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"Lund, Peter D."
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Review of Recent Offshore Photovoltaics Development
2022
Photovoltaic power generation (PV) has significantly grown in recent years and it is perceived as one of the key strategies to reach carbon neutrality. Due to a low power density, PV requires much space, which may limit PV expansion in the future. Placing PV on water has therefore become an interesting alternative siting solution in several countries. China has the largest fleet of water floating photovoltaic power stations. Water-based PV is typically installed on inland shores, but now offshore areas may become the next step of development. In this paper, the background of offshore photovoltaic power generation and an analysis of existing offshore photovoltaic systems is presented. Fixed pile-based photovoltaic systems are stationary PV systems in offshore or tidal areas characterized by higher safety, but also a higher initial investment. Wave-proof PV systems are highly modular, easier to install, and more practical in countries with high population density and less available land. Floating platform photovoltaic systems are built on a floating platform with a floating body and frame structure. The photovoltaic module is installed on the floating platform at a certain height, which can avoid the direct action of waves. Floating thin-film PV is one of the most recently developed water-based PV systems. It has a reinforced film that can fluctuate with the waves, adapting to the wave and wind load. This paper finally discusses the challenges encountered by offshore PV and presents future prospects.
Journal Article
TiO2 nanotubes for dye‐sensitized solar cells—A review
by
Hou, Xuelan
,
Aitola, Kerttu
,
Lund, Peter D.
in
active area
,
Anodizing
,
Dye-sensitized solar cells
2021
TiO2 nanotubes (TNTs) are a potential candidate for the photoelectrode in dye‐sensitized solar cells (DSSCs). In this review, emphasis is given to the fabrication methods of the TNT photoelectrode, including the anodic oxidation method, the hydro/solvothermal method, and the template method. Modification of TNTs to improve the power conversion efficiency (PCE) and the long‐term stability of DSSCs is also covered. The active area of the DSSC strongly correlates with the PCE. Therefore, evaluating and comparing cell efficiencies with the same active area would be important. Reducing the material and manufacturing costs of TNT‐based DSSCs will be an important future target. TiO2 nanotubes (TNTs) are a potential candidate for the photoelectrode in dye‐sensitized solar cells (DSSCs). In this review, emphasis is given to the fabrication methods of the TNT photoelectrode, including the anodic oxidation method, the hydro/solvothermal method, and the template method. Modification of TNTs to improve the power conversion efficiency (PCE) and the long‐term stability of DSSCs is also covered. The active area of the DSSC strongly correlates with the PCE. Therefore, evaluating and comparing cell efficiencies with the same active area would be important. Reducing the material and manufacturing costs of TNT‐based DSSCs will be an important future target.
Journal Article
Machine Learning Improves Performance Prediction and Interpretation of Efficiency Influencing Factors of a Novel Basalt-Fiber-Bundle Thermal Flow-Reversal Reactor for Methane Recovery
by
Du, Bin
,
Liu, Yanying
,
Lund, Peter D.
in
Artificial intelligence
,
Basalt
,
basalt fiber bundle
2025
Low-concentration methane emissions from mines can be recovered using different reactor designs. Here, different artificial intelligence network techniques were employed to predict thermal performance of a basalt-fiber-bundle thermal flow-reversal reactor and investigate the influence of input parameters. The Back Propagation (BP) model gave the best accuracy (R2 = 0.974 for outlet temperature, 0.967 for thermal efficiency), exceeding that of traditional Computational Fluid Dynamics (CFD) simulations. For the present design, when flow velocity exceeded 1.5 m/s, the outlet gas temperature shifted from rising to falling, explained by the heat transfer between the gas and the solid inside the flow channel. Increasing the length of the flow-reversal period in the high-temperature phase reduced the outlet temperature, e.g., an increase from 60 s to 200 s decreased the outlet temperature by 34.1 K. Increasing inlet methane concentration (e.g., from 0.3% to 0.8%) first showed a slight improvement in thermal efficiency but further increase accelerated the oxidation reaction rate inside the reactor, reducing the temperature difference between the solid and gas in the channel, which slowed the heat exchange process and resulted in a downward trend in efficiency. The results indicate that the reactor can handle a wide range of exhaust gas concentrations, being suitable to treat low-methane-concentration exhaust gas. The BP model helped to establish the theoretical basis for setting optimal parameters values for the operation of the proposed reactor.
