ENVIRONMENTAL IMPACT ASSESSMENT OF SOLAR ENERGY SYSTEMS RESULTS FROM A LIFE CYCLE ANALYSIS

ENVIRONMENTAL IMPACT ASSESSMENT OF SOLAR ENERGY SYSTEMS RESULTS FROM A LIFE CYCLE ANALYSIS V.Gekas1, N.Frantzeskaki2 and T.Tsoutsos3 1,2 Department o...
9 downloads 2 Views 92KB Size
ENVIRONMENTAL IMPACT ASSESSMENT OF SOLAR ENERGY SYSTEMS RESULTS FROM A LIFE CYCLE ANALYSIS V.Gekas1, N.Frantzeskaki2 and T.Tsoutsos3 1,2

Department of Environmental Engineering Technical University of Crete, GR-73100, Chania 3 Centre for Renewable Energy Sources (CRES), 19th km Marathon Ave, GR-19009 Pikermi E-mail: [email protected]

ABSTRACT Nowadays it is widely accepted that the active Solar Energy Systems (photovoltaics, solar thermal, solar power) provide significant environmental benefits in comparison to the conventional energy sources, contributing to the sustainability of the human activities. To cope with their potential environmental implications an EIA is applied by using the LCA method. Additionally the technologies and techniques used to alleviate the environmental intrusion are presented.

ΕΚΤΙΜΗΣΗ ΠΕΡΙΒΑΛΛΟΝΤΙΚΩΝ ΕΠΙΠΤΩΣΕΩΝ ΗΛΙΑΚΩΝ ΣΥΣΤΗΜΑΤΩΝ AΠΟΤΕΛΕΣΜΑΤΑ ΑΠΟ ΑΝΑΛΥΣΗ ΚΥΚΛΟΥ ΖΩΗΣ 1,2

Β.Γκέκας1, Ν.Φραντζεσκάκη2 και Θ.Τσούτσος3 Τµήµα Μηχανικών Περιβάλλοντος, Πολυτεχνείο Κρήτης, GR-73100, Χανιά 3 Κέντρο Ανανεώσιµων Πηγών Ενέργειας (ΚΑΠΕ) 19ο χλµ Λ. Μαραθώνος, GR-19009 Πικέρµι E-mail: [email protected]

ΠΕΡΙΛΗΨΗ Σήµερα είναι κοινώς αποδεκτό ότι τα ενεργητικά Ηλιακά Συστήµατα (φωτοβολταϊκά, ηλιακά θερµικά, ηλιοθερµικά) παρέχουν σηµαντικά περιβαλλοντικά οφέλη σε σύγκριση µε τις συµβατικές πηγές ενέργειας, συνεισφέροντας σε µια αειφόρο προοπτική των ανθρωπίνων δραστηριοτήτων. Για την ελαχιστοποίηση των ενδεχοµένων περιβαλλοντικών επιπτώσεων έχει εφαρµοσθεί µία Ανάλυση Περιβαλλοντικών Επιπτώσεων σύµφωνα µε τη µεθοδολογία Ανάλυσης Κύκλου Ζωής. Επίσης, παρουσιάζονται τεχνολογίες και τεχνικές αντιµετώπισης και απαλοιφής των περιβαλλοντικών οχλήσεων των ηλιακών συστηµάτων.

Proceedings of the International Conference "Protection and Restoration of the Environment VI" Skiathos, July 1-5, 2002, Pages 1569-1576

Editors: A.G. Kungolos, A.B. Liakopoulos G.P. Korfiatis, A.D. Koutsospyros K.L. Κatsifarakis, A.C. Demetracopoulos

1570

Protection and restoration of the environment VI

1. ENVIRONMENTAL IMPACTS OF SETs Solar Energy Technologies (SETs) provide significant environmental benefits when compared to the conventional energy sources, contributing to the sustainable development. The use of SETs has positive environmental implications such as [1,2,3,4]: • reduction of the CO2 emissions; • improvement of the quality of water supplies; • reclamation of degraded land; • reduction of the number of the required power transmission lines. PRODUCTION

