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Faculty
- Fakultät 12 / Institut für Technologie und Ressourcenmanagement in den Tropen und Subtropen (28) (remove)
Water security is a major concern for water-scarce cities that face dynamic water challenges due to limited water supply, climate change and increasing water demand. Framing urban water security is challenging due to the complexity and uncertainties of the definitions and assessment frameworks concerning urban water security. Several studies have assessed water security by granting priority indicators equal weight without considering or adapting to the local conditions. This study develops a new urban water security assessment framework with application to the water-scarce city
of Madaba, Jordan. The study applies the new assessment framework on the study area and measures urban water security using the integrated urban water security index (IUWSI) and the analytic hierarchy process (AHP) as a decision management tool to prioritise and distinguish indicators that affect the four dimensions of urban water security: drinking water, ecosystems, climate change and water-related hazards, and socioeconomic aspects (DECS). The integrated urban water security index (IUWSI) highlights the state of water security and intervention strategies in Madaba. The study reveals that urban water security in Madaba is satisfactory to meet basic needs, with shortcomings in some aspects of the DECS. However, Madaba faces poor security in terms of managing climate- and water-related risks. The IUWSI framework assists with a rational and evidence-based decision-making process, which is important for enhancing water resources management in water-scarce cities.
Achieving urban water security is a major challenge for many countries. While several studies have assessed water security at a regional level, many studies have also emphasized the lack of assessment of water security and application of measures to achieve it at the urban level.
Recent studies that have focused on measuring urban water security are not holistic, and there is still no agreed-upon understanding of how to operationalize and identify an assessment framework to measure the current state and dynamics of water security. At present, there is also no clearly defined and widely endorsed definition of urban water security. To address this challenge, this study provides a systematic approach to better understand urban water security, with a working definition and an assessment framework to be applied in peri-urban and urban areas. The proposed working definition of urban water security is based on the United Nations (UN) sustainable development goal on water and sanitation and the human rights on water and sanitation. It captures issues of urban-level technical, environmental, and socio-economic indicators that emphasize credibility, legitimacy, and salience.
The assessment framework depends on four main dimensions to achieve urban water security: Drinking water and human beings, ecosystem, climate change and water-related hazards, and socio-economic factors (DECS). The framework further enables the analysis of relationships and trade-off between urbanization and water security, as well as between DECS indicators. Applying this framework will help governments, policy-makers, and water stakeholders to target scant resources more eff ectively and sustainably. The study reveals that achieving urban water security requires a holistic and integrated approach with collaborative stakeholders to provide a meaningful way to improve understanding and managing urban water security.
Life cycle assessment is a crucial tool in evaluating systems performances for sustainability and decision-making. This paper provided environmental impact of integrating renewable energy systems to the utility-grid based on a baseline optimized energy production data from “HOMER” for renewable systems modelling of a site in northern Nigeria. The ultimate goal was to ascertain the best hybrid option(s) in sustaining the environment. Different assumptions and scenarios were modelled and simulated using Ganzleitlichen Bilanz (GaBi). Uncertainty analysis was ensured to the impact data based on pedigree-matrix and Excel-program, as well as overall policy relevance. The results of the impact categories revealed first scenario (i.e., conventional path-based) with the highest impacts on global warming potential (GWP), acidification potential (AP), human toxicity potential (HTP), and abiotic depletion potential (ADP fossils). The lowest impacts arise in
the renewable-based scenarios for all the considered categories except the Ozone-layer depletion potential Category where the highest contribution falls in the third scenario (i.e., photovoltaic (PV)/biomass-biogas system) although all values being infinitesimal. In quantitative terms, the reduction in the GWP from the highest being the first scenario to the lowest being the fourth scenario (i.e., wind/biomass-biogas system) was 96.5%. Hence, with the outstanding contributions of the hybrid renewable systems, adopting them especially the lowest impact scenarios with expansions is relevant for environmental sustainability.
Changing our unsustainable linear water management pattern is necessary to face growing global water challenges. This article proposes an integrated framework to analyse and understand the role of different contextual conditions in the possible transition towards water circularity. Our framework combines a systematic multi-level perspective to explore the water system and the institutional work theory for technology legitimation. The framework consists of the following stages: (1) describing and understanding the water context, (2) assessment of the selected technologies’ circularity level, (3) assessment of the alternative circular technologies’ legitimacy, and (4) identification of the legitimation actions to support the upscale of alternative circular technologies. The practical applicability of the integrated assessment framework and its four assessment stages was demonstrated in the exploration of circular water technologies for the horticulture sector in Westland, the Netherlands. The results revealed the conditions that hinder or enable the legitimation of the circular water technologies, such as political environmentalism, trust in water governing authorities, and technical, financial, and knowledge capabilities.
