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What could be that big picture vision that could lead mankind to a way-forward path? My thoughts go to a piece I had posted two and a half years back. As I re-read it, I realise its perfect relevance to what is happening today. I am re-posting it here and at the end I have put forth some questions that come up for me at this point in time. So folks read on….. All life revolves. The world is awaiting a great awakening, which will occur with the dawning of the Age of Aquarius.

This great awakening will take place in the months and years to come and bring significant changes to our consciousness as human beings. The Age of Aquarius, Starts 21 st Century. Erudite and all encompassing as always, the President stressed issues of China and outsourcing. But what I really heard from the most powerful man on the globe was insecurity and fear. Of the slipping away of competences and strengths and not knowing what to do.

The competence and knowledge advantage which the US and developed world enjoyed from the beginning of the industrial age is fast seeping away. Other nations and societies are catching up faster. So what are the reasons for such competence and knowledge loss? What can be done to stop the hemorrhaging of this life blood?

Three Worlds, Three Mysteries

My thoughts veer towards Entropy, a concept in the realms of Thermodynamics. Entropy is a tendency towards disorder and Science postulates that this can only increase over time. Ultimately leading to a steady state in which random and uniform soupiness exists all over, the highest level of Entropy.

Of a Universe slowing down and coming to an end due to Entropy. I reflect on what we are experiencing in the world today. Is it the entropy effect on the competences and knowledge possessed by the developed world? Of the inevitable seeping loss to the rest of the world. What would the next turn of the screw bring? As we see Asia rising today, would we not see Africa rising tomorrow? And so on, till a flat world achieves steady state of uniform competence and knowledge levels all over. But do we see what this seeped competence and knowledge is doing?

It is raising the level of awareness all over. Awareness of social and political realities, awareness of heightened aspirations, awareness of the need to keep on improving and improvising. An awareness which is getting accentuated by rapidly evolving communication, networking and database access technologies. And with this heightened awareness has come the inevitability of consciousness.

I see mankind fast reaching a new level of human consciousness. As more of us become consciousness- conscious, as our thinking DNAs get re-programmed, we would start seeing and dealing with the world in significantly different ways. Be it through the manifestation of ego, false fronts or preconceived judgments. Good work will elicit a soulful response and one can place trust in a person who engages with the world that way, whether or not we all agree. I read that your video piece The Evangelists contains a 3D representation of a neighbour with a mental illness who tragically burned down your apartment and studio.

You decided to invite him to collaborate for something constructive, three years later. How may it be circumvented or resisted? We lost our home and it took some time for life to get back to normal. The idea itself felt like some sort of conversion of energy, rather than waste. I put everything I had into it. I was struggling with depression especially in those years and that everything went mostly ignored made it difficult to feel good about life in general.

I got divorced at the end of that year and lost my galleries. I think one could call that entropy. Because you asked me the question, I went back and watched parts of it. That really haunts me I have to say. What happens to that work? To the artist? Seen differently? Perhaps in trying to prevent entropy, one only spreads it. New Mexico, where I live, is one of the poorest states in the country. Rural poverty is quite a different thing from urban poverty.

When and how did the two of you meet? How has the event of having a partner who is a fellow artist impacted your creativity? Maja and I met briefly for the first time at some point while I was still married. I had been aware of her work for a couple years before that. The breaking down of rocks is globally called weathering. Now the CO2 molecules contained in the atmosphere come into play. These molecules dissolve in water H2O and are present in rain droplets.

These carbonate molecules can accumulate to the point where they will sink a bacteria down to the sea floor. In more advanced marine organisms the carbonate formation is useful in forming a protective shell that will also end up on the sea floor when the organism dies. In any case the carbonate accumulation will produce sedimentary layers. Another way by which carbonate sedimentary layers can form involves the photosynthesis process by the bacteria or other marine organisms, in which part of the captured Carbon from CO2 molecules dissolved in the sea combines with Calcium cations to form carbonate molecules at the surface of the bacteria, again sinking it to the sea floor.

These Carbon capture processes took place as soon as life appeared in the form of the simplest living organisms growing in heat vents, before they developed into organisms capable of photosynthesis. Of course the advent of photosynthesis must have accelerated the process because they allowed bacteria to proliferate everywhere. In any case, for a period of several billion years before the earth turned green, carbon capture and storage as carbonates must have already considerably reduced the amount of carbon dioxide in the atmosphere.

