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Building integrated photovoltaic (BIPV) is a promising solution for providing building energy and realizing net-zero energy buildings. Based on the developed mathematical model, this paper assesses the solar irradiation resources and BIPV potential of residential buildings in different climate zones of China. It is found that roofs are the first choice for BIPV installation, followed by south façades, especially in high-latitude cities, and then east and west facades. North façades could be recommended in some cities with frequent clouds. The photovoltaic (PV) contribution of a combined rooftop and south façade BIPV system to building energy is highlighted, where the PV covers 50 % of the roof and 40 % of the south façade area. The system can meet the net load of a 4, 8, 7, 6, 4, and 4-storey building in Harbin, Urumqi, Beijing, Shanghai, Chengdu, and Guangzhou, respectively. In areas with sufficient irradiation and low demand, such as Lhasa and Kunming, the proposed system is most likely to achieve net-zero energy consumption in high-rise residential buildings. Different from previous study, this study proposes a comprehensive research framework for assessing the potential of residential BIPV system in various regions of China, considering partial shading effects. Since many provinces have issued relevant policies to promote distributed PVs, the findings can provide guidance for BIPV deployment in China. [Display omitted] • The solar irradiation resources of building façades including the north façade are examined. • The photovoltaic contributions to net zero energy residential buildings are assessed in China. • Partial shading is considered for modeling the building integrated photovoltaic (BIPV) system. • A research framework for assessing the potential of residential BIPV system is proposed. [ABSTRACT FROM AUTHOR]

Highlights • The energy and economic impacts of solar photovoltaic soiling were modelled. • Relative net-present value change was defined to assess optimal cleaning intervals. • We compared the soiling-induced efficiency and economic losses in seven cities. • The efficiency loss is the lowest (<0.04) for Tokyo and highest (>0.8) for Doha. • The optimal intervals are 23–70 days (manual) and 17–49 days (machine). Abstract This work developed a framework to predict the energy and economic impacts of solar photovoltaic soiling. This framework includes the effects of relative humidity, precipitation and tilt angle on solar photovoltaic soiling. A concept of relative net-present value change was introduced to determine the optimal cleaning interval. The uncertainties in the economic analysis were accounted for using a Monte Carlo simulation method. The framework was used to study the soiling-induced efficiency and economic losses of solar photovoltaic modules in seven cities (i.e. Taichung, Tokyo, Hami, Malibu, Sanlucar la Mayor, Doha, and Walkaway). Overall, the efficiency loss (in ascending order) for Tokyo/Walkaway < Taichung < Sanlucar la Mayor < Malibu/Hami < Doha for a one-year study period. Doha experiences an efficiency loss over 80% for a 140-day exposure, while Tokyo has an efficiency loss less than 4% for a one-year exposure. Malibu has longest optimal cleaning intervals (70 days for manual cleaning and 49 days for machine-assisted cleaning) that leads to the relative net-present value changes of 1.7% and 1.1%. Doha has the shortest optimal cleaning intervals (23 days for manual cleaning and 17 days for machine-assisted cleaning) that leads to the relative net-present value changes of 21% and 19%. The work serves as an effective tool for designing optimal cleaning protocols for solar photovoltaic systems. [ABSTRACT FROM AUTHOR]

• Quantifies hourly generation potential of building-integrated PV (BIPV) for Tokyo. • Shading effects and morphological characteristics of building stock are considered. • PV potential equivalent to 15%–48% of the annual energy demand in the year 2050. • Changes in hourly net electricity load and potential impacts are evaluated. The installation of photovoltaic (PV) modules is one of the most effective measures for decarbonizing urban building stock. The considerable potential of the process has been demonstrated using building-integrated PV (BIPV) modules. Earlier studies have provided significant knowledge about the PV potential of buildings, but a detailed investigation of the large-scale installation of BIPV modules on building façades has not been undertaken. In the present study, a model for estimating the hourly PV potential of building surfaces on a regional scale was developed and applied to commercial building stock in Tokyo, Japan. Analytical results showed that the generated PV power would be capable of satisfying 15%–48% of the annual electricity demand of the building stock in 2050, based on the extent to which the PV potential of building surfaces, especially façades, was exploited. This demonstrates the usefulness of BIPV for achieving a decarbonized society. Additionally, hourly estimation results showed that, if a higher economic efficiency is pursued, the use of large-scale installation of BIPV together with rooftop-mounted PV could increase the PV power generation without altering the hourly PV power fluctuation. However, electricity demand and generation analyses revealed the negative impacts of the larger-scale BIPV installation on the power system: The reduction in asset utilization and the increase in the need for flexibility. The findings of this study promise to be useful to policymakers in formulating guidelines for the use of BIPV modules. [ABSTRACT FROM AUTHOR]

