energy from renewable sources, durable alternative for mankind in ...
ENERGY FROM RENEWABLE SOURCES, DURABLE ALTERNATIVE FOR MANKIND IN GENERATING ELECTRICAL AND THERMAL ENERGY Dr. Eng. Corneliu DIŢESCU, Technical Manager – S.C. CRAIOVA ENERGETIC COMPLEX S.A., Craiova, Dolj region, 147 Unirii Street, phone no. 0351 40.33.21, fax no. 0351 44.95.51, e-mail [email protected] Eng. Cristian COCOŞILĂ, Chief of Operation, Emergency Situations Prevention Department – S.C. CRAIOVA ENERGETIC COMPLEX S.A., Craiova, Dolj region, 147 Unirii Street, phone no. 0351 40.33.21, fax no. 0351 44.95.51, e-mail [email protected]
The exposition intends to be a short presentation of the recent, actual and future mankind energetical situations; this way we are trying to define perspectives in this field in quite large limits, starting with, to obtain by economical and social factors sensitivation the undertaking for measures, now and perpetually, intended to increase the chances to take advantage from a normal living also for the future generations. The Authors. Motto: The nature gives us various alternatives for energy generating. The only problem is how to transform the solar light, the wind, the biomass, the geothermal energy or hydropower into electricity or heat in an ecological and lower cost way . 1. Introduction Concordant to actual knowledge and technical development level, it is considered that the surrounding Universe exists in two shapes: substance and force. The substance is characterized by two fundamental parameters: mass and energy. The mass represents a measure of inertia and gravity, and energy is a measure of substance movement. Any energetical policy is faced with the energy cost problem, and this is ultimately a matter of time. Society development is directly dependent of the energy consumption. Statistic processing of the correlations between energy consumption, industrial development and national product reflects a tight connection between those factors. The exhaustible character of energetic resources promotes the future energetical options problem. 2. Actual situation The elementary energy forms that actually takes part in the greatest extent in energetical needs satisfying are: coals, liquid and gaseous hydrocarbons, hydraulic energy and nuclear energy. The globally made studies regarding energy supply and demand for the next 50 years indicated that the world will succeed in crossing this energetical crisis period, but with the maximum effort price, in two difficult stages, respectively: 1
- switching from natural liquid hydrocarbons to synthetic liquid fuels; - development for technologies of energy extraction from renewable resources, especially solar energy. Intensive use of fosil fuels changed substantially the CO2 level in the atmosphere, causing an overall heating, generated by the greenhouse effect. Also, because of the high sulphur content it generates sulphuric acid having a corrosive effect on the appliances and beeing a source in acid rain generation. Romania possesses gas and oil reserves, but in restricted conditions, specific to the geographic area, respectively: - the pit coal is estimated as a reserve for about 925 mil. tonnes, from which reliable reserves about 400 mil. tonnes, concentrated in Jiu Valley and Banat mining fields; The pit coal from local sources is insufficient, causing the need for import to satisfy the necessities. - the lignite is the safe reserve for Romania, most of the reliable reserves (88%, i.e. 2800 million tonnes) are situated in Oltenia; - the oil still represents a reserve for Romania, last estimated value is 90 million tonnes; the power plants use actually 65 - 70% of the national oil consumption; because the fuel oil resulted from the local oil processing is insufficient, the need covering is made by imports, too; - the natural gas reserve for Romania is estimated to be 407 billion cubic meters; actually it imports substantially from CSI (about 35% of the consumption); - regarding the hydraulic energy, the installed power of hydropower plants is about 5800 MW, around 30% of the national hydroenergetic potential. Production cost of electrical energy from hydro sources is attractive, possibly resulting in using electrical energy for house heating by a more consistent proportion. Large investment costs (up to 2000 euro/kW), long carrying out duration and the necessity to make specific elaborate studies generate big obstacles in realizing these assets. In Romania are started but not completed investments for more than 100 micro hydropower plants, in different accomplishment stages. 