Papers by Nieves Espinosa
Incineration of organic solar cells: Efficient end of life management by quantitative silver recovery
Energy Environ. Sci., 2016
Detailed information is here documented about the building of the life cycle inventory associated... more Detailed information is here documented about the building of the life cycle inventory associated with the manufacture, deployment and dismantling of a solar park that uses organic solar cells (OPV) technology. The OPV solar park is composed of several parts, as shown in in the manuscript. It is composed of OPV modules and several components, which are known as balance of system (BOS). It is a group of auxiliary components such as inverter, mounting structure, wiring and an aluminium wagon (used for the installation of the OPV module rolls). See below for a detailed overview of the model, as well as the system boundaries for the solar park in in the manuscript. The different aspects addressed in Supplementary Methods cover: 1. General assumptions. 2. Materials for the solar cells. 3. The OPV manufacturing steps. 4. Deployment of the solar park. 5. End of life of solar park. 6. Life cycle inventories and impact assessment. 7. Supplementary data for the model. 8. Other modelling assumptions. 9. Scenarios for the assessment. A resulting life cycle inventory corresponding to the annual supply of 1 kWh (high voltage) to the grid in Denmark (considering manufacturing in Denmark as well) is provided in ESI-2. S3 Figure SM 1. Flowchart of a detailed production of a solar park that includes all stages: modules manufacturing, assembly of the solar park, use and disposal.
Ecodesign of organic photovoltaic modules from Danish and Chinese perspectives
Energy Environ. Sci., 2015
Solar Energy Materials and Solar Cells, 2014
One approach to use solar radiation more effectively in solar cells is to stack, in series, multi... more One approach to use solar radiation more effectively in solar cells is to stack, in series, multiple photoactive layers with complementary absorption spectra. Such devices are often termed tandem or multi-junction solar cells. The larger number of different materials and processing steps involved in their making when compared with the single junction solar cell has to be justified and compensated by a higher efficiency. A central question to ask is how much energy you need to invest in a system in order for it to produce energy and return the investment at least once and preferably a number of times. As an initial investigation into the potential viability of the tandem or multi-junction approach we have engaged in a detailed analysis based on the manufacturing energy for each step within the tandem module supply chain for full ambient processing of thin flexible polymer tandem solar cells prepared entirely by roll processing methods. We present a comprehensive overview of relevant research results on how the energy consumption affects the energy balance when using single and multi-junction solar cells. Based on the above question we calculate the minimum efficiency that the tandem or multijunction should present to determine the minimum energy payback time; that is whether (or when) the increase in materials use and complexity of the tandem architecture is compensated by better performance. After analysing the performance and the consideration of a series of technical improvement opportunities, we project that the tandem solar cell has to be $ 20% higher performing than the corresponding single junction solar cell to be warranted. We also highlight that there is a range in the reciprocal EBPT-efficiency relationship where the tandem solar cell is an advantage. Specific to polymer and organic solar cells are however that they embody very little energy and this implies that the single junction may be an advantage, especially in cases where land mass is not critical.
Laurent & Espinosa 2015 ES-2 Global Electricity Environmental sustainability EES
Energy Science & Engineering, 2013
Here, we present a process based on roll-to-roll (R2R) technology which allows for very fast proc... more Here, we present a process based on roll-to-roll (R2R) technology which allows for very fast processing of polymer thermoelectric (TE) devices and we furthermore demonstrate a simplified but more efficient way of serially connecting these devices by means of R2R thin-film processing. The new device architecture makes it possible to use only one TE material (opposed to two materials which are employed in well-known Peltier elements), and a total of 18,000 serially connected junctions were prepared by flexoprinting of silver electrodes and by rotary screen printing of poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) as the TE material. Testing of devices revealed that the new architecture clearly showed to be functioning as expected, but also pointed toward challenges for thin-film TE development which is the influence of the substrate thickness on the thermal gradient over a device and the currently low performance available. A life-cycle assessment (LCA) was carried out in order to evaluate the sustainability of the new architecture and to estimate the requirements for development of a successful technology.
Energy Environ. Sci., 2015
The generation of electricity has been known to cause important damages to ecosystems and human h... more The generation of electricity has been known to cause important damages to ecosystems and human health.