Decisions on irrigation water management are usually made at different levels, including farms, water user associations (WUAs), and regional water planning agencies. The latter generally have good access to information and decision tools regarding water resources management. However, these remain out of reach to the final water users, namely the farmers. The study, conducted in the irrigated district of Cherfech, north Tunisia, had the main objective of investigating farmer’s perceptions of, and acceptance for, the use of an irrigation advisory service (IAS) to be implemented by their WUA. The suggested IAS provides the following information: (1) reference evapotranspiration (ETo) and rainfall; (2) crop water requirement (CWR) of the most cultivated crops; (3) irrigation water requirement (IWR) of the farmer’s crop; and (4) crop monitoring and real-time estimation of IWR of crops settled, using soil moisture sensors. Such services and information would be available at the WUA level and provided in a timely manner to farmers for more effective decision making at the plot level. Prior to the acceptance study, we launched a technical study to determine the required tools and equipment required for the implementation of the IAS, followed by a farmer survey to assess their respective perceptions and acceptance towards this IAS. Results showed that only 54% of the farmers are satisfied by WUAs work, but that 77% of them accepted using the suggested IAS. Farmers are also willing to pay for most of the IAS packages suggested. The financial profitability of investing in the IAS at the WUA level shows the venture is financially viable, with a benefit cost ratio (BCR) of 1.018. The project will be even more profitable if we add the social benefits, which may result in water savings at the WUA level.
Water scarcity drives governments in arid and semi-arid regions to promote strategies for improving water use efficiency. Water-related research generally also plays an important role in the same countries and for the same reason. However, it remains unclear how to link the implementation of new government strategies and water-related research. This article’s principal objective is to present a novel approach that defines water-related research gaps from the point of view of a government strategy. The proposed methodology is based on an extensive literature review, followed by a systematic evaluation of the topics covered both in grey and peer-reviewed literature. Finally, we assess if and how the different literature sources contribute to the goals of the water strategy. The methodology was tested by investigating the impact of the water strategy of Jordan’s government (2008–2022) on the research conducted in the Azraq Basin, considering 99 grey and peer-reviewed documents. The results showed an increase in the number of water-related research documents from 37 published between 1985 and 2007 to 62 published between 2008 and 2018. This increase should not, however, be seen as a positive impact of increased research activity from the development of Jordan’s water strategy. In fact, the increase in water-related research activity matches the increasing trend in research production in Jordan generally. Moreover, the results showed that only about 80% of the documents align with the goals identified in the water strategy. In addition, the distribution of the documents among the different goals of the strategy is heterogeneous; hence, research gaps can be identified, i.e., goals of the water-strategy that are not addressed by any of the documents sourced. To foster innovative and demand-based research in the future, a matrix was developed that linked basin-specific research focus areas (RFAs) with the MWI strategy topics. In doing so, the goals that are not covered by a particular RFA are highlighted. This analysis can inspire researchers to develop and apply new topics in the Azraq Basin to address the research gaps and strengthen the connection between the RFAs and the strategy topics and goals. Moreover, the application of the proposed methodology can motivate future research to become demand-driven, innovative, and contribute to solving societal challenges.
This investigation attempts to understand the eco‐hydrology of, and accordingly suggest an option to manage floodwater for agriculture in, the understudied and data‐sparse ephemeral Baraka River Basin within the hyper‐arid region of Sudan. Reference is made to the major feature of the basin, that is, the Toker Delta spate irrigation scheme. A point‐to‐pixel comparison of gridded and ground‐based data sets is performed to enhance the estimates of rainfall. Analysis of remotely sensed land use/cover data is performed. The results show a significant reduction of the grassland and barren areas explained by a significant expansion of the cropland and open shrubland (invasive mesquite trees) areas in the delta. The cotton sown area is highly dependent on the flooded area and the discharge volume in the delta. However, the area of this major crop has declined since the early 1990s in favour of cultivation of more profitable food crops. Expansion of mesquite in the delta is problematic, taking hold under increased floodwater, and can only be manged by clearance to provide crop cultivation area. There is a great potential for floodwater harvesting during the rainfall season (June to September). A total seasonal runoff volume of around 4.6 and 10.8 billion cubic metres is estimated at 90 and 50% probabilities of exceedance (reliabilities), respectively. Rather than leaving the runoff generated from rainfall events to pass to the Red Sea or be consumed by mesquite trees, a location for runoff harvesting structure in a highly suitable area is proposed. Such a structure will support any policy shifts towards planning and managing the basin water resources for use in irrigating the agricultural scheme.
