| 1. |
- Ramírez Villegas, Ricardo, 1981-, et al.
(författare)
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Combined environmental and economic assessment of energy efficiency measures in a multi-dwelling building
- 2019
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 12:13
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study is to assess how different renovation scenarios affect the environmental and economic impacts of a multi-dwelling building in a Nordic climate, how these aspects are correlated and how different energy carriers affect different environmental impact categories. In order to reduce greenhouse gas emissions, the European Union has set an agenda in order to reduce energy use in buildings. New buildings on the European market have a low replacement rate, which makes building renovation an important factor for achieving the European Union goals. In this study, eight renovation strategies were analyzed following the European Committee for Standardization standards for life cycle assessment and life cycle costs of buildings. This study covers all life cycle steps from cradle to grave. The renovation scenarios include combinations of photovoltaics, geothermal heat pumps, heat recovery ventilation and improved building envelopes. Results show that, depending on the energy carrier, reductions in global warming potential can be achieved at the expense of an increased nuclear waste disposal. It also shows that for the investigated renovation strategies in Sweden there is no correlation between the economic and the environmental performance of the building. Changing energy carriers in Sweden in order to reduce greenhouse gas emissions can be a good alternative, but it makes the system more dependent on nuclear power.
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| 2. |
- Azizi, Shoaib, 1989-, et al.
(författare)
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Adoption of Energy Efficiency Measures in Renovation of Single-Family Houses : A Comparative Approach
- 2020
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 13:22
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Tidskriftsartikel (refereegranskat)abstract
- Inclusion of energy efficiency measures (EEMs) in the renovation of the single-family housing stock can unlock the potential for much-needed energy efficiency to tackle climate change. Energy renovation (ER) in single-family houses is often promoted as an aggregate process, and EEMs are treated homogenously without sufficient attention to their differences. This study applies a comparative analysis on common EEMs using chi-square test to investigate the influence of factors already found affecting the implementation of ER. This paper addresses the “personal” and “house-related” factors influencing the adoption of EEMs regardless of motives or barriers leading the adopters’ decisions. This strategy is useful to highlight the contexts leading to an increase in the adoption rate of different EEMs. The analysis is based on a questionnaire survey mailed in spring 2017 to 1550 single-family homeowners in the northern region of Sweden. Approximately 60% of respondents showed interest in adopting at least one EEM if they implement a major renovation. About 46% of respondents stated to have at least one indoor environmental problem (IEP) in their houses, and IEPs are found to have significant relations with homeowners’ interest to adopt several different EEMs. The policy implications related to different EEMs are discussed.
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| 3. |
- Azizi, Shoaib, et al.
(författare)
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Effects of Positioning of Multi-Sensor Devices on Occupancy and Indoor Environmental Monitoring in Single-Occupant Offices
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:19
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Tidskriftsartikel (refereegranskat)abstract
- The advancements in sensor and communication technologies drive the rapid developments in the applications of occupancy and indoor environmental monitoring in buildings. Currently, the installation standards for sensors are scarce and the recommendations for sensor positionings are very general. However, inadequate sensor positioning might diminish the reliability of sensor data, which could have serious impacts on the intended applications such as the performance of demand-controlled HVAC systems and their energy use. Thus, there is a need to understand how sensor positioning may affect the sensor data, specifically when using multi-sensor devices in which several sensors are being bundled together. This study is based on the data collected from 18 multi-sensor devices installed in three single-occupant offices (six sensors in each office). Each multi-sensor device included sensors to measure passive infrared (PIR) radiation, temperature, CO2, humidity, and illuminance. The results show that the positions of PIR and CO2 sensors significantly affect the reliability of occupancy detection. The typical approach of positioning the sensors on the ceiling, in the middle of offices, may lead to relatively unreliable data. In this case, the PIR sensor in that position has only 60% accuracy of presence detection. Installing the sensors under office desks could increase the accuracy of presence detection to 84%. These two sensor positions are highlighted in sensor fusion analysis as they could reach the highest accuracy compared to other pairs of PIR sensors. Moreover, sensor positioning can affect various indoor environmental parameters, especially temperature and illuminance measurements.
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| 4. |
- Carrasco, Cristhian, et al.