Note that this process necessarily requires the presence of carbon dioxide in the atmosphere, the presence of water, and possibly also the presence of elementary living organisms. This is why one way to look for the presence of life on other planets such as Mars consists in looking for the presence of carbonates.

NASA has placed in orbit around Mars satellites whose purpose was precisely to look for the presence of carbonates. The discovery of carbonates would prove that water must have been present at some time at the surface of Mars, and that the existence of life on this planet is likely. Carbonates have indeed been identified on Mars, they provide part of the evidence for the presence of water. Carbon storage as fossil fuels on the million year time scale Fossil fuels have preserved the chemical energy resulting from the photosynthesis process over hundreds of millions of years.

Although only a very small fraction of the total living organisms produced over the years has been preserved in this way, fossil fuels constituted a formidable energy reservoir. Until recently, mankind has used very little of this reservoir. Fossil carbon storage started much later 24 The Entropy Crisis than carbonate formation as it required the existence of extended inland plant life, which started to spread only about million years ago. Here is a brief account of what went on, based on various datation methods.

Formation of coal deposits: the carboniferous age Four hundred million years ago plants had developed to the point where they were forests of trees. The distinction between land and sea was not as clear cut and as stable as it is to day. Variations in the level of the oceans and land movements resulted in portions of the land being alternatively over and under water. Swamps were common. Trees would end up covered by waters where they underwent transformation resulting in the formation of peat deposits, the lowest usable form of carbon storage.

At that time, continents were located quite differently from where they are today. Places where large coal deposits have been found such as Pennsylvania were then in the tropics, much further south than where they are found now. Abundant rain and higher temperatures were favorable for forest growth, probably like in our present rain forests. The rate of carbon capture from atmospheric CO2, more abundant than it is now, was high due to a higher temperature, high humidity and rainfall. Abundant rains play a multiple role in coal formation. They bring water inland which is necessary for photosynthesis to take place; then they participate in the weathering process and form the rivers that transport sediments and peat beds down to sea levels.

Further sedimentary layers result in burial of the peat beds under thicker and thicker deposits. Peat beds are then under pressure from these upper layers, they progressively lose their water content and volatile elements. As time evolves they are progressively transformed into lignite, then bituminous and finally anthracite, the highest grade of coal.

Later tectonic movements followed by erosion of upper layers may bring coal seams back up near to, or sometimes at, the surface where they can be exploited. A Short History of the Biosphere 25 This is the Carboniferous Period, extending from million to million years ago — all said a period of about million years when most of the coal deposits where formed. From the beginning to the end of this time frame CO2 atmospheric content in the atmosphere went down by a factor of 5, to a level similar to what it is today, and the average temperature decreased by 10 degrees Celsius.

This lower temperature does not immediately stop the formation of coal beds, because a large belt of high land now exists in the tropics region where temperatures remain high enough and rains are sufficient for the process of forests growth, peat bed formation and sediment transport down to sea level to continue.

Eventually, however, an ice age puts an end to this process.

Variation in time of CO2 atmospheric content. Time is obtained from Carbon isotope ratios. The graph compares raw and smoothed data. At the beginning of the carboniferous age, million years ago, the CO2 content was about 5 times higher than in the middle of that age and today. In the interval, the temperature not shown went down by about 10 degrees Celsius, and is comparable to what it is today after R.

Berner and Z. Kothavala, American J. Oil and gas deposits The formation of oil and gas deposits is not as well understood as that of coal. Most geologists believe that they were formed by a process similar to that of coal deposits, through the accumulation of organic matter, but from smaller organisms not from trees , maybe primarily from marine life forms. This would have occurred on the million time scale, again through compression of organic deposits under further sedimentary layers.

Here however the end product is not Carbon but hydrocarbons. A competing, recent theory holds that in fact molecules composed of carbon and hydrogen were formed from deeper layers of the earth and not from atmospheric carbon dioxide. It can be called the bottom up theory, as compared to the more generally accepted top down theory. Ice ages When we discuss the rate at which we burn fossil fuels today it is important to remember the time frame of about million years of the carboniferous age during which they where formed.

In this relatively recent and better known period the carbon dioxide content went down, a shown above, by a factor of 5 see Fig. If we calculate on this basis what would be the effect of an increase of the current CO2 concentration by a factor of 2 we get a temperature increase of a couple of degrees, closer to current estimates than our first evaluation. But again this is much too simple an approach. CO2 removal from the atmosphere during the carboniferous age and the resulting diminished greenhouse effect were not the only driver for a decreasing temperature.