Aim: European cities are facing heighten hydrological risks as a result of climate change at the same time as ecological degradation has reduced the environmental capacity to absorb and regulate such fluctuations. Climate forecasts predict more intense convective rainfall and winter flood events in the Wupper Basin in Germany, against a background trend of reduced mean rainfall during the summer months. On 14 July 2021 intense convective rainfall fell at points across Western Germany and led to flash floods in the Wupper Basin, many sites were inundated and the Wupper and Dhünn rivers rose to new record highs. Green-blue infrastructure offers strategies to reduce the impacts of hazards at the same time as providing a range of co-benefits. A study was undertaken to find which green-blue interventions will be most effective at reducing the impacts of hydrometeorological hazards for a study area in the west of the Wupper basin. Furthermore, as landscape features are highly influential in hydrology, the study sought to establish which sites within the landscape can provide maximum results from green-blue interventions, with a minimum of change to current land uses.
Region: Europe, peri-urban and rural, undulating, low mountainous landscapes
Methods: Literature findings on observed and projected climate data are summarised and long-term rainfall data from the study area is analysed to confirm rainfall trends. A state-of-the-art review is conducted and summarised to form a toolbox of potential interventions. The most recent hazardous hydrometeorological event is analysed to inform the locational priorities of potential interventions. Landscape features that have the most influence on basin hydrology are identified from the literature. These sites are paired with green-blue interventions that are shown to have the highest potential impact on interception, infiltration, runoff and flooding. A series of spatial analyses are carried out to produce maps detailing location and intervention with high potential to reduce the impact of hydrometeorological hazards in the study area. All of the evidence gathered from the literature analysis is combined in an implementation guide for green-blue interventions in the Wupper Basin.
Results: The hazards caused by the hydrometeorological extremes of flooding and drought are addressed or minimised through the green-blue interventions that increase interception and infiltration and reduce runoff and flooding. Priority locations are identified as the riparian zone with slope ≤15%, hilltop, lower slope and toe slope, all locations with a slope ≥30% and areas with a high topographic wetness index (TWI). A series of spatial analyses were carried out and suggestions made including potential locations for retention or detention areas and ponds, sites for revegetation and potential locations for implementation of shelterbelts/hedgerows, buffer strips, conservation tillage or strip tillage, reduced mowing intensity or frequency and biochar additions. An implementation guide is created that provides a summary of the highest potential green-blue interventions and landscape locations, and a description of the mechanisms involved in addressing the hydrometeorological hazards.
Keywords: Green-blue interventions, hydrometeorological hazard reduction, Wupper Basin hydrology
The majority of Niger ’s population faces a widespread lack of access to electricity. Althoughthe country lies in the Sahara belt, exploitation of solar energy is so far minimal. Due to ongoing fossilfuel exploration in the country, this fuel might dominate the future electricity supply. Today, Nigerimports the most of its electricity from Nigeria. There is a need to expand electricity generation andsupply infrastructures in Niger. When doing so, it is important to choose a proper set of electricitygeneration resource/technology that fulfils sustainability criteria. Thus, the objective of this work isto analyze a methodology in order to assess different energy technologies for Niger. A multi-criteriadecision approach was selected to assess the most accessible energy system for the country. Forthis purpose, indicators were developed and weighted for ranking electricity generation options.Altogether 40 indicators are selected under six dimensions (availability, risk, technology, economics,environment and social) to assess eight different alternatives, considering the aggregated results andcorresponding scores under each dimension. A merit list of technology and resources for electricitygeneration presented in this work could support the stakeholders in their decision-making for furtherprojects implementation in the country.
Anaerobic Digestion of spent grains: Potential use in small-scale Biogas Digesters in Jos, Nigeria
(2014)
In order to ascertain biogas yield potential and applicability of spent grains (SG)1 in small-scale biogas production, laboratory batch fermentation was performed with various masses of dry and wet SG using sewage sludge (SS)2 and digested maize silage (DMs) 3 as inoculums. Different volumes of biogas and CH4 were measured with higher volumes observed for batch fermentation with DMs in com-parison to those produced by SS. Results from the study reveals minimum biogas yield of 118.10 L/kg
VS and maximum yields of 769.46 L/kg VS, which are indicative of the possible use of SG for domestic biogas production in Jos, Nigeria. The study established the fact that the use of both dry and wet SG results in the yield of a useful amount of biogas having 40 - 60 % CH4 content depending on the inoculum and amount of volatile solids present. Using the parameters of dry matter and volatile solids contents analysed for SG and DMs, it was estimated that a reactor volume of 6.47 m3 would be capable of meeting the daily cooking needs of rural households in Jos, Nigeria.