• Solar photovoltaic-assisted ground-source heat pumps are studied in Nordic climate. • Ground regeneration with solar thermal energy improves long-term performance. • Designs are compared in terms of energy efficiency, cost, and ground heat transfer. • Photovoltaic-thermal leads to lower investment costs by reducing the borehole size. Ground source heat pumps (GSHP), as a renewable energy technology, are highly efficient systems suitable for meeting the heating needs of buildings, particularly in heating-dominated regions like Scandinavia. This study aims to better define the scope of application and sizing of GSHP combined with photovoltaic-thermal (PVT) collectors in Nordic conditions. The study compares seasonal performance factors (SPF), average ground temperatures, and investment costs for heating different numbers of apartment blocks in two distinct Nordic climates: Baltic climate and cold continental climate. To assess the long-term effects on the energy performance of GSHP + PVT systems, dynamic simulations using the TRNSYS software are conducted over a period of 50 years. The results demonstrate that PVT improves the long-term system performance, particularly in large and compact borehole (BH) fields, while in smaller BH fields, natural regeneration keeps playing a substantial role. For instance, PVT added to a GSHP system with large BH field can limit the ground temperature reduction after 50 years by 33 % compared to the configurations without PVT. In contrast, this reduction is only 13 % for systems with small BH fields. Moreover, the results show that GSHP + PVT can lead to a reduction of up to 95 % in the required area for installing the BH field while maintaining (almost) the same energy performance compared to a conventional GSHP. Notably, this study shows that the utilization of GSHP + PVT leads to a substantial reduction in BH length (up to 50 %) while maintaining a similar system SPF. It leads to a decrease in investment costs of up to 9.32 % and 22.92 % for the scenarios located in Norway and Sweden, respectively, compared to the case with PV instead of PVT. These findings suggest that PVT integration holds promise for advancing the GSHP adoption in high-latitude regions, especially in larger installations and colder climates, by mitigating investment costs while preserving the system SPF and ground temperature stability. [ABSTRACT FROM AUTHOR]

In the past decades, solar heat for industrial processes (SHIP) have been rapidly developed and applied, and also getting more and more attention all over the world. China is the largest energy consumer with industry accounting for almost 70% of its total energy consumption. Low- and medium-temperature heat takes up 45% of process heat, covering 50–70% of industrial energy consumption, which provides a favorable condition for solar application in industrial processes. China has built developed some demonstration projects to make industrial processes well integrated with solar heating systems. This paper briefly summarizes the status of China's energy consumption, integration of SHIP, as well as available matching solar technologies. Ten typical industrial sectors are selected to specifically describe their potential of SHIP. Moreover, 26 SHIP cases covering the selected 10 sectors are presented by field researches, with capacity of energy saving and emission reduction previously investigated according to their own proportion of SHIP. The potential of SHIP in the 10 sectors are further predicted by optimistically and conservatively making their proportion in SHIP 5.5% and 2% respectively during the period of 2016–2020. The results show that at least 39.40 million tons of coal equivalent and 98.22 million tons of CO 2 emission is expected to be reduced in 2020 in China's all industrial sectors although solar can meet different proportions of heat demand in different industrial sectors. [ABSTRACT FROM AUTHOR]

