Richard J. Randle-Boggis

This paper explores agrivoltaic deployment scenarios in Europe based on land-use constraints, ecological sensitivity, and grid decarbonisation. Land across Europe is increasingly contested, for example between energy infrastructure, food production, and habitat conservation. With solar PV deployment accelerating, the need to identify land-use strategies that enhance renewable electricity generation without compromising agricultural productivity or biodiversity has become critical. Agrivoltaics offer a potential solution to these constraints by integrating PV within farming systems such that farming and energy outputs are produced concurrently.The paper investigates two novel research questions to inform agrivoltaic site selection and determine potential synergies:(1) how do land-use constraints and agrivoltaic implementation affect the renewable energy mix in a decarbonised European energy system?(2) to what extent do agrivoltaics mitigate land competition and reduce reliance on ecologically sensitive sites?The highRES model of Europe will be used to address these questions. The model is designed to analyse the effects of high shares of variable renewable energy on the energy system. Deployment scenarios will be modelled with varying land protection constraints to assess whether farmland can be leveraged to relieve pressure on contested land. The findings will demonstrate whether integrating dual-use and alternative PV technologies enables stricter land protection policies whilst maintaining energy system performance.

Agrivoltaics, also known as solar sharing or agri-PV, represents a pioneering con- cept that seeks to optimise land use by combining agriculture with photovoltaics on the same land area. While research and development on this topic have increased significantly, few studies address the issue in the Continental Subarctic Climate zone. In this paper, we report on the modelling and installation of a 48 kWp agrivoltaic system at the Skjetlein High School in Trondheim (Norway, lat. 63.34), which is currently the highest latitude system in the World, and we present the initial results of the impacts of the system on Timothy grass biomass. This work takes the first steps towards realising agrivoltaic opportunities for a broad area of Norwegian agriculture.

Agrivoltaics address energy, food, and water security concomitantly, yet little research has addressed the opportunities and barriers for this technology in East Africa, a region facing substantial challenges across the water-energy-food nexus. Here, we identify possible use cases for the technology in five East African nations and determine the factors influencing delivery of potential benefits, before assessing the spatial suitability of the technology for two of the emergent use cases: agribusiness and marginal farming. Our findings show there is a moderate to high suitability for AV across both use cases, with a range of biophysical and social factors driving successful outputs; land tenure and solar radiation were the most important for determining suitability. Our analysis indicates where AVs would be best developed to improve access to, and resilience of, energy and food production in East Africa, and our methods could be applied to other locations to support agrivoltaics development internationally.

Septic tanks are widely deployed for off-grid sewage management but are typified by poor treatment performance, discharge of polluting effluents and the requirement for frequent de-sludging. The Solar Septic Tank (SST) is a novel septic tank design that uses passive heat from the sun to raise in-tank temperatures and improves solids degradation, resulting in a cleaner effluent. Treatment has been shown to exceed conventional systems, however, the underlying biology driving treatment in the system is poorly understood. We used next generation sequencing (Illumina Miseq (San Diego, CA, USA), V4 region 16S DNA) to monitor the microbiology in the sludge and effluent of two mature systems, a conventional septic tank and an SST, during four months of routine operation in Bangkok, Thailand, and evaluated the ecology against a suite of operating and performance data collected during the same time period. Significant differences were observed between the microbiome of the sludge and effluent in each system and the dominant taxa in each appeared persistent over time. Furthermore, variation in the microbial community composition in the system effluents correlated with effluent water quality and treatment performance parameters, including the removal of chemical and biochemical oxygen demand and the concentration of fecal and total coliforms in the effluent. Thus, we propose that a wide-scale survey of the biology underlying decentralised biotechnologies for sewage treatment such as the SST could be conducted by sampling system effluent rather than sampling sludge. This is advantageous as accessing sludge during sampling is both hazardous and potentially disruptive to the anaerobic methanogenic consortia underlying treatment in the systems.

The impacts of increased flooding frequency on soil microbial communities and potential functions, in line with predicted environmental changes, were investigated in a laboratory‐controlled environment. More frequent flooding events altered microbial community composition and significantly increased the resolved species alpha‐diversity (Shannon index). The Bacteria:Archaea ratio was greater at the end of the experiment than at the start, more‐so after only one flood. Significant changes in taxa and functional gene abundances were identified and quantified. These include genes related to the reduction and oxidation of substances associated with anoxia, for example, those involved in nitrogen and sulfur cycling. No significant changes were observed in the methanogenesis pathway, another function associated with anoxia and which contributes to the emission of greenhouse gases.

The advent of next-generation sequencing has allowed huge amounts of DNA sequence data to be produced, advancing the capabilities of microbial ecosystem studies. The current challenge is to identify from which microorganisms and genes the DNA originated. Several tools and databases are available for annotating DNA sequences. The tools, databases and parameters used can have a significant impact on the results: naïve choice of these factors can result in a false representation of community composition and function. We use a simulated metagenome to show how different parameters affect annotation accuracy by evaluating the sequence annotation performances of MEGAN, MG-RAST, One Codex and Megablast. This simulated metagenome allowed the recovery of known organism and function abundances to be quantitatively evaluated, which is not possible for environmental metagenomes. The performance of each program and database varied, e.g. One Codex correctly annotated many sequences at the genus level, whereas MG-RAST RefSeq produced many false positive annotations. This effect decreased as the taxonomic level investigated increased. Selecting more stringent parameters decreases the annotation sensitivity, but increases precision. Ultimately, there is a trade-off between taxonomic resolution and annotation accuracy. These results should be considered when annotating metagenomes and interpreting results from previous studies.