3. Cogeneration in Romania Electroenergetic national system concentrated a lot of the electrical power suppliers in cogeneration facilities placed in the big cities neighbourhood. They provided with thermal energy (industrial steam), until 15 years ago, their industrial areas – constant consumptions – and, by the district heating system, the urban network for thermal energy distribution to the population – variable consumption summer/winter. Because most of the industrial platforms have been reorganized, the industrial consumption being drastically reduced, also because of a wrong tariff policy, the cogeneration production units became, especially in the summertime, only or mainly electrical energy production units, operating at low energetic efficiencies. The consequence was the increasing of the thermal energy cost and big fluctuations in its delivery for certain areas, caused by the disconnection of a major part of the domestic consumers (about 25%) and the development of the individual heating installations market. So it was reached the following: - conversion of the cogeneration facilities to facilities with an yearly average efficiency below 50%; - district heating system hydraulic unballancing; - emergence of the own steam production facilities at the industrial consumers; - high costs for thermal energy production; - limited investments in modernization and rehabilitation of the district heating systems and finally: - distrust in the district heating centralized systems. 2
The keys for thermal energy efficient production, considering actual and future environment restrictions, finally decrease the probability to use on long term fosil fuels as fuel sources for the thermal and electrical energy suppliers. Providing the energy by the continuously growing weight of the renewable sources is bringing fund availabilities for the financial mechanisms established by the Kyoto Protocol (CO2 credits). 4. Energetic development strategy, basis of the durable society development Durable development concept – actual needs satisfying without mortgage the future generations capacity to fulfill their own necessities – basically involves providing the worldwide balance between economic development, social equity and environment protection. In 1997, by Kyoto treaty, it was set as a goal 5,2% greenhouse gases emissions reduction worldwide until 2010 compared to 1990. European Union assumed an 8% emission reduction for 2010, each of the members assuming their own part of emissions considering each state peculiarities. To stop CO2 concentration growth until 2050, actual emissions have to be halved at worldwide level by 3 to 5 times reduction at developed states level. 4.1. European Union and durable energetic development Early 2000 European Comission made renewable energies development a political priority written in The White Paper – Energy for the Future and Green Paper – A European Strategy for Sustainable, Competitive and Secure Energy. The Comission set as a target doubling the renewable energies weight in the overall energy consumption, from 6% in 1997 to 12% in 2010. This target is inserted by a supplying security strategy and durable development. A relevant effort have to be achieved in the energetic area. In the European Union frame, the energy share produced by renewable sources have to reach 22,1% in 2010, compared to 14,2% in 1999. This target, initially set for Europe of 15 was dramatically revised for Europe of 25, the weight for the electric power produced by renewable energy sources (RES) having to reach 22%. Member states base records of the targets for contribution regarding electric power generation from renewable sources until 2010.
State Belgium Denmark Germany Greece Spain France Ireland Italy Luxembourg Netherlands Austria Portugal Finland
Electric energy generated from RES (1997) [TWh] 0,86 3,21 24,91 3,94 3,15 66,0 0,84 46,46 0,14 3,45 39,05 14,30 19,03
Electric energy weight generated from RES (1997) [%] 1,1 8,7 4,5 8,6 19,9 15,0 3,6 16,0 2,1 3,5 70,0 38,5 24,7
Electric energy weight generated from RES (2010) [%] 6,0 29,0 12,5 20,1 29,4 21,0 13,2 25,0 5,7 9,0 78,1 39,0 31,5 3
Sweden United Kingdom European Union
72,03 7,04 338,41
49,1 1,7 13,9
60,0 10,0 22,0
One of the favorable consequences of the electric power market opening is a decentralized generation development based on cogeneration ans especially from renewable sources. Embedding into the system of the renewable energy sources, of those depending on the climate (solar and eolian) in particular, and in a greater extent decentralized generation, entails the unuse of the thermal and electrical energy transport and distribution networks by engaging new installations, equipment and management methods. The final goal is maintaining reliability and quality of the natural persons and industrial units energy supplying, in the context of electric energy market liberalization and utilization as intense as posssible of the random renewable energy sources. The thermal and electrical energy transport and distribution networks existence creates, among the energetic system components, the most unpleasant impact on the environment, the main aspects of the pollution being as follows: - visual; - sonorous; - psychic and the potential to occure danger of accidents; - ecological. 