In this work, the small-scale downdraft gasification system was integrated with a set of internal combustion engine power generation and successfully used for converting biomass waste into energy in the forms of electricity and heat. The performance of integrated system was investigated by using redwood pellets with a lower heating value of 17 MJ/kg as a feedstock. Experimental results show that the maximum syngas yield of 33.6 Nm 3 /h can be achieved from the gasifier. From thermodynamics analysis, the maximum energy and exergy efficiencies of the whole integrated system were found to be 31.9% and 15.6%, respectively, considering both electricity and heat generated. Apart from syngas, gasification system also generates significant amount of bottom ash that can be harmful to the environment and public health if it is not treated properly. Therefore, this work also focused on the reutilization of bottom ash in order to reduce the environment and health concerns associated with its disposal, making the overall process more environmentally friendly. From elemental analysis, bottom ash produced from redwood pellets gasification contains significant amount of silica, making it become a highly potential source for synthesizing silica-containing compounds. In this work, alkali hydrothermal reaction has been successfully used to convert this bottom ash into zeolite (or aluminosilicate compound) which can be potentially used as an adsorbent material. [ABSTRACT FROM AUTHOR]

A novel epitrochoidal rotary reactor was proposed to perform efficient solar-driven water-splitting based on thermochemical redox cycling of ceria. This study is focused on the geometry optimization of the epitrochoidal rotary reactor to achieve the optimal thermodynamic solar-to-fuel energy conversion efficiency. The mathematical descriptions of kinematic synthesis of the conjugate rotor and stator profiles are derived in detail. The geometric compression ratio is statistically estimated using a hit-or-miss Monte Carlo method. A thermodynamic model considering the solid and gas phase heat recovery is developed to evaluate the performance of the epitrochoidal rotary reactors in various geometries. Among all geometrical parameters instigated, the cam-to-rotor size ratio and the number of rotor sides are found to have the most significant impact on the solar-to-fuel energy conversion efficiency. The optimal design of the epitrochoidal rotary reactor with a curved triangle rotor offers a geometrical compression ratio of 13 and a solar-to-fuel efficiency of 17% under a concentrated solar radiative flux of 3000 suns. [Display omitted] • A conceptual epitrochoidal rotary reactor is proposed for solar hydrogen production. • The geometry of the epitrochoidal rotary reactor is mathematically formulated. • A hit-or-miss Monte Carlo method is used to predict the geometric compression ratio. • The reactor with a triangle rotor outperforms the alternative designs. • The energy efficiency is improved to 17% from the previously reported 13%. [ABSTRACT FROM AUTHOR]

The auto-regressive distributed lag (ARDL) bound testing approach was used to study the relationships between the monthly household electricity consumption and outdoor PM 2.5 concentration with the consideration of ambient temperature and the number of rainy days for Singapore and Shanghai. It is shown that there are significant long-run relationships between the household electricity consumption and the regressors for both Singapore and Shanghai. For Singapore, a 20% increase in the PM 2.5 concentration of a single month is in the long-run significantly related to a 0.8% increase in the household electricity consumption. This corresponds to an electricity overconsumption of 5.0 GWh, a total of 0.7–1.0 million USD in electricity cost, and 2.1 kilotons of CO 2 emission associated with electricity generation. For Shanghai, a 20% decrease in the PM 2.5 concentration of a single month is in the long-run significantly related to a 2.2% decrease in the household electricity consumption. This corresponds to a 35.0 GWh decrease in the overall household electricity consumption, 1.6–5.1 million USD decrease in electricity cost, and 17.5 kilotons of CO 2 emission. The results suggest that the cost of electricity consumption should be included in the economic cost analysis of PM 2.5 pollution in the future. A 1 °C increase in the monthly temperature is in the long-run significantly related to a 13.6% increase in the monthly electricity consumption for Singapore, while a 30 degree days increase in heating & cooling days ( HCDD ) is in the long-run significantly related to a 24.9% increase in the monthly electricity consumption for Shanghai. A 5-day increase in the number of rainy days per month is in the long-run significantly related to a 3.0% and 5.8% increase in the monthly electricity consumption for Singapore and Shanghai, respectively. [ABSTRACT FROM AUTHOR]

