Small-scale Systems Research Articles

Performance of Small-Scale Hermetic Storage Systems Under Periodic Access

This study characterizes the grain management performance of a novel integrated grain drying and storage system (iGDSS) adapted from 208 L drums to combat postharvest loss in developing countries through providing in situ mechanized drying and hermetic storage. The six-month storage trials of 14% moisture content maize compared different access mechanisms and two levels of pest pressure: 0 and 10 maize weevils/kg grain. This experiment allowed comparisons of differential oxygen consumption rates in small-scale hermetic systems with and without storage pests, which has not been widely reported in the literature. The iGDSS system was found to maintain grain quality parameters in dry grains with and without storage pests. After six months of storage, the results demonstrated no statistically significant difference in the moisture content, test weight, germination, proportion of broken and damaged kernels, and presence of colony-forming units between inoculated and non-inoculated systems. The iGDSS was also found to maintain oxygen intrusion rates of 0.10–0.13% O2/day, below recommended thresholds of 0.15% required to maintain benefits of modified atmosphere storage. These results indicate that the iGDSS can provide safe and reliable grain storage to smallholder farmers in developing countries, and that the drying functions of iGDSS can promote outcomes in hermetic storage.

GREEN ECONOMY DENGAN PENGELOLAAN LIMBAH BERBASIS ILMU PENGETAHUAN DAN TEKNOLOGI PADA BANK SAMPAH 3G

Garbage remains a significant issue in Greenary Permai Bojong Gede Housing, leading to an unhealthy environment, particularly when waste collection is inconsistent. In response, the 3G waste bank initiated several waste reduction activities. However, progress has been slow due to limited waste management knowledge, incomplete equipment, low community awareness, and manual record-keeping. To address these challenges, training was provided on managing organic and plastic waste, and repurposing used cooking oil into candles and soap. Financial application training was also given to improve the recording process. The goal was to enable the community and partners to adopt a small-scale waste management system and integrate it into daily habits. Using Participatory Action Research (PAR), community members, including waste bank administrators, were directly involved in hands-on training to ensure participants understood the objectives. Since the socialization of this initiative in April 2024, significant progress has been made. Questionnaire results showed 95% of participants understood the activity's purpose. Monitoring and evaluation revealed that residents and partners have successfully adopted composting, ecobrick-making, and proper recycling of used cooking oil into candles or soap, demonstrating sustainable practices and optimal use of the financial applications.

The value of indigenous knowledge for enhancing smallholders’ resilience to climate change and food insecurity: a case study of small-scale irrigation system in Niger

ABSTRACT The global south faces challenges in enhancing smallholder farmers' resilience to climate change and food insecurity. Indigenous knowledge and small-scale irrigation (SSI) systems are being promoted as a viable solution to address these challenges. This paper explores how smallholder farmers use local knowledge to establish informal and farmer-led SSI to enhance smallholders' resilience in agriculture and livelihoods. A qualitative research approach with 79 semi-structured interviews was carried out with farmers' households in Tamaske rural community in Southwest Niger, followed by thematic and statistical analysis. The results revealed that an alternative SSI strategy is mostly based on internal agencies rather than externally supported and it serves as a tool to enhance household food and income security amid climate change. The empirical case allows us to assess the value of indigenous knowledge in agriculture by asking how local people can bring together ideas and resources to enhance SSI and build resilience to climate change. The study suggests that the initiation and multiplication of SSI systems can be achieved by farmers' own agencies if appropriate technology and cooperation mechanisms are selected. The policy focus should promote simple, root-based technology as limited government financial support in the global south may hinder this progress.