Another important factor was the way continents were located. Around million years ago, two major continental blocks that existed in the southern and in the northern hemisphere were joined in one single continental mass, extending fully between the two poles. It is believed that when a continental mass extends from the southern to the northern pole, as A Short History of the Biosphere 27 was then the case and is also almost the case today, circulation of equatorial warm waters is hindered and they transport less heat to polar regions, which get colder.

Ice sheets extend further from the poles. Because they are white they reflect most of the incoming solar radiation directly back into space, and as their extension increases more solar radiation is reflected, less is transformed into heat. Earth cools down. The result is an ice age, defined as a period of time where extended ice sheets exist at the poles. According to this definition, we are in an ice age today, in spite of global warming. Eventually, as a larger fraction of the land is covered by ice, plant growth is reduced, and less CO2 is taken away from the atmosphere. If there is sufficient replenishment by volcanic activity its concentration can rise again, and the increased greenhouse effect will bring the temperature back up.

Ice sheets will start to melt and a new cycle of plant growth can start. This is apparently what happened million years ago, when CO2 concentration and temperature went simultaneously back up. Coal deposits started again some million years ago, but at a slower rate. The last 10 million years For the last 10 million years the CO2 content in the atmosphere has been on the average as low as it was at the end of the carboniferous age, and for the last 3 million years the temperature, on the average, has also been similar to what it was at that time, namely rather cold. For all of that period large and thick ice sheets have been prominent on the Antarctica continent at the southern pole, and they have blocked the seas at the northern pole all year long.

In spite of recent warming, the earth is still at the moment in an ice age. But detailed records available for the last one million years show that there have been substantial variations in the climate during this ice age. There have been strong and quasi-periodical variations of temperature, CO2 concentration and thickness and 28 The Entropy Crisis extension of the ice sheets. While the average global base temperature has been about 6 degrees lower than what it is today, interglacial periods have occurred every , years, each lasting on the order of 10, years during which the temperature was about the same as today.

The earth is right now in such an interglacial period. During this one million year period, variations of CO2 concentration and temperature are synchronous, CO2 concentration being low when the temperature is low. However, unlike what happened during the carboniferous age, it is unlikely that there is a causal relationship between the two, namely it is unlikely that the periods of lower temperature are due to a reduced greenhouse effect.

One reason is that the variation in CO2 concentration is too small to explain the amplitude of temperature changes, about 6 to 10 degrees. The second is the clear periodicity of interglacial periods, which points out to an astronomical effect. While details still remain to be worked out, it is believed that the succession of alternate glacial and interglacial periods is due to changes in the incoming solar radiation and its complex interaction with the bio-sphere.

This is discussed in more detail in Chapter 5. The current interglacial period started about 10, years ago. It is during that period of time that civilizations have flourished on earth, based on sedentary life made possible by the development of agriculture, itself made possible by the stable climate. At the start of this period, rising sea levels must have changed the landscape considerably in coastal areas, possibly wiping out settlements as recounted in the story of Noah and in many other mythological stories of a number of civilizations.

Possible changes in climatic conditions have since been a constant worry, as they would A Short History of the Biosphere 29 endanger our current civilization in which we get almost all our food from agriculture, rather than from hunting or fishing as did our farther ancestors. Together with the motion of the continents, it has led to an overall tendency to ice ages, but what has made our current civilization possible is an interglacial period.

Various views on how long it will last are reviewed in Chapter 5. We are not sure when it will end, if it is in the next years or 10, years or more. But it will, and this is one of the major concerns for the continuation of civilization itself in the long term. If glaciers were advancing again in Europe and North America, not much would be left of our towns and overall infrastructure in these regions.

It is against this background that we will consider the possible impact of global warming, possibly due today to the increasing level of atmospheric CO2, but before we get to that point more quantitative discussions of energy and entropy are necessary. One of the basic laws of physics is that energy is conserved, but unfortunately, we do not have an intuitive understanding of what energy is.

Concepts such as heat and force are obvious to us, because we directly feel heat and force. We also measure speed easily. Another quantity that is conserved is momentum, the product of speed and mass, and we can experiment with this law when we play billiard; but the concept of energy and of its conservation is really only useful when energy is being transformed from one form to another.

