Efficient use of solar chargers with the help of ambient light sensors on smartphones

This paper discusses the possibilities to measure the amount of light with the help of portable devices such as mobile phones and tablets. Focus is directed to the accuracy of the ambient light sensor on smartphones in order to obtain the illuminance indoors and the solar radiation level outdoors. In general, information on the ambient conditions is vital to improve the performance of solar chargers. For example, if users are able to allocate beneficial locations to deploy solar chargers inside buildings, up to 100 times more energy can be gathered during the same periodic time. Similarly, under outdoor environmental conditions, solar modules can be aligned better towards the sun to increase the possible amount of output power. We analyse the accuracy of ambient light sensors which are available in today's low-cost and upper-class smartphones. Additionally, we present calibration strategies for ambient light sensors in order to minimise the error between conventional measurement equipment and mobile phones

Off-Grid mobile phone charging systems for rural energy needs

For several decades, rural electrification has remained a formidable challenge, particularly in Nigeria. Financial constraints, difficult rural terrain, inefficient policy, and a lack of industrial community development have all contributed to the grid expansion problem in these areas. These areas are energy-deficient, and their energy demands to keep up with cutting-edge communication technology are constantly rising. As a result, rural areas are confronted with the issue of charging. Consequently, many rural residents are forced to rely on diesel/petrol generators or travel long distances and pay a premium to have their mobile phones charged. Thus, this paper proposes an off-grid solar-powered charging system as an alternative, sustainable solution to meet rural mobile phone energy demand. The methodology employed six-tier architectural features, with the economic comparison metric based on net present value and payback period. Furthermore, the proposed model's performance analysis revealed that the charging rate is dependent on the phone battery type and charger type. Furthermore, the off-grid mobile charging system has a higher net present value ($20,658US) and a shorter payback period of 2.5 years than the alternative investment of a gasolne generator

Towards sustainable energy materials: broadening life cycle assessment for emerging technology development and resource-effective choices

Energy materials are particularly important from a sustainability perspective for advancing renewable energy systems, including energy production and storage. Their appropriate use and development require quantitative assessment methods. Life Cycle Assessment (LCA) is a method to support sustainable development that can be used to identify environmental hotspots and compare different technologies. The purpose of this research is to support development of several energy materials and make LCA a more relevant tool for sustainability assessment by extending its use in two emerging directions: assessment of technologies at the early stage of development, and by supporting more resource-effective choices for a circular economy. The research objectives focus on informing the development of technologies and identifying methodological challenges and opportunities by applying LCA to three energy-technology case studies, each at a different technological maturity level. In the first case study, alkaline batteries, currently at a high maturity level (incumbent products), are evaluated using LCA in combination with a circular economy indicator, the Material Circularity Indicator (MCI). The aim was to investigate opportunities to combine the two methods, while considering trade-offs between indicators for different strategies for battery design and management. In the second case study, nickel-cobalt hydroxide charge storage electrodes, currently at a low maturity level (laboratory-scale), are evaluated to investigate environmental hotspots and preferred synthesis route. In the third case study, organic photovoltaic portable chargers for small electronics, currently at a medium maturity level (pilot-scale), are evaluated for replacing conventional electricity grid for charging a mobile phone. The results of the alkaline batteries case study show the value and meaning of the MCI circular economy indicator to evaluate resource strategies as compared to LCA category and indicator results. In this context, an approach for combining and presenting the MCI indicator is proposed, and a need to improve characterization of material quality losses of secondary (recycled) material was identified. The electrodes case study offers insights on the environmental hotspots and relative status among technology alternatives, including the benefit of certain process stages and synthesis routes. The most favorable operating parameters in terms of current density and device lifetime expectations are identified. The analysis of photovoltaic chargers shows their environmental-performance potential given the geographical and use-intensity contexts. The chargers have shown as potentially valuable substitutes to local electricity grids in three of six countries given frequent use, and for specific impact categories. Case studies on electrodes and chargers demonstrate uncertainties in relation to allocation of reference flow to functional unit, which are addressed conducting scenario and break-even analysis. Given challenge and carried out responses, involve increasing efforts in the interpretation phase of LCA, an observation with potentially broader implications to the assessment of emerging technologies in LCA. Further research should consider how circular economy indicators and could be used with and complement quantitative assessment methods such as LCA. In the context of LCA of emerging technologies, it is recommended that more emphasis is given to further classification of future-oriented LCA studies of emerging technologies, in order to better frame and organize methodological advancements in this area. A recommendation is also made in consideration to application of attributional and consequential LCA approaches in guiding technology development at different stages of technological maturity