Silage Making of Napier Grass and Sugarcane Top at Different Proportions: Evolution of Natural Fermentation Characteristics, Chemical Composition, and Microbiological Profile

The co-ensiling technique is widely used to improve silage quality; however, it remains unclear as to what high-quality silages can be made by co-ensiling Napier grass (NG) with Sugarcane top (ST). The aim of this study was to evaluate the fermentation characteristics, chemical composition, and microbiological profile of silage produced from mixtures of NG and ST in varying ratios. Silage was prepared using a small-scale fermentation system, and treatments were designed as control silage (NG ensiled alone) or with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 100%ST on a fresh matter basis with six replicates, respectively. Increasing ST in the silage reduced the contents of crude protein, ash, acetic acid, butyric acid, ammonia-N, as well as pH, but increased the contents of dry matter, ether extract, neutral detergent fiber, acid detergent fiber, water-soluble carbohydrate, lactic acid, and lactic acid bacteria. Lactobacillales and Enterobacterales were the dominant orders, with Lactiplantibacillus and Weissella as the dominant genera. Co-ensiling NG with ST enhanced microbial diversity and richness. ST, as a local by-product, is a viable additive to improve NG silage quality and nutrition. This study suggests that good-quality silages can be produced with NG: ST ratios of 40:60 to 20:80 and that these silages offer an opportunity to optimize the nutrient supply for ruminants.

On the stability of the dislocation structure of speckle fields

The features of propagation in free space of light beams with a dislocation structure of the wavefront are considered. The stability to the influence of diffraction of small-scale dislocation systems providing spatial super-resolution is analyzed. Based on a comparison of the characteristics of various dislocation formations, a conclusion is made about the greatest structural stability of systems with special type screw dislocations. Such dislocations can be obtained by azimuthal rotation of edge dislocations characterized by a sharp phase jump of light oscillations along the singular line. The obtained results will find application in optimizing the characteristics of optical devices with ultra-high spatial resolution, as well as in developing software for the operation of spatial light modulators forming beams with a specified amplitude-phase profile.

Evaluating the levelized costs and life cycle greenhouse gas emissions of electricity generation from rooftop solar photovoltaics: a Swiss case study

Abstract The transition to renewable energy sources is pivotal in addressing global climate change challenges, with rooftop solar photovoltaic (PV) systems playing a crucial role. For informed decision-making in energy policy, it is important to have a comprehensive understanding of both the economic and environmental performance of rooftop solar PV. This study provides a high-resolution analysis of existing rooftop solar PV systems in Switzerland by assessing the robustness of the potential estimation to properly derive the amount of electricity generated by individual systems, and subsequently quantify the levelized cost of electricity and life cycle greenhouse gas (GHG) emissions of electricity generation from PV and compare them with those of grid electricity supplies. Our results indicate substantial geographical variations between potential estimations and real-world installations, with notable underestimations of approximately 1.3 Gigawatt-peak, primarily for systems around 10 kWp in size, mainly due to the quality of input data and conservative estimation. The study finds that in many regions and for most of the installed capacity, electricity generated from rooftop PV systems is more economical than the grid electricity supply, mainly driven by factors including high electricity prices, larger installations and abundant solar irradiance. The GHG emissions assessment further emphasizes the importance of methodological choice, with stark contrasts between electricity certificate-based approaches and others that are based on the consumption mix. This study suggests the need for more accurate geographical potential estimations, enhanced support for small-scale rooftop PV systems, and more incentives to maximize the potential of their roof area for PV deployment. As Switzerland progresses towards its renewable energy goals, our research underscores the importance of informed policymaking based on a retrospective analysis of existing installations, essential for maximizing the potential and benefits of rooftop solar PV systems.

Sun-powered solutions: Investigating productivity and economics of small-scale solar desalination system

Freshwater demand is one of the most critical challenges facing many countries in the world. Jordan is a country in the middle east that is considered one of the poorest countries for renewable freshwater supplies in the world. Though desalination may be one of the solutions to the problem, the cost and energy expenses could be an obstruction. However, with an abundance of annual solar irradiance in Jordan, solar desalination systems, particularly small-scale ones, are considered better alternatives. In this study, a residential-scale solar desalination system is investigated. The design includes evacuated-tube solar heaters with a heat pipe, and flashing units comprising three desalination stages. The experiments included single-stage, double-stage, and triple-stage desalination. The results showed that production rates of 2.2 kg/m2 using single-stage, 4.7 kg/m2 using double-stage, and 6.4 kg/m2 using triple-stage desalination were obtained from the system. The solar water heater used in the system exhibited an average thermal efficiency of 73 %. The economic analysis revealed that the payback period for the triple-stage desalination system is 8 years. The annualized rate of return was calculated to be 2.2 %, assuming the system operates for 4 h per day and 300 days per year.