Newton himself, giant amongst the giants of Science, did not have a clear notion of what energy is. He thought that the energy of a moving body, which we call kinetic energy, is proportional to its speed, while it is proportional to its square, as rightly claimed by Leibnitz. While energy is undoubtedly conserved when transformed from one form to another, it is our common experience that this is not the whole story. If the total energy was all that mattered, we could not have an energy crisis, so we know that some essential concept is missing from the conservation statement.

Heat collected in solar water heaters can be used to produce vapor from a fluid that will activate a turbine, but the conversion efficiency will be very low. It was Carnot who first showed that the efficiency with which heat can be transformed into mechanical energy, like in a steam engine that operates between a high temperature TH that of the boiler and a low temperature Tc that of the condenser , can never be higher than a limiting value. It is reached for a particular cycle — the Carnot cycle — during which the entropy 31 32 The Entropy Crisis release is zero A more quantitative discussion of entropy will be found in the next chapter.

Different forms of energy and power In order to discuss usefully our energy requirements, we must first consider the different forms of energy that we use and conversion possibilities from one form to another, heat and mechanical energies being only two examples amongst several more forms. Table 3. Different forms of energy and possible conversions.

Devices that can convert different energy forms into one another. See text for details and possible conversion efficiencies. The main forms of energy are: mechanical; heat; electrical; chemical; electro-magnetic radiation; nuclear; food. Power is the energy spent divided by the time over which it has been spent.

In order to allow comparisons between different forms of energy, we must use the same system of units for all of them. For practical reasons, power is often used as the primary quantity, and energy is expressed as the power spent multiplied by the time How Much Energy do We Need? Power is usually expressed in units of kilowatt, and energy in units of kilowatt-hours. We are familiar with kilowatt-hours, or kWh, because this unit of energy is used to calculate our electricity bill.

This is the unit of energy that we shall use for our comparisons. Mechanical energy is the work that we produce when we move a body at constant velocity over a length L by applying a force F to it, if the force is applied along the direction of the displacement. A good example is that of a horse carriage. The horse applies a certain force to the carriage, and if the road is straight the product of that force by the distance over which the horse has moved the carriage is equal to the work produced by the horse. One horse-power is equal to 0. That power is of the same order as that of a one-room small air conditioning unit.

The engine under the hood of a typical car can develop horse-power, or 74 kW. If we drive it for one hour at full power, or for two hours at half power which would be typical for daily commuting to work, we will have spent 74 kWh. Incidentally, these horses under the hood of our motorcar are a good illustration of our modern way of life. Not long ago, only kings could afford to own horses and their ancillary equipment stables, care takers of different kinds and so on.

To day, in the developed world, everybody has them and in the developing world everybody wants to have them.

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Heat energy is still often expressed in units of calories. One calorie is the amount of heat necessary to heat one gram or one cubic centimeter of water by one degree.


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It is equivalent to 4. To heat up liters of water by 50 degrees, which is roughly what a family of 4 may need for its daily domestic hot water use, we need 7,, calories, or 9 kWh. Electrical energy is familiar to us as the energy spent in appliances such as air conditioning units, refrigerators, vacuumcleaners, mixers, light bulbs, furnaces, washing machines and dishwashers. In these various appliances, electrical energy is easily and 34 The Entropy Crisis efficiently converted into mechanical energy, radiation and heat.

Just as heat flows from hot to cold regions, electricity flows from high to low potential. Electrical power spent is equal to the flow of electricity measured in Amperes A multiplied by the difference in potential, measured in Volts V. When a current of one A flows down a potential difference of one Volt, a power of one Watt is being dissipated the flow of electrical current is that of electrons, each of them carrying a very small electric charge denoted by e.

The power dissipated in a light bulb or in a personal computer is of the order of W, while the power dissipated in heavier appliances such as refrigerators, air conditioning units and so on is of the order of 1 kW. It has been estimated that the average electrical energy spent on appliances in a household is of the order of 10 kWh per day in Europe. Chemical energy is a term which we use here in a broad sense. It covers not only the energy stored in fossil fuels coal, oil, oil sands, natural gas , and biomass, but also hydrogen and energy stored in batteries.

Energy is recovered in the form of heat because this reaction is exothermic.