AbstractThe Ganges-Brahmaputra (GB) delta is one of the most disaster-prone areas in the world due to a combination of high population density and exposure to tropical cyclones, floods, salinity intrusion and other hazards. Due to the complexity of natural deltaic processes and human influence on these processes, structural solutions like embankments are inadequate on their own for effective hazard mitigation. This article examines nature-based solutions (NbSs) as a complementary or alternative approach to managing hazards in the GB delta. We investigate the potential of NbS as a complementary and sustainable method for mitigating the impacts of coastal disaster risks, mainly cyclones and flooding. Using the emerging framework of NbS principles, we evaluate three existing approaches: tidal river management, mangrove afforestation, and oyster reef cultivation, all of which are actively being used to help reduce the impacts of coastal hazards. We also identify major challenges (socioeconomic, biophysical, governance and policy) that need to be overcome to allow broader application of the existing approaches by incorporating the NbS principles. In addition to addressing GB delta-specific challenges, our findings provide more widely applicable insights into the challenges of implementing NbS in deltaic environments globally.
Climate change includes the change of the long-term average values and the change of the tails of probability density functions, where the extreme events are located. However, obtaining average values are more straightforward than the high temporal resolution information necessary to catch the extreme events on those tails. Such information is difficult to get in areas lacking sufficient rain stations. Thanks to the development of Satellite Precipitation Estimates with a daily resolution, this problem has been overcome, so Extreme Precipitation Indices (EPI) can be calculated for the entire Colombian territory. However, Colombia is strongly affected by the ENSO (El Niño—Southern Oscillation) phenomenon. Therefore, it is pertinent to ask if the EPI’s long-term change due to climate change is more critical than the anomalies due to climate variability induced by the warm and cold phases of ENSO (El Niño and La Niña, respectively). In this work, we built EPI annual time series at each grid-point of the selected Satellite Precipitation Estimate (CHIRPSv2) over Colombia to answer the previous question. Then, the Mann-Whitney-Wilcoxon test was used to compare the samples drawn in each case (i.e., change tests due to both long-term and climatic variability). After performing the analyses, we realized that the importance of the change depends on the region analyzed and the considered EPI. However, some general conclusions became evident: during El Niño years (La Niña), EPI’s anomaly follows the general trend of reduction -drier conditions- (increase; -wetter conditions-) observed in Colombian annual precipitation amount, but only on the Pacific, the Caribbean, and the Andean region. In the Eastern plains of Colombia (Orinoquía and Amazonian region), EPI show a certain insensitivity to change due to climatic variability. On the other hand, EPI’s long-term changes in the Pacific, the Caribbean, and the Andean region are spatially scattered. Still, long-term changes in the eastern plains have a moderate spatial consistency with statistical significance.
Due to its location at the south-west coast of Ireland County (Co.) Cork is frequently affected by post tropical cyclones (PTCs). There have been several records of these post hurricanes in the past with the last severe PTC being Hurricane Ophelia in 2017. It caused severe disruption in the whole country, especially in Co. Cork with several thousand people without water, power and mobile service for up to 10 days and thousands of uprooted trees which blocked roads. PTCs, like Ophelia, will become more frequent under climate change conditions due to warmer sea surface temperatures and decreased vertical wind shear. Hence, hurricanes can reach northern latitudes more easily and have a higher chance of making landfall in Co. Cork. This thesis assesses the risk perception towards natural hazards (NHs) and the perception of the risk communication of hurricane Ophelia by the citizens of Co. Cork and suggests improvements in communication based on the people’s perception. This was achieved by conducting a standardised survey to analyse the perception. The risk communication chain, its content and media involved were evaluated with interviews with professionals involved in risk management in Ireland. Improvement suggestions were extracted of the survey and the expert interviews as well and have been ranked by the participating experts according to their importance. The people of Co. Cork are not overly concerned about being affected by NHs. The three hazards they feel threatened by most, after Ophelia hit the country, are storms, river floodings and hurricanes. Before Ophelia made landfall, they only ranked hurricanes in the 8th place (out of 8). Ergo, after experiencing Ophelia people are much more aware of hurricane risk in Ireland. People were very satisfied with the information they received during Ophelia. The improvements they wished for are: 1) information on how to deal with and how to prepare for impacts of the storm, 2) the impacts that can be expected locally and 3) information where to go to in case of severe impact to property. These are mostly in line with the improvements the experts ranked as most important for Cork. Experts voted the suggestion to include information on behavioural advice into risk communication before the NH hits and advice on how to organise for impacts afterwards as their number one priority. Their second rank is to have education and training for the citizens in Cork. On third place they voted for a change to impact forecasting. Even there are no central buildings or shelters available in Co. Cork, this improvement suggestion was only voted on rank 13 by the experts (out of 14). Having a participatory approach in risk communication can overcome the discrepancies between the wishes of the population and the ones of the experts and would lead to a better understanding of all stakeholders involved in risk communication and can reduce vulnerability of the people in Co. Cork to the impacts of NHs. The implementation of these activities would be in line with best practice examples and would support the guidelines of the Irish Framework for Major Emergency Management.