Journal Article
Electricity Load Lost in the Largest Windstorms—Is the Fragility-Based Model up to the Task?
by
Heikkinen, Tatu
,
Lund, Peter D.
,
Jasiūnas, Justinas
in
Analysis
,
distribution grid
,
Electric power systems
2023
Most existing models for estimating electric system impacts from windstorms tend to have detailed representation only for the electric or only for the meteorological system. As a result, there is little evidence on how models with detailed electric systems and realistic wind gust field representations would perform in different windstorm cases. This work explores the evidence for the ability of such a fragility-based model to generate realistic spatiotemporal lost load profiles for the most impactful windstorm cases in Finland. The literature review shows multiple driving factors for windstorm impacts that are difficult to assess analytically, and similarities between the most impactful windstorms. All the available interruption data for thirteen years were analyzed, with their grouping by individual storm and calm periods. The fixing of time distribution fits for these periods show most faults as being within the 20% uncertainty bounds of the severity-dependent distribution trendlines. The medium-voltage electricity grid impact model with national coverage was applied for the three most impactful and most recent windstorm cases, with the model calibrated for one case. The generated spatiotemporal lost load profiles in all cases recreate historic profiles within the similar error margins of approximately 20%.
Journal Article
Effect of Heat Demand on Integration of Urban Large-Scale Renewable Schemes—Case of Helsinki City (60 °N)
2020
Heat demand dominates the final energy use in northern cities. This study examines how changes in heat demand may affect solutions for zero-emission energy systems, energy system flexibility with variable renewable electricity production, and the use of existing energy systems for deep decarbonization. Helsinki city (60 °N) in the year 2050 is used as a case for the analysis. The future district heating demand is estimated considering activity-driven factors such as population increase, raising the ambient temperature, and building energy efficiency improvements. The effect of the heat demand on energy system transition is investigated through two scenarios. The BIO-GAS scenario employs emission-free gas technologies, bio-boilers and heat pumps. The WIND scenario is based on large-scale wind power with power-to-heat conversion, heat pumps, and bio-boilers. The BIO-GAS scenario combined with a low heat demand profile (−12% from 2018 level) yields 16% lower yearly costs compared to a business-as-usual higher heat demand. In the WIND-scenario, improving the lower heat demand in 2050 could save the annual system 6–13% in terms of cost, depending on the scale of wind power.
Journal Article
A Review of the Compound Parabolic Concentrator (CPC) with a Tubular Absorber
by
Zhang, Yaoming
,
Yang, Song
,
Jiang, Chuan
in
compound parabolic concentrator
,
Efficiency
,
Heat
2020
The compound parabolic concentrator (CPC) is a highly interesting solar collector technology for different low-concentration applications due to no tracking requirement. The CPC with a tubular absorber is the most common type of CPC. Here, a comprehensive state-of-the-art review of this CPC type is presented, including design features, structure, applications, etc. Key design guidelines, structural improvements, and recent developments are also presented.
Journal Article
Thermal Performance Analysis of a Direct-Heated Recompression Supercritical Carbon Dioxide Brayton Cycle Using Solar Concentrators
by
Lund, Peter D.
,
Zhu, Hongxia
,
Wang, Jun
in
Alternative energy sources
,
Capital costs
,
Carbon dioxide
2019
In this study, a direct recompression supercritical CO2 Brayton cycle, using parabolic trough solar concentrators (PTC), is developed and analyzed employing a new simulation model. The effects of variations in operating conditions and parameters on the performance of the s-CO2 Brayton cycle are investigated, also under varying weather conditions. The results indicate that the efficiency of the s-CO2 Brayton cycle is mainly affected by the compressor outlet pressure, turbine inlet temperature and cooling temperature: Increasing the turbine inlet pressure reduces the efficiency of the cycle and also requires changing the split fraction, where increasing the turbine inlet temperature increases the efficiency, but has a very small effect on the split fraction. At the critical cooling temperature point (31.25 °C), the cycle efficiency reaches a maximum value of 0.4, but drops after this point. In optimal conditions, a cycle efficiency well above 0.4 is possible. The maximum system efficiency with the PTCs remains slightly below this value as the performance of the whole system is also affected by the solar tracking method used, the season and the incidence angle of the solar beam radiation which directly affects the efficiency of the concentrator. The choice of the tracking mode causes major temporal variations in the output of the cycle, which emphasis the role of an integrated TES with the s-CO2 Brayton cycle to provide dispatchable power.