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The energy recovered is that of the chemical bonds between the carbon and oxygen atoms, broken in the combustion process. It is of the order of one electron-volt or one eV which is the energy one must spend to elevate the potential of one electron by one Volt. To get an order of magnitude, the combustion of one liter of liquid fuel releases about 10 kWh. But hydrogen can also be converted into electricity in a fuel cell where it is recombined with oxygen to form water, and chemical energy stored in a battery is directly recovered as electrical energy.

Radiation energy is the form of energy that we receive from the sun. Expressed in units of kWh, or even Wh, the energy of a photon is extremely small. It is more convenient to express it in units of electron-volt, denoted above as eV. When we calculate the energy of one photon in the visible part of the solar spectrum, which has a wave length of the order of 1 micron, we find that it is of the order of 1 eV.

This is the order of magnitude of the energy needed to break up a chemical bond, which is the reason why photons can trigger chemical reactions. This is what occurs in photo-synthesis, as we have discussed in the previous chapter. Nuclear Energy is produced when a heavy unstable nucleus is split into two parts whose total mass is slightly smaller than that of the original nucleus. In a typical nuclear fission event such as occurs when the Uranium isotope meaning the isotope of Uranium that has an atomic mass of units, the hydrogen nucleus having a mass of 1 is split for instance when hit by a neutron , the energy released is of the order of tens of MeV 1 MeV is one million eV.

The energy is released in the form of kinetic energy of the reaction products which are emitted with a high velocity. In a nuclear reactor this kinetic energy is then transformed into heat, which will be further converted into mechanical energy and electricity which is why we have not listed nuclear energy in Table 3. It will be appreciated that the energy obtained from a fission event is about 10 million times larger than in a chemical reaction. Food energy is really a form of chemical energy, but we give it a special mention because after all it is for us the most essential form of energy.

We can eat wheat and corn, vegetables, fruits, meat — but we cannot feed ourselves on coal, gasoline, or 36 The Entropy Crisis electricity. Food energy is produced from solar radiation by photosynthesis. As we have seen in Chapter 1, a photon breaks up a molecule of water, oxygen is released into the atmosphere and hydrogen is combined with CO2 molecules from the atmosphere to form carbohydrate molecules. The way our body burns food is by breaking up these molecules and eventually releasing CO2 and water molecules. Back to square one.

In many publications, food energy does not appear amongst the list of our energy needs. From which one may be tempted to conclude that it is negligible compared to other energy needs. In fact this is not quite true. For a family of four, this represents an energy expenditure of the same order as the electrical energy used for appliances.

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Food energy can represent close to a quarter of the total energy spent in the framework of a household. This figure varies of course with the socio-economical level of the particular household considered. It will be less for well to do families because their house is bigger and uses more appliances, and larger for lower income families. For more details, see Section 3.

Energy conversion Table 3. Here we indicate possible conversion efficiencies. Heat energy can be converted into mechanical energy within the limits imposed by the Carnot law, discussed in some detail in Chapter 4. Direct conversion of heat flow into electrical power is possible but not very efficient. A hot body emits radiation as we can see when we burn wood in our chimney — or when we sun-bath. Electrical energy is very versatile. It can be converted with high efficiency into mechanical energy by electrical motors, into heat like in an electrical resistance , into chemical energy like in a battery or by electrolysis to produce hydrogen , and into radiation like in a microwave oven.

Nuclear energy, by contrast with electrical energy, can only be converted into heat, at least in the present state of technology. Chemical energy is usually first converted into heat, except in fuel cells and batteries where it can be converted directly into electricity as mentioned above. Fuel cells perform the reverse operation from electrolysis, hydrogen being recombined with oxygen to form water while electricity is generated.

Of course hydrogen must be produced in the first place, for instance by electrolysis. All said, hydrogen is used in fuel cells as an agent to effectively store electricity. The advantage over conventional storage by batteries is that the energy stored by unit weight is much higher, because hydrogen is the lightest of all elements. However hydrogen is a gas that must be stored in some condensed way other wise it would take too much space.

This entails the considerable additional weight of high pressure containers, except if hydrogen is stored in liquid form as it is in space rockets. Radiation energy is as versatile as electrical energy. The energy of photons is converted into heat when they hit a body that absorbs the radiation a black body. This conversion is used for instance in solar water heaters.

A built-in electric field then separates the electron from the hole. They move in opposite directions, giving an electrical current. Calculated on the basis of a day and night global average, incoming radiation from the sun on a horizontal surface in inhabited regions amounts to W per square meter. On the geological time scale, solar radiation energy has been transformed into chemical energy in the form of fossil fuels, as we have seen in the preceding chapter.