Currently, difficulties such as the depletion of fossil fuel resources and the associated environmental pollution have driven the rise of other energy systems based on green energy sources.
In this research, modeling and a viability study of grid-connected and islanded photovoltaic (PV) power systems for supplying the residential load in Mekelle City, Ethiopia, were carried out considering the country’s emerging utility tariff plan for 2021 and beyond. The technical viability of the proposed supply option was analyzed using PVGIS, PVWatts and HOMER Pro tool, while the economic and environmental optimization aspects were carried out using HOMER Pro. Sensitivity analyses and output comparisons among the three renewable energy simulation tools are presented.
The results showed that under the consideration of an incremental electricity tariff plan (up to 2021), the analyzed cost of energy of the grid/PV system is around 12% lower than the utility grid tariff. Moreover, we also found that by taking the continuous global solar PV cost reduction into account, the cost of energy of the modeled islanded operation of solar PV power units totally broke the grid tariff in Ethiopia after 2029 based on the tariff for 2021 and well before with the expected escalation of the grid tariff on an annual basis. The technical performance of the system realized through PVGIS and PVWatts was almost comparable to the HOMER Pro outputs. Thus, this investigation will offer a clear direction to the concerned target groups and policy developers in the evolution of PV power supply options throughout the technically viable locations in the country.
Against the background of a worldwide decrease in the number of gauging stations,the estimation of river discharge using spaceborne data is crucial for hydrological research, rivermonitoring, and water resource management. Based on the at-many-stations hydraulic geometry(AMHG) concept, a novel approach is introduced for estimating river discharge using Sentinel-1time series within an automated workflow. By using a novel decile thresholding method, no a prioriknowledge of the AMHG function or proxy is used, as proposed in previous literature. With arelative root mean square error (RRMSE) of 19.5% for the whole period and a RRMSE of 15.8%considering only dry seasons, our method is a significant improvement relative to the optimizedAMHG method, achieving 38.5% and 34.5%, respectively. As the novel approach is embedded intoan automated workflow, it enables a global application for river discharge estimation using solelyremote sensing data. Starting with the mapping of river reaches, which have large differences inriver width overthe year, continuous river width time series are created using high-resolution andweather-independent SAR imaging. It is applied on a 28 km long section of the Mekong River nearVientiane, Laos, for the period from 2015 to 2018.
In the literature, many studies outline the advantages of agrivoltaic (APV) systems from different viewpoints: optimized land use, productivity gain in both the energy and water sector, economic benefits, etc. A holistic analysis of an APV system is needed to understand its full advantages. For this purpose, a case study farm size of 0.15 ha has been chosen as a reference farm at a village in Niger, West Africa. Altogether four farming cases are considered. They are traditional rain-fed, irrigated with diesel-powered pumps, irrigated with solar pumps, and the APV system. The APV system is further analyzed under two scenarios: benefits to investors and combined benefits to investors and farmers. An economic feasibility analysis model is developed. Different economic indicators are used to present the results: gross margin, farm profit, benefit-cost ratio, and net present value (NPV). All the economic indicators obtained for the solar-powered irrigation system were positive, whereas all those for the diesel-powered system were negative. Additionally, the diesel system will emit annually about 4005 kg CO2 to irrigate the chosen reference farm. The land equivalent ratio (LER) was obtained at 1.33 and 1.13 for two cases of shading-induced yield loss excluded and included, respectively.