4.2. Technological expectations Is difficult to identify technologies thet will play a decisive role in the future in fighting against greenhouse effect. The future energetic system having low greenhouse emissions will be based, probably, on a combination of energies, of energy converting factors, which will be found in different forms in various regions of the world. It can be distinguished a few trends of our energetic future: An increase of the renewable energy weight is predictable, but its extent will depend on costs reduction and the progresses made related to the massive storage of the electric energy, that will allow the integration into grids of large electric energy quantities discontinuously generated and distributed. For long term, is probable that each of the renewable sources to overcome 10% of the worldwide energy needs, but based on the most optimistic predictions their combinations could allow reaching up to 50% of the market by the second half of the century (early 2000 renewable energies aggregate represented 10% of the energetic generation). Energies generated on fossil fuel basis will be used for many decades, supporting energy weight which generation assume a low carbon level in fuel, like natural gas. Carbon dioxide collecting and storage in economically acceptable conditions represent the only technological option susceptible to empower utilization of fossil resources, restricting in the same time CO2 level in the atmosphere, during the expectation of some major technological evolutions. Nuclear energy doesn't generate CO2 except for the one emitted during power plants construction and the process of enriching the fuel consumed in these power plants. This type of energy will continue to be developed in a certain number of states, against the background of making sure a proper waste treatment, developing of safer reactor generations, then for long term, by developing nuclear fusion, which perspectives are outlined by 2050 year. Combustion reactors development could allow development of a "hydrogen economy". Hydrogen production doesn't generate CO2 if the hydrogen is produced by renewable, nuclear or fossil energies, with CO2 collection. Even United States, which didn't ratify Kyoto treaty, considering it as a restricting factor for their economy, have started in 2003 an ambitious rersearch program ment to lower 4
the hydrogen production costs, greenhouse gas emissions control, their storage coordination and decreasing of combustion reactors costs. In conclusion, controlling of greenhouse gas emissions can't be materialized in absence of major programs for energetic efficiency in all activity areas. The purpose is to utilize less energy to meet the same needs. 4.3. Solar energy Solar energy consist in caloric, light wave, radio or other nature radiations emitted by the sun. It is practically undepletable and represent the cleanest energy on Earth; huge available quantities are the base for almost all natural processes on the planet. Total energy received by the terrestrial crust is 720 x 106 TWh/year, this energy availability depending on the day/night cycle, the latitude of the area where is received, the seasons, nebulosity. a) Thermal solar energy assumes the domestic warm water and heating agent producing. The generation of electric energy by converting thermal solar energy presents efficiencies below 15%. Ocean surface waters in tropical areas, naturally heated by the sun represents a huge energy reservoir. The projects of "this sea thermal energy extraction" are based on action of thermotechnic installations that generates mechanical work as a result of the temperature difference between two water layers (shallow water 25 – 30°C and deep water 5°C). b) Photovoltaic solar energy is based on direct energy generation by silicium cells. The sun provides an average power of 1 kW/m2. Photovoltaic panels allow the conversion for only 10-15% of this power, the electric energy production of a one unit surface panel varying with the solar intensity increasing or decreasing: 100kW/m2 and year in Northern Europe and more in the mediterranean area. 4.3.1. Energy production weight by solar energy conversion in Romania and European Union 4.3.1.1. In Romania Solar energy has a low weight in Romania's energy production, one could say that nowadays is represented at experimental level. According to the data provided by the Romanian Agency for Energy Preservation (RAEP) is indicated for 2010 year a solar energy weight estimated for 7500 toe (tonne of oil equivalent) and for 2015 year estimated for 17000 toe, of which thermal solar 7340 toe, respective 16000 toe, and electric solar 160 toe, respective 100 toe. 18000 16000 14000
[tep]
12000
Energie solara (total)
10000
Energie solara termica
8000
Energie solara electrica
6000 4000 2000 0 prezent
2010
2015
[an]
The Romania's energetic potential which derives from the solar energy quantity is estimated to 1000 kW/m2 and year, geographical repartition of this potential is made in 5 areas, of which zero area with over 1250 kW/m2 and year potential, and fourth area with over 950 kW/m2 and year potential. Solar radiation with values over 1200 kW/m2 and year are registered for more than 50% of the overall country area. 5
Utilization of solar energetic potential is made by thermal solar systems for domestic heating and warm water for individual homes, or small-scale centralized installations. In order to be used with high efficiency, these systems have to operate in "hybrid condition" with other conventional or unconventional thermal systems. The potential to be used in thermal solar systems is estimated for 1,434 million toe.