Until now these fossil fuels constitute our principal primary energy source. They are not renewable on our time scale, since their formation took on the order of million years. Biomass energy. On a renewable basis, we can of course burn plants, either directly or after converting them into liquid fuel.

This is called biomass energy. Although the primary conversion efficiency in the photosynthesis process is high — about the same as in photovoltaic cells — the effective efficiency of biomass production is in fact quite low because some of the incoming radiation is reflected, and because plant growth requires respiration which requires energy. Energy needed for planting and harvesting further reduces this figure to about 0. Conversion of radiation into food is of course of primary importance for us.

Food production uses solar radiation but in principle we could use radiation from a different source, provided it had the appropriate wave length. Supply of water and carbon dioxide molecules, as well as oxygen, are not a concern since the system would operate in a closed cycle. We give these examples not just for fun, but to make an important point. This spatial vessel or underground station where life can be sustained with the help of an energy source — here nuclear — are conceptually not different from our biosphere. It is also a closed system, except for the input of solar radiation.

Maintaining life requires an energy input. A discussion of how much is needed is precisely the object of this chapter. Energy use and entropy release In the end, energy that we use in all its forms is generally transformed into heat, often called waste heat or low grade heat. This heat, rejected into the environment increases its entropy. Heat rejection Let us consider for instance the use we make of electrical energy.

We have given a few examples of how it can be produced, but after a number of transformations heat will always be the end result. This is what happens in our household. In most light bulbs a large fraction of the power is directly dissipated in the form of heat. Then the radiation light itself will be eventually absorbed by the environment walls and so on and transformed into heat.

A refrigerator produces heat, part of it is of course that ejected from its inside into the kitchen, but heat is also generated by the electrical motor and the compressor it drives. The same is true for air-conditioning units. Energy spent on transportation all ends up as heat, whether we use chemical energy in cars, buses or airplanes, or electrical energy in trains. The mechanical work that it produces eventually ends up as heat by friction against the atmosphere, tires deformation, and internal friction in the transmission. But there is one interesting exception to the general rule that needs to be mentioned.

This is when energy is used to produce materials that later on can themselves be used to produce energy. For instance, the manufacture of photovoltaic modules requires the production of materials that are not found in nature, such as pure silicium, glass, aluminum and so on.


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  • This production requires energy: just as is the case for agriculture, harvesting the sun first demands an energy investment. As one last example of heat rejection let us go back to our own energy needs. Again, the W or so that our body dissipates end up as heat: our body operates at 37 degrees centigrades, a temperature higher than that of the environment under normal conditions perspiration can help us survive in slightly higher temperatures.

    We take in energy in the form of food chemical energy , and eject it as heat into the environment. This occurs even if we do not perform any physical work. Why is that? Clearly, we are different in this respect from all the equipment we use. When appliances are switched off, no energy is spent. Yet, if we consider ourselves as a subsystem of a larger one let us say of the household, which is itself a subsystem of the society at large , we do see that at all levels we operate in similar ways.

    We understood in Chapter 1 that an energy input into the household is necessary just to keep it in good order. We do not turn on the vacuum-cleaner arbitrarily: we need to use it in order to keep the house clean. The same applies to us. Even if we do not produce any physical work, an energy input — here in the form of How Much Energy do We Need? We, as our household, are systems that need to be kept in a properly functioning steady state. The consequence of this up-keep is that we — ourselves, our household and society at large — eject low grade heat into the external world, and in addition we also pollute it.

    Entropy release In the language of physicists, ejection of low grade heat and pollutants into the environment amount to release of entropy. All, or nearly all see the case of photovoltaic cells , the energy that mankind consumes ends up as an increase of entropy in the biosphere.

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    The only counterweight to that increase is photosynthesis, which decreases the entropy of the biosphere if part of plant production is eventually stored, as it has been in the past, in the form of fossil fuels. We are now almost in a position to estimate what the overall entropy balance is, which we will do a little bit later. It suffices to say at this point that in modern times there is a net increase in entropy of the biosphere. From that standpoint, it does not really matter whether we burn fossil fuels, nuclear fuel or biomass. What we need now are a few quantitative definitions to justify the above statements.