(författare)
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Hydrothermal pretreatment of water-extracted and aqueous ethanol-extracted quinoa stalks for enzymatic saccharification of cellulose
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:14
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Tidskriftsartikel (refereegranskat)abstract
- Auto-catalyzed hydrothermal pretreatment (A-HTP) and sulfuric-acid-catalyzed hydrothermal pretreatment (SA-HTP) were applied to quinoa stalks in order to reduce their recalcitrance towards enzymatic saccharification. Prior to pretreatment, quinoa stalks were extracted with either water or a 50:50 (v/v) ethanol–water mixture for removing saponins. Extraction with water or aqueous ethanol, respectively, led to removal of 52 and 75% (w/w) of the saponins contained in the raw material. Preliminary extraction of quinoa stalks allowed for a lower overall severity during pretreatment, and it led to an increase of glucan recovery in the pretreated solids (above 90%) compared with that of non-extracted quinoa stalks (73–74%). Furthermore, preliminary extraction resulted in enhanced hydrolysis of hemicelluloses and lower by-product formation during pretreatment. The enhancement of hemicelluloses hydrolysis by pre-extraction was more noticeable for SA-HTP than for A-HTP. As a result of the pretreatment, glucan susceptibility towards enzymatic hydrolysis was remarkably improved, and the overall conversion values were higher for the pre-extracted materials (up to 83%) than for the non-extracted ones (64–69%). Higher overall conversion was achieved for the aqueous ethanol-extracted quinoa stalks (72–83%) than for the water-extracted material (65–74%).
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| 5. |
- Gandla, Madhavi Latha, et al.
(författare)
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Analytical Enzymatic Saccharification of Lignocellulosic Biomass for Conversion to Biofuels and Bio-Based Chemicals
- 2018
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 11:11
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Forskningsöversikt (refereegranskat)abstract
- Lignocellulosic feedstocks are an important resource for biorefining of renewables to bio-based fuels, chemicals, and materials. Relevant feedstocks include energy crops, residues from agriculture and forestry, and agro-industrial and forest-industrial residues. The feedstocks differ with respect to their recalcitrance to bioconversion through pretreatment and enzymatic saccharification, which will produce sugars that can be further converted to advanced biofuels and other products through microbial fermentation processes. In analytical enzymatic saccharification, the susceptibility of lignocellulosic samples to pretreatment and enzymatic saccharification is assessed in analytical scale using high-throughput or semi-automated techniques. This type of analysis is particularly relevant for screening of large collections of natural or transgenic varieties of plants that are dedicated to production of biofuels or other bio-based chemicals. In combination with studies of plant physiology and cell wall chemistry, analytical enzymatic saccharification can provide information about the fundamental reasons behind lignocellulose recalcitrance as well as about the potential of collections of plants or different fractions of plants for industrial biorefining. This review is focused on techniques used by researchers for screening the susceptibility of plants to pretreatment and enzymatic saccharification, and advantages and disadvantages that are associated with different approaches.
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| 6. |
- Lage, Sandra, et al.
(författare)
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Algal Biomass from Wastewater and Flue Gases as a Source of Bioenergy
- 2018
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 11:3
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Forskningsöversikt (refereegranskat)abstract
- Algae are without doubt the most productive photosynthetic organisms on Earth; they are highly efficient in converting CO2 and nutrients into biomass. These abilities can be exploited by culturing microalgae from wastewater and flue gases for effective wastewater reclamation. Algae are known to remove nitrogen and phosphorus as well as several organic contaminants including pharmaceuticals from wastewater. Biomass production can even be enhanced by the addition of CO2 originating from flue gases. The algal biomass can then be used as a raw material to produce bioenergy; depending on its composition, various types of biofuels such as biodiesel, biogas, bioethanol, biobutanol or biohydrogen can be obtained. However, algal biomass generated in wastewater and flue gases also contains contaminants which, if not degraded, will end up in the ashes. In this review, the current knowledge on algal biomass production in wastewater and flue gases is summarized; special focus is given to the algal capacity to remove contaminants from wastewater and flue gases, and the consequences when converting this biomass into different types of biofuels.
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| 7. |
- Lidberg, Tina, 1982-, et al.
