate the balance of the CO2
emission: E = E1 + E2 + E3
“Sponsored” by the solar energy absorbtion of CO2 (A) is often attributed
solely to the forests (the growing there trees and other plants). Therefore
unavoidable effect of the diminishing area of the cut down forests seems to be
increase of the CO2 content in the atmosphere. It is not however taken in
consideration that parallel are increasing areas of different plantations (grains,
root plants, sugar cane, cotton, vineyards etc) which absorb the carbon dioxyde
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(A2). The total absorbtion A is equal to the sum A1 + A2 . - We know A1 decreases
and A2 increases in time, but we do not know how does change their sum. Is their
ratio A1 /A2 > or < than 1 ? How, it will change in the future? We do not have either
reliable data to estimate the value of the ratio E/A (>1 increasing content of the
CO2 in the atmosphere, <1 would cause restrain of the plant vegetation). The more
we do not know how E/A will be changing in the future.
Lack of these information causes that the hypothesis of the “global warming
effect” being result of the ”growing emission of the CO 2 “ are not convincingly
documented (are doubtful?).
Energetics based on the nuclear reactions
That method of “energy production” has several advantages. Properly acting
reactors do not pollute the environment. The consumption of fuel (uranium) in the
reactors is very low, in comparison to the combustion processes. Therefore the
uranium ore deposits will do for a long period of time. Would the reaction of the
nuclear synthesis be mastered on the technical scale then the problem of the fuel
reserves will disappear.
The mass of the uranium ores, compared to that of the “carbon fuels”
needed to obtain the equivalent quota of the electric energy, is several ranges in
magnitude smaller and therefore the mining and transport costs are respectively
lower. The method has however several serious disadvantages as well. The main
are high costs of the reactors construction and of the protection systems making
them possibly safe.
The nuclear reactors dliver, like the combustion processes, heat needed to
get high pressure steam. Generators, coupled with the turbines driven by steam,
supply electric energy i.e. the form of energy easy to be transferred over the long
distances.
Today roughly 60 to 70% of the electric energy is obtained in the power
stations basing on the combustion processes (mainly coal) and almost 20% in the
nuclear power stations. A significant share in this balance have also hydro power
stations.
Nuclear energy technology presents also numerous difficult problems to be
solved. - Very sophisticated and expensive are the processes of working up the
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radioactive ores. Very high are the costs of the reactors construction and of the
creation of their satisfactory security system. – Storage of the spend, but still
radioactive, reactor fuel presents a serious, still not satisfactorily solved, problem
In the case of the coal combustion leftovers (ashes, slags) it is much less
troublesome.
The danger of a nuclear catastrophe, which may destroy life on a large area
for a long time, is usually mentioned by the opponents. It may happen in effect of
errors in handling of the reactors, errors in their construction or some materials
defects. To eliminate these potential threats the staffs are continuously trained,
and a permanent search for the better technologies and materials is carried out.
All these efforts may decrease but not eliminate the danger of a possible
catastrophe. – It does not exist also any method of the full scale protection of the
reactors against, rarely happening but possible events like earth quake or terrorist
attacks. In the case of war enemy reactors, specially those situated deep in the
enemy territory, would be probably one of the first targets.
At the moment there are not any methods of a direct conversion of the
energy of the nuclear reactions into the mechanical or electric one (like conversion
of the energy of chemical reactions in the internal combustion engines or in the
electrochemical cells). – The size of the nuclear reactors and of the coupled with
them boilers andturbines, supplying mechanical energy, makes it practically
impossible to use them in cars or in the trains. Such aggregates may be used solely
on the big ships. It should be kept in mind that when such ship sinks it may
contaminate a considerable area of the sea.
Other sources of energy
Up to XIX th century, when the steam and electricity age has began, energy to run the flour mills, pumps (drainage of the mines and of the marshes), hammers,
pulling presses etc. - was supplied mainly by the human and animal muscles. To a
lesser extend it was also delivered by the wind and water mills. Today these mills,
coupled with generators, usually supply electric energy. The share of the energy
delivered by such power stations driven by the flowing water is greater than of
those exploiting winds. The former are however confined to the regions where
rivers with large water flow exist.
