UNESCO Desire – Net project Sustainable Development Pietro La Mendola

1. UNESCO Desire – Net project Sustainable Development Pietro La Mendola pietro.lamendola@casaccia.enea.it UNESCO Rome, 2006 19 July

2. In past times the low technological level reduced the possibility to change type of energetic materials and to differentiate the supplying sources The different energetic materials had independent prices. The prices of the energy, deriving from a thermal conversion or from hydroelectric sources, were predominantly constituted by taxes and they were various in the different countries. DOES A REAL VALUE OF EVERY SOURCE OF ENERGY EXIST ?

3. The ability to employ various energetic materials of various origin has strongly increased a market of the energy in which the prices will be determined principally through the thermodynamic value and through effects on the environment of particular source of the energy and less and less through trade and fiscal relationships. The temperature of energy conversion obtained though burning process depends on the system technology. It can be much higher than the usually so-called "theoretical temperature of combustion". SOURCES OF ENERGY

4. The obtainable temperature through thermal type solar systems can be compared to that one that comes from heat recovery systems. The coming energy is directly usable as heat < 100 °C With solar systems able to concentrate the radiation, temperatures can be obtained, comparable to those of combustion process, similar conversion factor and economic value even if we are not able to foresee the impact on the environment. SOURCES OF ENERGY

5. Many international movements of opinion ask the governments to adopt environment political measures, oriented to cancel the modifications produced by mankind. The result of these provisions would be the restoration of the previous environmental conditions. TO RESTORE THE NATURAL ATMOSPHERE. WHAT AGE?

6. What we consider natural environment, because it is previous to the current excessive use of energy conversions, it often was already deeply modified by human presence as well as through natural phenomena. A correct approach is trying to achieve goals for planned modifications of the territory. It is hoped for consequences of the modifications in the long term which are foreseen and that we are able to correct the errors. TO RESTORE THE NATURAL ATMOSPHERE. WHAT AGE?

7. It is not possible converting energy without degrading a part of it into a so low temperature heat that it cannot be used anymore. On the other hand, the high enthalpy energy tends to be converted spontaneously and therefore every form of accumulation always is a danger. The greater is danger, the larger is the amount of accumulated energy and the higher is the enthalpy. ENERGY CONVERSION ONLY IF NECESSARY

8. We can consider: large hydroelectric river basins at a high altitude large deposits of combustible materials big tanks of high pressure compressed gasses etc. The most prudent behaviour about the energy problems is to help the use of kind of energy fitting to the aims and to resort to the conversion when it is the only solution. ENERGY CONVERSION ONLY IF NECESSARY

9. For example, the use of the energy as electricity is reasonable for: Motors Lighting system Communications Computer science ENERGY CONVERSION ONLY IF NECESSARY

10. On the contrary, it is not justified resorting to a cycle including the conversion of high temperature heat in electricity, losing beyond 60%, in order to make a second conversion in a low temperature heat: For example: electrical water heaters electrical stoves ENERGY CONVERSION ONLY IF NECESSARY

11. A different budget can be made when the energy as electricity is reconverted in order to realize thermodynamic cycles allowing to use heat supplies already available by raising the temperature. For instance, the heat pump systems of heating. Or electrical oven in comparison with those heated by fuel without thermal recovery like the gas kitchen oven. In cases as these, the conversion of the electricity in heat can be justified, since it takes part in a favourable total cycle. ENERGY CONVERSION ONLY IF NECESSARY

12. Concerning the sustainability, the energy transport permits to rationalize many applications. According to the current level of technology, the conversion in electricity allows the transport of energy with small losses and reduced dangers, in comparison with other transport system. ELECTRICITY AND HYDROGEN, ENERGY CARRIERS

13. The electrical net requires high investments in infrastructures, both economic ones and those of converted energy in order to construct them. In the electrical net there is no transport of materials, there are a few machineries in motion, and the episodes of interruption of the transport are frequent only if the net is excessively complex. ELECTRICITY AND HYDROGEN, ENERGY CARRIERS

14. Conversion in electricity allows storage methods with reduced capacity, high cost and low efficiency, dedicated only to the emergency systems. On the contrary, the situation, which some analysts foresee for a close future time, about hydrogen production for energy use, is different. ELECTRICITY AND HYDROGEN, ENERGY CARRIERS