REJECTION/ WASTE MANAGEMENT

TRANSPORTATION

MAINTENANCE

INSTALLATION

OPERATION

Figure 1. Stages of Life Cycle Analysis and Assessment for Solar Energy Systems. From the socio-economic viewpoint the benefits of the use of SETs include: • reduction of the national dependency on fuel imports; • diversification and security of energy supply; • provision of significant job opportunities and working positions; • support of the energy market deregulation; • acceleration of the rural electrification in developing countries. The potential environmental burdens of SETs depend on the size and nature of the project and are frequently site specific. These burdens are usually associated with loss of amenity (e.g. visual impact or noise) and the impacts can be minimized by [5,6]: • appropriate siting, which involves careful evaluation of alternative locations and estimation of expected impact; • EIA studies, which propose appropriate mitigation measures; • the use of the best available technologies/techniques; • evaluating the local, regional and global benefit and cost; • engaging the public and relevant organizations in the early stages of planning, in order to ensure public acceptance. 2. SOLAR THERMAL (ST) SYSTEMS 2.1 Environmental impacts (i) Environmental benefits: Τhe large-scale adoption of ST technologies will significantly reduce the consumption of fossil fuels and will consequently reduce the environmental impacts associated with these fuels [7].

Environmental impact assessment and risk analysis

1571

(ii) Land use: For low/medium systems, land use depends on the characteristics of the particular selected system and on the landscape. Communal low-temperature systems might use some land, though again the collection surfaces might well be added on already existing buildings [4]. (iii) Routine and accidental discharges of pollutants: Once the system is operational, coolant liquids may need change on regular basis. Furthermore the risk of accidental pollution of potable water supplies through leaks of heat transfer fluid is not negligible [7]. (iv) Visual impact: The aesthetic impact of solar panels is similar to those of the television aerials [4]. (v) Effect on buildings: The addition to the building fabric may increase the fire risk –theoretically-, and the water intrusion into the roof space [7]. 2.2 Technologies/ techniques to mitigate the environmental impacts Almost all potential impacts of ST systems can be avoided or mitigated: • By siting and installation of the ST systems on existing roofs to minimize visual impacts, as the glare from solar panel glazing [8]. This can be ameliorated by allowing architectural integration into already existing or new buildings with minimum or even positive visual impact. It is also recommended to avoid the siting of solar panels on buildings of historic interest or in conservation areas. • In the case of large-scale systems predevelopment assessments can diminish the loss of habitat and cause changes to the ecosystem and visual intrusion. Sites of significant natural beauty are avoided in order to mitigate visual and ecological intrusion [4]. • Accidental discharges and leakages of used chemicals can be avoided by good working practice and by using appropriate equipment during installation and maintenance. Recycling of the used chemicals and appropriate disposal of the chemicals is expected to minimize indirect environmental impacts [4,7]. • Effect on building can be avoided by safety systems installed in the buildings, as well as by good working practice (e.g. protection from water leakages). 3. PHOTOVOLTAIC (PV) POWER GENERATION 3.1 Environmental impacts (i) Environmental benefits: Significant emission reductions can be accomplished through PV electricity (PVe) production since PVs do not generate noise or chemical pollutants during their normal operation. Besides, PV cells help the increase of soil humidity and improve flora formation in dry/arid areas [4,7,9]. (ii) Social impacts: Some direct benefits are related to lighting for domestic and community activities and mainly to the opportunity to suburban and borderland’s habitants to have access to computers, lighting, radio and phone. Therefore PVe improves the quality of life and reduces migration. During installation and maintenance full- and part-time jobs creation improves local microeconomics and drives to poverty alleviation [4,7,9]. (iii) Land use: The impact of land use on natural ecosystems is depended on specific factors such as the topography, the area and the type of the land covered by the system, the distance from areas of natural beauty or sensitive ecosystems and the biodiversity. The impacts and the modification on the landscape are likely to come up during construction stage, by activities such as earth movements