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In the XIXth century attempts have started to use, on a wider scale, energy
of the solar radiation and also the geothermal energy mainly f or the communal
purposes but also for the industry.
In the regions of the intensive solar irradiation sets of connected with each
other tubes coated with a radiation absorbing layer, are exposed to the sun. Water
flowing through these tubes, sometimes preheated to almost 100o C, is used usually
for communal purposes. It is also possible to obtain high pressure steam in the
boilers heated by the solar radiation concentrated, on their surface, by the
parabolic mirrors. All these installations may be effective solely in the regions
where insolation is intensive. Of course they do not act in the night.
Direct conversion of the solar radiation to the electric energy takes place in
the photoelectric cells. Several cells, combined in one panel called a sun battery,
may deliver up to two hundred W of electric energy per square meter. Such
batteries are often used as additional domestic sources of energy (batteries
situated on the roofs). To get hundreds or thousands of MW for the big cities or for
the heavy industry many square kilometers of batteries should be installed.
Sometimes unrealistic opinions are expressed that such batteries could be installed
on the existing thousands of square kilometers of deserts and barrens. The costs of
construction and of the maintenance of such installations would be immense. It
should be also taken into consideration that depriving such large areas of the solar
heat may lead to the perturbations of the local climate.
Output of the solar batteries is determined by the intensity of the light and
by the time of its operation. It depends therefore on the season of the year, on the
weather and of course on the place where the batteries are situated.
In some regions just at the depth of a few hundred meters exist zones of the
torrid porous rocks. The heat accumulated there, the geothermal energy, may be
exploited passing water, by system of pipes, in such bed and recovering it by “exit”
pipes situated in some distance from the entrance ones. That water, heated almost
to 100oC, circulating in a close circuit, is used mainly for communal purposes in
small villages. – This method applied to gain significantly more energy may have
some unexpected negative effects. Cooling of large areas of the deeply situated
rocks may induce some serious stresses and in effect create seismic instability in
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that region. This problem should be analyzed in details by the geologists and
seismologists.
Fuel cells, especially hydrogen – oxygen ones, are sometimes mentioned as
one of the energy sources. – Electric cars, using such cells, are ecologists dream.
Combustion gases of these cars (water vapor) would not contaminate environment.
It should be however remembered that the fuel cells are a secondary source of
energy. To obtain hydrogen and oxygen, for instance by electrolysis, energy
obtained in some other way must be used
(usually combustion processes, or
nuclear reactions – high pressure steam – turbine driven generator).Substitution of
the contemporary combustion engine driven cars by the electric ones, using the
hydrogen fuel cells, would eliminate millions, circulating now on the roads, noxious
gases producers, by burning of the equivalent masses of the carbon fuels or by the
nuclear reactions. performed in the powerhouses. – Exploitations costs of cars
driven by the fuel cells are today higher than those driven by the combustion
engines. - Collision of cars, carrying high pressure hydrogen containers , would be
extremely dangerous.
Conclusions
Numerous advantages of the energy consuming civilization are so obvious
that we almost do not notice them any more. It does not seem probable that
contemporary society would be ready to give them up. Therefore high level of the
energy production and its further rise seem to be unavoidable.
In the coming decades the main sources of energy probably will remain
combustion processes (of coal, oil and gas) and nuclear reactions.
The share of energy supplied by other methods will probably increase but
not to such extend to be significantly competitive to the two mentioned. It is still
to decide which of these methods should get priority. That decision should be
done by the society adequately informed , avoiding the exaggerated optimism or
pessimism of the enthusiasts or contestants of each of these methods.
Opinions expressed sometimes that it is possible to maintain all advantages of
the today high energy consuming civilization avoiding any threats and dangers,
unavoidably accompanying the energy “production”, is naïve and misleading.
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* Translation of some fragments of the opinion - of the Geological Science
Committee of the Polish Academy of Science (PAN), Warszawa – Wrocław,
12.02.2009
The geological structures prove that periodic changes are characteristic feature of
the global climate…. They occur in the cycles lasting from several years to several
hundreds thousands years
In the past four hundreds thousands years (i.e. still in absence of humans J.S.) the
CO2 concentration in the atmosphere has been several times four times higher than
today.
The detailed monitoring of the climate parameters is carried out, solely in some
countries, for no more than for two centuries.
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