Energy & Environmental Science, 2014
With the development of patterns that connect all cells in series, organic photovoltaics have lea... more With the development of patterns that connect all cells in series, organic photovoltaics have leapt a step forward being ahead of other solar and even other energy technologies in terms of manufacturing speed and energy density. The important questions of how they are meant to be installed for producing power and what the requirements are yet to be explored. We present here the installation of organic solar cell modules in different settings (terrestrial, marine and airborne). For the evaluation of these installations deployed at DTU, we have used the life cycle assessment tools, and calculated key parameters in order to assess their environmental impact. The novel technology when installed in a solar park system can generate more than 1300 kW h kW p À1 of electricity a year, which means that the whole system can pay the energy invested back before the first year of operation, in 320 days. If this electricity is fed back to the same electricity supply system that was used for manufacturing the potential saving of more than 13 GJ of primary energy per kW p per year can be reached. With the real data logged, a dynamic energy payback time has been furthermore calculated for the case of the solar tube installation, giving a value of 1.1 years.
Energy & Environmental Science, 2014
Large 100 m long polymer solar cell modules were installed in a solar park using fast installatio... more Large 100 m long polymer solar cell modules were installed in a solar park using fast installation (>100 m min À1 ) and operated for 5 months ensuring a meaningful energy return factor (ERF > 1) followed by fast de-installation (>200 m min À1 ) and end-of-life management. Focus was on recovery of silver that is an essential component of the two electrodes. We employed life cycle analysis as a tool to evaluate the most efficient silver extraction method as well as the impact on the overall life cycle of the solar cells. Silver from the electrodes could be recovered as silver chloride in 95% yield, which diminishes the overall energy payback time by 13%. The efficient recovery of silver justifies the use of silver electrodes in OPV even in a scenario where it is scaled to production volumes of 1 GW p per day.
Advanced Engineering Materials, 2015
The transformative power of photovoltaics depends on both the cost of the system and on the cost ... more The transformative power of photovoltaics depends on both the cost of the system and on the cost and availability of electricity in the area of installation. For any new technology targeting large scale energy production, another challenge lies in the need for finding a solution that is as environmentally sustainable as possible, with low environmental impacts over the entire life cycle of the system, i.e., from its manufacturing through its deployment and operation up to its final disposal.
Silver, carbon, copper and aluminium all have excellent properties that make them ideal to be par... more Silver, carbon, copper and aluminium all have excellent properties that make them ideal to be part of organic solar cells, but also drawbacks. Silver unique properties of ductility, reflectivity and being the most conductive of all metals, make it interesting for its use as electrode. The relatively high cost, and scarcity (the world demand for silver is 25% higher than the current production) already impose a high recycling rate. Carbon based solar cells have been proved as being the "ultimate electrode" due to its superiority with regard to material availability, cost and easy deposition. Carbon electrodes for electronics usually are in the form of an ink containing graphite and carbon black and abundant graphite that can be processed by roll to roll. The suitability of Aluminium as an electrode material has also been evaluated due to its potential: it is the most abundant metal in earth crust; it is light, cheap and has good mechanical properties for flexible devices such as organic solar cells. The mining of aluminium and extraction from bauxite demands a high energy input, which imposes (as in the case of silver) recycling practices. Copper is a widely used metal due its good conductivity, corrosion resistance and relatively low cost. It is therefore also a suitable candidate for electrodes in OPV modules. Like aluminium, to form a thin conductive layer copper needs to be cured, which can limit the use of flexible substrates like
Advanced Energy Materials, 2015
Solution-processed organic solar cells have recently gained considerable attention and are becomi... more Solution-processed organic solar cells have recently gained considerable attention and are becoming a future solar technology option. This study is intended to improve the assessment of the operation parameters of these manufacturing technologies in order to propose a low-cost patterning technique suitable for a successful high-volume manufacturing of full organic solar cells. The assessment will take into account quantitative and qualitative parameters, such as technical issues, environmental impact or reproducibility of the fabrication output. Multi-criteria decision making methods will be used to model the problem of fabrication technique selection, combining these techniques with fuzzy numbers which serve to assess the criteria valued with linguistic labels.
Life cycle assessment and geographical dependence study of the environmental impact of a 222kWp grid-connected CdTe photovoltaic system
Life-cycle assessment as a guided-research tool to reduce the environmental impact of polymer solar cells
Will organic photovoltaic technology render benefits in a 30-year horizon?
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Papers by Nieves Espinosa