Legenda: Zona 0:
Ps > 1250 kW/m2 an
Zona I: an
1250 ≥ Ps > 1200 kW/m2
Zona II: 1200 ≥ Ps > 1050 kW/m2 an Zona III: 1050 ≥ Ps > 950 kW/m2 an Zona IV: Ps ≤ 950 kW/m2 an
Also, solar energetic potential can be used by photovoltaic conversion systems, dedicated mainly for electric energy supplying to some isolated consumers. The exploitable potential by photovoltaic systems in our country is estimated to be about 1200 GWh/year. In Romania it were realized photovoltaic systems of various powers, in different operating conditions, against the background of performing some demonstrative research-development programs. 6
So, it were realized autonomous supply systems for some isolated consumers, radio-communication stations, water-pumping installations, public light or traffic signalize systems, and objectives subscribed in the rural development programs. Also, it were realized systems connected to the public electric network (photovoltaic experimental stations with mobile panels, building integrated systems, so on). The solar photovoltaic systems are useful in isolated geographical regions applications or the ones with limited access to the electrical network . In the photovoltaic applications it were separated several kind of projects, like: autonomous photovoltaic systems for rural electrification, with applications in Apuseni Mountains or other isolated areas (North Moldova, Danube Delta) and photovoltaic systems connected to the electric energy transportation or distribution existing systems . The demonstrative projects for thermal energy generation from solar source is realized by solar thermal systems with superior performances, having the possibility to operate banked with the classic heating systems . 4.3.1.2. Inside European Union According to RAEC, for electric energy generation by using photovoltaic panels at E.U. level it is respected the White Paper which provide for 2010 an installed power of 3000 MW. This step was overcome in 2006, when the installed power was 3420 MW, 50% more than 2005 year forecasts; for 2010 year it will be probably reached a 9000 MW power . The new capacities market in 2006 was 1245 MW, the leader in this sector being Germany (1150MW) followed by Spain, Italy, France and Austria. Out of this capacity, 1238 MW consist of connected systems to the public networks and 7 MW of autonomous systems. Regarding the thermal solar energy generation, in 2006 it was produced a quantity of 12087 MWth, corresponding to a 17,267 million s.m. collection area, and for 2010 it is forecasted a 22500 MWth production, corresponding to a 32,1 million s.m. In conclusion, the installed power in European Union was about 562,3 MW in 2003, distributed as follows: 397,6 MW in Germany, 48,63MW in Nederlands, 27,26MW in Spain, 26,02MW in Italy, 21,71MW in France, 2,07MW in Portugal and the remaining 1,06MW in Belgium. We can notice that unfortunatelly is not the Southern Europe countries developing preferably the photovoltaic network. 5. Conclusions Despite the successes gained in the developing of energy generation technologies from renewable energetic sources, the cost of electric energy obtained by these resources is still substantially higher than the cost of electric energy generated by fossil fuels burning. A way to reduce the electric energy generated by renewable resources cost could be deducing from its value the indirect costs (for environment depollution, medical costs, energy securitization costs) afferent to energy generation by conventional resources, emphasing the real cost. Renewable energies utilization degree was improved a lot in the last years, taking advantage of the direct support of the governments in several countries. Although it is risky to make forecasts, we consider that the renewable energy will get in the fore and will play an important role in the tomorrow world, starting with actual decade. Possible scenarios reveal that unconventional energies share will be flattened starting with 2020-2030, but the contribution of the renewable sources energy will continue to grow, getting in 2040-2050 to cover over 30-35% of worldwide energy need. In the XXI-st century, if the world population would not increase any more, actually being about 6 billion people, it will require a substantially bigger energetic consumption than it is now. Other forecasts present a population evolution up to 10 billion people, corresponding to an increased energetic consumption. It hopes that renewable resources will satisfy these requirements for energetic production increase. 7