Decision-making frameworks for assessment of small-scale off-grid photovoltaic home system-based design concepts in rural context of north-east India

Energy security plays an influential role in developing sustainable cities and promoting a better quality of life for the population. The United Nations' sustainable development goal focuses on energy security. Against the backdrop of India's energy concerns in the northeastern region, the study investigates the user-centric challenges related to the designs of solar photovoltaic home system concepts to facilitate access to energy. This is followed by the proposal of design concepts for solar photovoltaic home systems that take due cognizance of the identified challenges. To facilitate determining the optimal design concept in the context of small-scale off-grid photovoltaic home systems the paper proposes and applies an extended TOmada de Decisao Interativa Multicriteria (TODIM) methodology wherein the linguistic evaluations have been modelled using T-Spherical fuzzy sets. The information was aggregated using T-Spherical Fuzzy Aczel-Alsina Hammy Mean and T-Spherical Fuzzy Aczel-Alsina Weighted Hammy Mean operators. Ten design concepts were developed and evaluated through the proposed decision-making frameworks. Five performance metrics arising out of the field study: Functionality, Reliability, Affordability, Novelty and Usability have been chosen to appraise the conceptualized design concepts. Design concept 3 has been revealed to be the optimal design concept for the application of the proposed approach. Sensitivity analysis of the ranking results revealed that although both the proposed methodologies are robust, the methodology based on T-Spherical fuzzy Aczel-Alsina Weighted Hammy Mean operator was revealed to be the superior of the two. By presenting an effective method to address the complexities in design assessment for off-grid PV systems, this research offers practical insights to guide context-specific design in the region.

Analysis of Electricity Supply and Demand Balance in Residential Microgrids Integrated with Micro-CAES in Northern Portugal

As global energy demand continues to rise, integrating renewable energy sources (RES) into power systems has become increasingly important. However, the intermittent nature of RES, such as solar and wind, presents challenges for maintaining a stable energy supply. To address this issue, energy storage systems are essential. One promising technology is micro-compressed air energy storage (micro-CAES), which stores excess energy as compressed air and releases it when needed to balance supply and demand. This study investigates the integration of micro-CAES with RES in a 19-home microgrid in northern Portugal. The research aims to evaluate the effectiveness of a microgrid configuration that includes 100 kW of solar PV, 70 kW of wind power, and a 50 kWh micro-CAES system. Using real-world data on electricity consumption and local renewable potential, a simulation is conducted to assess the performance of this system. The findings reveal that this configuration can supply up to 68.8% of the annual energy demand, significantly reducing reliance on the external grid and enhancing the system’s resilience. These results highlight the potential of micro-CAES to improve the efficiency and sustainability of small-scale renewable energy systems, demonstrating its value as a key component in future energy solutions.

Application End Evaluation of Electrostatic Precipitation for Control PM and NOx Emissions from Small-Scale Combustions

Electrostatic precipitators (ESPs) have shown promise in reducing particulate matter (PM) emissions, but their potential for simultaneous NOx reduction in small-scale combustion systems remains underexplored. This study focuses on using non-thermal plasma generated in a corona discharge to reduce PM and NOx emissions from small-scale combustion. ESP was specifically designed for a commercially available 15 kW boiler with wood pellet combustion and used with both positive and negative discharge polarity to control emissions without any chemical additives. ESP performance was evaluated across a range of specific input energies (SIE) in terms of particle mass and number concentrations and NOx concentrations obtained by continuous gas analysis. ESP ensured the reduction in PM concentrations from 48 mg/m3 to the magnitude of PM content in the ambient air. The highest precipitation efficiency was observed for particles in the 20–200 nm range. Concurrently, NOx emissions were reduced by up to 78%, from 178 mg/m3 to 39 mg/m3. These results were achieved at specific input energies of 36 for positive and 48 J/L for negative corona, which is significantly lower than those reported for many existing separate PM and NOx control systems. This study demonstrates the potential of ESPs as a compact, energy-efficient solution for simultaneous PM and NOx removal in small-scale combustion systems, offering promising implications for improving air pollution control technologies for small-scale combustion systems.

