Showing papers in "Wiley Interdisciplinary Reviews: Energy and Environment in 2021"

How to finance energy renovation of residential buildings: Review of current and emerging financing instruments in the EU

Abstract: The Paris Agreement goals require net‐zero CO2 emissions by mid‐century The European Commission in its recent proposal for climate and energy strategy for 2050 indicated the need for more intensified actions to substantially improve the energy performances of buildings With the rate of new construction in Europe, the challenge is to increase both the pace and depth of building energy renovations Several barriers inhibit the wide uptake of comprehensive energy renovations, including the inability or inertia to finance upfront costs of energy renovations Despite various policies implemented to address some of these barriers, current investments in buildings remain at suboptimal levels The paper reviews current financing practices for energy renovations and investigates some innovative instruments with a special focus on their applicability to residential buildings In addition to “traditional” financial schemes such as subsidies, tax incentives, and loans, the paper assesses innovative financing schemes: On property tax and on‐bill financing, energy efficiency mortgages, and energy efficiency feed‐in tariffs The paper also investigates the concept of one‐stop shops for building renovations and crowdfunding The paper offers an assessment of the characteristics, benefits, and challenges of each analyzed financing instrument and provides policy recommendations for their successful implementation In general, as financing instruments involve different stakeholders and due to complex nature of the sector, there is no single solution to accelerate energy renovation investment in buildings The emerging financial models offer the potential to address the long‐standing barriers to investment in energy efficiency

Current status and perspective of colored photovoltaic modules

Abstract: Photovoltaic (PV) systems, which directly convert solar light into electricity, are one of the most attractive renewable energy sources to fulfill the increased demand for clean energy. The accumulated installation of PV systems has expanded rapidly, reaching over 700 GW in 2020. Although black colored PVs maximize energy generation by harvesting a broad range of solar light, their monotonous color limits their installation in urban areas and portable devices where the harmonization of color with neighboring exterior elements is a high priority. Moreover, it is not suitable for covering transparent area of buildings, such as window and curtain wall. Hence, the demand for aesthetic PV systems is increasing significantly. In this review, we focus on the current status of colored PV systems and their prospects for aesthetic energy harvesting system. This work reviews possible approaches to realize colored PV systems by implementing semitransparent cells, selective reflective films, and luminophores. Additionally, the research progress to minimize light sacrifice for color production has been investigated. Moreover, the technical limitations of each technology for colored PV systems are presented in terms of color purity and efficiency. Finally, obstacles to commercialization and their solutions are discussed. Therefore, this study provides a crucial review of the latest developments and current status in the field of colored PV systems. This article is categorized under: Photovoltaics > Science and Materials

Power system stability in the transition to a low carbon grid: A techno-economic perspective on challenges and opportunities

Abstract: Increasing power system stability challenges are being witnessed worldwide, while transitioning toward low-carbon grids with a high-share of power electronic converter (PEC)-interfaced renewable energy sources (RESs) and distributed energy resources (DERs). Concurrently, new technologies and operational strategies are being implemented or proposed to tackle these challenges. Since electricity grids are deregulated in many jurisdictions, such technologies need to be integrated within a market framework, which is often a challenge in itself due to inevitable regulatory delays in updating grid codes and market rules. It is also highly desirable to ensure that an economically feasible optimal technology mix is integrated in the power system, without imposing additional burdens on electricity consumers. This article provides a comprehensive overview of emerging power system stability challenges posed by PEC-interfaced RES and DER, particularly related to low inertia and low system strength conditions, while also introducing new technologies that can help tackle these challenges and discussing the need for suitable techno-economic considerations to integrate them into system and market operation. As a key point, the importance of recognizing the complexity of system services to guarantee stability in low-carbon grids is emphasized, along with the need to carefully integrate new grid codes and market mechanisms in order to exploit the full benefits of emerging technologies in the transition toward ultra-low carbon futures. This article is categorized under: Energy Systems Economics > Economics and Policy Energy Systems Analysis > Systems and Infrastructure Energy and Development > Systems and Infrastructure.

Conception and policy implications of photovoltaic modules end-of-life management in China

Abstract: China has become the world's largest market for photovoltaic (PV). Effective management of end‐of‐life PV components is critical to the sustainable development of renewable energy. However, the scale of PV recycle industry is still small in China, and there is a lack of supporting policies and public attention. Issues and solutions regarding PV end‐of‐life management have not been well covered by the research community, and this article aimed at filling this gap. This article first examined the growing need for PV modules end‐of‐life management in China as a result of rapid PV installation expansion fueled by governments’ policy promotion and fiscal incentives, especially with special programs such as the Photovoltaic Poverty Alleviation Initiative. Then, factors leading to the PV components recycling issues, policies adopted in other countries and regions to promote PV recycle, and various business modes that can be applied to enable PV recycle were reviewed. Finally, a more effective institutional hierarchy was presented for PV modules end‐of‐life management, with a set of specific recommendations on actions that can help strengthen PV end‐of‐life management. This article is categorized under: Photovoltaics > Economics and Policy Photovoltaics > Systems and Infrastructure