1572

Protection and restoration of the environment VI

and by transport movements [7]. Also an application of a system in once-cultivable land is possible to reserve soil productive areas. Thus the siting in arid areas is recommended. (iv) Visual impact: Visual intrusion is highly dependent on the frame design and the surroundings of the PVs. It is obvious that, for a system near an area of natural beauty, the visual impact will be significantly high [4]. (v) Effect on building: PV is a viable technology in an urban environment, to replace the existing building’s cladding materials. Also, PV panels can be directly used into the façade of a building instead of mirrors. (vi) Accidental releases and occupational health: Emissions into soil and groundwater may be caused by inadequate storage of materials. In large-scale plants a release of these hazardous materials is likely to occur as a result of abnormal plant operations, damaged modules or fire and therefore to pose a small risk to public and occupational health [4,7]. The increased potential danger of electrocution from the direct current produced by systems, needs to be taken into account especially by untrained users. (vii) Air pollution: The emissions associated with transport of the modules are minor in comparison to those associated with manufacture. Transport emissions were still only 1% of manufacturing related emissions [7,9]. (viii) Depletion of natural sources and energy consumption: The production of current generation poly- and mono-crystalline modules is rather energy intensive. Other indirect impacts include the requirement of large quantities of bulk materials and small quantities of scarce (In/Te/Ga) and/or toxic (Cd) materials. Options for energy demand reduction must always be considered along with the assessment of PV applications [4,7,9]. (ix) Waste management: In the case of stand alone systems the effects on health of chemical substances included in the batteries should also be studied. Moreover a large amount of energy and raw materials is required for their production. A battery-recycling scheme can assist. As it usually goes for construction activities, there will be little noise during operation of electrical equipment [7,9,10]. 3.2 Technologies/Techniques to mitigate the environmental impacts Almost all the negative environmental impacts can be faced: • PVs can be used in isolated areas, avoiding ecologically sensitive areas or archeological sites. The integration in large commercial buildings (facades, roofs) it is also recommended as well as the use as sound isolation in highways or nearby hospitals, on condition of proper siting and frequent maintenance [4]. • Careful system design and production of cells in variable shapes, which can be easily integrated in buildings as architectural elements and replace mirrors or metallic areas used to decorate modern buildings. Furthermore the PV use as a cladding material for commercial buildings is showing their architectural possibilities. Referring to construction activities, site restoration is needed to alleviate visual impacts. Color can be used to assemble the PV modules in large-scale systems. • Occupational accidents can be averted by good working practices and by the use protective sunglasses and clothing during construction, maintenance and decommission stage [4,7,8]. • Integrated PVe schemes help to regenerate rural areas.

Environmental impact assessment and risk analysis

1573

4. SOLAR THERMAL ELECTRICITY 4.1 Environmental impacts (i) Environmental benefits: ST electricity (STE) systems present the basic environmental benefit of the avoidance of emissions associated with conventional electricity generation. Some emissions arise from materials processing and manufacture, but they are lower compared to those avoided by the systems operation [11]. (ii) Materials’ Processing and Manufacture: Energy use and emissions (CO2, SO2, NOx) in materials’ processing and manufacture of STE systems are noticeable. The impacts of these emissions vary according to location, and are fewer than those from conventional fossil fuel technologies. (iii) Construction: These are the usual environmental impacts associated with any engineering scheme during the construction phase (impact on landscape, effects on local ecosystems and habitats, noise, virtual intrusion, and topical vexation such as noise and temporally pollutant emissions due to increased traffic, occupational accidents, temporal tarnish etc.) [8]. (iv) Land use: STE systems are amongst the most efficient SETs when it comes to land use (they produce about 4-5 GWh/ha/year). To date, most sites used or considered for ST systems are in arid desert areas, which typically have fragile soil and plant communities. (v) Ecosystem, flora and fauna: Care and attention during the planning, construction and operation phases can minimize the effects on vegetation, soil and habitat. Furthermore, the shade offered by the reflectors has a beneficial effect on microclimate around the scheme and on vegetation, too. Provided that such schemes are not deployed in ecologically sensitive areas or in areas of natural beauty, it is unlikely that any of the above changes would be considered as significant. Central power systems (which concentrate light) could pose a danger to birds, but operational experience shows that birds avoid any danger areas [4,7]. (vi) Visual impact: In addition to the collector systems, the main visual impact would come from the tower of the central receiver systems. However, the atmospheric requirements for these systems point to their deployment in areas of low population densities, so provided that areas of outstanding natural beauty are avoided, visual intrusion is insignificant. (vii) Noise intrusion: The noise from the generating plant of large-scale schemes is unlikely to cause any disturbance to the public. Noise would be generated primarily only during the day; at night, when people are more sensitive, the system is unable to operate. STE systems are not noisier than the stand-by diesel generating sets, which they generally displace. Also, new advanced Stirling engines are constructed to operate noiselessly [7]. (viii) Water resources: Parabolic trough and central tower systems using conventional steam plant to generate electricity require cooling water. This could place a significant strain on water resources in arid areas. In addition, there may be some pollution of water resources, through thermal discharges and accidental release of plant chemicals, although the latter can be avoided by good operating practice. Stand-alone parabolic dish systems require no water, other than for periodic cleaning of reflective surfaces and so they have little impact on water resources [7]. (ix) Health and safety: The accidental release of heat transfer fluids (water and oil) from parabolic trough and central receiver systems could form a health hazard [7]. The hazard could be substantial in some central tower systems, which use liquid sodium or molten salts as the heat-transfer medium.