Optimized design of SynRM drive systems for high-efficiency solar water pumps

This study presents the design and implementation of a Synchronous Reluctance Motor (SynRM) with an integrated drive circuit for a 4-inch submersible pump motor, tailored for small-scale solar photovoltaic water pumping systems. The SynRM operates efficiently at low voltage levels, eliminating the need for a boost converter and allowing direct connection to low-voltage power sources. With a power output of 0.55 kW and an ultra-premium efficiency rating of 86.5%, the motor integrates the drive circuit within its casing for a compact design. It operates across a voltage range of 15 V to 95 V, using efficient buck converters for required output voltages. This paper discusses the design, optimization, and prototyping of the motor and drive circuit, highlighting innovative solutions for advancing small-scale solar-powered water pumping systems. Electric motors, especially pump motors, are major consumers of electrical energy. Enhancing their efficiency can significantly impact total energy consumption. This study's SynRM and integrated drive system, optimized for high efficiency, durability, and cost-effectiveness, can be directly powered by PV panels, offering a compact and efficient alternative to traditional systems.

Equity as a priority in EAT-Lancet-aligned food system transformations.

Food systems drive human and environmental change, reflect diverse cultural and ecological contexts, and, in their diversity, can bolster nutrition and planetary health. Ignoring structural inequities in food system transformations risks offsetting potential gains. We summarize current evidence on the context-dependent implications of EAT-Lancet goals and propose six priority areas to guide equitable food system transformations, targeting food and nutrition security, just sustainability and cultural diversity. Priority areas-namely, diverse and nutritious food access, food industry regulation, climate-resilient food production, localized, small-scale food systems, cultural diversity and social well-being-can be achieved through public, private and civil society action.

Thermodynamic Performance Characterization of a Small-Scale Organic Rankine Cycle with 5 kW Net Power Output

Abstract Indonesia’s current energy landscape predominantly depends on fossil fuels and non-renewable energy sources, thereby exacerbating the issue of global warming. On the other side, geothermal utilization in the country still needs to be expanded to reduce the dependency on fossil fuels, particularly through organic Rankine cycle (ORC) systems. As an example, Ulumbu Geothermal Power Plant in Flores Island currently uses a back pressure turbine, which releases expanded steam directly into the atmosphere at 98.7°C and 0.98 bar. This paper presents a thermodynamic analysis of a small-scale Organic Rankine Cycle with 5kW Net power output based on the waste heat data of the Ulumbu Geothermal Power Plant. The study includes selecting the working fluid based on Ozone Depletion Potential (ODP) and Global Warming Potential (GWP) values, thermal efficiency, refrigerant, and steam mass flow rate calculation. Among 20 refrigerants available in Indonesia, R245fa shows promise, offering a Rankine system efficiency of 10-11%, zero ODP, a GWP of 850, and the lowest refrigerant mass flow rate. These parameters inform useful initial parameters for designing a small-scale ORC system producing 5 kW of net power, promoting cleaner and sustainable energy solutions for communities.

Smallholder farmers' participation in small-scale irrigation system: Insight from Lume District, Ethiopia.

Irrigation systems play a crucial role in ensuring food security and mitigating the impacts of drought and water scarcity. Numerous farmers do not possess the technical expertise required for efficient irrigation management. Therefore, this study examined the determinants that affect participation in small-scale irrigation in the Lume District of Ethiopia. Random sampling techniques were used to select four kebeles from a total of thirteen kebeles that have access to small-scale irrigation in the district. Data was gathered from a sample of 176 randomly selected farm households. The households in these kebeles were divided into two groups: the irrigation users and non-users. The overall sample consisted of 121 irrigation users and 55 non-users, accounting for 68.75% and 31.25% of the total sample, respectively. A binary logistic regression model was utilized to pinpoint the factors influencing participation in these irrigation systems. The results revealed that key factors such as the age of the household head, the family size of the household head, land ownership, proximity to irrigation sources, and access to credit significantly influence engagement in small-scale irrigation. The study suggests that policymakers and stakeholders should enhance credit accessibility and improve the distance to irrigation sites to encourage more significant participation in small-scale irrigation systems.

