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Many refugee camps exist for decades but associated infrastructure needs are only planned for the very short term, including provision of power. This study advocates a shift in approach to sustainable electrification of essential services in refugee camps for lighting, refrigeration, health, water, education, alongside camp operations. Qualitative and quantitative surveys were conducted in refugee camps in Uganda and Bangladesh which assessed the electrical supply needs across such categories. A range of solar photovoltaic (PV) power systems (Solar Home Systems, AC/DC mini grids) and their emission mitigation potential were modelled based on survey data. Proposed designs were compared with presently-used diesel systems in terms of applicability, environmental impact and economics. Results indicate significant cost savings are achievable through the PV systems deployment for different areas in two major refugee camps. Estimated savings range from USD31,000-140,000 and USD166,000-653,000 for five-year and twenty-year project lifetimes respectively. These savings apply to sub-areas of much larger camps, with potential savings increasing substantially if scaled to the whole camp. Results indicate that PV-battery systems were more cost-effective than diesel, even for five-year projects, with investments recoverable in second year of operation. Furthermore, replacing the existing 50 kW diesel generator in Bidi-bidi camp with a 40kWp PV-battery system would result in a reduction of 2.4 MtCO 2 e over a 20-year project lifetime. Adopting presented approaches will enhance humanitarian service provisions, reducing both cost and emissions. These findings are applicable to many refugee camps in Africa and Asia that have similar solar resource and lack of grid access., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025. Published by Elsevier Ltd.)

A validated numerical model of tidal flows and sediment transport around the Alderney South Banks was used to investigate the potential effects of large (300 MW) tidal turbine arrays at different locations in Alderney territorial waters. Two methods were used, firstly looking at hydrodynamic changes only and secondly modelling sediment transport over a non-erodible bed. The baseline hydrodynamic model was validated relative to ADCP velocity data collected in the immediate vicinity of the sandbank. Real-world sand transport rates were inferred from sand-wave migrations and agree favourably with sediment transport residuals calculated from model outputs. Outputs from the sediment model reproduced realistic morphological behaviours over the bank. Seventeen different locations were considered; most did not result in significant hydrodynamic changes over the South Banks; however, three array locations were singled out as requiring extra caution if development were to occur. The results provide a case for optimizing the array locations for twin objectives of maximizing array power and minimizing impacts on the sandbanks. This article is part of the theme issue 'New insights on tidal dynamics and tidal energy harvesting in the Alderney Race'.

This research provides an updated energy yield assessment for a large tidal stream turbine array in the Alderney Race. The original array energy yield estimate was presented in 2004. Enhancements to this original work are made through the use of a validated two-dimensional hydrodynamic model, enabling the resolution of flow modelling to be improved and the impacts of array blockage to be quantified. Results show that a range of turbine designs (i.e. rotor diameter and power capacity) are needed for large-scale development, given the spatial variation in bathymetry and flow across the Alderney Race. Array blockage causes a reduction in flow speeds in the array of up to 2.5 m s -1 , increased flow speeds around the array of up to 1 m s -1 and a reduction in the mean volume flux through the Alderney Race of 8%. The annual energy yield estimate of the array is 3.18 TWh, equivalent to the electricity demand of around 1 million homes. The capacity factor of the array is 18%, implying sub-optimal array design. This result demonstrates the need for turbine rated speed to be selected based on the altered flow regime, not the ambient flow. Further enhancement to array performance is explored through increases to rotor diameter and changes to device micro-siting, demonstrating the significant potential for array performance improvement. This article is part of the theme issue 'New insights on tidal dynamics and tidal energy harvesting in the Alderney Race'.