15. The hydrogen is widespread on the earth, but it composes materials like the water with strong energy of chemical link. For the breaking of this linkage is necessary to convert very precious energy and the efficiency of this process is not very high. HYDROGEN FEATURES

16. Other disadvantages of the energy system based on hydrogen are: Low density, and consequently heavy high pressure tanks or large gasometers. Very frequent losses from tanks and piping. Hazard of flare-up High speed of climbing in the stratosphere and great chemical affinity with ozone. Demand for high pumping power in the pipes. Temperature of liquefaction very low <20°K. HYDROGEN FEATURES

17. The hydrogen is therefore an artificial fuel difficult to transport and to accumulate, it does not give emission of CO2 if is obtained from the water, but its use for the production of low temperature heat is unreasonable. It always offers interesting prospects for the possibility of inverse electrolysis if the technological problems connected to its manipulation are solved.. HYDROGEN FEATURES

18. The heat conversion in electrical energy has had a greater expansion than it was technically justifiable. Power stations have been built more and more powerful in the same place, because of: better efficiency for the scale factor difficulty to find new locations being favourable for the construction, especially for nuclear power stations lower expenses for the staff devoted to management On other hand, the constructions of single or few number systems have become too much expensive. CENTRALIZED OR DIFFUSE CONVERSION ?

19. The hydroelectric plants, where energy conversion does not occur since the natural resource is already mechanical energy, are built in a position obliged by the hydro geologic situation. Often the big systems have deeply modified the territory. They force people to leave the flooded regions and they are not free from risks. The electric power coming from these plants in centralized way usually needs be distributed in far localities. CENTRALIZED OR DIFFUSE CONVERSION ?

20. The convenience criteria about the transformations of solar or wind energy are opposite. The solar radiation has a power density of equivalent magnitude as one demanded for final use and it is very discontinuous. The wind energy has a greater power density, but it is characterized by extreme irregularity. CENTRALIZED OR DIFFUSE CONVERSION ?

21. Any is the applied technology both these natural resources will become convenient if: The primary conversion occurs close to the place of the final use Accumulation of energy is obtained through small and distributed devices The final uses do not needs energy in continuous way Integration with energy from other sources is achievable. CENTRALIZED OR DIFFUSE CONVERSION ?

22. The solar and wind low power systems and distributed in the territory also offer the advantage of being cheaper than those that are centralized, because they can be manufactured in series and in unified way. Moreover, they can be installed and managed by staff with modest technical qualification. In the current condition of technology, hardly it will become convenient converting the solar and wind energy in centralized way and distributing energies in the territory that are naturally already available in distributed way. CENTRALIZED OR DIFFUSE CONVERSION ?

23. Many applications of the solar energy do not demand the conversion in mechanical energy otherwise realizing favourable and economic cycles. The solar energy has been for millennia used for the salt separation from the sea water through evaporation, because the valuable material was the salt and the technical knowledge allowed only this process. FROM SUN DRINKABLE WATER, CLIMATISATION AND ONCE-THROUGH COOLING

24. Nowadays, in many places the precious material is the freshwater and efficient processes can be developed in order to obtain it from the sea. through photovoltaic cells and osmotic membranes through multiple stage evaporation process at low pressure The freshwater or feebly salt water for agricultural and alimentary use can easily be accumulated and distributed. It re-enters in the energetic resources of the type of entropy reduction. FROM SUN DRINKABLE WATER, CLIMATISATION AND ONCE-THROUGH COOLING

25. Other human needs, which can be satisfied by the solar energy in disseminated modality without the phase of the conversion in electricity, are related to the air conditioning. The necessity to heat or to cool air in the buildings, thermally insulated from the outside, in order to obtain comfortable conditions for people or in order to conserve fresh goods, can be satisfied resorting to plants that take advantage of the solar heat, or directly or through refrigeration cycles. Systems of this type need for the construction and the management staff with basic technical knowledge. FROM SUN CLIMATISATION AND ONCE-THROUGH COOLING

26. It is obligatory, even if we use the sources of energy defined renewable, operating with great precaution and respect for the nature. Taking hydraulic, solar and wind energy away can modify also deeply the atmosphere in which beings exist and they reproduce themselves. ATMOSPHERE MODIFICATIONS DUE TO TAKING ENERGY AWAY

27. Beyond the accumulating hydroelectric systems, which have been pointed out, all kinds of hydraulic systems steal energy from water course reducing the natural ability to modify, through the erosion and the carrying materials, the shape of the river bed and the depuration of the water with the turbulence and the oxygenation. HYDRAULIC ENERGY