A transformer-less DC-DC converter for grid-connected PV systems using TSTS-ZSI voltage boost-buck technique

This research introduces an innovative design for a grid-connected photovoltaic (PV) system utilizing a transformer-less DC-DC converter. The converter is based on the TSTS-ZSI (Three-Switch Transformer-less Z-Source Inverter) voltage boost-buck technique, which enhances voltage regulation and energy transfer, making it ideal for micro-inverter applications. The primary goal of the study is to improve energy efficiency while ensuring seamless integration with the grid. The proposed system not only boosts voltage but also ensures efficient buck operation, leading to enhanced power injection into the grid under fluctuating conditions. By utilizing advanced control techniques, the converter minimizes power losses, reduces stress on the components, and maintains stability in a wide range of grid scenarios. Simulations performed using MATLAB/Simulink demonstrate that the converter delivers stable and efficient power with minimal energy loss. The results validate its effectiveness in small-scale grid-connected systems, achieving enhanced power management under various operating conditions. The converter's ability to operate efficiently without a transformer reduces magnetic losses and electromagnetic interference, making it a cost-effective and compact solution. The research presents a valuable contribution to the field of renewable energy integration, with its applications extending to both residential and commercial grid-connected PV systems.'

Weakening characteristics of pile group foundations in clayey soil under vertical cyclic loading: Experimental and numerical investigation

Long-term cyclic loading can substantially reduce the bearing capacity of pile foundations, potentially compromising the structural integrity of offshore foundations. A small-scale model test system for vertical cyclic loading of pile foundations is independently designed. Model experiments and numerical simulations were conducted to investigate the weakening characteristics of four foundation types (i.e., slab foundation, single pile with cap, 2 × 2 pile group foundation, and 3 × 3 pile group foundation) in clayey soil under cyclic loading. The results of both methods demonstrate that 3 × 3 pile group foundations exhibit the greatest resistance to deformation, followed by 2 × 2 pile groups, single piles with a cap, and slab foundations under cyclic loading. Furthermore, a 3D numerical model was developed to simulate the real-world behavior of a pile group foundation for an offshore wind turbine. Results reveal that although the ultimate compressive bearing capacity decreases with higher cyclic loading levels, typical cyclic loads (0.1–0.2) encountered in practice do not greatly affect the long-term bearing capacity of the foundations. The proposed experimental and numerical simulation methods offer valuable insights into the weakening characteristics of pile group foundations under cyclic loading.

Adaptive reactive power control for voltage rise mitigation on distribution network with high photovoltaic penetration

This research addresses the challenge of voltage rise on low voltage distribution networks with high photovoltaic penetration. The proliferation of distributed generators, particularly small-scale PV systems, has raised concerns about voltage stability and power quality in these networks. Existing reactive power control techniques, such as fixed power factor and voltage-based methods (Q(V)), have limitations in effectively mitigating voltage rise while considering load variations and network sensitivity. To overcome these limitations, an adaptive reactive power control technique is proposed in this research. The technique combines both PV active power injection and network voltage considerations in real-time to dynamically adjust reactive power output. Unlike traditional methods, which directly link reactive power reference to PV active power or voltage, the adaptive technique calculates the change in reactive power reference (ΔQ) based on both factors. This dynamic approach enables more responsive and accurate voltage regulation. The effectiveness of the adaptive technique is demonstrated through MATLAB simulations on a representative low voltage distribution network. The results show that the adaptive technique outperforms existing methods, providing better voltage regulation and reduced losses. The technique's adaptability to different scenarios and variations is also highlighted. However, it is noted that the adaptive technique may have a slightly slower response time compared to existing methods due to its dynamic nature.