Proper satellite-based crop monitoring applications at the farm-level often require near-daily imagery at medium to high spatial resolution. The combination of data from different ongoing satellite missions Sentinel 2 (ESA) and Landsat 7/8 (NASA) provides this unprecedented opportunity at a global scale; however, this is rarely implemented because these procedures are data demanding and computationally intensive. This study developed a robust stream processing for the harmonization of Landsat 7, Landsat 8 and Sentinel 2 in the Google Earth Engine cloud platform, connecting the benefit of coherent data structure, built-in functions and computational power in the Google Cloud. The harmonized surface reflectance images were generated for two agricultural schemes in Bekaa (Lebanon) and Ninh Thuan (Vietnam) during 2018–2019. We evaluated the performance of several pre-processing steps needed for the harmonization including the image co-registration,
Bidirectional Reflectance Distribution Functions correction, topographic correction, and band adjustment. We found that the misregistration between Landsat 8 and Sentinel 2 images varied from 10 m in Ninh Thuan (Vietnam) to 32 m in Bekaa (Lebanon), and posed a great impact on the quality of the final harmonized data set if not treated. Analysis of a pair of overlapped L8-S2 images over the Bekaa region showed that, after the harmonization, all band-to-band spatial correlations were greatly improved. Finally, we demonstrated an application of the dense harmonized data set for crop mapping and monitoring. An harmonic (Fourier) analysis was applied to fit the detected unimodal, bimodal and trimodal shapes in the temporal NDVI patterns during one crop year in Ninh Thuan province. The derived phase and amplitude values of the crop cycles were combined with max-NDVI as an R-G-B false composite image. The final image was able to highlight croplands in bright colors (high phase and amplitude), while the non-crop areas were shown with grey/dark (low phase and amplitude). The harmonized data sets (with 30 m spatial resolution) along with the Google Earth Engine scripts used are provided for public use.
Wetlands offer different ecosystem services that contribute to human well-being (Kovács et al., 2015). According to the Ramsar Convention Secretariat (2018) wetland located in urban areas have been threatened by several activities such as drainage, pollution, encroachment, agriculture, among others. On the other hand, wetland degradation reduces the resilience of hazards like floods and storm surges (Kumar et al., 2017). For that reason, ecosystem-based disaster risk reduction (Eco-DRR) is an important strategy which enhances the conservation and restoration of ecosystems to reduce disaster risk aiming to sustainable development and resilience (Estrella & Saalismaa, 2013). Despite international recognition of the importance of wetlands, urban wetlands have diminished their capacity to cope with flood threats (Boyer and Polasky, 2006) due to the aforementioned human impacts.
That is why this thesis aimed to identify the role of urban wetlands in Bogota, Colombia, that has an urban wetland complex that is recognised as a Ramsar site in 2018. However, wetlands in the city reduced its area from 50.000 hectares to less than 800, approximately, in less than 40 years, mainly because of urban expansion and encroachment (IDIGER, 2018). To achieve this objective, an analysis of the city’s risk management framework was conducted, as well as a stakeholder analysis based on semi-structured interviews and a spatial-temporal analysis for the period 1998-2017, for which the Jaboque wetland was used as a case study. This wetland is located near the Bogotá River and is in the area threatened by flooding.
It was possible to determine that national and district policies on wetlands, biodiversity, and climate change adaptation address some ecosystem functions. Still, disaster risk reduction is not strongly linked to them. Thus, based on the case study, the wetlands in Bogota have not played a decisive role in flood risk management in the city.
Austria is committed to the net-zero climate goal along with the European Union. This requires all sectors to be decarbonized. Hereby, hydrogen plays a vital role as stated in the national hydrogen strategy. A report commissioned by the Austrian government predicts a minimum hydrogen demand of 16 TWh per year in Austria in 2040. Besides hydrogen imports, domestic production can ensure supply. Hence, this study analyses the levelized cost of hydrogen for an off-grid production plant including a proton exchange membrane electrolyzer, wind power and solar photovoltaics in Austria. In the first step, the capacity factors of the renewable electricity sources are determined by conducting a geographic information system analysis. Secondly, the levelized cost of electricity for wind power and solarphotovoltaics plants in Austria is calculated. Thirdly, the most cost-efficient portfolio of wind power and solar photovoltaics plants is determined using electricity generation profiles with a 10-min granularity. The modelled system variants differ among location, capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. Finally, selected variables are tested for their sensitivities. With the applied model, the hydrogen production cost for decentralized production plants can be calculated for any specific location. The levelized cost of hydrogen estimates range from 3.08 EUR/kg to 13.12 EUR/kg of hydrogen, whereas it was found that the costs are most sensitive to the capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. The novelty of the paper stems from the model applied that calculates the levelized cost of renewable hydrogen in an off-grid hydrogen production system. The model finds a cost-efficient portfolio of directly coupled wind power and solar photovoltaics systems for 80 different variants in an Austria-specific context.
