ABSTRACT Net metering is widely treated as a technical connection rule. This article reviews evidence that it operates as a distributive instrument, allocating value between utilities, adopting households and non‐adopting households. Three literatures usually kept apart are synthesized: compensation rule design, financing constraints on participation, and the carbon abatement cost of distributed generation. Evidence from high‐income systems shows that retail‐rate compensation transfers value toward wealthier adopters where network costs are recovered volumetrically, and that a uniform national rule does not produce uniform incidence. Evidence from emerging economies shows that utility cost recovery pressures determine which reforms are feasible. The review then turns to Bangladesh, where one national rule operates through utilities paying different bulk buyback rates, holding policy constant while compensation varies. Simulation of residential systems from 1 to 4 kWp across three zones yields a present‐value gap of BDT 130,300 for an identical 4 kWp system. Financing terms rather than technology cost determine participation, and concessional lending extends access downward by one to two income quintiles. Carbon abatement cost falls below the social cost of carbon at 3 kWp and above and exceeds it at 1 kWp, so climate cost‐effectiveness and affordability diverge across the size range. This study recommends a national floor buyback rate, paired with concessional credit and a tiered capital subsidy.
ABSTRACT Floating solar photovoltaics (FSPV) have emerged as a promising alternative to traditional ground‐mounted photovoltaic (GPV) systems. By deploying solar panels over water bodies such as lakes and reservoirs, FSPV systems mitigate land‐use constraints while enhancing energy performance and contributing to more effective water‐resource management. This paper presents a comprehensive review of FSPV technology, including its operational principles, technological developments, techno‐economic feasibility, environmental impacts, system reliability, and sustainability implications. One of the major advantages of FSPV systems is their enhanced energy generation compared with GPV installations. The presence of water beneath the modules provides a natural cooling effect that lowers the operating temperature of the panels and improves their efficiency. However, the level of performance improvement depends on climatic conditions, installation configuration, and system design. Beyond electricity generation, FSPV systems also provide several ancillary benefits related to water‐resource conservation and management. The coverage of water surfaces reduces evaporation losses and can support water conservation. Despite these benefits, FSPV deployment may also affect aquatic ecosystems and water quality. Therefore, proper site selection and environmental impact assessments are essential to minimize ecological disturbances. From an economic perspective, the initial capital cost of FSPV systems is generally higher than GPV systems because of floating structures, anchoring systems, and specialized installation requirements. Addressing the remaining technical, environmental, economic, and regulatory challenges will require coordinated research, technological standardization, and policy support. Overall, FSPV systems represent an important solution within the energy‐water‐climate nexus and can contribute significantly to global climate goals and sustainable energy development.
ABSTRACT Although investments in renewable energy, particularly solar photovoltaic (PV) systems, have increased over the past decade, the energy transition still faces dilemmas related to several socio‐technical and environmental aspects. To clarify the benefits, challenges, and trade‐offs of distributed urban solar PV, this article conducts a multidimensional literature review and develops an integrated trade‐off framework that considers technical, economic, social, regulatory, and environmental perspectives. The review highlights the controversial aspects that support and challenge the potential of on‐grid urban solar systems to enhance energy security, improve efficiency, and support community engagement through technological innovation and novel social practices. Several concerns arise, including investment risks, social equity, energy security, environmental impact, maintenance, and aesthetics, all of which require strategic mitigation. Integrating solar PV into smart urban environments also presents constraints related to energy storage, consumer adaptability, business model innovation (BMI), stakeholder engagement, and potential health hazards. Addressing these issues requires balancing socio‐technical and environmental aspects. Based on a systematic assessment of European case studies—including Amsterdam's solar‐EV ecosystem, Spain's post‐2018 regulatory reforms, and France's inclusive financing models—we find that successful pathways combine modernized interconnection standards, streamlined permitting, collective self‐consumption frameworks, performance‐based regulation, and targeted financial instruments for low‐income households. BMI and policy reforms are essential drivers for the successful diffusion of solar PV systems. Achieving a sustainable energy future in urban areas requires stakeholder collaboration, public‐private partnerships (PPPs), innovative solutions, and careful balancing of multiple trade‐offs. This article sheds light on the current state of the art on distributed solar PV and emphasizes the need for informed decision‐making to address the complexities of on‐grid urban solar systems, aiming for a sustainable, resilient, efficient, and inclusive urban energy future.
Biodiesel, a renewable alternative to petroleum diesel, can be produced via esterification, hydro-esterification, or transesterification reactions catalyzed by acids, bases, or enzymes. Enzymatic catalysis, particularly with lipases, offers several advantages over traditional catalysts, including high selectivity, milder reaction conditions, and reduced byproduct formation, such as soaps. Although enzyme cost remains a primary barrier to industrial adoption, recent advancements in enzyme engineering, immobilization techniques, and process optimisation have improved efficiency and reduced costs. Enzymes exhibit tolerance to water and free fatty acids, allowing for recycling and reuse, thereby enhancing their sustainability potential. Moreover, enzymatic routes produce biodiesel and glycerol of higher purity, thereby reducing downstream processing requirements and environmental impact. Considering the global energy transition, environmental and sustainability factors-such as lower emissions, reduced waste, and alignment with ESG criteria and the Sustainable Development Goals (SDGs) -should weigh heavily in technology assessments. While economic feasibility remains a concern, particularly due to slower reaction rates and higher enzyme-to-substrate ratios, a comprehensive evaluation that considers environmental benefits and product quality is essential. Policy support, market incentives, and enzyme accessibility are key to overcoming current limitations. This article critically analyses enzymatic biodiesel production, highlighting both the technical and strategic considerations necessary for its scale-up. Despite cost-related challenges, enzymatic catalysis offers a cleaner, more sustainable route with the potential to make significant contributions to green energy goals.
ABSTRACT Parabolic trough solar collectors (PTSCs) can play a crucial role in providing industrial process heat (IPH) by harnessing solar energy efficiently. To contribute to this domain, this review maps the global industrial footprint of PTSC‐based IPH installations. It identifies possible integration strategies (preheating, steam generation, and process heating) along with practical constraints (space availability, data scarcity, etc.). The review shows that system‐level design choices, such as thermal energy storage and operational flexibility, often govern achievable solar fraction and economic competitiveness more than collector performance alone. Additionally, several studies on the optimization of PTSCs for industrial use are presented and analyzed. It reveals a clear shift from single‐parameter tuning toward AI‐assisted and multiobjective paradigms that simultaneously address thermal performance, cost metrics, and operational reliability. Further, literature on dynamic modeling of the PTSC and its control is examined. It highlights the necessity of maintaining stable operations amid fluctuating solar input and varying industrial load conditions. Overall, the review distils convergent trends, highlights persistent gaps, and outlines actionable research directions to accelerate robust PTSC deployment for industrial decarbonization. This article is categorized under: Sustainable Energy > Solar Energy Sustainable Development > Goals Sustainable Energy > Energy Efficiency