Recent progress on carbon and metal based electrocatalysts for vanadium redox flow battery

Abstract: Attractive features of vanadium redox flow battery (VRFB) such as long durability, easy scalability, and low levelized cost of energy have influenced its prominence in the sectors where renewable energy is to be stored at a large scale. However, viability of VRFB to be used for a wide‐range of applications such as household electrification, electric vehicle charging infrastructure, and so on has been limited by its low power density. In principle, the power density of VRFB is dependent upon rate of electrochemical reaction on the electrode. The electrochemical properties of the electrode can be improved either by pretreatment of the electrode or by depositing electrocatalyst on the electrode. The use of electrocatalyst helps to lower overpotential losses and reduces the charge‐transfer resistance, which results the VRFB to operate at higher current densities. This review discusses the development and progress of carbon and metal‐based electrocatalyst that have been used for VRFB applications. This article is categorized under: Fuel Cells and Hydrogen > Science and Materials Energy Efficiency > Science and Materials Energy and Development > Science and Materials

Behind-the-meter energy storage in China: Lessons from California's approach

Abstract: Behind‐the‐meter (BTM) energy storage creates benefits for a large number of stakeholders, enhancing system operation, and mitigating the increase in peak demand, as well as offering potential income from arbitraging peak/off‐peak electricity tariff differentials, mitigating demand charges, and other ancillary service sources. The United States and China are among the leaders in development of energy storage, but these two countries are at different stages in terms of the storage policy landscape. The US system of federalism enables state‐level policy reform, and California has been leading the country for more than a decade with policy instruments addressing BTM storage. These policy instruments include procurement targets, financial incentive plans, as well as regulatory adaptations. Under China's centralized pattern of energy governance, the deployment of new technology largely relies on signals from the national level. The first standalone national‐level policy for energy storage was released in 2017, but major market barriers remain. This review draws insights from the experience of California, whose partially deregulated power market is relevant for China's ongoing market reform. In order to investigate whether the country's current market environment provides adequate opportunities for investors, this review outlines an investment analysis assessing the economics of BTM storage in China with different revenue sources. Results show that traditional revenue sources for BTM storage, namely price arbitrage and demand charge reduction, are inadequate to recover costs for investors in China. The review thus proposes policy recommendations for regulators in China aiming to further promote the deployment of BTM energy storage. This article is categorized under: Energy Infrastructure > Economics and Policy Energy Infrastructure > Systems and Infrastructure Energy Systems Economics > Economics and Policy

Stabilization of non-native polymorphs for electrocatalysis and energy storage systems

Abstract: Evolution in material centric devices like batteries and electrocatalytic reactors have predominantly been made possible via the exploitation of the thermodynamic ground state of pristine or defective bulk crystal, referred to as the “Native polymorph” (NP) here. A significant increase in the material search space is possible by utilizing “Non‐Native polymorphs (NNP),” which are materials that have different translational symmetry with respect to NP. As the NNP have a distinct coordination structure from that of the NP, critical material properties can be anticipated to be different, making NNP a potential substitute material for the aforementioned applications, which are the focus of this review. To obtain a structure–function relationship, systematic approaches to the synthesis of NNP has been demonstrated. Following certain generalities behind NNP, we classify synthesis techniques into few categories with the hope of rationalizing the underlying mechanism of these synthesis and stabilization strategies. We discuss the utility of NNPs in the context of electrochemical water electrocatalytic reactions. Typically, the NNPs have more open volume space enabling lower lithium‐ion diffusion barrier, higher lithium‐ion binding energies, thereby making NNP efficient in the context of energy storage material. However, NNP have lesser stability than the NP and methods to calibrate and improve the stability of NNP are important. Overall, the discussion of polymorphic materials by demarcating them as NP and NNP provides a systematic approach towards modulating material properties as a trade‐off between thermodynamics and kinetics of physicochemical processes. Finally, the challenges and perspectives in this emerging field are discussed. This article is categorized under: Fuel Cells and Hydrogen > Science and Materials Energy Research & Innovation > Science and Materials Energy and Development > Science and Materials

Long-term trends of Nordic power market: A review

Abstract: The Nordic power system will play an important role in a future carbon‐neutral European power market. In this study, 43 scenarios in 15 Nordic power market outlooks published between 2016 and 2019 are reviewed. Most scenarios see high future power prices with substantial correlation with assumed gas and emission quota prices. The underlying uncertainties in gas and emission quota prices are passed on to future power prices. The power prices are well above the cost of wind power, indicating that the wind deployment is either underestimated or might be largely dependent on non‐market factors. The models used for the outlooks have limited sector coverage and trade‐offs are made between computational resources and complexity. A set of recommendations for future outlook publications are proposed based on this review experience. Moving towards a low‐carbon future, more attention should be put to the demand side, especially with increasing importance of sector coupling and electrification. Also, to assess the profound uncertainties in the energy transition period, techniques besides scenario analysis can be applied. Explicit assessments on impacts of emerging topics, such as social oppositions to particular technologies and increased awareness of sustainability indicators besides clean energy, will add values for long‐term decision making in the power markets. Last but not the least, best efforts of clarity and transparency should always be ensured. This article is categorized under: Energy Systems Economics > Economics and Policy Energy Systems Analysis > Economics and Policy Energy Policy and Planning > Economics and Policy