In Latin America and the Caribbean, river restoration projects are increasing, but many lack strategic planning and monitoring. We tested the applicability of a rapid visual social–ecological stream assessment method for restoration planning, complemented by a citizen survey on perceptions and uses of blue and green infrastructure. We applied the method at three urban streams in Jarabacoa (Dominican Republic) to identify and prioritize preferred areas for nature-based solutions. The method provides spatially explicit information for strategic river restoration planning, and its efficiency makes it suitable for use in data-poor contexts. It identifies well-preserved, moderately altered, and critically impaired areas regarding their hydromorphological and socio-cultural conditions, as well as demands on green and blue infrastructure. The transferability of the method can be improved by defining reference states for assessing the hydromorphology of tropical rivers, refining socio-cultural parameters to better address river services and widespread urban challenges, and balancing trade-offs between ecological and social restoration goals.
The European heating sector is currently heavily dominated by fossil fuels. Composting is a naturally occurring process in which heat is liberated from the composting substrate at a higher rate than the process needs to support itself. This difference could be harnessed for low-heat applications such as residential consumption, alleviating some of the impacts fossil fuel emissions represent. In this study, the composting heat recovery reported in the literature was compared to the energy demand for space and water heating in four European countries. A review of potential heat production from the waste representative of the residential sector was performed. We found that the theoretically recoverable composting heat does not significantly reduce the need for district heating. However, it can significantly reduce the energy demand for water heating, being able to supply countries such as Greece with between 36% and 100% of the yearly hot water demand, or 12% to 53% of the yearly hot water of countries such as Switzerland, depending on the efficiency of heat recovery.
Remote rural populations do not often have the luxury of viable multisource electricity generation systems. Considering fossil fuels for remote populated areas is not often a viable option due to the fuel transportation costs and the population’s socioeconomic status. Extending the grid is often economically prohibitive. This paper proposes possible ways in which Mali could increase the rate of population with access to electricity by 2050 using Low Emission Analysis Platform (LEAP) and geographical information tools. The current energy situation is assessed, and multiple demand and supply scenarios are created to find the most viable option in environmental and economic dimensions. A minimum of 50% reduction of biomass consumption in the residential sector and a maximum of 71% was achieved through the combination of grid extension and decentralized solar PV. Solar PV becomes the preferable option when enough time for the effects of electricity on income is given. When these effects are not present, solar PV is still a better option, as the amount of biomass replaced with electricity is reduced.
For sustainable climate, an exponential growth in renewable heating and cooling is compulsory to reduce consumption of the fossil fuels for production of heat. An essential step from European Commission as an introduction of the strategy for renewable heat has
given a platform to the solar thermal market to tap the highest possible potential. To grab the opportunity given, capacity of the production is to be increased as well as reduction in cost of solar thermal product is to be achieved by any suitable alternate means. Polymer
based hybrid collector, named as OPVT collector, is the innovation from Fraunhofer Institute of Solar Energy Systems to break the road blocks for the solar thermal market. A polymer solar cell and a polymer solar thermal collector, both, technologies have tendency
of high initial investments and extremely low running cost in business. The aims of this study were to develop a calculation tool for determination of production cost of different OPVT collector concepts and evaluate their potential with reference to market size. The tool was expected to be uniform for all possible concepts of OPVT collector and flexible in
usage during the early stage of technological development. In this study, “Microsoft Excel” software based calculation tool is developed for estimation of production cost for different concepts. A Car washing station for water based OPVT collector and a bus station for air based OPVT collector are found be most suitable for start-up of the business. The analysis of results has highlighted that the minimum cost of OPVT collector can be referenced as its material cost. The OPVT collector business has huge potential and
possibility of early break-even point in the
production. As production costs are sensitive to
material costs, input values to the tool must be accurate. Presence of dominance of the material cost
is due to high cost of OPV. In industry, OPV is still being considered as the technological product instead the commodity product. This market potential study for
OPVT collector technology has been the important step in giving the confidence to solar thermal, polymer and plastic processing industries for business investment.
Keywords – OPVT collector, production cost, calculation tool, market size
Effects on the combustion properties of wheat straw after different thermobiological pretreatments
(2022)
Wheat straw could be used for pellet production and therefore as solid fuel. However, it presents challenges due to its inferior combustion properties such as high ash content, low gross calorific value (GCV), and low ash melting temperature.