28. The species living in the water course would be established in modified environment regarding: oxygen presence temperature organic sediments and bacterial flora other species of the alimentary chain The equilibriums among species are often unstable and they can change strongly. HYDRAULIC ENERGY

29. Equally it can happen when energy is captured excessively from the atmospheric currents at a low altitude. The air kinetic energy participates in a great number of dynamic and thermodynamic phenomena. ENERGY FROM THE WIND

30. Its decrease can cause remarkable changes regarding: Composition Organic and inorganic pollens and other carried materials Temperature pressure and humidity ENERGY FROM THE WIND

31. Its decrease can cause remarkable changes regarding: Ability to dilution of injurious elements and transport at distance of nourishing substances Perhaps there is not any risk to change the climatology of the Earth, but locally the living rainfall and equilibriums among species can be modified, above all among bugs which are often in relation with the vegetation, and the alimentary chains are based on them. ENERGY FROM THE WIND

32. The absorption and radiation factors of the land surface can be modified through installation of large extensions of solar panels in order to obtain either low temperatures or high temperatures through concentration systems or direct conversion panels. These installations have effects on the atmosphere which are comparable to what it would happen destroying forests or asphalting great extensions of land. They change the thermal upward currents and all the local meteorology and the all living beings suffer the situation. SOLAR PANELS

33. The actions on the natural energetic system are renewable and sustainable only if they are accurately planned and if the concentration limits are not exceeded, which are different for each type of territory. As consequence of the natural limits impending over every modality of taking energy away we can always rely on: saving of energy reasonable use of the type of energy temperature at final use as much as possible near to the primary one of the used resource SAVING AND REASONABLE USE

34. Saving and reasonable use are certainly the most renewable and sustainable sources of energy we can imagine. These sources have to be integrated with all the judiciousness and the knowledge that is available as far as the watchful saving of the entropy and constant separation of all those materials reacting spontaneously or blending themselves or containing latent energy, that can still be useful if correctly managed. SAVING AND REASONABLE USE

35. Do not mix sewer waters and waters containing detergents Recycle glasses, metals, cellulose, feeds etc Recover the heat of lukewarm waters before releasing in the atmosphere Recover the heat discharged from the thermodynamic cycles (co-generation) Construct buildings with low energy loss Power lines with low dispersion Transports optimized for the impact on the atmosphere and the conversion of energy SAVING AND REASONABLE USE

36. The low temperature heat comes from thermodynamic cycles and industrial waste, but also from lukewarm water from civil use, whose residual heat can be captured through opportune means. Other resources of heat at low temperature are of natural origin due to secondary volcanic activity. The recovery of the heat, destined in great part to the civil uses, demands the construction of complex and expensive thermal nets. The countries that have this kind of nets are typically those that have very cold climates and short time of investment recovery. With raise of the fuel price and the costs of the pollution the thermal nets will be able to be diffused also in different climatic areas. SAVING AND REASONABLE USE

37. The thermal energy at temperature =< 100 °C has a relevant economic value and it can be recycled with great advantage for the safeguard of the environment because the following aspects are avoided: the alteration of the thermal condition of the atmosphere where the unusable heat is discharged the combustion of valuable materials and the emission of corresponding smoke the improper use of energy sources adapted to reach higher temperatures THERMAL NETS AND GEOTERMIA, INVESTMENTS AND SAVINGS

38. Another source of not renewable energy, free from atmospheric emissions energy, that it is proposed but it must be estimated with great precaution, is the hydroelectric exploitation of the sea water through the flooding of areas that are under the sea level. Often in the past these areas were invaded from the sea from which they were separated by the movements of earth. ENERGY FROM THE SEA, PLANS OF FLOODING OF THE LOW LEVEL AREAS

39. Their flooding, beyond the exploitation of the water energy in the filling phase, can carry some mitigations of the climate and the possibility of sustainable activities, such as: fish breeding drinkable water from the sea fishing inland navigation ENERGY FROM THE SEA, PLANS OF FLOODING OF THE LOW LEVEL AREAS

40. For the immense extension of these areas, these plans must be examined with precaution, because the alteration of the environment connected to them can large and hardly expectable. ENERGY FROM THE SEA, PLANS OF FLOODING OF THE LOW LEVEL AREAS