Are Technological Developments Improving the Environmental Sustainability of Photovoltaic Electricity?
Blanco, Carlos Felipe ; Cucurachi, Stefano ; Peijnenburg, Willie J.G.M. ; Beames, Alistair ; Vijver, Martina G. - \ 2020
Energy Technology (2020). - ISSN 2194-4288
environmental impacts - life-cycle assessments - photovoltaics - solar - sustainability
Innovation in photovoltaics (PV) is mostly driven by the cost per kilowatt ratio, making it easy to overlook environmental impacts of technological enhancements during early research and development stages. As PV technology developers introduce novel materials and manufacturing methods, the well-studied environmental profile of conventional silicon-based PV may change considerably. Herein, existing trends and hotspots across different types of emerging PV technologies are investigated through a systematic review and meta-analysis of life-cycle assessments (LCAs). To incorporate as many data points as possible, a comprehensive harmonization procedure is applied, producing over 600 impact data points for organic, perovskite (PK), dye-sensitized, tandem, silicon, and other thin-film cells. How the panel and balance of system components affect environmental footprints in comparable installations is also investigated and discussed. Despite the large uncertainties and variabilities in the underlying LCA data and models, the harmonized results show clear positive trends across the sector. Seven potential hotspots are identified for specific PV technologies and impact categories. The analysis offers a high-level guidance for technology developers to avoid introducing undesired environmental trade-offs as they advance to make PV more competitive in the energy markets.
A wavelet analysis of the relationship between Loess Plateau erosion and sunspots
Gao, P. ; Geissen, V. ; Temme, A.J.A.M. ; Ritsema, C.J. ; Mu, X. ; Wang, F. - \ 2014
Geoderma 213 (2014). - ISSN 0016-7061 - p. 453 - 459.
soil-erosion - yellow-river - climate-change - sediment discharge - solar - variability - china - periodicities - identification - streamflow
The Chinese Loess Plateau is one of the most rapidly eroding regions in the world. The purpose of this study is to find out to which extent soil erosion on the Loess Plateau is driven by sunspot activity. We analyzed the relation between annual sediment discharge (from 1919 to 2010) from the Loess Plateau and the relative sunspot number, using Complex Morlet wavelets. We divided sediment discharge into 2 periods: before and after 1980 the year where the large-scale implementation of soil and water conservation techniques started. Before 1980, sediment discharge followed a 6 and 11-year period, the 11-year period being the most important one within a 25-year scale. After 1980, the impact of soil and water conservation techniques on the soil erosion in the Loess Plateau became obvious. The period of sediment discharge changed to, 4, 7 and 12-year periods, the 12-year period dominating the record. Similar analyses were conducted for the sunspot relative number, with an 11-year period dominating the record from 1919 to 2010. In different periods, the population, farm land area, land use/cover patterns and other factors have changed significantly. Although this has certainly affected sediment magnitudes, solar activity remains a clear (indirect) forcing factor for soil erosion in the Loess Plateau throughout the period of analysis. This underlines that solar activity influences Earth processes and argues for a more complete analysis of the pathways through which this happens.
Performance of a concentrated photovoltaic energy system with static linear Fresnel lenses
Sonneveld, P.J. ; Swinkels, G.L.A.M. ; Tuijl, B.A.J. van; Janssen, H.J.J. ; Campen, J.B. ; Bot, G.P.A. - \ 2011
Solar Energy 85 (2011)3. - ISSN 0038-092X - p. 432 - 442.
solar - collector
A new type of greenhouse with linear Fresnel lenses in the cover performing as a concentrated photovoltaic (CPV) system is presented. The CPV system retains all direct solar radiation, while diffuse solar radiation passes through and enters into the greenhouse cultivation system. The removal of all direct radiation will block up to 77% of the solar energy from entering the greenhouse in summer, reducing the required cooling capacity by about a factor 4. This drastically reduce the need for cooling in the summer and reduce the use of screens or lime coating to reflect or block radiation. All of the direct radiation is concentrated by a factor of 25 on a photovoltaic/thermal (PV/T) module and converted to electrical and thermal (hot water) energy. The PV/T module is kept in position by a tracking system based on two electric motors and steel cables. The energy consumption of the tracking system, ca. 0.51 W m-2, is less than 2% of the generated electric power yield. A peak power of 38 W m-2 electrical output was measured at 792 W m-2 incoming radiation and a peak power of 170 W m-2 thermal output was measured at 630 W m-2 incoming radiation of. Incoming direct radiation resulted in a thermal yield of 56% and an electric yield of 11%: a combined efficiency of 67%. The annual electrical energy production of the prototype system is estimated to be 29 kW h m-2 and the thermal yield at 518 MJ m-2. The collected thermal energy can be stored and used for winter heating. The generated electrical energy can be supplied to the grid, extra cooling with a pad and fan system and/or a desalination system. The obtained results show a promising system for the lighting and temperature control of a greenhouse system and building roofs, providing simultaneous electricity and heat. It is shown that the energy contribution is sufficient for the heating demand of well-isolated greenhouses located in north European countries.
Design process of an area-efficient photobioreactor
Zijffers, J.F. ; Janssen, M.G.J. ; Tramper, J. ; Wijffels, R.H. - \ 2008
Marine Biotechnology 10 (2008)4. - ISSN 1436-2228 - p. 404 - 415.
light - system - solar
This article describes the design process of the Green Solar Collector (GSC), an area-efficient photobioreactor for the outdoor cultivation of microalgae. The overall goal has been to design a system in which all incident sunlight on the area covered by the reactor is delivered to the algae at such intensities that the light energy can be efficiently used for biomass formation. A statement of goals is formulated and constraints are specified to which the GSC needs to comply. Specifications are generated for a prototype which form and function achieve the stated goals and satisfy the specified constraints. This results in a design in which sunlight is captured into vertical plastic light guides. Sunlight reflects internally in the guide and eventually scatters out of the light guide into flat-panel photobioreactor compartments. Sunlight is focused on top of the light guides by dual-axis positioning of linear Fresnel lenses. The shape and material of the light guide is such that light is maintained in the guides when surrounded by air. The bottom part of a light guide is sandblasted to obtain a more uniform distribution of light inside the bioreactor compartment and is triangular shaped to ensure the efflux of all light out of the guide. Dimensions of the guide are such that light enters the flat-panel photobioreactor compartment at intensities that can be efficiently used by the biomass present. The integration of light capturing, transportation, distribution and usage is such that high biomass productivities per area can be achieved