(författare)
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Impact of Domestic Hot Water Systems on District Heating Temperatures
- 2019
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Ingår i: Energies. - Basel, Schweiz : MDPI AG. - 1996-1073. ; 12:24
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Tidskriftsartikel (refereegranskat)abstract
- When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system.
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| 8. |
- Mehariya, Sanjeet, et al.
(författare)
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Integrated approach for wastewater treatment and biofuel production in microalgae biorefineries
- 2021
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 14:8
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Forskningsöversikt (refereegranskat)abstract
- The increasing world population generates huge amounts of wastewater as well as large energy demand. Additionally, fossil fuel’s combustion for energy production causes the emission of greenhouse gases (GHG) and other pollutants. Therefore, there is a strong need to find alternative green approaches for wastewater treatment and energy production. Microalgae biorefineries could represent an effective strategy to mitigate the above problems. Microalgae biorefineries are a sustainable alternative to conventional wastewater treatment processes, as they potentially allow wastewater to be treated at lower costs and with lower energy consumption. Furthermore, they provide an effective means to recover valuable compounds for biofuel production or other applications. This review focuses on the current scenario and future prospects of microalgae biorefineries aimed at combining wastewater treatment with biofuel production. First, the different microalgal cultivation systems are examined, and their main characteristics and limitations are discussed. Then, the technologies available for converting the biomass produced during wastewater treatment into biofuel are critically analyzed. Finally, current challenges and research directions for biofuel production and wastewater treatment through this approach are outlined.
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| 9. |
- Nordin, Andreas, et al.
(författare)
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Co-Combustion of Municipal Sewage Sludge and Biomass in a Grate Fired Boiler for Phosphorus Recovery in Bottom Ash
- 2020
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 13:7
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Tidskriftsartikel (refereegranskat)abstract
- Phosphorus has been identified as a critical element by the European Union and recycling efforts are increasingly common. An important phosphorus-containing waste stream for recycling is municipal sewage sludge (MSS), which is used directly as fertilizer to farmland. However, it contains pollutants such as heavy metals, pharmaceutical residues, polychlorinated bi-phenyls (PCBs) and nano-plastics. The interest in combustion of MSS is continuously growing, as it both reduces the volume as well as destroys the organic materials and could separate certain heavy metals from the produced ashes. This results in ashes with a potential for either direct use as fertilizer or as a suitable feedstock for upgrading processes. The aim of this study was to investigate co-combustion of MSS and biomass to create a phosphorus-rich bottom ash with a low heavy metal content. A laboratory-scale fixed-bed reactor in addition to an 8 MWth grate-boiler was used for the experimental work. The concentration of phosphorus and selected heavy metals in the bottom ashes were compared to European Union regulation on fertilizers, ash application to Swedish forests and Swedish regulations on sewage sludge application to farmland. Element concentrations were determined by ICP-AES complemented by analysis of spatial distribution with SEM-EDS and XRD analysis to determine crystalline compounds. The results show that most of the phosphorus was retained in the bottom ash, corresponding to 9-16 wt.% P2O5, while the concentration of cadmium, mercury, lead and zinc was below the limits of the regulations. However, copper, chromium and nickel concentrations exceeded these standards.
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| 10. |
- Nydahl, Helena, 1990-, et al.
(författare)
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Environmental Performance Measures to Assess Building Refurbishment from a Life Cycle Perspective
- 2019
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Ingår i: Energies. - : MDPI. - 1996-1073. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Energy efficiency investments in existing buildings are an effective way of reducing the environmental impact of the building stock. Even though policies in the European Union and elsewhere promote a unilateral focus on operational energy reduction, scientific studies highlight the importance of applying a life cycle perspective to energy refurbishment. However, life cycle assessment is often perceived as being complicated and the results difficult to interpret by the construction sector. There is also a lack of guidelines regarding the sustainable ratio between the embodied and accumulated operational impact. The scope of this study is to introduce a life cycle assessment method for building refurbishment that utilizes familiar economic performance tools, namely return on investment and annual yield. The aim is to use the introduced method to analyze a case building with a sustainability profile. The building was refurbished in order to reduce its operational energy use. The introduced method is compatible with a theory of minimum sustainable environmental performance that may be developed through backcasting from defined energy and GHG emissions objectives. The proposed approach will hopefully allow development of sustainable refurbishment objectives that can support the choice of refurbishment investments.
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