Journal Article
How to Assess Policy Impact in National Energy and Climate Plans
by
Dolge, Kristiāna
,
Lund, Peter D.
,
Balode, Lauma
in
Climate policy
,
composite sustainability index
,
Developmental stages
2021
It is the responsibility of each member state of the European Union, to prepare a national energy and climate plan and set achievable climate targets and meaningful measures and policies to achieve the targets set. Annex 4 of the Latvian National Energy and Climate Plan for 2030 (hereinafter – NECP) provides an overview of policies and measures to achieve the climate targets. The NECP does not provide information on the impact of the policies or which measures are more important and which are less crucial Similarly, the measures in Annex 4 of the NECP were not determined by industry experts but by ministry officials, therefore, it is not clear whether the proposed measures will achieve the set climate targets, a point also made by European Commission in its evaluation report on NECP. The aim of the study is to develop a tool for the early assessment of the impact of energy and climate policy measures. The study developed a methodology to pre-assess the impacts of the policies identified in the NECP, impacts were described by measures effectiveness and stage of development. With this methodology, it is possible to assess the impact of energy policies using indicators to characterize the effectiveness of the policy and the level of development. The study confirmed that both the multi-criteria analysis and composite index method can be used as methods. The results showed that high impact measures were related to the promotion of energy efficiency in buildings, but low impact measures were comprehensive horizontal measures such as measures related principle ‘energy efficiency first’ and review of energy efficiency obligation schemes. The indicators with the highest impact on sustainability rate were possible side effects and transparency of policies.
Journal Article
Advances in energy systems : the large-scale renewable energy integration challenge
by
Byrne, John
,
Haas, Reinhard
,
Lund, Peter D.
in
Energiepolitik
,
Energiewirtschaft
,
Erneuerbare Energie
2019
A guide to a multi-disciplinary approach that includes perspectives from noted experts in the energy and utilities fields
Advances in Energy Systems offers a stellar collection of articles selected from the acclaimed journal Wiley Interdisciplinary Review: Energy and Environment. The journalcovers all aspects of energy policy, science and technology, environmental and climate change. The book covers a wide range of relevant issues related to the systemic changes for large-scale integration of renewable energy as part of the on-going energy transition.
The book addresses smart energy systems technologies, flexibility measures, recent changes in the marketplace and current policies. With contributions from a list of internationally renowned experts, the book deals with the hot topic of systems integration for future energy systems and energy transition. This important resource:
* Contains contributions from noted experts in the field
* Covers a broad range of topics on the topic of renewable energy
* Explores the technical impacts of high shares of wind and solar power
* Offers a review of international smart-grid policies
* Includes information on wireless power transmission
* Presents an authoritative view of micro-grids
* Contains a wealth of other relevant topics
Written forenergy planners, energy market professionals and technology developers, Advances in Energy Systems is an essential guide with contributions from an international panel of experts that addresses the most recent smart energy technologies.
Importance of Energy Efficiency in Manufacturing Industries for Climate and Competitiveness
by
Dolge, Kristiāna
,
Āzis, Reinis
,
Lund, Peter D.
in
Clean energy
,
Competitiveness
,
decomposition analysis
2021
The manufacturing industry in Europe is currently enfacing one of its greatest challenges due to the emission reductions needed to reach carbon neutrality by the middle of this century. The European Union’s Energy Efficiency Directive and Green Deal will force manufacturing industries to significantly reduce their present energy consumption, but at the same time sustain their competitiveness globally. Here we use the Latvian manufacturing industry as a case to analyse how different macro-level factors have affected its energy use and how the industrial energy efficiency has progressed during the last decade. We apply the Log-Mean Divisia index decomposition method to decompose the energy use in the manufacturing subsectors over the period of the past ten years from 2010 to 2019. The findings unravel the key driving factors of industrial energy consumption, which could serve as a valuable basis for effective energy efficiency policymaking in the future. The results show that energy consumption trends differed across industrial subsectors and the effect of industrial energy efficiency improvements was more pronounced in the period following the entry into force of Energy Efficiency Law in Latvia. Significant increases in energy consumption are observed in the two largest Latvian manufacturing subsectors, such as the non-metallic minerals production sector and the wood processing sector, where the current pace of energy efficiency improvements cannot compensate for the effect of increasing industrial activity, which increases overall industrial energy consumption. The results suggest that the Latvian manufacturing industry is at the crossroads of the sustainability dilemma between economic gains and energy saving targets.
Journal Article