Thermodynamic Cycles for Solar Thermal Power Plants: A Review

Abstract: Solar thermal power plants for electricity production include, at least, two main systems: the solar field and the power block. Regarding this last one, the particular thermodynamic cycle layout and the working fluid employed, have a decisive influence in the plant performance. In turn, this selection depends on the solar technology employed. Currently, the steam Rankine cycle is the most widespread and commercially available power block option, usually coupled to a parabolic trough solar field. However, other configurations have been implemented in solar thermal plants worldwide. Most of them are based on other solar technologies coupled to a steam Rankine cycle, although integrated solar Combined cycles have a significant level of implementation. In the first place, power block configurations based on conventional thermodynamic cycles -Rankine, Brayton and combined Brayton-Rankine- are described. The achievements and challenges of each proposal are highlighted, for example, the benefits involved in hybrid solar source/fossil fuel plants. In the second place, proposals of advanced power block configuration are analyzed, standing out: supercritical CO2 Brayton cycles, advanced organic cycles and innovative integrated solar combined cycles. Each of these proposals show some advantages compared to the conventional layouts in certain power or source temperature ranges and hence they could be considered attractive options in the medium term. At last, a brief review of proposals of solar thermal integration with other renewable heat sources is also included.

Comparative assessment of the challenges faced by the solar energy industry in Ethiopia before and during the COVID-19 pandemic

Abstract: The COVID-19 pandemic is having an unprecedented impact on social, economic, and political situations of all countries around the world with no sight to its end. Business sectors such as solar distributors, which have been instrumental in supporting the governments' ambitious universal electrification programs, have been negatively affected by the pandemic. The main aim of this paper is therefore to explore and conduct a comparative assessment before and during the COVID-19 pandemic of the key challenges of solar-based businesses in Ethiopia focusing on the distributors and installers and to provide policy recommendations. Qualitative and quantitative assessments were employed during this study. The results show that before the pandemic, finding a skilled workforce, gaining a technical knowledge of the technology, competing in the market, and lack of consumer awareness and initial investment were the key challenges. The importation of solar technologies has been halted by the arrival of the COVID-19 exacerbating existing challenges and threatening the very existence of the businesses. The impact of the pandemic on income levels of end-users of solar technologies, together with the lack of sufficient supply of technologies to the businesses, most of the businesses are forced to lay off their employees deepening the unemployment rate and, in some cases, forcing businesses to be closed. These circumstances affect economic development and dents the progress made so far in facilitating energy access to remote communities. To protect these vulnerable but very essential small businesses, necessary interventions are recommended. This article is categorized under:Photovoltaics > Economics and Policy.

Integration schemes for hybrid and polygeneration concentrated solar power plants

Abstract: Concentrated solar power (CSP) technologies have been developed over the past four decades for commercial operation, establishing them as reliable power generation sources in regions with high direct solar irradiance. The sizing of the solar field, thermal energy storage systems, and power block enables CSP plants to operate under various operating conditions, while also exhibiting capabilities to generate multiple products such as electricity, heat, desalination, and cooling. The limitations of CSP systems can be reduced by utilizing the positive traits of other technologies, thus resulting in hybrid plant configurations that can fully exploit different technology strengths while minimizing their individual weaknesses. This review presents the state of the art on CSP stand‐alone plants for both power generation and combined generation of different products. Subsequently, the characteristics of CSP plants hybridized with photovoltaics, wind, fossil fuels, and biomass systems are discussed for both power multiple‐product generation. The review of assessment methodologies provides suggestions for both assessment and performance analysis and comparison with other generation technologies. This review shows that hybrid CSP plants have clear advantages in terms of cost, flexibility of operation, adaptability, and capability for the multigeneration of different products compared with stand‐alone plants used to generate each product individually. Hybrid CSP plants have advantages and can be designed to satisfy multiple demands on a case‐by‐case basis and are valid alternatives to combinations of stand‐alone plants. This article is categorized under: Concentrating Solar Power > Systems and Infrastructure

Hybrid heterojunction solar cells based on single-walled carbon nanotubes and amorphous silicon thin films

Abstract: The doctoral dissertation is conducted under a convention for the joint supervision of thesis at Aalto University (Finland) and Skolkovo Institute of Science and Technology (Russia) for the degree of Doctor of Science (Technology) at Aalto University.