Romania has a good renewable resources potential, gathering till now through researchdevelopment activities in this sector, at least the necessary experience for the future. Among these, at this century end the solar energy could represent worldwide the main electric power source, nowadays the role of this resource being neglected in a certain degree because of the pretty high production costs. Among all energy resources that comes in the ecological and renewable category, the solar energy assumes relativelly simple installations, which operate at low temperatures, the water temperature in the solar thermal energy generation being only 40 degrees higher than the environmental temperature. That's why utilizing solar energy becomes peculiarly interesting, prevailingly in domestic water and buildings heating. Our country is a proper area for solar panels utilization and that is why the investments in solar energy generation will have a guaranteed interest. Being situated in southern Europe – B zone, the solarization degree is high, meaning that the solar panels as a heating solution in the first place is highly enforced . 6. Bibliography 1. Sârbu I., Kalmar F. – Energetical optimization, Matrix Rom publisher, Bucharest, 2002 2. World Energy Council – Survey of Energy Resources, 2001 3. The XVIIIth World Energy Congress Papers, Buenos Aires, 2001 4. www.greenpeace.ro – Clean Energy for Romania 5. Directive 77/2001/CE of the European Parliament
8
The exposition intends to be a short presentation of the recent, actual and future mankind energetical situations; this way we are trying to define perspectives in this field in quite large limits, starting with, to obtain by economical and social factors sensitivation the undertaking for measures, now and perpetually, intended to increase the chances to take advantage from a normal living also for the future generations. The Authors. Motto: The nature gives us various alternatives for energy generating. The only problem is how to transform the solar light, the wind, the biomass, the geothermal energy or hydropower into electricity or heat in an ecological and lower cost way . 1. Introduction Concordant to actual knowledge and technical development level, it is considered that the surrounding Universe exists in two shapes: substance and force. The substance is characterized by two fundamental parameters: mass and energy. The mass represents a measure of inertia and gravity, and energy is a measure of substance movement. Any energetical policy is faced with the energy cost problem, and this is ultimately a matter of time. Society development is directly dependent of the energy consumption. Statistic processing of the correlations between energy consumption, industrial development and national product reflects a tight connection between those factors. The exhaustible character of energetic resources promotes the future energetical options problem. 2. Actual situation The elementary energy forms that actually takes part in the greatest extent in energetical needs satisfying are: coals, liquid and gaseous hydrocarbons, hydraulic energy and nuclear energy. The globally made studies regarding energy supply and demand for the next 50 years indicated that the world will succeed in crossing this energetical crisis period, but with the maximum effort price, in two difficult stages, respectively: 1
- switching from natural liquid hydrocarbons to synthetic liquid fuels; - development for technologies of energy extraction from renewable resources, especially solar energy. Intensive use of fosil fuels changed substantially the CO2 level in the atmosphere, causing an overall heating, generated by the greenhouse effect. Also, because of the high sulphur content it generates sulphuric acid having a corrosive effect on the appliances and beeing a source in acid rain generation. Romania possesses gas and oil reserves, but in restricted conditions, specific to the geographic area, respectively: - the pit coal is estimated as a reserve for about 925 mil. tonnes, from which reliable reserves about 400 mil. tonnes, concentrated in Jiu Valley and Banat mining fields; The pit coal from local sources is insufficient, causing the need for import to satisfy the necessities. - the lignite is the safe reserve for Romania, most of the reliable reserves (88%, i.e. 2800 million tonnes) are situated in Oltenia; - the oil still represents a reserve for Romania, last estimated value is 90 million tonnes; the power plants use actually 65 - 70% of the national oil consumption; because the fuel oil resulted from the local oil processing is insufficient, the need covering is made by imports, too; - the natural gas reserve for Romania is estimated to be 407 billion cubic meters; actually it imports substantially from CSI (about 35% of the consumption); - regarding the hydraulic energy, the installed power of hydropower plants is about 5800 MW, around 30% of the national hydroenergetic potential. Production cost of electrical energy from hydro sources is attractive, possibly resulting in using electrical energy for house heating by a more consistent proportion. Large investment costs (up to 2000 euro/kW), long carrying out duration and the necessity to make specific elaborate studies generate big obstacles in realizing these assets. In Romania are started but not completed investments for more than 100 micro hydropower plants, in different accomplishment stages. 