Social-ecological resilience: Knowledge of agrobiodiversity by campesinos and migrants in the face of global changes

There is concern that agrobiodiversity is being irreversibly eroded in the face of agricultural industrialization. While academic and policy debates stress loss of landraces, little attention has been paid to evaluating how agricultural knowledge systems endure in response to broader social-ecological changes (i.e., “system's resilience”). For being resilient, agricultural knowledge systems should incorporate new information (modern seed varieties) whilst maintaining its traditional components (landraces) and functions. However, the loss or continuing utilization of landraces may be influenced by several social-ecological filters, which are processes that selectively remove varieties according to their phenotype, local uses, or value. We examined the resilience of agricultural knowledge systems in the southern Andes. These systems include the knowledge of landraces and modern varieties by campesinos and lifestyle migrants. We further assessed the association of social-ecological filters with the knowledge of agrobiodiversity. Over four years (2018–2022), we used mixed-methods including semi-structured interviews with gardener experts and conducted knowledge exercises of seed varieties and surveys of gardeners (n = 132). We assessed the association of ‘knowledge score on varieties’ (general, landraces, and modern) with a priori-defined social-ecological filters. Gardeners with more proficient knowledge of landraces were more knowledgeable of modern varieties too. The general knowledge of agrobiodiversity and the knowledge of landraces, but not of modern varieties, was higher for campesinos than migrants. The main seed source of gardeners, the participation in seed exchanges, gardeners' origin, and gardeners' age were the social-ecological filters that influenced gardeners′ knowledge of agrobiodiversity. We highlight that social-ecological, small-scale farming systems, are being resilient when they have the capacity of incorporating new information (knowledge of modern varieties) whilst maintaining their identity (knowledge of landraces) without undergoing a major shift in their basic structures and functions in this Important Agricultural Heritage Site and Global Biodiversity Hotspot, and beyond.

Towards an efficient variational quantum algorithm for solving linear equations

Variational quantum algorithms are promising methods with the greatest potential to achieve quantum advantage, widely employed in the era of noisy intermediate-scale quantum computing. This study presents an advanced variational hybrid algorithm (EVQLSE) that leverages both quantum and classical computing paradigms to address the solution of linear equation systems. Initially, an innovative loss function is proposed, drawing inspiration from the similarity measure between two quantum states. This function exhibits a substantial improvement in computational complexity when benchmarked against the variational quantum linear solver. Subsequently, a specialized parameterized quantum circuit structure is presented for small-scale linear systems, which exhibits powerful expressive capabilities. Through rigorous numerical analysis, the expressiveness of this circuit structure is quantitatively assessed using a variational quantum regression algorithm, and it obtained the best score compared to the others. Moreover, the expansion in system size is accompanied by an increase in the number of parameters, placing considerable strain on the training process for the algorithm. To address this challenge, an optimization strategy known as quantum parameter sharing is introduced, which proficiently minimizes parameter volume while adhering to exacting precision standards. Finally, EVQLSE is successfully implemented on a quantum computing platform provided by IBM for the resolution of large-scale problems characterized by a dimensionality of 220.

Typologies of South African small-scale farmers and their risk perceptions: an unsupervised machine learning approach

PurposeSmall-scale farmers are highly heterogeneous with regard to their types of farming, levels of technology adoption, degree of commercialization and many other factors. Such heterogeneous types, respectively groups of small-scale farming systems require different forms of government interventions. This paper applies a machine learning approach to analyze the typologies of small-scale farmers in South Africa based on a wide range of objective variables regarding their personal, farm and context characteristics, which support an effective, target-group-specific design and communication of policies.Design/methodology/approachA cluster analysis is performed based on a comprehensive quantitative and qualitative survey among 212 small-scale farmers, which was conducted in 2019 in the Limpopo Province of South Africa. An unsupervised machine learning approach, namely Partitioning Around Medoids (PAM), is applied to the survey data. Subsequently, the farmers' risk perceptions between the different clusters are analyzed and compared.FindingsAccording to the results of the cluster analysis, the small-scale farmers of the investigated sample can be grouped into four types: subsistence-oriented farmers, semi-subsistence livestock-oriented farmers, semi-subsistence crop-oriented farmers and market-oriented farmers. The subsequently analyzed risk perceptions and attitudes differ considerably between these types.Originality/valueThis is the first typologisation of small-scale farmers based on a comprehensive collection of quantitative and qualitative variables, which can all be considered in the analysis through the application of an unsupervised machine learning approach, namely PAM. Such typologisation is a pre-requisite for the design of more target-group-specific and suitable policy interventions.