    Energy needs and costs We are now equipped to evaluate and compare our different energy needs and see how they could be covered. Food energy Food energy requirements are basically the same for all humans. They do not vary substantially with race and conditions of living. Another universal constraint is that there is basically no choice as to the form of energy used to produce food: there exists at present no alternative to solar radiation and photosynthesis. As already said, we cannot feed ourselves on coal, oil or electricity.

    The power that we dissipate, of the order of W, and the corresponding energy needed per day of about 3 kWh, are relatively modest in regard to other energy needs in developed countries. But they are not at all negligible in third world countries. For instance, the total average power used per person in Canada is 14 kW, two orders of magnitude more than the power that our body dissipates. By contrast, in Nigeria the average power consumption per person, excluding food, is only 43 W. The worldwide average power consumption per person is about 2.

    In view of the enormous difference between the power consumed per capita in developed and third world countries, this average does not have much meaning. Hundreds of millions of human beings consume much more, and billions much less. From an economic standpoint, the price of a kWh of food is much more expensive than a kWh of say electricity, see Table 3. There are a number of reasons for that, many of them related to dietary habits which can vary considerably according to the standard of living.

    For instance, a kWh of meat is evidently more expensive than a kWh of rice. But the high cost of food energy has also a fundamental reason. Food is basically produced by photosynthesis, which has a low yield compared to photovoltaic conversion, as mentioned above. Now remember that photovoltaic electricity is itself expensive compared say to that produced by burning conventional fuels, roughly by a factor of 4 today. It is therefore no surprise that even a kWh of basic food cereals, rice, bread is more expensive than a kWh of electricity.

    This has immediate economic consequences when it comes to the budget we live on. While the W that we dissipate are negligible compared to the total power consumed in developed How Much Energy do We Need? In middle class families it can represent from a quarter to a half of their total budget. But in third world countries, it is close to percent. Therefore, we must be very careful not to forget food energy needs on a global scale. This is in fact a very sensitive issue. For instance, replacing petrol by biofuels may appear as an attractive proposition in developed countries, possibly for political reasons, but if this replacement were to take place on a large scale, the resulting reduction in food production and price increase would I believe mean hunger for hundreds of millions.

    A doubling of the price of basic foods cereals, rice has already occurred in recent years. Massive production of biofuels on a large scale in the Americas and in some countries in Europe is one of the factors behind this increase. It will make people unhappy everywhere but will not much affect those who live in developed countries.

    For most people in the third world, it might mean starvation. Food versus other energy needs We accept as a fact that our basic food energy needs — those W that we dissipate no matter what — are ireducible. On the other hand, we consider that we can save on our other energy needs. Maybe this difference in attitude is worth a little digression. This will take us right back to entropy. As all living organisms we need energy just to keep ourselves alive, irrespective of the work we do. Living organisms are not stable if left to themselves, contrary to inanimate forms such as crystals.

    In crystals, atoms are fixed in space for eternity unless some external agent attacks them, but in living organisms atoms and molecules are in a constant flux. The organism may look the same all the time but in fact if we were to look at it on the microscopic scale we would find that molecules are all the time exchanged.

    Cells die and are replaced by new ones. Entropy is all the time released, just as in the example of the household that we 44 The Entropy Crisis discussed in Chapter 1 and, just as in the household we need an energy input to keep this increasing entropy in check. The entropy generated in living organisms is dumped in the external world, again just as in the case of the household. Without an energy input, living organisms will die just as our house hold will disintegrate.

    The W that we dissipate is a measure of how much power input we need to keep ourselves in a good state of repair. Perhaps the most striking example is the brain. It consumes around a fifth of our total power dissipation, while evidently not doing any work in the usual sense: it does not move at all.

    Its dissipation level of about 20 W is the result of a long evolution. When compared to the dissipation of personal computers, which is of the order of a few W, its performance is truly impressive: it does so much more. Instead of looking at global numbers at the society level, we shall take the same approach as in Chapter 1 — looking at a household.

    Let us take the example of a family of four living under one roof. Besides food energy, it consumes energy in the form of electricity for appliances, of electricity, or fuel, or natural gas for heating, and of petrol for car transportation. In order to compare the different components of its energy budget, we use the same unit — kWh per day — for these different kinds of needs.

    The numbers in the following table are indicative for a family living in a moderate western climate, let us say Switzerland to illustrate the point. Numbers in Table 3. The reader can easily go through the little exercise of drawing a more accurate table for their own case. What is important here is to note the order of magnitude.