3. Cogeneration in Romania Electroenergetic national system concentrated a lot of the electrical power suppliers in cogeneration facilities placed in the big cities neighbourhood. They provided with thermal energy (industrial steam), until 15 years ago, their industrial areas – constant consumptions – and, by the district heating system, the urban network for thermal energy distribution to the population – variable consumption summer/winter. Because most of the industrial platforms have been reorganized, the industrial consumption being drastically reduced, also because of a wrong tariff policy, the cogeneration production units became, especially in the summertime, only or mainly electrical energy production units, operating at low energetic efficiencies. The consequence was the increasing of the thermal energy cost and big fluctuations in its delivery for certain areas, caused by the disconnection of a major part of the domestic consumers (about 25%) and the development of the individual heating installations market. So it was reached the following: - conversion of the cogeneration facilities to facilities with an yearly average efficiency below 50%; - district heating system hydraulic unballancing; - emergence of the own steam production facilities at the industrial consumers; - high costs for thermal energy production; - limited investments in modernization and rehabilitation of the district heating systems and finally: - distrust in the district heating centralized systems. 2
The keys for thermal energy efficient production, considering actual and future environment restrictions, finally decrease the probability to use on long term fosil fuels as fuel sources for the thermal and electrical energy suppliers. Providing the energy by the continuously growing weight of the renewable sources is bringing fund availabilities for the financial mechanisms established by the Kyoto Protocol (CO2 credits). 4. Energetic development strategy, basis of the durable society development Durable development concept – actual needs satisfying without mortgage the future generations capacity to fulfill their own necessities – basically involves providing the worldwide balance between economic development, social equity and environment protection. In 1997, by Kyoto treaty, it was set as a goal 5,2% greenhouse gases emissions reduction worldwide until 2010 compared to 1990. European Union assumed an 8% emission reduction for 2010, each of the members assuming their own part of emissions considering each state peculiarities. To stop CO2 concentration growth until 2050, actual emissions have to be halved at worldwide level by 3 to 5 times reduction at developed states level. 4.1. European Union and durable energetic development Early 2000 European Comission made renewable energies development a political priority written in The White Paper – Energy for the Future and Green Paper – A European Strategy for Sustainable, Competitive and Secure Energy. The Comission set as a target doubling the renewable energies weight in the overall energy consumption, from 6% in 1997 to 12% in 2010. This target is inserted by a supplying security strategy and durable development. A relevant effort have to be achieved in the energetic area. In the European Union frame, the energy share produced by renewable sources have to reach 22,1% in 2010, compared to 14,2% in 1999. This target, initially set for Europe of 15 was dramatically revised for Europe of 25, the weight for the electric power produced by renewable energy sources (RES) having to reach 22%. Member states base records of the targets for contribution regarding electric power generation from renewable sources until 2010.
State Belgium Denmark Germany Greece Spain France Ireland Italy Luxembourg Netherlands Austria Portugal Finland
Electric energy generated from RES (1997) [TWh] 0,86 3,21 24,91 3,94 3,15 66,0 0,84 46,46 0,14 3,45 39,05 14,30 19,03
Electric energy weight generated from RES (1997) [%] 1,1 8,7 4,5 8,6 19,9 15,0 3,6 16,0 2,1 3,5 70,0 38,5 24,7
Electric energy weight generated from RES (2010) [%] 6,0 29,0 12,5 20,1 29,4 21,0 13,2 25,0 5,7 9,0 78,1 39,0 31,5 3
Sweden United Kingdom European Union
72,03 7,04 338,41
49,1 1,7 13,9
60,0 10,0 22,0
One of the favorable consequences of the electric power market opening is a decentralized generation development based on cogeneration ans especially from renewable sources. Embedding into the system of the renewable energy sources, of those depending on the climate (solar and eolian) in particular, and in a greater extent decentralized generation, entails the unuse of the thermal and electrical energy transport and distribution networks by engaging new installations, equipment and management methods. The final goal is maintaining reliability and quality of the natural persons and industrial units energy supplying, in the context of electric energy market liberalization and utilization as intense as posssible of the random renewable energy sources. The thermal and electrical energy transport and distribution networks existence creates, among the energetic system components, the most unpleasant impact on the environment, the main aspects of the pollution being as follows: - visual; - sonorous; - psychic and the potential to occure danger of accidents; - ecological. 