To evaluate its combustion properties and based on recent work that improved methane production, wheat straw was subjected to thermobiological pretreatments. Nine pretreated samples based on wheat straw and nine pretreated samples based on compost-wheat straw mixture were produced. In addition, due to the ability to remove minerals and decrease the ash content, a washing process with water as a solvent was used. Ash content, net calorific value (NCV) and ash melting temperatures were evaluated.
For the pretreated wheat straw (SW) samples, a 5,8% reduction in ash content was obtained due to the pretreatments when compared to untreated wheat straw. A 55% decrease in ash content was obtained when comparing the same materials before and after the washing process. No statistically significant changes in GCV were found. As for the ash melting temperatures, due to the incubation pretreatment, an average increase in the shrinkage starting temperature (SST) of 4,4% was obtained for anaerobic conditions and a decrease of 2,5% for aerobic conditions, compared to the same material without heat treatment. In addition, an increase in all ash melting temperatures was observed because of the washing process. It was possible to obtain a pellet complying with standard ISO 17225-6 that can be used in medium or large burners and significantly reduces the effort during combustion.
For samples pretreated with a homogeneous compost-wheat straw (SKW) mixture, an average ash content decrease of 27% was obtained after using autoclave pretreatment at 140°C, compared to the same material without thermal pretreatment. The biggest decrease was due to the washing process, reducing the ash content on average by 43% when comparing the same materials before and after washing. GCV were 13% lower than samples pretreated with wheat straw, due to the low calorific value and high ash content of the compost. During ash melting temperature tests, an average 60% increase in SST was observed compared to pretreated SW ashes due to the high melting temperature of compost. Results are considered satisfactory since pellets based on this mixture would not cause ash sintering or slagging. However, counter effects were observed as the addition of compost increased the ash content and decreased the GCV, not complying with ISO 17225-6 for non-woody pellets. To achieve a pellet based on a compost-wheat straw mixture that complies with the standards, it is recommended for future research to control the percentage of compost added to the mixture.
Due to the global phenomenon of climate change the region of Mara Siana is projected to increasingly face extreme weather events that particularly comprise prolonged droughts and
heavier rainfalls. To be able to adequately adapt to these changing circumstances and maintain their livelihoods communities need to build respective capacities. As the main objective, this research aims at determining landowners’ climate change adaptative capacity (CCAC) across different villages in Mara Siana. Accordingly, a semi-quantitative approach was carried out including qualitative interviews and the subsequent quantitative calculation of CCAC based on a multidimensional indicator set and a respective coding
system. In addition to predominantly positive results of socio-cultural characteristics and the quality of natural resources, this work reveals clear weaknesses and potential for improvement in the areas of income security and financial stability, the expansion and resilience of infrastructure, and the relationship between communities and local authorities. Moreover, differences in capacity results are not only identified between the investigated villages as well as between individual households but also systemic disadvantage in capacity building affecting female landowners and community members can be indicated from the obtained interview data. Therefore, this research gives concrete recommendations for the implementation and verification of suitable adaptive measures that are particularly tailored for the improvement of low-performance indicators while following a gendertransformative approach and thus hold the potential to increase CCAC in the long-term.
Circular economy (CE) has received considerable interest in recent years as a strategy to resolve some of our modern urban resource challenges, and circular city models often incorporate systems of urban agriculture in their design. Much work has analyzed the benefits of urban agriculture for creating a resilient food system and as a strategy for supporting urban green space and social cohesion, however, the contributions from business models that operate within urban agriculture have not been thoroughly studied. Many urban agriculture businesses often claim high levels of resource recycling and material circularity, though whether a resource efficiency throughout the entire product lifetime (including energy and material footprint for the cultivation equipment) in comparison to current industrial strategies is truly feasible or even possible is still to be debated. This thesis builds upon work that incorporates social dimensions of CE definitions and begins to research whether the potential resource efficiency contradiction can be justified as to make urban agriculture a valid approach for circular city design. This study examined an urban mushroom farm that implements a circular business model. A qualitative summary of the business operations and resource flows were unpacked and sorted into 24 socio-economic contributions based on their interpreted relevance. The interpreted data shows that an urban agriculture business model can contribute to the building blocks of a CE through economic, ecological, social, and spatial contributions. While these contributions can contribute positively to the operationalization of CE, potential trade-offs regarding resource efficiency, use of urban space, and investment priorities need to be considered and addressed to avoid a possible watering down or greenwashing of the CE concept.