Due to the high dehumidification performance realized by removing adsorption heat by inner cooing, desiccant coated heat exchanger (DCHE) has been proposed and widely studied. The heat pump is usually used as the cooling and heat sources of the dehumidification system composed of DCHE because the cooling and heat capacity could be provided by the heat pump at the same time. Moreover, considering the advantage of low-grade thermal energy utilization, solar thermal energy can be used to further enhance the regeneration of DCHE to improve dehumidification performance and energy efficiency. In this paper, the solar-enhanced fresh air dehumidification system using DCHE driven by heat pump was proposed and a series of experiments were conducted under typical Shanghai summer high humidity conditions. The typical moisture removal of the system can be increased by about 15% to 10.14 g/kgDA and the COP could be further increased by over 25% to 5.39. In addition, the influence of different regeneration temperatures enhanced by solar thermal energy on the system has also been studied. Considering the dehumidification performance improvement and energy utilization efficiency, the optimal regeneration temperature is between 60 °C and 65 °C for the system proposed in this paper. • Moisture removal and COP can be increased by 6%–28% by solar enhanced. • Performance enhanced is more obvious when regeneration temperature is below 65 °C. • Solar enhanced dehumidification 1.43 (g·kgDA−1)/kW and 1.12 kg/kWh can be achieved. • Higher efficiency solar collectors will achieve higher solar enhanced performance. [ABSTRACT FROM AUTHOR]

• Hybrid bottom-up model to integrate geo-referenced and synthetic stock models. • Demonstrate multi-scale and long-term transitional workflow for commercial building stock. • Identify drivers and determinants of energy usage in the commercial building stock. • 32% cumulative performance gap if concurrent consideration of physical and technical factors is disregarded. • Introducing the unit block concept to determine minimum viable requirements. For energy modelling of commercial building stock (CBS), several methodologies were developed focusing on technology alternatives and retrofits for climate change mitigation, but they often have limitations to involve a differentiated description of practices and policies across a range of scales and sectors. This paper presents a novel hybrid model by integrating spatial and synthetic modelling approaches to facilitate the concurrent consideration of multiple building-oriented elements. The model is further implemented on Japanese building stock to demonstrate multi-scale and long-term framework for energy modelling of CBS. The results indicate the following findings: the scale choice introduces significant variability in energy consumption estimation with a relative error of 10–17% mainly depending on building geometry and plug loads; the long-term model exhibits a higher scale-bounded uncertainty in terms of energy saving potential that varies by 2–3 times when a non-representative scale is applied; disregarding physical and technical factors results in a cumulative performance gap of up to 32%; and the accuracy and extent of the model across the stock are more sensitive to technical factors, such as building system stock dynamics and the heterogeneity of HVAC systems, than physical factors. The model provides a multi-tier framework using spatial intelligence building stock approach to develop long-term energy efficiency monitoring strategies for CBS. [ABSTRACT FROM AUTHOR]

Abstract: Component performance and seasonal operational experiences have been analysed for desiccant cooling systems powered by solar air collectors. Measurements during the commissioning phase in Spain (public library) and in Germany (production hall) showed that the dehumidification efficiency of the sorption rotors was 80% and the humidification efficiency of the contact evaporators was 85–86%. Only in a two-stage desiccant system monitored in China (laboratory building), a dehumidification efficiency of 88% was reached. The rotary heat exchangers only had 62–68% measured heat recovery efficiency, which is lower than specified. Seasonal performance monitoring carried out in the German installation showed that average seasonal COP’s were close to 1.0, when related to all operation hours. COP’s increase if low regeneration temperatures are used with low dehumidification rates, which is often sufficient for moderate German climatic conditions, but much less so in the humid Chinese climate. Electrical COP’s for the German system including air distribution were between 1.7 and 4.6 and reach values of 7.4, when only additional pressure drops of the desiccant unit are considered. It could be shown that conventional control strategies lead to high auxiliary energy consumption, for example if fixed heating setpoint temperatures are used. Furthermore the solar air collector energy yield was very low in the German system, as regeneration was only used when all other options such as humidification at high air volume flows did not reduce the room air temperature enough. The studies showed that the measured auxiliary energy consumption could be reduced to near zero, if regeneration temperature setpoints were not fixed to constant values. The solar air collector efficiency was good at about 50% both for the flat plate collectors used in Spain and Germany and the Chinese vacuum tube solution. A cost analysis demonstrated the viability of the concept, if some funding of the high investment costs is provided. [Copyright &y& Elsevier]

