Despite comparable solar irradiation and strong economic capacity, Denmark, Finland, Norway, and Sweden exhibit markedly different solar photovoltaics (PV) deployment trajectories. By 2025, Denmark and Sweden had each surpassed 5 GW of installed PV capacity, while Finland and Norway had only recently reached 1 GW. This paper explains these divergent outcomes by comparing market dimensions, energy resource endowments, and policy development across these four Nordic countries. Secondary data on PV deployment, electricity prices, cost of capital, energy mixes, and policy instruments shows that differences in solar diffusion cannot explain the different deployment rates. Instead, deployment patterns are strongly shaped by policy design, timing, and stability, and by how PV competes with incumbent low-carbon resources. Countries with early, generous, but unstable support schemes experienced rapid yet volatile growth, while more gradual and predictable policy frameworks enabled steadier expansion. Further, high end-user electricity prices and access to low-cost capital have favored distributed, self-consumption-oriented PV, whereas weak incentives and complex permitting have constrained utility-scale deployment. These findings highlight how accountable energy governance-through clear targets, stable policy frameworks, and limited politicization-conditions solar PV diffusion in wealthy latecomer countries. The identified key dynamics are broadly applicable to wealthy latecomers in national energy transitions.
Characterization and monitoring of the snow cover is highly applicable for numerous problems in mountain and arctic environments, including avalanche hazard and hydrology assessments. Remote sensing techniques from space or air are conventionally used to map and monitor large areas. To bridge the gap between satellite and ground scales, we propose the use of UAV-borne GPR systems to optimize areal coverage, resolution and repeatability for snowpack information. We present an extensive study of the potential applications and limitations when using UAV-borne GPR for snowpack characterization. We discuss the operational constraints and demonstrate various examples conducted in different environments. We tested low (400 MHz) and high (1 GHz) frequency GPR systems on a commercial off-the-shelf UAV equipped with a radar altimeter and terrain following capabilities. GPR data were acquired at three field sites in central and western Norway. We demonstrate that data repeatability is satisfactory and that any measurement differences are due to aircraft positioning errors. We also tested data acquisition from various flight altitudes above the snow surface which led us to the conclusion that recording data between altitudes of 2 to 4 m above the surface is the best compromise between flight safety and data quality. Regarding flight speeds, if we focus on layer tracking and do not require high lateral resolution for discrete target mapping, data can be acquired at 2 m/s or more as long as flight safety is ensured. We recommend recording data along pre-determined flight paths, downslope starting from the highest elevation and following profiles parallel to the slope. Kinematic timelapse surveys recorded at a two-week interval highlighted the capabilities for thin layer detection. Centimeter thick melt-freeze crust layers are visible on GPR profiles and are correlated with observed layers in neighboring snowpits. Additional tests in wet snowpacks showed that the penetration depth was limited with the 1 GHz antenna due to the attenuation related to the presence of liquid water in the snowpack. The use of a lower frequency antenna (400 MHz) enabled sufficient penetration depth even though it caused a loss in resolution for mapping the upper layers of the snowpack. Overall, the UAV GPR surveys showed promising results towards recording highly repeatable snow height and snow layering data which can be helpful for avalanche forecasting and hydrology studies.
Underwater robots typically use both cameras and sonar for perception to leverage the rich semantic details of vision and the robust range measurements of acoustics. However, learning to map between these modalities via cross-modal prediction remains underexplored due to limited sonar-visual paired datasets. We present SOVIS, a sonar-visual dataset for cross-modal underwater perception. SOVIS comprises over 76,000 paired frames collected across 17 dives at six sites in the Trondheimfjord, supported by an end-to-end pipeline that cleans and synchronizes the cross-modal sensor data. We also introduce an interactive annotation tool designed to accelerate the labeling process for this paired data. Finally, we demonstrate a proof-of-concept cross-modal fish detection task using a small subset of labeled data, achieving a 7x improvement in mAP@0.10 over a monocular camera baseline. SOVIS serves as the first step toward advancing cross-modal underwater perception research, enabling research directions such as dense sonar prediction from monocular images.
Ferromanganese (FeMn) is an essential alloy whose production relies on metallurgical coke as a reducing agent, leading to hard-to-abate carbon dioxide emissions. The use of biocarbon as an alternative reductant and carbon capture and storage (CCS) are key mitigation strategies of FeMn production, yet their environmental performances are still unexplored. This study evaluates the possible environmental co-benefits and trade-offs of replacing metallurgical coke with biocarbon, with and without CCS, in Norway. The climate impact of FeMn production is 2312 f 110 kg CO2-equivalents per tonne of alloy (mean f 5th/95th percentiles). Emission reductions are about 57 f 3.0 % at a full substitution rate and 29 f 3.7 % at a more realistic substitution rate of 50 %. CCS alone can reduce emissions of 53 f 4.8 %. The combination of biocarbon with CCS can achieve negative emissions when the biocarbon substitution is higher than 78 %. More efficient material and energy use throughout the value chain is key to maximise climate benefits. The main trade-offs can occur with terrestrial acidification and particulate matter formation, and are mostly due to biomass pyrolysis. A 50 % substitution of the metallurgical coke annually used for FeMn production in Norway requires around 25 % of currently unused forest residues, or 8 % of the today's wood harvest volume. Although some economic and technological barriers remain to be overcome, this study offers an initial quantification of the environmental implications that can be expected from a value chain perspective in connection to local resource availability and technical challenges.
Dypingite has recently been found to have promising applications in material and environmental sciences. However, its exploitation is limited due to its ambiguous identification via powder X-ray diffraction (PXRD), which is caused by the occurrence of several phases with similar structures and PXRD patterns to that of dypingite. Multiple dypingite-like phases with partially overlapping X-ray diffraction traces appear to exist. To better understand dypingite, we studied samples from Dypingdal and Feragen Ultramafic Body, Norway. Dypingite sensu stricto (s.s.), several dypingite-like phases, and hydromagnesite were identified by PXRD. Three regions of 2θ (CuKα) were recognized where diffraction peaks are readily observed to transition between dypingite s.s., dypingite-like phases, and hydromagnesite. The position of the peak at around 8.5° 2θ varies with the H2O contents measured by the thermogravimetric and Fourier transform infrared analyses, suggesting that structural and compositional characteristics of dypingite-like phases form a continuum between dypingite s.s. and hydromagnesite. Humidity incubation experiments at room temperature indicated a reversible change of H2O content between dypingite s.s. and dypingite-like phases. High humidity conditions increased H2O contents of dypingite-like phases to dypingite s.s., whereas low humidity conditions reversed the direction towards hydromagnesite, but without complete reaction. Such transition behavior suggests that the structures of dypingite s.s. and the dypingite-like phases are very similar, probably identical in building unit topology but with different degrees of hydration, whereas the structure of hydromagnesite is less closely related. This study draws attention to the sample processing on dypingite hydration series, contributes to the applications of this series in CO2 sequestration, and gives suggestions to the refinement of structures of dypingite and dypingite-like phases.