1574

Protection and restoration of the environment VI

These dangers will be avoided on moving to volumetric systems that use air as the heat-transfer medium. Central tower systems have the potential to concentrate light to intensities that could damage eyesight. Under normal operating conditions there is no danger to operators. (x) Social impacts: There will be some employment benefits during the construction and operational phase. 4.2 Technologies/techniques to mitigate the environmental impact Most potential impacts of STE systems can be avoided or mitigated by: • Proper siting (away from densely populated areas and not in protected areas or areas of significant natural beauty); • Proper operational practices (reasonable water use, safety measures, waste disposal practices, use of possible biodegradable chemicals etc.); • Improvement of technology (e.g., use of air as the heat-transfer medium in central tower systems, ‘advanced’ noiseless Stirling engines); • Cultivation of photo-sensitive mosses or bushes in the area where shaded by the reflectors [10,12]; • Exploitation of warm water in the nearest industry in the production stream; • Training of workers, familiarization with the system [4,8]; • Re-establishment of local flora and fauna, giving the environment enough time to come up again to its previously state [7]; • Good operating practices and compliance with existing safety regulations [8]. 5. CONCLUSIONS & RECOMMENTATIONS SETs provide significant socio-economic benefits. On the other hand, it must be realized that no man-made project can completely avoid some impact on the environment, neither can SET installations. Potential environmental burdens are associated with loss of amenity, depend on the size and nature of the project and are often site specific. However, adverse effects are generally small and can be minimized by appropriate mitigation measures, technologies or techniques that may involve the use of air emission or odor control equipment, design tools for optimal design and siting of the installations, best practice guidelines, improved pieces of equipment (such as gearless or lubricant-free motors), or, completely innovative design (e.g., closed-cycle plants, submerged plants, etc.). It is up to the involved factors (investors, developers, and permitting authorities) to make the appropriate decisions by taking environmental issues into serious consideration. REFERENCES 1. Tsoutsos Τ. et al (1997) ‘RES and environment’ CRES, ALTENER Programme. 2. Boyle G., Ed. (1996) ‘Renewable Energy. Power for a Sustainable Future’ The Open

University, Oxford Press, London. 3. Johansson T. B., Ed., Laurie Burnham, ex. Ed (1993) ‘Renewable energy. Sources for Fuels

and Electricity’, Island Press. 4. Tsoutsos T. (2001) ‘Environmental Impact Assessment foe Energy Projects’, educational

notes, Environmental Department, Technical University of Crete, Chania. 5. Various, (1996) ‘Environmental Impacts from the Use of Solar Energy Technologies’,

THERMIE-B STR/1000/96/HE project. 6. ETSU (1996) ‘The Environmental Implications of Renewables’, Interim report for the UK

Department of Trade and Industry, DTI, UK. 7. OECD/IEA (1998) ‘Benign Energy? The Environmental Implications of Renewables’,

International Energy Agency, Paris. 8. Theodoratos P.C. and Karakasidis N.G. (1997) ‘Hygiene - Occupational Safety and

Environmental impact assessment and risk analysis

1575

Environmental protection’, Ion, (in Greek). 9. EC (1999) Evaluation of the PREP Component: ‘PV Systems for Rural Electrification in

Kiribati & Tuvalu’, (Reference: Final Report – Issue 1 (7 ACP RPR 175), March 1999 For the European commission DGVII Development. 10. Fernandez-Baco et al (1998) ‘Diurnal and seasonal variations in chlorophyll a fluorescence in two Mediterranean-grassland species under field conditions’ PHOTOSYNTHETICA, Vol.35 (4), p.535-544. 11. Norton B. (1998) ‘Full-energy-chain analysis of greenhouse gas emissions for solar thermal electric power generation systems’ Renewable Energy, Vol. 15 p.131-136. 12. Rossa B. and Dieter J. von Willert (1999) ‘Physiological characteristics of geophytes in semiarid Namaqualand, South Africa’ Plant Ecology, Vol.142, p. 121–132, June 1999, Kluwer Academic Publishers.

1576

Protection and restoration of the environment VI

Suggest Documents