[Display omitted] • Biochar-assisted HSAD and steam gasification were coupled to treat food waste. • Over-acidification in HSAD was boosted with biochar assistance. • Steam gasification is a feasible and efficient technology to treat the digestates. • The final biochar product with a comparable amount of nutrients can be fertilizer. • Energy recovery efficiency was improved by the HSAD-steam gasification system. A food waste treating system was proposed in this study by combining biochar-assisted high-solid anaerobic digestion and subsequent steam gasification of the digestate. The effect of solid level, biochar dosage in anaerobic digestion on the properties of biogas, syngas, and final biochar products were investigated. Results showed that at a high total solid level and biochar dosage of 25 g/L and 50 g/L, the accumulative methane yield reached 110.3 mL CH 4 /g VS and 126.7 mL CH 4 /g VS, respectively. From steam gasification of different digestates under 850 °C for 15 min, a maximum of 34.92 mmol/g for the hydrogen yield and 11.44 MJ/m3 for the higher heating value could be obtained for the syngas. Furthermore, the by-product produced from steam gasification was a nutrient-enriched porous biochar, which was suitable to be used as compost. This study demonstrated a pathway for food waste treating to produce methane-enriched biogas, hydrogen-enriched syngas, and nutrient-enriched biochar. [ABSTRACT FROM AUTHOR]

• A decentralized system was set up to transfer food waste to electricity and heat. • 30 kg food waste produced a methane yield of 0.55 L CH 4 /g VS in a current system. • A scale-up system was simulated to output 74.80kWh electricity at 500 kg feed per day. • Electrical and thermal energy outputs of optimized system increased by 135% and 87%. Biogas derived from the decentralized anaerobic digestion (AD) of food waste may be used to generate electrical and thermal energy for nearby residents through combined heat and power generation technology. A mobile food-waste-to-energy system in conjunction with an anaerobic digester and biogas engine was developed for food waste (FW) treatment and energy output. The scale-up was simulated to explore the methane yield and energy flow at different ambient temperatures of 0 °C, 10 °C, 20 °C, 30 °C and different feedstock of 200 kg, 500 kg FW. Accordingly, the results demonstrated that the installed system with a 1 m3 digester had a methane yield of 0.55L CH 4 /g VS when the feedstock load was 30 kg FW/d and the Organic Load Rate (OLR) was 5.4 g VS /L, while the thermal and electrical efficiencies of this system were 31% and 16%, respectively. The corresponding exhaust gas of the thermal energy from the biogas combustion was recovered by a heat exchanger in order to keep the digester at mesophilic conditions. The simulations carried out on the scale-up systems under loads of 200 kg FW/d and 500 kg FW/d achieved a thermal energy balance at different ambient temperatures of 0 °C, 10 °C, 20 °C and 30 °C. Improvements were proposed in the optimized system by optimizing pre-treatment facilities as well as the AD reactor, biogas engine and heat exchanger. The net thermal and electrical energy output of the optimized system at 500 kg FW/d were 175.93kWh and 163.90kWh, respectively. The energy generated by the FW-to-energy system illustrated by the Sankey diagrams depicts that was enough for operation without the need of extra heat and a power supply, moreover, the surplus energy may be utilized for its neighboring communities. In addition, the optimized system under the same OLR were increased by 87% and 135%, regards the thermal and electrical energy outputs, respectively in comparison with the current system. [ABSTRACT FROM AUTHOR]