4.2. Technological expectations Is difficult to identify technologies thet will play a decisive role in the future in fighting against greenhouse effect. The future energetic system having low greenhouse emissions will be based, probably, on a combination of energies, of energy converting factors, which will be found in different forms in various regions of the world. It can be distinguished a few trends of our energetic future: An increase of the renewable energy weight is predictable, but its extent will depend on costs reduction and the progresses made related to the massive storage of the electric energy, that will allow the integration into grids of large electric energy quantities discontinuously generated and distributed. For long term, is probable that each of the renewable sources to overcome 10% of the worldwide energy needs, but based on the most optimistic predictions their combinations could allow reaching up to 50% of the market by the second half of the century (early 2000 renewable energies aggregate represented 10% of the energetic generation). Energies generated on fossil fuel basis will be used for many decades, supporting energy weight which generation assume a low carbon level in fuel, like natural gas. Carbon dioxide collecting and storage in economically acceptable conditions represent the only technological option susceptible to empower utilization of fossil resources, restricting in the same time CO2 level in the atmosphere, during the expectation of some major technological evolutions. Nuclear energy doesn't generate CO2 except for the one emitted during power plants construction and the process of enriching the fuel consumed in these power plants. This type of energy will continue to be developed in a certain number of states, against the background of making sure a proper waste treatment, developing of safer reactor generations, then for long term, by developing nuclear fusion, which perspectives are outlined by 2050 year. Combustion reactors development could allow development of a "hydrogen economy". Hydrogen production doesn't generate CO2 if the hydrogen is produced by renewable, nuclear or fossil energies, with CO2 collection. Even United States, which didn't ratify Kyoto treaty, considering it as a restricting factor for their economy, have started in 2003 an ambitious rersearch program ment to lower 4
the hydrogen production costs, greenhouse gas emissions control, their storage coordination and decreasing of combustion reactors costs. In conclusion, controlling of greenhouse gas emissions can't be materialized in absence of major programs for energetic efficiency in all activity areas. The purpose is to utilize less energy to meet the same needs. 4.3. Solar energy Solar energy consist in caloric, light wave, radio or other nature radiations emitted by the sun. It is practically undepletable and represent the cleanest energy on Earth; huge available quantities are the base for almost all natural processes on the planet. Total energy received by the terrestrial crust is 720 x 106 TWh/year, this energy availability depending on the day/night cycle, the latitude of the area where is received, the seasons, nebulosity. a) Thermal solar energy assumes the domestic warm water and heating agent producing. The generation of electric energy by converting thermal solar energy presents efficiencies below 15%. Ocean surface waters in tropical areas, naturally heated by the sun represents a huge energy reservoir. The projects of "this sea thermal energy extraction" are based on action of thermotechnic installations that generates mechanical work as a result of the temperature difference between two water layers (shallow water 25 – 30°C and deep water 5°C). b) Photovoltaic solar energy is based on direct energy generation by silicium cells. The sun provides an average power of 1 kW/m2. Photovoltaic panels allow the conversion for only 10-15% of this power, the electric energy production of a one unit surface panel varying with the solar intensity increasing or decreasing: 100kW/m2 and year in Northern Europe and more in the mediterranean area. 4.3.1. Energy production weight by solar energy conversion in Romania and European Union 4.3.1.1. In Romania Solar energy has a low weight in Romania's energy production, one could say that nowadays is represented at experimental level. According to the data provided by the Romanian Agency for Energy Preservation (RAEP) is indicated for 2010 year a solar energy weight estimated for 7500 toe (tonne of oil equivalent) and for 2015 year estimated for 17000 toe, of which thermal solar 7340 toe, respective 16000 toe, and electric solar 160 toe, respective 100 toe. 18000 16000 14000
[tep]
12000
Energie solara (total)
10000
Energie solara termica
8000
Energie solara electrica
6000 4000 2000 0 prezent
2010
2015
[an]
The Romania's energetic potential which derives from the solar energy quantity is estimated to 1000 kW/m2 and year, geographical repartition of this potential is made in 5 areas, of which zero area with over 1250 kW/m2 and year potential, and fourth area with over 950 kW/m2 and year potential. Solar radiation with values over 1200 kW/m2 and year are registered for more than 50% of the overall country area. 5
Utilization of solar energetic potential is made by thermal solar systems for domestic heating and warm water for individual homes, or small-scale centralized installations. In order to be used with high efficiency, these systems have to operate in "hybrid condition" with other conventional or unconventional thermal systems. The potential to be used in thermal solar systems is estimated for 1,434 million toe.
Legenda: Zona 0:
Ps > 1250 kW/m2 an
Zona I: an
1250 ≥ Ps > 1200 kW/m2
Zona II: 1200 ≥ Ps > 1050 kW/m2 an Zona III: 1050 ≥ Ps > 950 kW/m2 an Zona IV: Ps ≤ 950 kW/m2 an
Also, solar energetic potential can be used by photovoltaic conversion systems, dedicated mainly for electric energy supplying to some isolated consumers. The exploitable potential by photovoltaic systems in our country is estimated to be about 1200 GWh/year. In Romania it were realized photovoltaic systems of various powers, in different operating conditions, against the background of performing some demonstrative research-development programs. 6
So, it were realized autonomous supply systems for some isolated consumers, radio-communication stations, water-pumping installations, public light or traffic signalize systems, and objectives subscribed in the rural development programs. Also, it were realized systems connected to the public electric network (photovoltaic experimental stations with mobile panels, building integrated systems, so on). The solar photovoltaic systems are useful in isolated geographical regions applications or the ones with limited access to the electrical network . In the photovoltaic applications it were separated several kind of projects, like: autonomous photovoltaic systems for rural electrification, with applications in Apuseni Mountains or other isolated areas (North Moldova, Danube Delta) and photovoltaic systems connected to the electric energy transportation or distribution existing systems . The demonstrative projects for thermal energy generation from solar source is realized by solar thermal systems with superior performances, having the possibility to operate banked with the classic heating systems . 4.3.1.2. Inside European Union According to RAEC, for electric energy generation by using photovoltaic panels at E.U. level it is respected the White Paper which provide for 2010 an installed power of 3000 MW. This step was overcome in 2006, when the installed power was 3420 MW, 50% more than 2005 year forecasts; for 2010 year it will be probably reached a 9000 MW power . The new capacities market in 2006 was 1245 MW, the leader in this sector being Germany (1150MW) followed by Spain, Italy, France and Austria. Out of this capacity, 1238 MW consist of connected systems to the public networks and 7 MW of autonomous systems. Regarding the thermal solar energy generation, in 2006 it was produced a quantity of 12087 MWth, corresponding to a 17,267 million s.m. collection area, and for 2010 it is forecasted a 22500 MWth production, corresponding to a 32,1 million s.m. In conclusion, the installed power in European Union was about 562,3 MW in 2003, distributed as follows: 397,6 MW in Germany, 48,63MW in Nederlands, 27,26MW in Spain, 26,02MW in Italy, 21,71MW in France, 2,07MW in Portugal and the remaining 1,06MW in Belgium. We can notice that unfortunatelly is not the Southern Europe countries developing preferably the photovoltaic network. 5. Conclusions Despite the successes gained in the developing of energy generation technologies from renewable energetic sources, the cost of electric energy obtained by these resources is still substantially higher than the cost of electric energy generated by fossil fuels burning. A way to reduce the electric energy generated by renewable resources cost could be deducing from its value the indirect costs (for environment depollution, medical costs, energy securitization costs) afferent to energy generation by conventional resources, emphasing the real cost. Renewable energies utilization degree was improved a lot in the last years, taking advantage of the direct support of the governments in several countries. Although it is risky to make forecasts, we consider that the renewable energy will get in the fore and will play an important role in the tomorrow world, starting with actual decade. Possible scenarios reveal that unconventional energies share will be flattened starting with 2020-2030, but the contribution of the renewable sources energy will continue to grow, getting in 2040-2050 to cover over 30-35% of worldwide energy need. In the XXI-st century, if the world population would not increase any more, actually being about 6 billion people, it will require a substantially bigger energetic consumption than it is now. Other forecasts present a population evolution up to 10 billion people, corresponding to an increased energetic consumption. It hopes that renewable resources will satisfy these requirements for energetic production increase. 7
Romania has a good renewable resources potential, gathering till now through researchdevelopment activities in this sector, at least the necessary experience for the future. Among these, at this century end the solar energy could represent worldwide the main electric power source, nowadays the role of this resource being neglected in a certain degree because of the pretty high production costs. Among all energy resources that comes in the ecological and renewable category, the solar energy assumes relativelly simple installations, which operate at low temperatures, the water temperature in the solar thermal energy generation being only 40 degrees higher than the environmental temperature. That's why utilizing solar energy becomes peculiarly interesting, prevailingly in domestic water and buildings heating. Our country is a proper area for solar panels utilization and that is why the investments in solar energy generation will have a guaranteed interest. Being situated in southern Europe – B zone, the solarization degree is high, meaning that the solar panels as a heating solution in the first place is highly enforced . 6. Bibliography 1. Sârbu I., Kalmar F. – Energetical optimization, Matrix Rom publisher, Bucharest, 2002 2. World Energy Council – Survey of Energy Resources, 2001 3. The XVIIIth World Energy Congress Papers, Buenos Aires, 2001 4. www.greenpeace.ro – Clean Energy for Romania 5. Directive 77/2001/CE of the European Parliament
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